--- /dev/null
+/*
+ * hdm_i2c.c - Hardware Dependent Module for I2C Interface
+ *
+ * Copyright (C) 2013-2015, Microchip Technology Germany II GmbH & Co. KG
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * This file is licensed under GPLv2.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+
+#include <mostcore.h>
+
+enum { CH_RX, CH_TX, NUM_CHANNELS };
+
+#define MAX_BUFFERS_CONTROL 32
+#define MAX_BUF_SIZE_CONTROL 256
+
+/**
+ * list_first_mbo - get the first mbo from a list
+ * @ptr: the list head to take the mbo from.
+ */
+#define list_first_mbo(ptr) \
+ list_first_entry(ptr, struct mbo, list)
+
+
+/* IRQ / Polling option */
+static bool polling_req;
+module_param(polling_req, bool, S_IRUGO);
+MODULE_PARM_DESC(polling_req, "Request Polling. Default = 0 (use irq)");
+
+/* Polling Rate */
+static int scan_rate = 100;
+module_param(scan_rate, int, 0644);
+MODULE_PARM_DESC(scan_rate, "Polling rate in times/sec. Default = 100");
+
+struct hdm_i2c {
+ bool is_open[NUM_CHANNELS];
+ bool polling_mode;
+ struct most_interface most_iface;
+ struct most_channel_capability capabilities[NUM_CHANNELS];
+ struct i2c_client *client;
+ struct rx {
+ struct delayed_work dwork;
+ wait_queue_head_t waitq;
+ struct list_head list;
+ struct mutex list_mutex;
+ } rx;
+ char name[64];
+};
+
+#define to_hdm(iface) container_of(iface, struct hdm_i2c, most_iface)
+
+/**
+ * configure_channel - called from MOST core to configure a channel
+ * @iface: interface the channel belongs to
+ * @channel: channel to be configured
+ * @channel_config: structure that holds the configuration information
+ *
+ * Return 0 on success, negative on failure.
+ *
+ * Receives configuration information from MOST core and initialize the
+ * corresponding channel.
+ */
+static int configure_channel(struct most_interface *most_iface,
+ int ch_idx,
+ struct most_channel_config *channel_config)
+{
+ struct hdm_i2c *dev = to_hdm(most_iface);
+
+ BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
+ BUG_ON(dev->is_open[ch_idx]);
+
+ if (channel_config->data_type != MOST_CH_CONTROL) {
+ pr_err("bad data type for channel %d\n", ch_idx);
+ return -EPERM;
+ }
+
+ if (channel_config->direction != dev->capabilities[ch_idx].direction) {
+ pr_err("bad direction for channel %d\n", ch_idx);
+ return -EPERM;
+ }
+
+ if (channel_config->direction == MOST_CH_RX) {
+ if (dev->polling_mode)
+ schedule_delayed_work(&dev->rx.dwork,
+ msecs_to_jiffies(MSEC_PER_SEC / 4));
+ }
+ dev->is_open[ch_idx] = true;
+
+ return 0;
+}
+
+/**
+ * enqueue - called from MOST core to enqueue a buffer for data transfer
+ * @iface: intended interface
+ * @channel: ID of the channel the buffer is intended for
+ * @mbo: pointer to the buffer object
+ *
+ * Return 0 on success, negative on failure.
+ *
+ * Transmit the data over I2C if it is a "write" request or push the buffer into
+ * list if it is an "read" request
+ */
+static int enqueue(struct most_interface *most_iface,
+ int ch_idx, struct mbo *mbo)
+{
+ struct hdm_i2c *dev = to_hdm(most_iface);
+ int ret;
+
+ BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
+ BUG_ON(!dev->is_open[ch_idx]);
+
+ if (ch_idx == CH_RX) {
+ /* RX */
+ mutex_lock(&dev->rx.list_mutex);
+ list_add_tail(&mbo->list, &dev->rx.list);
+ mutex_unlock(&dev->rx.list_mutex);
+ wake_up_interruptible(&dev->rx.waitq);
+ } else {
+ /* TX */
+ ret = i2c_master_send(dev->client, mbo->virt_address,
+ mbo->buffer_length);
+ if (ret <= 0) {
+ mbo->processed_length = 0;
+ mbo->status = MBO_E_INVAL;
+ } else {
+ mbo->processed_length = mbo->buffer_length;
+ mbo->status = MBO_SUCCESS;
+ }
+ mbo->complete(mbo);
+ }
+
+ return 0;
+}
+
+/**
+ * poison_channel - called from MOST core to poison buffers of a channel
+ * @iface: pointer to the interface the channel to be poisoned belongs to
+ * @channel_id: corresponding channel ID
+ *
+ * Return 0 on success, negative on failure.
