--- /dev/null
+
+ ==========================================
+ Xillybus driver for generic FPGA interface
+ ==========================================
+
+Author: Eli Billauer, Xillybus Ltd. (http://xillybus.com)
+Email: eli.billauer@gmail.com or as advertised on Xillybus' site.
+
+Contents:
+
+ - Introduction
+ -- Background
+ -- Xillybus Overview
+
+ - Usage
+ -- User interface
+ -- Synchronization
+ -- Seekable pipes
+
+- Internals
+ -- Source code organization
+ -- Pipe attributes
+ -- Host never reads from the FPGA
+ -- Channels, pipes, and the message channel
+ -- Data streaming
+ -- Data granularity
+ -- Probing
+ -- Buffer allocation
+ -- Memory management
+ -- The "nonempty" message (supporting poll)
+
+
+INTRODUCTION
+============
+
+Background
+----------
+
+An FPGA (Field Programmable Gate Array) is a piece of logic hardware, which
+can be programmed to become virtually anything that is usually found as a
+dedicated chipset: For instance, a display adapter, network interface card,
+or even a processor with its peripherals. FPGAs are the LEGO of hardware:
+Based upon certain building blocks, you make your own toys the way you like
+them. It's usually pointless to reimplement something that is already
+available on the market as a chipset, so FPGAs are mostly used when some
+special functionality is needed, and the production volume is relatively low
+(hence not justifying the development of an ASIC).
+
+The challenge with FPGAs is that everything is implemented at a very low
+level, even lower than assembly language. In order to allow FPGA designers to
+focus on their specific project, and not reinvent the wheel over and over
+again, pre-designed building blocks, IP cores, are often used. These are the
+FPGA parallels of library functions. IP cores may implement certain
+mathematical functions, a functional unit (e.g. a USB interface), an entire
+processor (e.g. ARM) or anything that might come handy. Think of them as a
+building block, with electrical wires dangling on the sides for connection to
+other blocks.
+
+One of the daunting tasks in FPGA design is communicating with a fullblown
+operating system (actually, with the processor running it): Implementing the
+low-level bus protocol and the somewhat higher-level interface with the host
+(registers, interrupts, DMA etc.) is a project in itself. When the FPGA's
+function is a well-known one (e.g. a video adapter card, or a NIC), it can
+make sense to design the FPGA's interface logic specifically for the project.
+A special driver is then written to present the FPGA as a well-known interface
+to the kernel and/or user space. In that case, there is no reason to treat the
+FPGA differently than any device on the bus.
+
+It's however common that the desired data communication doesn't fit any well-
+known peripheral function. Also, the effort of designing an elegant
+abstraction for the data exchange is often considered too big. In those cases,
+a quicker and possibly less elegant solution is sought: The driver is
+effectively written as a user space program, leaving the kernel space part
+with just elementary data transport. This still requires designing some
+interface logic for the FPGA, and write a simple ad-hoc driver for the kernel.
+
+Xillybus Overview
+-----------------
+
+Xillybus is an IP core and a Linux driver. Together, they form a kit for
+elementary data transport between an FPGA and the host, providing pipe-like
+data streams with a straightforward user interface. It's intended as a low-
+effort solution for mixed FPGA-host projects, for which it makes sense to
+have the project-specific part of the driver running in a user-space program.
+
+Since the communication requirements may vary significantly from one FPGA
+project to another (the number of data pipes needed in each direction and
+their attributes), there isn't one specific chunk of logic being the Xillybus
+IP core. Rather, the IP core is configured and built based upon a
+specification given by its end user.
+
+Xillybus presents independent data streams, which resemble pipes or TCP/IP
+communication to the user. At the host side, a character device file is used
+just like any pipe file. On the FPGA side, hardware FIFOs are used to stream
+the data. This is contrary to a common method of communicating through fixed-
+sized buffers (even though such buffers are used by Xillybus under the hood).
+There may be more than a hundred of these streams on a single IP core, but
+also no more than one, depending on the configuration.
+
+In order to ease the deployment of the Xillybus IP core, it contains a simple
+data structure which completely defines the core's configuration. The Linux
+driver fetches this data structure during its initialization process, and sets
+up the DMA buffers and character devices accordingly. As a result, a single
+driver is used to work out of the box with any Xillybus IP core.
+
+The data structure just mentioned should not be confused with PCI's
+configuration space or the Flattened Device Tree.
+
+USAGE
+=====
+
+User interface
+--------------
+
+On the host, all interface with Xillybus is done through /dev/xillybus_*
+device files, which are generated automatically as the drivers loads. The
+names of these files depend on the IP core that is loaded in the FPGA (see
+Probing below). To communicate with the FPGA, open the device file that
+corresponds to the hardware FIFO you want to send data or receive data from,
+and use plain write() or read() calls, just like with a regular pipe. In
+particular, it makes perfect sense to go:
+
+$ cat mydata > /dev/xillybus_thisfifo
+
+$ cat /dev/xillybus_thatfifo > hisdata
+
+possibly pressing CTRL-C as some stage, even though the xillybus_* pipes have
+the capability to send an EOF (but may not use it).
+
+The driver and hardware are designed to behave sensibly as pipes, including:
+
+* Supporting non-blocking I/O (by setting O_NONBLOCK on open() ).
+
+* Supporting poll() and select().
+
+* Being bandwidth efficient under load (using DMA) but also handle small
+ pieces of data sent across (like TCP/IP) by autoflushing.
+
+A device file can be read only, write only or bidirectional. Bidirectional
+device files are treated like two independent pipes (except for sharing a
+"channel" structure in the implementation code).
+
+Synchronization
+---------------
+
+Xillybus pipes are configured (on the IP core) to be either synchronous or
+asynchronous. For a synchronous pipe, write() returns successfully only after
+some data has been submitted and acknowledged by the FPGA. This slows down
+bulk data transfers, and is nearly impossible for use with streams that
+require data at a constant rate: There is no data transmitted to the FPGA
+between write() calls, in particular when the process loses the CPU.
+
+When a pipe is configured asynchronous, write() returns if there was enough
+room in the buffers to store any of the data in the buffers.
+
+For FPGA to host pipes, asynchronous pipes allow data transfer from the FPGA
+as soon as the respective device file is opened, regardless of if the data
+has been requested by a read() call. On synchronous pipes, only the amount
+of data requested by a read() call is transmitted.
+
+In summary, for synchronous pipes, data between the host and FPGA is
+transmitted only to satisfy the read() or write() call currently handled
+by the driver, and those calls wait for the transmission to complete before
+returning.
+
+Note that the synchronization attribute has nothing to do with the possibility
+that read() or write() completes less bytes than requested. There is a
+separate configuration flag ("allowpartial") that determines whether such a
+partial completion is allowed.
+
+Seekable pipes
+--------------
+
+A synchronous pipe can be configured to have the stream's position exposed
+to the user logic at the FPGA. Such a pipe is also seekable on the host API.
+With this feature, a memory or register interface can be attached on the
+FPGA side to the seekable stream. Reading or writing to a certain address in
+the attached memory is done by seeking to the desired address, and calling
+read() or write() as required.
+
+
+INTERNALS
+=========
+
+Source code organization
+------------------------
+
+The Xillybus driver consists of a core module, xillybus_core.c, and modules
+that depend on the specific bus interface (xillybus_of.c and xillybus_pcie.c).
+
+The bus specific modules are those probed when a suitable device is found by
+the kernel. Since the DMA mapping and synchronization functions, which are bus
+dependent by their nature, are used by the core module, a
+xilly_endpoint_hardware structure is passed to the core module on
+initialization. This structure is populated with pointers to wrapper functions
+which execute the DMA-related operations on the bus.
+
+Pipe attributes
+---------------
+
+Each pipe has a number of attributes which are set when the FPGA component
+(IP core) is built. They are fetched from the IDT (the data structure which
+defines the core's configuration, see Probing below) by xilly_setupchannels()
+in xillybus_core.c as follows:
+
+* is_writebuf: The pipe's direction. A non-zero value means it's an FPGA to
+ host pipe (the FPGA "writes").
+
+* channelnum: The pipe's identification number in communication between the
+ host and FPGA.
+
+* format: The underlying data width. See Data Granularity below.
+
+* allowpartial: A non-zero value means that a read() or write() (whichever
+ applies) may return with less than the requested number of bytes. The common
+ choice is a non-zero value, to match standard UNIX behavior.
+
+* synchronous: A non-zero value means that the pipe is synchronous. See
+ Syncronization above.
+
+* bufsize: Each DMA buffer's size. Always a power of two.
+
+* bufnum: The number of buffers allocated for this pipe. Always a power of two.
+
+* exclusive_open: A non-zero value forces exclusive opening of the associated
+ device file. If the device file is bidirectional, and already opened only in
+ one direction, the opposite direction may be opened once.
+
+* seekable: A non-zero value indicates that the pipe is seekable. See
+ Seekable pipes above.
+
+* supports_nonempty: A non-zero value (which is typical) indicates that the
+ hardware will send the messages that are necessary to support select() and
+ poll() for this pipe.
+
+Host never reads from the FPGA
+------------------------------
+
+Even though PCI Express is hotpluggable in general, a typical motherboard
+doesn't expect a card to go away all of the sudden. But since the PCIe card
+is based upon reprogrammable logic, a sudden disappearance from the bus is
+quite likely as a result of an accidental reprogramming of the FPGA while the
+host is up. In practice, nothing happens immediately in such a situation. But
+if the host attempts to read from an address that is mapped to the PCI Express
+device, that leads to an immediate freeze of the system on some motherboards,
+even though the PCIe standard requires a graceful recovery.
+
+In order to avoid these freezes, the Xillybus driver refrains completely from
+reading from the device's register space. All communication from the FPGA to
+the host is done through DMA. In particular, the Interrupt Service Routine
+doesn't follow the common practice of checking a status register when it's
+invoked. Rather, the FPGA prepares a small buffer which contains short
+messages, which inform the host what the interrupt was about.
+
+This mechanism is used on non-PCIe buses as well for the sake of uniformity.
+
+
+Channels, pipes, and the message channel
+----------------------------------------
+
+Each of the (possibly bidirectional) pipes presented to the user is allocated
+a data channel between the FPGA and the host. The distinction between channels
+and pipes is necessary only because of channel 0, which is used for interrupt-
+related messages from the FPGA, and has no pipe attached to it.
+
+Data streaming
+--------------
+
+Even though a non-segmented data stream is presented to the user at both
+sides, the implementation relies on a set of DMA buffers which is allocated
+for each channel. For the sake of illustration, let's take the FPGA to host
+direction: As data streams into the respective channel's interface in the
+FPGA, the Xillybus IP core writes it to one of the DMA buffers. When the
+buffer is full, the FPGA informs the host about that (appending a
+XILLYMSG_OPCODE_RELEASEBUF message channel 0 and sending an interrupt if
+necessary). The host responds by making the data available for reading through
+the character device. When all data has been read, the host writes on the
+the FPGA's buffer control register, allowing the buffer's overwriting. Flow
+control mechanisms exist on both sides to prevent underflows and overflows.
+
+This is not good enough for creating a TCP/IP-like stream: If the data flow
+stops momentarily before a DMA buffer is filled, the intuitive expectation is
+that the partial data in buffer will arrive anyhow, despite the buffer not
+being completed. This is implemented by adding a field in the
+XILLYMSG_OPCODE_RELEASEBUF message, through which the FPGA informs not just
+which buffer is submitted, but how much data it contains.
+
+But the FPGA will submit a partially filled buffer only if directed to do so
+by the host. This situation occurs when the read() method has been blocking
+for XILLY_RX_TIMEOUT jiffies (currently 10 ms), after which the host commands
+the FPGA to submit a DMA buffer as soon as it can. This timeout mechanism
+balances between bus bandwidth efficiency (preventing a lot of partially
+filled buffers being sent) and a latency held fairly low for tails of data.
+
+A similar setting is used in the host to FPGA direction. The handling of
+partial DMA buffers is somewhat different, though. The user can tell the
+driver to submit all data it has in the buffers to the FPGA, by issuing a
+write() with the byte count set to zero. This is similar to a flush request,
+but it doesn't block. There is also an autoflushing mechanism, which triggers
+an equivalent flush roughly XILLY_RX_TIMEOUT jiffies after the last write().
+This allows the user to be oblivious about the underlying buffering mechanism
+and yet enjoy a stream-like interface.
+
+Note that the issue of partial buffer flushing is irrelevant for pipes having
+the "synchronous" attribute nonzero, since synchronous pipes don't allow data
+to lay around in the DMA buffers between read() and write() anyhow.
+
+Data granularity
+----------------
+
+The data arrives or is sent at the FPGA as 8, 16 or 32 bit wide words, as
+configured by the "format" attribute. Whenever possible, the driver attempts
+to hide this when the pipe is accessed differently from its natural alignment.
+For example, reading single bytes from a pipe with 32 bit granularity works
+with no issues. Writing single bytes to pipes with 16 or 32 bit granularity
+will also work, but the driver can't send partially completed words to the
+FPGA, so the transmission of up to one word may be held until it's fully
+occupied with user data.
+
+This somewhat complicates the handling of host to FPGA streams, because
+when a buffer is flushed, it may contain up to 3 bytes don't form a word in
+the FPGA, and hence can't be sent. To prevent loss of data, these leftover
+bytes need to be moved to the next buffer. The parts in xillybus_core.c
+that mention "leftovers" in some way are related to this complication.
+
+Probing
+-------
+
+As mentioned earlier, the number of pipes that are created when the driver
+loads and their attributes depend on the Xillybus IP core in the FPGA. During
+the driver's initialization, a blob containing configuration info, the
+Interface Description Table (IDT), is sent from the FPGA to the host. The
+bootstrap process is done in three phases:
+
+1. Acquire the length of the IDT, so a buffer can be allocated for it. This
+ is done by sending a quiesce command to the device, since the acknowledge
+ for this command contains the IDT's buffer length.
+
+2. Acquire the IDT itself.
+
+3. Create the interfaces according to the IDT.
+
+Buffer allocation
+-----------------
+
+In order to simplify the logic that prevents illegal boundary crossings of
+PCIe packets, the following rule applies: If a buffer is smaller than 4kB,
+it must not cross a 4kB boundary. Otherwise, it must be 4kB aligned. The
+xilly_setupchannels() functions allocates these buffers by requesting whole
+pages from the kernel, and diving them into DMA buffers as necessary. Since
+all buffers' sizes are powers of two, it's possible to pack any set of such
+buffers, with a maximal waste of one page of memory.
+
+All buffers are allocated when the driver is loaded. This is necessary,
+since large continuous physical memory segments are sometimes requested,
+which are more likely to be available when the system is freshly booted.
+
+The allocation of buffer memory takes place in the same order they appear in
+the IDT. The driver relies on a rule that the pipes are sorted with decreasing
+buffer size in the IDT. If a requested buffer is larger or equal to a page,
+the necessary number of pages is requested from the kernel, and these are
+used for this buffer. If the requested buffer is smaller than a page, one
+single page is requested from the kernel, and that page is partially used.
+Or, if there already is a partially used page at hand, the buffer is packed
+into that page. It can be shown that all pages requested from the kernel
+(except possibly for the last) are 100% utilized this way.
+
+Memory management
+-----------------
+
+The tricky part about the buffer allocation procedure described above is
+freeing and unmapping the buffers, in particular if something goes wrong in
+the middle, and the allocations need to be rolled back. The three-stage
+probing procedure makes this even more crucial, since temporary buffers are
+set up and mapped in the first of its two stages.
+
+To keep the code clean from complicated and bug-prone memory release routines,
+there are special routines for allocating memory. For example, instead of
+calling kzalloc, there's
+
+void *xilly_malloc(struct xilly_cleanup *mem, size_t size)
+
+which effectively allocates a zeroed buffer of size "size". Its first
+argument, "mem", is where this allocation is enlisted, so that it's released
+when xillybus_do_cleanup() is called with the same "mem" structure.
+
+Two other functions enlist allocations in this structure: xilly_pagealloc()
+for page allocations and xilly_map_single_*() for DMA mapping.
+
+The "nonempty" message (supporting poll)
+---------------------------------------
+
+In order to support the "poll" method (and hence select() ), there is a small
+catch regarding the FPGA to host direction: The FPGA may have filled a DMA
+buffer with some data, but not submitted that buffer. If the host waited for
+the buffer's submission by the FPGA, there would be a possibility that the
+FPGA side has sent data, but a select() call would still block, because the
+host has not received any notification about this. This is solved with
+XILLYMSG_OPCODE_NONEMPTY messages sent by the FPGA when a channel goes from
+completely empty to containing some data.
+
+These messages are used only to support poll() and select(). The IP core can
+be configured not to send them for a slight reduction of bandwidth.
--- /dev/null
+/*
+ * linux/drivers/misc/xillybus_core.c
+ *
+ * Copyright 2011 Xillybus Ltd, http://xillybus.com
+ *
+ * Driver for the Xillybus FPGA/host framework.
+ *
+ * This driver interfaces with a special IP core in an FPGA, setting up
+ * a pipe between a hardware FIFO in the programmable logic and a device
+ * file in the host. The number of such pipes and their attributes are
+ * set up on the logic. This driver detects these automatically and
+ * creates the device files accordingly.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the smems of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ */
+
+#include <linux/list.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/crc32.h>
+#include <linux/poll.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include "xillybus.h"
+
+MODULE_DESCRIPTION("Xillybus core functions");
+MODULE_AUTHOR("Eli Billauer, Xillybus Ltd.");
+MODULE_VERSION("1.07");
+MODULE_ALIAS("xillybus_core");
+MODULE_LICENSE("GPL v2");
+
+/* General timeout is 100 ms, rx timeout is 10 ms */
+#define XILLY_RX_TIMEOUT (10*HZ/1000)
+#define XILLY_TIMEOUT (100*HZ/1000)
+
+#define fpga_msg_ctrl_reg 0x0002
+#define fpga_dma_control_reg 0x0008
+#define fpga_dma_bufno_reg 0x0009
+#define fpga_dma_bufaddr_lowaddr_reg 0x000a
+#define fpga_dma_bufaddr_highaddr_reg 0x000b
+#define fpga_buf_ctrl_reg 0x000c
+#define fpga_buf_offset_reg 0x000d
+#define fpga_endian_reg 0x0010
+
+#define XILLYMSG_OPCODE_RELEASEBUF 1
+#define XILLYMSG_OPCODE_QUIESCEACK 2
+#define XILLYMSG_OPCODE_FIFOEOF 3
+#define XILLYMSG_OPCODE_FATAL_ERROR 4
+#define XILLYMSG_OPCODE_NONEMPTY 5
+
+static struct class *xillybus_class;
+
+/*
+ * ep_list_lock is the last lock to be taken; No other lock requests are
+ * allowed while holding it. It merely protects list_of_endpoints, and not
+ * the endpoints listed in it.
+ */
+
+static LIST_HEAD(list_of_endpoints);
+static struct mutex ep_list_lock;
+struct workqueue_struct *xillybus_wq;
+
+/*
+ * Locking scheme: Mutexes protect invocations of character device methods.
+ * If both locks are taken, wr_mutex is taken first, rd_mutex second.
+ *
+ * wr_spinlock protects wr_*_buf_idx, wr_empty, wr_sleepy, wr_ready and the
+ * buffers' end_offset fields against changes made by IRQ handler (and in
+ * theory, other file request handlers, but the mutex handles that). Nothing
+ * else.
+ * They are held for short direct memory manipulations. Needless to say,
+ * no mutex locking is allowed when a spinlock is held.
+ *
+ * rd_spinlock does the same with rd_*_buf_idx, rd_empty and end_offset.
+ *
+ * register_mutex is endpoint-specific, and is held when non-atomic
+ * register operations are performed. wr_mutex and rd_mutex may be
+ * held when register_mutex is taken, but none of the spinlocks. Note that
+ * register_mutex doesn't protect against sporadic buf_ctrl_reg writes
+ * which are unrelated to buf_offset_reg, since they are harmless.
+ *
+ * Blocking on the wait queues is allowed with mutexes held, but not with
+ * spinlocks.
+ *
+ * Only interruptible blocking is allowed on mutexes and wait queues.
+ *
+ * All in all, the locking order goes (with skips allowed, of course):
+ * wr_mutex -> rd_mutex -> register_mutex -> wr_spinlock -> rd_spinlock
+ */
+
+static void malformed_message(u32 *buf)
+{
+ int opcode;
+ int msg_channel, msg_bufno, msg_data, msg_dir;
+
+ opcode = (buf[0] >> 24) & 0xff;
+ msg_dir = buf[0] & 1;
+ msg_channel = (buf[0] >> 1) & 0x7ff;
+ msg_bufno = (buf[0] >> 12) & 0x3ff;
+ msg_data = buf[1] & 0xfffffff;
+
+ pr_warn("xillybus: Malformed message (skipping): "
+ "opcode=%d, channel=%03x, dir=%d, bufno=%03x, data=%07x\n",
+ opcode, msg_channel, msg_dir, msg_bufno, msg_data);
+}
+
+/*
+ * xillybus_isr assumes the interrupt is allocated exclusively to it,
+ * which is the natural case MSI and several other hardware-oriented
+ * interrupts. Sharing is not allowed.
+ */
+
+irqreturn_t xillybus_isr(int irq, void *data)
+{
+ struct xilly_endpoint *ep = data;
+ u32 *buf;
+ unsigned int buf_size;
+ int i;
+ int opcode;
+ unsigned int msg_channel, msg_bufno, msg_data, msg_dir;
+ struct xilly_channel *channel;
+
+ /*
+ * The endpoint structure is altered during periods when it's
+ * guaranteed no interrupt will occur, but in theory, the cache
+ * lines may not be updated. So a memory barrier is issued.
+ */
+
+ smp_rmb();
+
+ buf = ep->msgbuf_addr;
+ buf_size = ep->msg_buf_size/sizeof(u32);
+
+
+ ep->ephw->sync_single_for_cpu(ep,
+ ep->msgbuf_dma_addr,
+ ep->msg_buf_size,
+ DMA_FROM_DEVICE);
+
+ for (i = 0; i < buf_size; i += 2)
+ if (((buf[i+1] >> 28) & 0xf) != ep->msg_counter) {
+ malformed_message(&buf[i]);
+ pr_warn("xillybus: Sending a NACK on "
+ "counter %x (instead of %x) on entry %d\n",
+ ((buf[i+1] >> 28) & 0xf),
+ ep->msg_counter,
+ i/2);
+
+ if (++ep->failed_messages > 10)
+ pr_err("xillybus: Lost sync with "
+ "interrupt messages. Stopping.\n");
+ else {
+ ep->ephw->sync_single_for_device(
+ ep,
+ ep->msgbuf_dma_addr,
+ ep->msg_buf_size,
+ DMA_FROM_DEVICE);
+
+ iowrite32(0x01, /* Message NACK */
+ &ep->registers[fpga_msg_ctrl_reg]);
+ }
+ return IRQ_HANDLED;
+ } else if (buf[i] & (1 << 22)) /* Last message */
+ break;
+
+ if (i >= buf_size) {
+ pr_err("xillybus: Bad interrupt message. Stopping.\n");
+ return IRQ_HANDLED;
+ }
+
+ buf_size = i;
+
+ for (i = 0; i <= buf_size; i += 2) { /* Scan through messages */
+ opcode = (buf[i] >> 24) & 0xff;
+
+ msg_dir = buf[i] & 1;
+ msg_channel = (buf[i] >> 1) & 0x7ff;
+ msg_bufno = (buf[i] >> 12) & 0x3ff;
+ msg_data = buf[i+1] & 0xfffffff;
+
+ switch (opcode) {
+ case XILLYMSG_OPCODE_RELEASEBUF:
+
+ if ((msg_channel > ep->num_channels) ||
+ (msg_channel == 0)) {
+ malformed_message(&buf[i]);
+ break;
+ }
+
+ channel = ep->channels[msg_channel];
+
+ if (msg_dir) { /* Write channel */
+ if (msg_bufno >= channel->num_wr_buffers) {
+ malformed_message(&buf[i]);
+ break;
+ }
+ spin_lock(&channel->wr_spinlock);
+ channel->wr_buffers[msg_bufno]->end_offset =
+ msg_data;
+ channel->wr_fpga_buf_idx = msg_bufno;
+ channel->wr_empty = 0;
+ channel->wr_sleepy = 0;
+ spin_unlock(&channel->wr_spinlock);
+
+ wake_up_interruptible(&channel->wr_wait);
+
+ } else {
+ /* Read channel */
+
+ if (msg_bufno >= channel->num_rd_buffers) {
+ malformed_message(&buf[i]);
+ break;
+ }
+
+ spin_lock(&channel->rd_spinlock);
+ channel->rd_fpga_buf_idx = msg_bufno;
+ channel->rd_full = 0;
+ spin_unlock(&channel->rd_spinlock);
+
+ wake_up_interruptible(&channel->rd_wait);
+ if (!channel->rd_synchronous)
+ queue_delayed_work(
+ xillybus_wq,
+ &channel->rd_workitem,
+ XILLY_RX_TIMEOUT);
+ }
+
+ break;
+ case XILLYMSG_OPCODE_NONEMPTY:
+ if ((msg_channel > ep->num_channels) ||
+ (msg_channel == 0) || (!msg_dir) ||
+ !ep->channels[msg_channel]->wr_supports_nonempty) {
+ malformed_message(&buf[i]);
+ break;
+ }
+
+ channel = ep->channels[msg_channel];
+
+ if (msg_bufno >= channel->num_wr_buffers) {
+ malformed_message(&buf[i]);
+ break;
+ }
+ spin_lock(&channel->wr_spinlock);
+ if (msg_bufno == channel->wr_host_buf_idx)
+ channel->wr_ready = 1;
+ spin_unlock(&channel->wr_spinlock);
+
+ wake_up_interruptible(&channel->wr_ready_wait);
+
+ break;
+ case XILLYMSG_OPCODE_QUIESCEACK:
+ ep->idtlen = msg_data;
+ wake_up_interruptible(&ep->ep_wait);
+
+ break;
+ case XILLYMSG_OPCODE_FIFOEOF:
+ channel = ep->channels[msg_channel];
+ spin_lock(&channel->wr_spinlock);
+ channel->wr_eof = msg_bufno;
+ channel->wr_sleepy = 0;
+
+ channel->wr_hangup = channel->wr_empty &&
+ (channel->wr_host_buf_idx == msg_bufno);
+
+ spin_unlock(&channel->wr_spinlock);
+
+ wake_up_interruptible(&channel->wr_wait);
+
+ break;
+ case XILLYMSG_OPCODE_FATAL_ERROR:
+ ep->fatal_error = 1;
+ wake_up_interruptible(&ep->ep_wait); /* For select() */
+ pr_err("xillybus: FPGA reported a fatal "
+ "error. This means that the low-level "
+ "communication with the device has failed. "
+ "This hardware problem is most likely "
+ "unrelated to xillybus (neither kernel "
+ "module nor FPGA core), but reports are "
+ "still welcome. All I/O is aborted.\n");
+ break;
+ default:
+ malformed_message(&buf[i]);
+ break;
+ }
+ }
+
+ ep->ephw->sync_single_for_device(ep,
+ ep->msgbuf_dma_addr,
+ ep->msg_buf_size,
+ DMA_FROM_DEVICE);
+
+ ep->msg_counter = (ep->msg_counter + 1) & 0xf;
+ ep->failed_messages = 0;
+ iowrite32(0x03, &ep->registers[fpga_msg_ctrl_reg]); /* Message ACK */
+
+ return IRQ_HANDLED;
+}
+EXPORT_SYMBOL(xillybus_isr);
+
+/*
+ * A few trivial memory management functions.
+ * NOTE: These functions are used only on probe and remove, and therefore
+ * no locks are applied!
+ */
+
+void xillybus_do_cleanup(struct xilly_cleanup *mem,
+ struct xilly_endpoint *endpoint)
+{
+ struct list_head *this, *next;
+
+ list_for_each_safe(this, next, &mem->to_unmap) {
+ struct xilly_dma *entry =
+ list_entry(this, struct xilly_dma, node);
+
+ endpoint->ephw->unmap_single(entry);
+ kfree(entry);
+ }
+
+ INIT_LIST_HEAD(&mem->to_unmap);
+
+ list_for_each_safe(this, next, &mem->to_kfree)
+ kfree(this);
+
+ INIT_LIST_HEAD(&mem->to_kfree);
+
+ list_for_each_safe(this, next, &mem->to_pagefree) {
+ struct xilly_page *entry =
+ list_entry(this, struct xilly_page, node);
+
+ free_pages(entry->addr, entry->order);
+ kfree(entry);
+ }
+ INIT_LIST_HEAD(&mem->to_pagefree);
+}
+EXPORT_SYMBOL(xillybus_do_cleanup);
+
+static void *xilly_malloc(struct xilly_cleanup *mem, size_t size)
+{
+ void *ptr;
+
+ ptr = kzalloc(sizeof(struct list_head) + size, GFP_KERNEL);
+
+ if (!ptr)
+ return ptr;
+
+ list_add_tail((struct list_head *) ptr, &mem->to_kfree);
+
+ return ptr + sizeof(struct list_head);
+}
+
+static unsigned long xilly_pagealloc(struct xilly_cleanup *mem,
+ unsigned long order)
+{
+ unsigned long addr;
+ struct xilly_page *this;
+
+ this = kmalloc(sizeof(struct xilly_page), GFP_KERNEL);
+ if (!this)
+ return 0;
+
+ addr = __get_free_pages(GFP_KERNEL | __GFP_DMA32 | __GFP_ZERO, order);
+
+ if (!addr) {
+ kfree(this);
+ return 0;
+ }
+
+ this->addr = addr;
+ this->order = order;
+
+ list_add_tail(&this->node, &mem->to_pagefree);
+
+ return addr;
+}
+
+
+static void xillybus_autoflush(struct work_struct *work);
+
+static int xilly_setupchannels(struct xilly_endpoint *ep,
+ struct xilly_cleanup *mem,
+ unsigned char *chandesc,
+ int entries
+ )
+{
+ int i, entry, wr_nbuffer, rd_nbuffer;
+ struct xilly_channel *channel;
+ int channelnum, bufnum, bufsize, format, is_writebuf;
+ int bytebufsize;
+ int synchronous, allowpartial, exclusive_open, seekable;
+ int supports_nonempty;
+ void *wr_salami = NULL;
+ void *rd_salami = NULL;
+ int left_of_wr_salami = 0;
+ int left_of_rd_salami = 0;
+ dma_addr_t dma_addr;
+ int msg_buf_done = 0;
+
+ struct xilly_buffer *this_buffer = NULL; /* Init to silence warning */
+
+ channel = xilly_malloc(mem, ep->num_channels *
+ sizeof(struct xilly_channel));
+
+ if (!channel)
+ goto memfail;
+
+ ep->channels = xilly_malloc(mem, (ep->num_channels + 1) *
+ sizeof(struct xilly_channel *));
+
+ if (!ep->channels)
+ goto memfail;
+
+ ep->channels[0] = NULL; /* Channel 0 is message buf. */
+
+ /* Initialize all channels with defaults */
+
+ for (i = 1; i <= ep->num_channels; i++) {
+ channel->wr_buffers = NULL;
+ channel->rd_buffers = NULL;
+ channel->num_wr_buffers = 0;
+ channel->num_rd_buffers = 0;
+ channel->wr_fpga_buf_idx = -1;
+ channel->wr_host_buf_idx = 0;
+ channel->wr_host_buf_pos = 0;
+ channel->wr_empty = 1;
+ channel->wr_ready = 0;
+ channel->wr_sleepy = 1;
+ channel->rd_fpga_buf_idx = 0;
+ channel->rd_host_buf_idx = 0;
+ channel->rd_host_buf_pos = 0;
+ channel->rd_full = 0;
+ channel->wr_ref_count = 0;
+ channel->rd_ref_count = 0;
+
+ spin_lock_init(&channel->wr_spinlock);
+ spin_lock_init(&channel->rd_spinlock);
+ mutex_init(&channel->wr_mutex);
+ mutex_init(&channel->rd_mutex);
+ init_waitqueue_head(&channel->rd_wait);
+ init_waitqueue_head(&channel->wr_wait);
+ init_waitqueue_head(&channel->wr_ready_wait);
+
+ INIT_DELAYED_WORK(&channel->rd_workitem, xillybus_autoflush);
+
+ channel->endpoint = ep;
+ channel->chan_num = i;
+
+ channel->log2_element_size = 0;
+
+ ep->channels[i] = channel++;
+ }
+
+ /*
+ * The DMA buffer address update is atomic on the FPGA, so even if
+ * it was in the middle of sending messages to some buffer, changing
+ * the address is safe, since the data will go to either of the
+ * buffers. Not that this situation should occur at all anyhow.
+ */
+
+ wr_nbuffer = 1;
+ rd_nbuffer = 1; /* Buffer zero isn't used at all */
+
+ for (entry = 0; entry < entries; entry++, chandesc += 4) {
+ is_writebuf = chandesc[0] & 0x01;
+ channelnum = (chandesc[0] >> 1) | ((chandesc[1] & 0x0f) << 7);
+ format = (chandesc[1] >> 4) & 0x03;
+ allowpartial = (chandesc[1] >> 6) & 0x01;
+ synchronous = (chandesc[1] >> 7) & 0x01;
+ bufsize = 1 << (chandesc[2] & 0x1f);
+ bufnum = 1 << (chandesc[3] & 0x0f);
+ exclusive_open = (chandesc[2] >> 7) & 0x01;
+ seekable = (chandesc[2] >> 6) & 0x01;
+ supports_nonempty = (chandesc[2] >> 5) & 0x01;
+
+ if ((channelnum > ep->num_channels) ||
+ ((channelnum == 0) && !is_writebuf)) {
+ pr_err("xillybus: IDT requests channel out "
+ "of range. Aborting.\n");
+ return -ENODEV;
+ }
+
+ channel = ep->channels[channelnum]; /* NULL for msg channel */
+
+ bytebufsize = bufsize << 2; /* Overwritten just below */
+
+ if (!is_writebuf) {
+ channel->num_rd_buffers = bufnum;
+ channel->log2_element_size = ((format > 2) ?
+ 2 : format);
+ bytebufsize = channel->rd_buf_size = bufsize *
+ (1 << channel->log2_element_size);
+ channel->rd_allow_partial = allowpartial;
+ channel->rd_synchronous = synchronous;
+ channel->rd_exclusive_open = exclusive_open;
+ channel->seekable = seekable;
+
+ channel->rd_buffers = xilly_malloc(
+ mem,
+ bufnum * sizeof(struct xilly_buffer *));
+
+ if (!channel->rd_buffers)
+ goto memfail;
+
+ this_buffer = xilly_malloc(
+ mem,
+ bufnum * sizeof(struct xilly_buffer));
+
+ if (!this_buffer)
+ goto memfail;
+ }
+
+ else if (channelnum > 0) {
+ channel->num_wr_buffers = bufnum;
+ channel->log2_element_size = ((format > 2) ?
+ 2 : format);
+ bytebufsize = channel->wr_buf_size = bufsize *
+ (1 << channel->log2_element_size);
+
+ channel->seekable = seekable;
+ channel->wr_supports_nonempty = supports_nonempty;
+
+ channel->wr_allow_partial = allowpartial;
+ channel->wr_synchronous = synchronous;
+ channel->wr_exclusive_open = exclusive_open;
+
+ channel->wr_buffers = xilly_malloc(
+ mem,
+ bufnum * sizeof(struct xilly_buffer *));
+
+ if (!channel->wr_buffers)
+ goto memfail;
+
+ this_buffer = xilly_malloc(
+ mem,
+ bufnum * sizeof(struct xilly_buffer));
+
+ if (!this_buffer)
+ goto memfail;
+ }
+
+ /*
+ * Although daunting, we cut the chunks for read buffers
+ * from a different salami than the write buffers',
+ * possibly improving performance.
+ */
+
+ if (is_writebuf)
+ for (i = 0; i < bufnum; i++) {
+ /*
+ * Buffers are expected in descending
+ * byte-size order, so there is either
+ * enough for this buffer or none at all.
+ */
+ if ((left_of_wr_salami < bytebufsize) &&
+ (left_of_wr_salami > 0)) {
+ pr_err("xillybus: "
+ "Corrupt buffer allocation "
+ "in IDT. Aborting.\n");
+ return -ENODEV;
+ }
+
+ if (left_of_wr_salami == 0) {
+ int allocorder, allocsize;
+
+ allocsize = PAGE_SIZE;
+ allocorder = 0;
+ while (bytebufsize > allocsize) {
+ allocsize *= 2;
+ allocorder++;
+ }
+
+ wr_salami = (void *)
+ xilly_pagealloc(mem,
+ allocorder);
+ if (!wr_salami)
+ goto memfail;
+ left_of_wr_salami = allocsize;
+ }
+
+ dma_addr = ep->ephw->map_single(
+ mem,
+ ep,
+ wr_salami,
+ bytebufsize,
+ DMA_FROM_DEVICE);
+
+ if (!dma_addr)
+ goto dmafail;
+
+ iowrite32(
+ (u32) (dma_addr & 0xffffffff),
+ &ep->registers[
+ fpga_dma_bufaddr_lowaddr_reg]
+ );
+ iowrite32(
+ ((u32) ((((u64) dma_addr) >> 32)
+ & 0xffffffff)),
+ &ep->registers[
+ fpga_dma_bufaddr_highaddr_reg]
+ );
+ mmiowb();
+
+ if (channelnum > 0) {
+ this_buffer->addr = wr_salami;
+ this_buffer->dma_addr = dma_addr;
+ channel->wr_buffers[i] = this_buffer++;
+
+ iowrite32(
+ 0x80000000 | wr_nbuffer++,
+ &ep->registers[
+ fpga_dma_bufno_reg]);
+ } else {
+ ep->msgbuf_addr = wr_salami;
+ ep->msgbuf_dma_addr = dma_addr;
+ ep->msg_buf_size = bytebufsize;
+ msg_buf_done++;
+
+ iowrite32(
+ 0x80000000, &ep->registers[
+ fpga_dma_bufno_reg]);
+ }
+
+ left_of_wr_salami -= bytebufsize;
+ wr_salami += bytebufsize;
+ }
+ else /* Read buffers */
+ for (i = 0; i < bufnum; i++) {
+ /*
+ * Buffers are expected in descending
+ * byte-size order, so there is either
+ * enough for this buffer or none at all.
+ */
+ if ((left_of_rd_salami < bytebufsize) &&
+ (left_of_rd_salami > 0)) {
+ pr_err("xillybus: "
+ "Corrupt buffer allocation "
+ "in IDT. Aborting.\n");
+ return -ENODEV;
+ }
+
+ if (left_of_rd_salami == 0) {
+ int allocorder, allocsize;
+
+ allocsize = PAGE_SIZE;
+ allocorder = 0;
+ while (bytebufsize > allocsize) {
+ allocsize *= 2;
+ allocorder++;
+ }
+
+ rd_salami = (void *)
+ xilly_pagealloc(
+ mem,
+ allocorder);
+
+ if (!rd_salami)
+ goto memfail;
+ left_of_rd_salami = allocsize;
+ }
+
+ dma_addr = ep->ephw->map_single(
+ mem,
+ ep,
+ rd_salami,
+ bytebufsize,
+ DMA_TO_DEVICE);
+
+ if (!dma_addr)
+ goto dmafail;
+
+ iowrite32(
+ (u32) (dma_addr & 0xffffffff),
+ &ep->registers[
+ fpga_dma_bufaddr_lowaddr_reg]
+ );
+ iowrite32(
+ ((u32) ((((u64) dma_addr) >> 32)
+ & 0xffffffff)),
+ &ep->registers[
+ fpga_dma_bufaddr_highaddr_reg]
+ );
+ mmiowb();
+
+ this_buffer->addr = rd_salami;
+ this_buffer->dma_addr = dma_addr;
+ channel->rd_buffers[i] = this_buffer++;
+
+ iowrite32(rd_nbuffer++,
+ &ep->registers[fpga_dma_bufno_reg]);
+
+ left_of_rd_salami -= bytebufsize;
+ rd_salami += bytebufsize;
+ }
+ }
+
+ if (!msg_buf_done) {
+ pr_err("xillybus: Corrupt IDT: No message buffer. "
+ "Aborting.\n");
+ return -ENODEV;
+ }
+
+ return 0;
+
+memfail:
+ pr_err("xillybus: Failed to allocate write buffer memory. "
+ "Aborting.\n");
+ return -ENOMEM;
+dmafail:
+ pr_err("xillybus: Failed to map DMA memory!. Aborting.\n");
+ return -ENOMEM;
+}
+
+static void xilly_scan_idt(struct xilly_endpoint *endpoint,
+ struct xilly_idt_handle *idt_handle)
+{
+ int count = 0;
+ unsigned char *idt = endpoint->channels[1]->wr_buffers[0]->addr;
+ unsigned char *end_of_idt = idt + endpoint->idtlen - 4;
+ unsigned char *scan;
+ int len;
+
+ scan = idt;
+ idt_handle->idt = idt;
+
+ scan++; /* Skip version number */
+
+ while ((scan <= end_of_idt) && *scan) {
+ while ((scan <= end_of_idt) && *scan++)
+ /* Do nothing, just scan thru string */;
+ count++;
+ }
+
+ scan++;
+
+ if (scan > end_of_idt) {
+ pr_err("xillybus: IDT device name list overflow. "
+ "Aborting.\n");
+ idt_handle->chandesc = NULL;
+ return;
+ } else
+ idt_handle->chandesc = scan;
+
+ len = endpoint->idtlen - (3 + ((int) (scan - idt)));
+
+ if (len & 0x03) {
+ idt_handle->chandesc = NULL;
+
+ pr_err("xillybus: Corrupt IDT device name list. "
+ "Aborting.\n");
+ }
+
+ idt_handle->entries = len >> 2;
+
+ endpoint->num_channels = count;
+}
+
+static int xilly_obtain_idt(struct xilly_endpoint *endpoint)
+{
+ int rc = 0;
+ struct xilly_channel *channel;
+ unsigned char *version;
+
+ channel = endpoint->channels[1]; /* This should be generated ad-hoc */
+
+ channel->wr_sleepy = 1;
+ wmb(); /* Setting wr_sleepy must come before the command */
+
+ iowrite32(1 |
+ (3 << 24), /* Opcode 3 for channel 0 = Send IDT */
+ &endpoint->registers[fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+
+ wait_event_interruptible_timeout(channel->wr_wait,
+ (!channel->wr_sleepy),
+ XILLY_TIMEOUT);
+
+ if (channel->wr_sleepy) {
+ pr_err("xillybus: Failed to obtain IDT. Aborting.\n");
+
+ if (endpoint->fatal_error)
+ return -EIO;
+
+ rc = -ENODEV;
+ return rc;
+ }
+
+ endpoint->ephw->sync_single_for_cpu(
+ channel->endpoint,
+ channel->wr_buffers[0]->dma_addr,
+ channel->wr_buf_size,
+ DMA_FROM_DEVICE);
+
+ if (channel->wr_buffers[0]->end_offset != endpoint->idtlen) {
+ pr_err("xillybus: IDT length mismatch (%d != %d). "
+ "Aborting.\n",
+ channel->wr_buffers[0]->end_offset, endpoint->idtlen);
+ rc = -ENODEV;
+ return rc;
+ }
+
+ if (crc32_le(~0, channel->wr_buffers[0]->addr,
+ endpoint->idtlen+1) != 0) {
+ pr_err("xillybus: IDT failed CRC check. Aborting.\n");
+ rc = -ENODEV;
+ return rc;
+ }
+
+ version = channel->wr_buffers[0]->addr;
+
+ /* Check version number. Accept anything below 0x82 for now. */
+ if (*version > 0x82) {
+ pr_err("xillybus: No support for IDT version 0x%02x. "
+ "Maybe the xillybus driver needs an upgarde. "
+ "Aborting.\n",
+ (int) *version);
+ rc = -ENODEV;
+ return rc;
+ }
+
+ return 0; /* Success */
+}
+
+static ssize_t xillybus_read(struct file *filp, char *userbuf, size_t count,
+ loff_t *f_pos)
+{
+ ssize_t rc;
+ unsigned long flags;
+ int bytes_done = 0;
+ int no_time_left = 0;
+ long deadline, left_to_sleep;
+ struct xilly_channel *channel = filp->private_data;
+
+ int empty, reached_eof, exhausted, ready;
+ /* Initializations are there only to silence warnings */
+
+ int howmany = 0, bufpos = 0, bufidx = 0, bufferdone = 0;
+ int waiting_bufidx;
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+
+ deadline = jiffies + 1 + XILLY_RX_TIMEOUT;
+
+ rc = mutex_lock_interruptible(&channel->wr_mutex);
+
+ if (rc)
+ return rc;
+
+ rc = 0; /* Just to be clear about it. Compiler optimizes this out */
+
+ while (1) { /* Note that we may drop mutex within this loop */
+ int bytes_to_do = count - bytes_done;
+ spin_lock_irqsave(&channel->wr_spinlock, flags);
+
+ empty = channel->wr_empty;
+ ready = !empty || channel->wr_ready;
+
+ if (!empty) {
+ bufidx = channel->wr_host_buf_idx;
+ bufpos = channel->wr_host_buf_pos;
+ howmany = ((channel->wr_buffers[bufidx]->end_offset
+ + 1) << channel->log2_element_size)
+ - bufpos;
+
+ /* Update wr_host_* to its post-operation state */
+ if (howmany > bytes_to_do) {
+ bufferdone = 0;
+
+ howmany = bytes_to_do;
+ channel->wr_host_buf_pos += howmany;
+ } else {
+ bufferdone = 1;
+
+ channel->wr_host_buf_pos = 0;
+
+ if (bufidx == channel->wr_fpga_buf_idx) {
+ channel->wr_empty = 1;
+ channel->wr_sleepy = 1;
+ channel->wr_ready = 0;
+ }
+
+ if (bufidx >= (channel->num_wr_buffers - 1))
+ channel->wr_host_buf_idx = 0;
+ else
+ channel->wr_host_buf_idx++;
+ }
+ }
+
+ /*
+ * Marking our situation after the possible changes above,
+ * for use after releasing the spinlock.
+ *
+ * empty = empty before change
+ * exhasted = empty after possible change
+ */
+
+ reached_eof = channel->wr_empty &&
+ (channel->wr_host_buf_idx == channel->wr_eof);
+ channel->wr_hangup = reached_eof;
+ exhausted = channel->wr_empty;
+ waiting_bufidx = channel->wr_host_buf_idx;
+
+ spin_unlock_irqrestore(&channel->wr_spinlock, flags);
+
+ if (!empty) { /* Go on, now without the spinlock */
+
+ if (bufpos == 0) /* Position zero means it's virgin */
+ channel->endpoint->ephw->sync_single_for_cpu(
+ channel->endpoint,
+ channel->wr_buffers[bufidx]->dma_addr,
+ channel->wr_buf_size,
+ DMA_FROM_DEVICE);
+
+ if (copy_to_user(
+ userbuf,
+ channel->wr_buffers[bufidx]->addr
+ + bufpos, howmany))
+ rc = -EFAULT;
+
+ userbuf += howmany;
+ bytes_done += howmany;
+
+ if (bufferdone) {
+ channel->endpoint->ephw->
+ sync_single_for_device
+ (
+ channel->endpoint,
+ channel->wr_buffers[bufidx]->
+ dma_addr,
+ channel->wr_buf_size,
+ DMA_FROM_DEVICE);
+
+ /*
+ * Tell FPGA the buffer is done with. It's an
+ * atomic operation to the FPGA, so what
+ * happens with other channels doesn't matter,
+ * and the certain channel is protected with
+ * the channel-specific mutex.
+ */
+
+ iowrite32(1 | (channel->chan_num << 1)
+ | (bufidx << 12),
+ &channel->endpoint->registers[
+ fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+ }
+
+ if (rc) {
+ mutex_unlock(&channel->wr_mutex);
+ return rc;
+ }
+ }
+
+ /* This includes a zero-count return = EOF */
+ if ((bytes_done >= count) || reached_eof)
+ break;
+
+ if (!exhausted)
+ continue; /* More in RAM buffer(s)? Just go on. */
+
+ if ((bytes_done > 0) &&
+ (no_time_left ||
+ (channel->wr_synchronous && channel->wr_allow_partial)))
+ break;
+
+ /*
+ * Nonblocking read: The "ready" flag tells us that the FPGA
+ * has data to send. In non-blocking mode, if it isn't on,
+ * just return. But if there is, we jump directly to the point
+ * where we ask for the FPGA to send all it has, and wait
+ * until that data arrives. So in a sense, we *do* block in
+ * nonblocking mode, but only for a very short time.
+ */
+
+ if (!no_time_left && (filp->f_flags & O_NONBLOCK)) {
+ if (bytes_done > 0)
+ break;
+
+ if (ready)
+ goto desperate;
+
+ bytes_done = -EAGAIN;
+ break;
+ }
+
+ if (!no_time_left || (bytes_done > 0)) {
+ /*
+ * Note that in case of an element-misaligned read
+ * request, offsetlimit will include the last element,
+ * which will be partially read from.
+ */
+ int offsetlimit = ((count - bytes_done) - 1) >>
+ channel->log2_element_size;
+ int buf_elements = channel->wr_buf_size >>
+ channel->log2_element_size;
+
+ /*
+ * In synchronous mode, always send an offset limit.
+ * Just don't send a value too big.
+ */
+
+ if (channel->wr_synchronous) {
+ /* Don't request more than one buffer */
+ if (channel->wr_allow_partial &&
+ (offsetlimit >= buf_elements))
+ offsetlimit = buf_elements - 1;
+
+ /* Don't request more than all buffers */
+ if (!channel->wr_allow_partial &&
+ (offsetlimit >=
+ (buf_elements * channel->num_wr_buffers)))
+ offsetlimit = buf_elements *
+ channel->num_wr_buffers - 1;
+ }
+
+ /*
+ * In asynchronous mode, force early flush of a buffer
+ * only if that will allow returning a full count. The
+ * "offsetlimit < ( ... )" rather than "<=" excludes
+ * requesting a full buffer, which would obviously
+ * cause a buffer transmission anyhow
+ */
+
+ if (channel->wr_synchronous ||
+ (offsetlimit < (buf_elements - 1))) {
+
+ mutex_lock(&channel->endpoint->register_mutex);
+
+ iowrite32(offsetlimit,
+ &channel->endpoint->registers[
+ fpga_buf_offset_reg]);
+ mmiowb();
+
+ iowrite32(1 | (channel->chan_num << 1) |
+ (2 << 24) | /* 2 = offset limit */
+ (waiting_bufidx << 12),
+ &channel->endpoint->registers[
+ fpga_buf_ctrl_reg]);
+
+ mmiowb(); /* Just to appear safe */
+
+ mutex_unlock(&channel->endpoint->
+ register_mutex);
+ }
+
+ }
+
+ /*
+ * If partial completion is disallowed, there is no point in
+ * timeout sleeping. Neither if no_time_left is set and
+ * there's no data.
+ */
+
+ if (!channel->wr_allow_partial ||
+ (no_time_left && (bytes_done == 0))) {
+
+ /*
+ * This do-loop will run more than once if another
+ * thread reasserted wr_sleepy before we got the mutex
+ * back, so we try again.
+ */
+
+ do {
+ mutex_unlock(&channel->wr_mutex);
+
+ if (wait_event_interruptible(
+ channel->wr_wait,
+ (!channel->wr_sleepy)))
+ goto interrupted;
+
+ if (mutex_lock_interruptible(
+ &channel->wr_mutex))
+ goto interrupted;
+ } while (channel->wr_sleepy);
+
+ continue;
+
+interrupted: /* Mutex is not held if got here */
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+ if (bytes_done)
+ return bytes_done;
+ if (filp->f_flags & O_NONBLOCK)
+ return -EAGAIN; /* Don't admit snoozing */
+ return -EINTR;
+ }
+
+ left_to_sleep = deadline - ((long) jiffies);
+
+ /*
+ * If our time is out, skip the waiting. We may miss wr_sleepy
+ * being deasserted but hey, almost missing the train is like
+ * missing it.
+ */
+
+ if (left_to_sleep > 0) {
+ left_to_sleep =
+ wait_event_interruptible_timeout(
+ channel->wr_wait,
+ (!channel->wr_sleepy),
+ left_to_sleep);
+
+ if (!channel->wr_sleepy)
+ continue;
+
+ if (left_to_sleep < 0) { /* Interrupt */
+ mutex_unlock(&channel->wr_mutex);
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+ if (bytes_done)
+ return bytes_done;
+ return -EINTR;
+ }
+ }
+
+desperate:
+ no_time_left = 1; /* We're out of sleeping time. Desperate! */
+
+ if (bytes_done == 0) {
+ /*
+ * Reaching here means that we allow partial return,
+ * that we've run out of time, and that we have
+ * nothing to return.
+ * So tell the FPGA to send anything it has or gets.
+ */
+
+ iowrite32(1 | (channel->chan_num << 1) |
+ (3 << 24) | /* Opcode 3, flush it all! */
+ (waiting_bufidx << 12),
+ &channel->endpoint->registers[
+ fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+ }
+
+ /*
+ * Formally speaking, we should block for data at this point.
+ * But to keep the code cleaner, we'll just finish the loop,
+ * make the unlikely check for data, and then block at the
+ * usual place.
+ */
+ }
+
+ mutex_unlock(&channel->wr_mutex);
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+
+ return bytes_done;
+}
+
+/*
+ * The timeout argument takes values as follows:
+ * >0 : Flush with timeout
+ * ==0 : Flush, and wait idefinitely for the flush to complete
+ * <0 : Autoflush: Flush only if there's a single buffer occupied
+ */
+
+static int xillybus_myflush(struct xilly_channel *channel, long timeout)
+{
+ int rc = 0;
+ unsigned long flags;
+
+ int end_offset_plus1;
+ int bufidx, bufidx_minus1;
+ int i;
+ int empty;
+ int new_rd_host_buf_pos;
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+ rc = mutex_lock_interruptible(&channel->rd_mutex);
+
+ if (rc)
+ return rc;
+
+ /*
+ * Don't flush a closed channel. This can happen when the work queued
+ * autoflush thread fires off after the file has closed. This is not
+ * an error, just something to dismiss.
+ */
+
+ if (!channel->rd_ref_count)
+ goto done;
+
+ bufidx = channel->rd_host_buf_idx;
+
+ bufidx_minus1 = (bufidx == 0) ? channel->num_rd_buffers - 1 : bufidx-1;
+
+ end_offset_plus1 = channel->rd_host_buf_pos >>
+ channel->log2_element_size;
+
+ new_rd_host_buf_pos = channel->rd_host_buf_pos -
+ (end_offset_plus1 << channel->log2_element_size);
+
+ /* Submit the current buffer if it's nonempty */
+ if (end_offset_plus1) {
+ unsigned char *tail = channel->rd_buffers[bufidx]->addr +
+ (end_offset_plus1 << channel->log2_element_size);
+
+ /* Copy unflushed data, so we can put it in next buffer */
+ for (i = 0; i < new_rd_host_buf_pos; i++)
+ channel->rd_leftovers[i] = *tail++;
+
+ spin_lock_irqsave(&channel->rd_spinlock, flags);
+
+ /* Autoflush only if a single buffer is occupied */
+
+ if ((timeout < 0) &&
+ (channel->rd_full ||
+ (bufidx_minus1 != channel->rd_fpga_buf_idx))) {
+ spin_unlock_irqrestore(&channel->rd_spinlock, flags);
+ /*
+ * A new work item may be queued by the ISR exactly
+ * now, since the execution of a work item allows the
+ * queuing of a new one while it's running.
+ */
+ goto done;
+ }
+
+ /* The 4th element is never needed for data, so it's a flag */
+ channel->rd_leftovers[3] = (new_rd_host_buf_pos != 0);
+
+ /* Set up rd_full to reflect a certain moment's state */
+
+ if (bufidx == channel->rd_fpga_buf_idx)
+ channel->rd_full = 1;
+ spin_unlock_irqrestore(&channel->rd_spinlock, flags);
+
+ if (bufidx >= (channel->num_rd_buffers - 1))
+ channel->rd_host_buf_idx = 0;
+ else
+ channel->rd_host_buf_idx++;
+
+ channel->endpoint->ephw->sync_single_for_device(
+ channel->endpoint,
+ channel->rd_buffers[bufidx]->dma_addr,
+ channel->rd_buf_size,
+ DMA_TO_DEVICE);
+
+ mutex_lock(&channel->endpoint->register_mutex);
+
+ iowrite32(end_offset_plus1 - 1,
+ &channel->endpoint->registers[fpga_buf_offset_reg]);
+ mmiowb();
+
+ iowrite32((channel->chan_num << 1) | /* Channel ID */
+ (2 << 24) | /* Opcode 2, submit buffer */
+ (bufidx << 12),
+ &channel->endpoint->registers[fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+
+ mutex_unlock(&channel->endpoint->register_mutex);
+ } else if (bufidx == 0)
+ bufidx = channel->num_rd_buffers - 1;
+ else
+ bufidx--;
+
+ channel->rd_host_buf_pos = new_rd_host_buf_pos;
+
+ if (timeout < 0)
+ goto done; /* Autoflush */
+
+
+ /*
+ * bufidx is now the last buffer written to (or equal to
+ * rd_fpga_buf_idx if buffer was never written to), and
+ * channel->rd_host_buf_idx the one after it.
+ *
+ * If bufidx == channel->rd_fpga_buf_idx we're either empty or full.
+ */
+
+ rc = 0;
+
+ while (1) { /* Loop waiting for draining of buffers */
+ spin_lock_irqsave(&channel->rd_spinlock, flags);
+
+ if (bufidx != channel->rd_fpga_buf_idx)
+ channel->rd_full = 1; /*
+ * Not really full,
+ * but needs waiting.
+ */
+
+ empty = !channel->rd_full;
+
+ spin_unlock_irqrestore(&channel->rd_spinlock, flags);
+
+ if (empty)
+ break;
+
+ /*
+ * Indefinite sleep with mutex taken. With data waiting for
+ * flushing user should not be surprised if open() for write
+ * sleeps.
+ */
+ if (timeout == 0)
+ wait_event_interruptible(channel->rd_wait,
+ (!channel->rd_full));
+
+ else if (wait_event_interruptible_timeout(
+ channel->rd_wait,
+ (!channel->rd_full),
+ timeout) == 0) {
+ pr_warn("xillybus: "
+ "Timed out while flushing. "
+ "Output data may be lost.\n");
+
+ rc = -ETIMEDOUT;
+ break;
+ }
+
+ if (channel->rd_full) {
+ rc = -EINTR;
+ break;
+ }
+ }
+
+done:
+ mutex_unlock(&channel->rd_mutex);
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+
+ return rc;
+}
+
+static int xillybus_flush(struct file *filp, fl_owner_t id)
+{
+ if (!(filp->f_mode & FMODE_WRITE))
+ return 0;
+
+ return xillybus_myflush(filp->private_data, HZ); /* 1 second timeout */
+}
+
+static void xillybus_autoflush(struct work_struct *work)
+{
+ struct delayed_work *workitem = container_of(
+ work, struct delayed_work, work);
+ struct xilly_channel *channel = container_of(
+ workitem, struct xilly_channel, rd_workitem);
+ int rc;
+
+ rc = xillybus_myflush(channel, -1);
+
+ if (rc == -EINTR)
+ pr_warn("xillybus: Autoflush failed because "
+ "work queue thread got a signal.\n");
+ else if (rc)
+ pr_err("xillybus: Autoflush failed under "
+ "weird circumstances.\n");
+
+}
+
+static ssize_t xillybus_write(struct file *filp, const char *userbuf,
+ size_t count, loff_t *f_pos)
+{
+ ssize_t rc;
+ unsigned long flags;
+ int bytes_done = 0;
+ struct xilly_channel *channel = filp->private_data;
+
+ int full, exhausted;
+ /* Initializations are there only to silence warnings */
+
+ int howmany = 0, bufpos = 0, bufidx = 0, bufferdone = 0;
+ int end_offset_plus1 = 0;
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+
+ rc = mutex_lock_interruptible(&channel->rd_mutex);
+
+ if (rc)
+ return rc;
+
+ rc = 0; /* Just to be clear about it. Compiler optimizes this out */
+
+ while (1) {
+ int bytes_to_do = count - bytes_done;
+
+ spin_lock_irqsave(&channel->rd_spinlock, flags);
+
+ full = channel->rd_full;
+
+ if (!full) {
+ bufidx = channel->rd_host_buf_idx;
+ bufpos = channel->rd_host_buf_pos;
+ howmany = channel->rd_buf_size - bufpos;
+
+ /*
+ * Update rd_host_* to its state after this operation.
+ * count=0 means committing the buffer immediately,
+ * which is like flushing, but not necessarily block.
+ */
+
+ if ((howmany > bytes_to_do) &&
+ (count ||
+ ((bufpos >> channel->log2_element_size) == 0))) {
+ bufferdone = 0;
+
+ howmany = bytes_to_do;
+ channel->rd_host_buf_pos += howmany;
+ } else {
+ bufferdone = 1;
+
+ if (count) {
+ end_offset_plus1 =
+ channel->rd_buf_size >>
+ channel->log2_element_size;
+ channel->rd_host_buf_pos = 0;
+ } else {
+ unsigned char *tail;
+ int i;
+
+ end_offset_plus1 = bufpos >>
+ channel->log2_element_size;
+
+ channel->rd_host_buf_pos -=
+ end_offset_plus1 <<
+ channel->log2_element_size;
+
+ tail = channel->
+ rd_buffers[bufidx]->addr +
+ (end_offset_plus1 <<
+ channel->log2_element_size);
+
+ for (i = 0;
+ i < channel->rd_host_buf_pos;
+ i++)
+ channel->rd_leftovers[i] =
+ *tail++;
+ }
+
+ if (bufidx == channel->rd_fpga_buf_idx)
+ channel->rd_full = 1;
+
+ if (bufidx >= (channel->num_rd_buffers - 1))
+ channel->rd_host_buf_idx = 0;
+ else
+ channel->rd_host_buf_idx++;
+ }
+ }
+
+ /*
+ * Marking our situation after the possible changes above,
+ * for use after releasing the spinlock.
+ *
+ * full = full before change
+ * exhasted = full after possible change
+ */
+
+ exhausted = channel->rd_full;
+
+ spin_unlock_irqrestore(&channel->rd_spinlock, flags);
+
+ if (!full) { /* Go on, now without the spinlock */
+ unsigned char *head =
+ channel->rd_buffers[bufidx]->addr;
+ int i;
+
+ if ((bufpos == 0) || /* Zero means it's virgin */
+ (channel->rd_leftovers[3] != 0)) {
+ channel->endpoint->ephw->sync_single_for_cpu(
+ channel->endpoint,
+ channel->rd_buffers[bufidx]->dma_addr,
+ channel->rd_buf_size,
+ DMA_TO_DEVICE);
+
+ /* Virgin, but leftovers are due */
+ for (i = 0; i < bufpos; i++)
+ *head++ = channel->rd_leftovers[i];
+
+ channel->rd_leftovers[3] = 0; /* Clear flag */
+ }
+
+ if (copy_from_user(
+ channel->rd_buffers[bufidx]->addr + bufpos,
+ userbuf, howmany))
+ rc = -EFAULT;
+
+ userbuf += howmany;
+ bytes_done += howmany;
+
+ if (bufferdone) {
+ channel->endpoint->ephw->
+ sync_single_for_device(
+ channel->endpoint,
+ channel->rd_buffers[bufidx]->
+ dma_addr,
+ channel->rd_buf_size,
+ DMA_TO_DEVICE);
+
+ mutex_lock(&channel->endpoint->register_mutex);
+
+ iowrite32(end_offset_plus1 - 1,
+ &channel->endpoint->registers[
+ fpga_buf_offset_reg]);
+ mmiowb();
+ iowrite32((channel->chan_num << 1) |
+ (2 << 24) | /* 2 = submit buffer */
+ (bufidx << 12),
+ &channel->endpoint->registers[
+ fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+
+ mutex_unlock(&channel->endpoint->
+ register_mutex);
+
+ channel->rd_leftovers[3] =
+ (channel->rd_host_buf_pos != 0);
+ }
+
+ if (rc) {
+ mutex_unlock(&channel->rd_mutex);
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+
+ if (!channel->rd_synchronous)
+ queue_delayed_work(
+ xillybus_wq,
+ &channel->rd_workitem,
+ XILLY_RX_TIMEOUT);
+
+ return rc;
+ }
+ }
+
+ if (bytes_done >= count)
+ break;
+
+ if (!exhausted)
+ continue; /* If there's more space, just go on */
+
+ if ((bytes_done > 0) && channel->rd_allow_partial)
+ break;
+
+ /*
+ * Indefinite sleep with mutex taken. With data waiting for
+ * flushing, user should not be surprised if open() for write
+ * sleeps.
+ */
+
+ if (filp->f_flags & O_NONBLOCK) {
+ bytes_done = -EAGAIN;
+ break;
+ }
+
+ wait_event_interruptible(channel->rd_wait,
+ (!channel->rd_full));
+
+ if (channel->rd_full) {
+ mutex_unlock(&channel->rd_mutex);
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+
+ if (bytes_done)
+ return bytes_done;
+ return -EINTR;
+ }
+ }
+
+ mutex_unlock(&channel->rd_mutex);
+
+ if (!channel->rd_synchronous)
+ queue_delayed_work(xillybus_wq,
+ &channel->rd_workitem,
+ XILLY_RX_TIMEOUT);
+
+ if ((channel->rd_synchronous) && (bytes_done > 0)) {
+ rc = xillybus_myflush(filp->private_data, 0); /* No timeout */
+
+ if (rc && (rc != -EINTR))
+ return rc;
+ }
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+
+ return bytes_done;
+}
+
+static int xillybus_open(struct inode *inode, struct file *filp)
+{
+ int rc = 0;
+ unsigned long flags;
+ int minor = iminor(inode);
+ int major = imajor(inode);
+ struct xilly_endpoint *ep_iter, *endpoint = NULL;
+ struct xilly_channel *channel;
+
+ mutex_lock(&ep_list_lock);
+
+ list_for_each_entry(ep_iter, &list_of_endpoints, ep_list) {
+ if ((ep_iter->major == major) &&
+ (minor >= ep_iter->lowest_minor) &&
+ (minor < (ep_iter->lowest_minor +
+ ep_iter->num_channels))) {
+ endpoint = ep_iter;
+ break;
+ }
+ }
+ mutex_unlock(&ep_list_lock);
+
+ if (!endpoint) {
+ pr_err("xillybus: open() failed to find a device "
+ "for major=%d and minor=%d\n", major, minor);
+ return -ENODEV;
+ }
+
+ if (endpoint->fatal_error)
+ return -EIO;
+
+ channel = endpoint->channels[1 + minor - endpoint->lowest_minor];
+ filp->private_data = channel;
+
+
+ /*
+ * It gets complicated because:
+ * 1. We don't want to take a mutex we don't have to
+ * 2. We don't want to open one direction if the other will fail.
+ */
+
+ if ((filp->f_mode & FMODE_READ) && (!channel->num_wr_buffers))
+ return -ENODEV;
+
+ if ((filp->f_mode & FMODE_WRITE) && (!channel->num_rd_buffers))
+ return -ENODEV;
+
+ if ((filp->f_mode & FMODE_READ) && (filp->f_flags & O_NONBLOCK) &&
+ (channel->wr_synchronous || !channel->wr_allow_partial ||
+ !channel->wr_supports_nonempty)) {
+ pr_err("xillybus: open() failed: "
+ "O_NONBLOCK not allowed for read on this device\n");
+ return -ENODEV;
+ }
+
+ if ((filp->f_mode & FMODE_WRITE) && (filp->f_flags & O_NONBLOCK) &&
+ (channel->rd_synchronous || !channel->rd_allow_partial)) {
+ pr_err("xillybus: open() failed: "
+ "O_NONBLOCK not allowed for write on this device\n");
+ return -ENODEV;
+ }
+
+ /*
+ * Note: open() may block on getting mutexes despite O_NONBLOCK.
+ * This shouldn't occur normally, since multiple open of the same
+ * file descriptor is almost always prohibited anyhow
+ * (*_exclusive_open is normally set in real-life systems).
+ */
+
+ if (filp->f_mode & FMODE_READ) {
+ rc = mutex_lock_interruptible(&channel->wr_mutex);
+ if (rc)
+ return rc;
+ }
+
+ if (filp->f_mode & FMODE_WRITE) {
+ rc = mutex_lock_interruptible(&channel->rd_mutex);
+ if (rc)
+ goto unlock_wr;
+ }
+
+ if ((filp->f_mode & FMODE_READ) &&
+ (channel->wr_ref_count != 0) &&
+ (channel->wr_exclusive_open)) {
+ rc = -EBUSY;
+ goto unlock;
+ }
+
+ if ((filp->f_mode & FMODE_WRITE) &&
+ (channel->rd_ref_count != 0) &&
+ (channel->rd_exclusive_open)) {
+ rc = -EBUSY;
+ goto unlock;
+ }
+
+
+ if (filp->f_mode & FMODE_READ) {
+ if (channel->wr_ref_count == 0) { /* First open of file */
+ /* Move the host to first buffer */
+ spin_lock_irqsave(&channel->wr_spinlock, flags);
+ channel->wr_host_buf_idx = 0;
+ channel->wr_host_buf_pos = 0;
+ channel->wr_fpga_buf_idx = -1;
+ channel->wr_empty = 1;
+ channel->wr_ready = 0;
+ channel->wr_sleepy = 1;
+ channel->wr_eof = -1;
+ channel->wr_hangup = 0;
+
+ spin_unlock_irqrestore(&channel->wr_spinlock, flags);
+
+ iowrite32(1 | (channel->chan_num << 1) |
+ (4 << 24) | /* Opcode 4, open channel */
+ ((channel->wr_synchronous & 1) << 23),
+ &channel->endpoint->registers[
+ fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+ }
+
+ channel->wr_ref_count++;
+ }
+
+ if (filp->f_mode & FMODE_WRITE) {
+ if (channel->rd_ref_count == 0) { /* First open of file */
+ /* Move the host to first buffer */
+ spin_lock_irqsave(&channel->rd_spinlock, flags);
+ channel->rd_host_buf_idx = 0;
+ channel->rd_host_buf_pos = 0;
+ channel->rd_leftovers[3] = 0; /* No leftovers. */
+ channel->rd_fpga_buf_idx = channel->num_rd_buffers - 1;
+ channel->rd_full = 0;
+
+ spin_unlock_irqrestore(&channel->rd_spinlock, flags);
+
+ iowrite32((channel->chan_num << 1) |
+ (4 << 24), /* Opcode 4, open channel */
+ &channel->endpoint->registers[
+ fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+ }
+
+ channel->rd_ref_count++;
+ }
+
+unlock:
+ if (filp->f_mode & FMODE_WRITE)
+ mutex_unlock(&channel->rd_mutex);
+unlock_wr:
+ if (filp->f_mode & FMODE_READ)
+ mutex_unlock(&channel->wr_mutex);
+
+ if (!rc && (!channel->seekable))
+ return nonseekable_open(inode, filp);
+
+ return rc;
+}
+
+static int xillybus_release(struct inode *inode, struct file *filp)
+{
+ int rc;
+ unsigned long flags;
+ struct xilly_channel *channel = filp->private_data;
+
+ int buf_idx;
+ int eof;
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+
+ if (filp->f_mode & FMODE_WRITE) {
+ rc = mutex_lock_interruptible(&channel->rd_mutex);
+
+ if (rc) {
+ pr_warn("xillybus: Failed to close file. "
+ "Hardware left in messy state.\n");
+ return rc;
+ }
+
+ channel->rd_ref_count--;
+
+ if (channel->rd_ref_count == 0) {
+
+ /*
+ * We rely on the kernel calling flush()
+ * before we get here.
+ */
+
+ iowrite32((channel->chan_num << 1) | /* Channel ID */
+ (5 << 24), /* Opcode 5, close channel */
+ &channel->endpoint->registers[
+ fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+ }
+ mutex_unlock(&channel->rd_mutex);
+ }
+
+ if (filp->f_mode & FMODE_READ) {
+ rc = mutex_lock_interruptible(&channel->wr_mutex);
+ if (rc) {
+ pr_warn("xillybus: Failed to close file. "
+ "Hardware left in messy state.\n");
+ return rc;
+ }
+
+ channel->wr_ref_count--;
+
+ if (channel->wr_ref_count == 0) {
+
+ iowrite32(1 | (channel->chan_num << 1) |
+ (5 << 24), /* Opcode 5, close channel */
+ &channel->endpoint->registers[
+ fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+
+ /*
+ * This is crazily cautious: We make sure that not
+ * only that we got an EOF (be it because we closed
+ * the channel or because of a user's EOF), but verify
+ * that it's one beyond the last buffer arrived, so
+ * we have no leftover buffers pending before wrapping
+ * up (which can only happen in asynchronous channels,
+ * BTW)
+ */
+
+ while (1) {
+ spin_lock_irqsave(&channel->wr_spinlock,
+ flags);
+ buf_idx = channel->wr_fpga_buf_idx;
+ eof = channel->wr_eof;
+ channel->wr_sleepy = 1;
+ spin_unlock_irqrestore(&channel->wr_spinlock,
+ flags);
+
+ /*
+ * Check if eof points at the buffer after
+ * the last one the FPGA submitted. Note that
+ * no EOF is marked by negative eof.
+ */
+
+ buf_idx++;
+ if (buf_idx == channel->num_wr_buffers)
+ buf_idx = 0;
+
+ if (buf_idx == eof)
+ break;
+
+ /*
+ * Steal extra 100 ms if awaken by interrupt.
+ * This is a simple workaround for an
+ * interrupt pending when entering, which would
+ * otherwise result in declaring the hardware
+ * non-responsive.
+ */
+
+ if (wait_event_interruptible(
+ channel->wr_wait,
+ (!channel->wr_sleepy)))
+ msleep(100);
+
+ if (channel->wr_sleepy) {
+ mutex_unlock(&channel->wr_mutex);
+ pr_warn("xillybus: Hardware failed to "
+ "respond to close command, "
+ "therefore left in "
+ "messy state.\n");
+ return -EINTR;
+ }
+ }
+ }
+
+ mutex_unlock(&channel->wr_mutex);
+ }
+
+ return 0;
+}
+loff_t xillybus_llseek(struct file *filp, loff_t offset, int whence)
+{
+ struct xilly_channel *channel = filp->private_data;
+ loff_t pos = filp->f_pos;
+ int rc = 0;
+
+ /*
+ * Take both mutexes not allowing interrupts, since it seems like
+ * common applications don't expect an -EINTR here. Besides, multiple
+ * access to a single file desriptor on seekable devices is a mess
+ * anyhow.
+ */
+
+ if (channel->endpoint->fatal_error)
+ return -EIO;
+
+ mutex_lock(&channel->wr_mutex);
+ mutex_lock(&channel->rd_mutex);
+
+ switch (whence) {
+ case 0:
+ pos = offset;
+ break;
+ case 1:
+ pos += offset;
+ break;
+ case 2:
+ pos = offset; /* Going to the end => to the beginning */
+ break;
+ default:
+ rc = -EINVAL;
+ goto end;
+ }
+
+ /* In any case, we must finish on an element boundary */
+ if (pos & ((1 << channel->log2_element_size) - 1)) {
+ rc = -EINVAL;
+ goto end;
+ }
+
+ mutex_lock(&channel->endpoint->register_mutex);
+
+ iowrite32(pos >> channel->log2_element_size,
+ &channel->endpoint->registers[fpga_buf_offset_reg]);
+ mmiowb();
+ iowrite32((channel->chan_num << 1) |
+ (6 << 24), /* Opcode 6, set address */
+ &channel->endpoint->registers[fpga_buf_ctrl_reg]);
+ mmiowb(); /* Just to appear safe */
+
+ mutex_unlock(&channel->endpoint->register_mutex);
+
+end:
+ mutex_unlock(&channel->rd_mutex);
+ mutex_unlock(&channel->wr_mutex);
+
+ if (rc) /* Return error after releasing mutexes */
+ return rc;
+
+ filp->f_pos = pos;
+
+ /*
+ * Since seekable devices are allowed only when the channel is
+ * synchronous, we assume that there is no data pending in either
+ * direction (which holds true as long as no concurrent access on the
+ * file descriptor takes place).
+ * The only thing we may need to throw away is leftovers from partial
+ * write() flush.
+ */
+
+ channel->rd_leftovers[3] = 0;
+
+ return pos;
+}
+
+static unsigned int xillybus_poll(struct file *filp, poll_table *wait)
+{
+ struct xilly_channel *channel = filp->private_data;
+ unsigned int mask = 0;
+ unsigned long flags;
+
+ poll_wait(filp, &channel->endpoint->ep_wait, wait);
+
+ /*
+ * poll() won't play ball regarding read() channels which
+ * aren't asynchronous and support the nonempty message. Allowing
+ * that will create situations where data has been delivered at
+ * the FPGA, and users expecting select() to wake up, which it may
+ * not.
+ */
+
+ if (!channel->wr_synchronous && channel->wr_supports_nonempty) {
+ poll_wait(filp, &channel->wr_wait, wait);
+ poll_wait(filp, &channel->wr_ready_wait, wait);
+
+ spin_lock_irqsave(&channel->wr_spinlock, flags);
+ if (!channel->wr_empty || channel->wr_ready)
+ mask |= POLLIN | POLLRDNORM;
+
+ if (channel->wr_hangup)
+ /*
+ * Not POLLHUP, because its behavior is in the
+ * mist, and POLLIN does what we want: Wake up
+ * the read file descriptor so it sees EOF.
+ */
+ mask |= POLLIN | POLLRDNORM;
+ spin_unlock_irqrestore(&channel->wr_spinlock, flags);
+ }
+
+ /*
+ * If partial data write is disallowed on a write() channel,
+ * it's pointless to ever signal OK to write, because is could
+ * block despite some space being available.
+ */
+
+ if (channel->rd_allow_partial) {
+ poll_wait(filp, &channel->rd_wait, wait);
+
+ spin_lock_irqsave(&channel->rd_spinlock, flags);
+ if (!channel->rd_full)
+ mask |= POLLOUT | POLLWRNORM;
+ spin_unlock_irqrestore(&channel->rd_spinlock, flags);
+ }
+
+ if (channel->endpoint->fatal_error)
+ mask |= POLLERR;
+
+ return mask;
+}
+
+static const struct file_operations xillybus_fops = {
+ .owner = THIS_MODULE,
+ .read = xillybus_read,
+ .write = xillybus_write,
+ .open = xillybus_open,
+ .flush = xillybus_flush,
+ .release = xillybus_release,
+ .llseek = xillybus_llseek,
+ .poll = xillybus_poll,
+};
+
+static int xillybus_init_chrdev(struct xilly_endpoint *endpoint,
+ const unsigned char *idt)
+{
+ int rc;
+ dev_t dev;
+ int devnum, i, minor, major;
+ char devname[48];
+ struct device *device;
+
+ rc = alloc_chrdev_region(&dev, 0, /* minor start */
+ endpoint->num_channels,
+ xillyname);
+
+ if (rc) {
+ pr_warn("xillybus: Failed to obtain major/minors");
+ goto error1;
+ }
+
+ endpoint->major = major = MAJOR(dev);
+ endpoint->lowest_minor = minor = MINOR(dev);
+
+ cdev_init(&endpoint->cdev, &xillybus_fops);
+ endpoint->cdev.owner = endpoint->ephw->owner;
+ rc = cdev_add(&endpoint->cdev, MKDEV(major, minor),
+ endpoint->num_channels);
+ if (rc) {
+ pr_warn("xillybus: Failed to add cdev. Aborting.\n");
+ goto error2;
+ }
+
+ idt++;
+
+ for (i = minor, devnum = 0;
+ devnum < endpoint->num_channels;
+ devnum++, i++) {
+ snprintf(devname, sizeof(devname)-1, "xillybus_%s", idt);
+
+ devname[sizeof(devname)-1] = 0; /* Should never matter */
+
+ while (*idt++)
+ /* Skip to next */;
+
+ device = device_create(xillybus_class,
+ NULL,
+ MKDEV(major, i),
+ NULL,
+ devname);
+
+ if (IS_ERR(device)) {
+ pr_warn("xillybus: Failed to create %s "
+ "device. Aborting.\n", devname);
+ goto error3;
+ }
+ }
+
+ pr_info("xillybus: Created %d device files.\n",
+ endpoint->num_channels);
+ return 0; /* succeed */
+
+error3:
+ devnum--; i--;
+ for (; devnum >= 0; devnum--, i--)
+ device_destroy(xillybus_class, MKDEV(major, i));
+
+ cdev_del(&endpoint->cdev);
+error2:
+ unregister_chrdev_region(MKDEV(major, minor), endpoint->num_channels);
+error1:
+
+ return rc;
+}
+
+static void xillybus_cleanup_chrdev(struct xilly_endpoint *endpoint)
+{
+ int minor;
+
+ for (minor = endpoint->lowest_minor;
+ minor < (endpoint->lowest_minor + endpoint->num_channels);
+ minor++)
+ device_destroy(xillybus_class, MKDEV(endpoint->major, minor));
+ cdev_del(&endpoint->cdev);
+ unregister_chrdev_region(MKDEV(endpoint->major,
+ endpoint->lowest_minor),
+ endpoint->num_channels);
+
+ pr_info("xillybus: Removed %d device files.\n",
+ endpoint->num_channels);
+}
+
+
+struct xilly_endpoint *xillybus_init_endpoint(struct pci_dev *pdev,
+ struct device *dev,
+ struct xilly_endpoint_hardware
+ *ephw)
+{
+ struct xilly_endpoint *endpoint;
+
+ endpoint = kzalloc(sizeof(*endpoint), GFP_KERNEL);
+ if (!endpoint) {
+ pr_err("xillybus: Failed to allocate memory. Aborting.\n");
+ return NULL;
+ }
+
+ endpoint->pdev = pdev;
+ endpoint->dev = dev;
+ endpoint->ephw = ephw;
+ INIT_LIST_HEAD(&endpoint->cleanup.to_kfree);
+ INIT_LIST_HEAD(&endpoint->cleanup.to_pagefree);
+ INIT_LIST_HEAD(&endpoint->cleanup.to_unmap);
+ endpoint->msg_counter = 0x0b;
+ endpoint->failed_messages = 0;
+ endpoint->fatal_error = 0;
+
+ init_waitqueue_head(&endpoint->ep_wait);
+ mutex_init(&endpoint->register_mutex);
+
+ return endpoint;
+}
+EXPORT_SYMBOL(xillybus_init_endpoint);
+
+static int xilly_quiesce(struct xilly_endpoint *endpoint)
+{
+ endpoint->idtlen = -1;
+ wmb(); /* Make sure idtlen is set before sending command */
+ iowrite32((u32) (endpoint->dma_using_dac & 0x0001),
+ &endpoint->registers[fpga_dma_control_reg]);
+ mmiowb();
+
+ wait_event_interruptible_timeout(endpoint->ep_wait,
+ (endpoint->idtlen >= 0),
+ XILLY_TIMEOUT);
+
+ if (endpoint->idtlen < 0) {
+ pr_err("xillybus: Failed to quiesce the device on "
+ "exit. Quitting while leaving a mess.\n");
+ return -ENODEV;
+ }
+ return 0; /* Success */
+}
+
+int xillybus_endpoint_discovery(struct xilly_endpoint *endpoint)
+{
+ int rc = 0;
+
+ struct xilly_cleanup tmpmem;
+ int idtbuffersize = (1 << PAGE_SHIFT);
+
+ /*
+ * The bogus IDT is used during bootstrap for allocating the initial
+ * message buffer, and then the message buffer and space for the IDT
+ * itself. The initial message buffer is of a single page's size, but
+ * it's soon replaced with a more modest one (and memory is freed).
+ */
+
+ unsigned char bogus_idt[8] = { 1, 224, (PAGE_SHIFT)-2, 0,
+ 3, 192, PAGE_SHIFT, 0 };
+ struct xilly_idt_handle idt_handle;
+
+ INIT_LIST_HEAD(&tmpmem.to_kfree);
+ INIT_LIST_HEAD(&tmpmem.to_pagefree);
+ INIT_LIST_HEAD(&tmpmem.to_unmap);
+
+ /*
+ * Writing the value 0x00000001 to Endianess register signals which
+ * endianess this processor is using, so the FPGA can swap words as
+ * necessary.
+ */
+
+ iowrite32(1, &endpoint->registers[fpga_endian_reg]);
+ mmiowb(); /* Writes below are affected by the one above. */
+
+ /* Bootstrap phase I: Allocate temporary message buffer */
+
+ endpoint->num_channels = 0;
+
+ rc = xilly_setupchannels(endpoint, &tmpmem, bogus_idt, 1);
+
+ if (rc)
+ goto failed_buffers;
+
+ /* Clear the message subsystem (and counter in particular) */
+ iowrite32(0x04, &endpoint->registers[fpga_msg_ctrl_reg]);
+ mmiowb();
+
+ endpoint->idtlen = -1;
+
+ smp_wmb();
+
+ /*
+ * Set DMA 32/64 bit mode, quiesce the device (?!) and get IDT
+ * buffer size.
+ */
+ iowrite32((u32) (endpoint->dma_using_dac & 0x0001),
+ &endpoint->registers[fpga_dma_control_reg]);
+ mmiowb();
+
+ wait_event_interruptible_timeout(endpoint->ep_wait,
+ (endpoint->idtlen >= 0),
+ XILLY_TIMEOUT);
+
+ if (endpoint->idtlen < 0) {
+ pr_err("xillybus: No response from FPGA. Aborting.\n");
+ rc = -ENODEV;
+ goto failed_quiesce;
+ }
+
+ /* Enable DMA */
+ iowrite32((u32) (0x0002 | (endpoint->dma_using_dac & 0x0001)),
+ &endpoint->registers[fpga_dma_control_reg]);
+ mmiowb();
+
+ /* Bootstrap phase II: Allocate buffer for IDT and obtain it */
+ while (endpoint->idtlen >= idtbuffersize) {
+ idtbuffersize *= 2;
+ bogus_idt[6]++;
+ }
+
+ endpoint->num_channels = 1;
+
+ rc = xilly_setupchannels(endpoint, &tmpmem, bogus_idt, 2);
+
+ if (rc)
+ goto failed_idt;
+
+ smp_wmb();
+
+ rc = xilly_obtain_idt(endpoint);
+
+ if (rc)
+ goto failed_idt;
+
+ xilly_scan_idt(endpoint, &idt_handle);
+
+ if (!idt_handle.chandesc) {
+ rc = -ENODEV;
+ goto failed_idt;
+ }
+ /* Bootstrap phase III: Allocate buffers according to IDT */
+
+ rc = xilly_setupchannels(endpoint,
+ &endpoint->cleanup,
+ idt_handle.chandesc,
+ idt_handle.entries);
+
+ if (rc)
+ goto failed_idt;
+
+ smp_wmb(); /* mutex_lock below should suffice, but won't hurt.*/
+
+ /*
+ * endpoint is now completely configured. We put it on the list
+ * available to open() before registering the char device(s)
+ */
+
+ mutex_lock(&ep_list_lock);
+ list_add_tail(&endpoint->ep_list, &list_of_endpoints);
+ mutex_unlock(&ep_list_lock);
+
+ rc = xillybus_init_chrdev(endpoint, idt_handle.idt);
+
+ if (rc)
+ goto failed_chrdevs;
+
+ xillybus_do_cleanup(&tmpmem, endpoint);
+
+ return 0;
+
+failed_chrdevs:
+ mutex_lock(&ep_list_lock);
+ list_del(&endpoint->ep_list);
+ mutex_unlock(&ep_list_lock);
+
+failed_idt:
+ /* Quiesce the device. Now it's serious to do it */
+ rc = xilly_quiesce(endpoint);
+
+ if (rc)
+ return rc; /* FPGA may still DMA, so no release */
+
+ flush_workqueue(xillybus_wq);
+failed_quiesce:
+failed_buffers:
+ xillybus_do_cleanup(&tmpmem, endpoint);
+
+ return rc;
+}
+EXPORT_SYMBOL(xillybus_endpoint_discovery);
+
+void xillybus_endpoint_remove(struct xilly_endpoint *endpoint)
+{
+ xillybus_cleanup_chrdev(endpoint);
+
+ mutex_lock(&ep_list_lock);
+ list_del(&endpoint->ep_list);
+ mutex_unlock(&ep_list_lock);
+
+ xilly_quiesce(endpoint);
+
+ /*
+ * Flushing is done upon endpoint release to prevent access to memory
+ * just about to be released. This makes the quiesce complete.
+ */
+ flush_workqueue(xillybus_wq);
+}
+EXPORT_SYMBOL(xillybus_endpoint_remove);
+
+static int __init xillybus_init(void)
+{
+ int rc = 0;
+
+ mutex_init(&ep_list_lock);
+
+ xillybus_class = class_create(THIS_MODULE, xillyname);
+ if (IS_ERR(xillybus_class)) {
+ rc = PTR_ERR(xillybus_class);
+ pr_warn("xillybus: Failed to register class xillybus\n");
+
+ return rc;
+ }
+
+ xillybus_wq = alloc_workqueue(xillyname, 0, 0);
+
+ return 0; /* Success */
+}
+
+static void __exit xillybus_exit(void)
+{
+ /* flush_workqueue() was called for each endpoint released */
+ destroy_workqueue(xillybus_wq);
+
+ class_destroy(xillybus_class);
+}
+
+module_init(xillybus_init);
+module_exit(xillybus_exit);
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