+ *
+ * If channel direction is RX, complete the buffers in list with
+ * status MBO_E_CLOSE
+ */
+static int poison_channel(struct most_interface *most_iface,
+ int ch_idx)
+{
+ struct hdm_i2c *dev = to_hdm(most_iface);
+ struct mbo *mbo;
+
+ BUG_ON(ch_idx < 0 || ch_idx >= NUM_CHANNELS);
+ BUG_ON(!dev->is_open[ch_idx]);
+
+ dev->is_open[ch_idx] = false;
+
+ if (ch_idx == CH_RX) {
+ mutex_lock(&dev->rx.list_mutex);
+ while (!list_empty(&dev->rx.list)) {
+ mbo = list_first_mbo(&dev->rx.list);
+ list_del(&mbo->list);
+ mutex_unlock(&dev->rx.list_mutex);
+
+ mbo->processed_length = 0;
+ mbo->status = MBO_E_CLOSE;
+ mbo->complete(mbo);
+
+ mutex_lock(&dev->rx.list_mutex);
+ }
+ mutex_unlock(&dev->rx.list_mutex);
+ wake_up_interruptible(&dev->rx.waitq);
+ }
+
+ return 0;
+}
+
+static void request_netinfo(struct most_interface *most_iface,
+ int ch_idx)
+{
+ pr_info("request_netinfo()\n");
+}
+
+static void do_rx_work(struct hdm_i2c *dev)
+{
+ struct mbo *mbo;
+ unsigned char msg[MAX_BUF_SIZE_CONTROL];
+ int ret, ch_idx = CH_RX;
+ uint16_t pml, data_size;
+
+ /* Read PML (2 bytes) */
+ ret = i2c_master_recv(dev->client, msg, 2);
+ if (ret <= 0) {
+ pr_err("Failed to receive PML\n");
+ return;
+ }
+
+ pml = (msg[0] << 8) | msg[1];
+ if (!pml)
+ return;
+
+ data_size = pml + 2;
+
+ /* Read the whole message, including PML */
+ ret = i2c_master_recv(dev->client, msg, data_size);
+ if (ret <= 0) {
+ pr_err("Failed to receive a Port Message\n");
+ return;
+ }
+
+ for (;;) {
+ /* Conditions to wait for: poisoned channel or free buffer
+ available for reading */
+ if (wait_event_interruptible(dev->rx.waitq,
+ !dev->is_open[ch_idx] ||
+ !list_empty(&dev->rx.list))) {
+ pr_err("wait_event_interruptible() failed\n");
+ return;
+ }
+
+ if (!dev->is_open[ch_idx])
+ return;
+
+ mutex_lock(&dev->rx.list_mutex);
+
+ /* list may be empty if poison or remove is called */
+ if (!list_empty(&dev->rx.list))
+ break;
+
+ mutex_unlock(&dev->rx.list_mutex);
+ }
+
+ mbo = list_first_mbo(&dev->rx.list);
+ list_del(&mbo->list);
+ mutex_unlock(&dev->rx.list_mutex);
+
+ mbo->processed_length = min(data_size, mbo->buffer_length);
+ memcpy(mbo->virt_address, msg, mbo->processed_length);
+ mbo->status = MBO_SUCCESS;
+ mbo->complete(mbo);
+}
+
+/**
+ * pending_rx_work - Read pending messages through I2C
+ * @work: definition of this work item
+ *
+ * Invoked by the Interrupt Service Routine, most_irq_handler()
+ */
+static void pending_rx_work(struct work_struct *work)
+{
+ struct hdm_i2c *dev = container_of(work, struct hdm_i2c, rx.dwork.work);
+
+ do_rx_work(dev);
+
+ if (dev->polling_mode) {
+ if (dev->is_open[CH_RX])
+ schedule_delayed_work(&dev->rx.dwork,
+ msecs_to_jiffies(MSEC_PER_SEC
+ / scan_rate));
+ } else
+ enable_irq(dev->client->irq);
+}
+
+/*
+ * most_irq_handler - Interrupt Service Routine
+ * @irq: irq number
+ * @_dev: private data
+ *
+ * Schedules a delayed work
+ *
+ * By default the interrupt line behavior is Active Low. Once an interrupt is
+ * generated by the device, until driver clears the interrupt (by reading
+ * the PMP message), device keeps the interrupt line in low state. Since i2c
+ * read is done in work queue, the interrupt line must be disabled temporarily
+ * to avoid ISR being called repeatedly. Re-enable the interrupt in workqueue,
+ * after reading the message.
+ *
+ * Note: If we use the interrupt line in Falling edge mode, there is a
+ * possibility to miss interrupts when ISR is getting executed.
+ *
+ */
+static irqreturn_t most_irq_handler(int irq, void *_dev)
+{
+ struct hdm_i2c *dev = _dev;
+
+ disable_irq_nosync(irq);
+
+ schedule_delayed_work(&dev->rx.dwork, 0);
+
+ return IRQ_HANDLED;
+}
+
+/*
+ * i2c_probe - i2c probe handler
+ * @client: i2c client device structure
+ * @id: i2c client device id
+ *
+ * Return 0 on success, negative on failure.
+ *
+ * Register the i2c client device as a MOST interface
+ */
+static int i2c_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+ struct hdm_i2c *dev;
+ int ret, i;
+ struct kobject *kobj;
+
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev)
+ return -ENOMEM;
+
+ /* ID format: i2c-<bus>-<address> */
+ snprintf(dev->name, sizeof(dev->name), "i2c-%d-%04x",
+ client->adapter->nr, client->addr);
+
+ for (i = 0; i < NUM_CHANNELS; i++) {
+ dev->is_open[i] = false;
+ dev->capabilities[i].data_type = MOST_CH_CONTROL;
+ dev->capabilities[i].num_buffers_packet = MAX_BUFFERS_CONTROL;
+ dev->capabilities[i].buffer_size_packet = MAX_BUF_SIZE_CONTROL;
+ }
+ dev->capabilities[CH_RX].direction = MOST_CH_RX;
+ dev->capabilities[CH_RX].name_suffix = "rx";
+ dev->capabilities[CH_TX].direction = MOST_CH_TX;
+ dev->capabilities[CH_TX].name_suffix = "tx";
+
+ dev->most_iface.interface = ITYPE_I2C;
+ dev->most_iface.description = dev->name;
+ dev->most_iface.num_channels = NUM_CHANNELS;
+ dev->most_iface.channel_vector = dev->capabilities;
+ dev->most_iface.configure = configure_channel;
+ dev->most_iface.enqueue = enqueue;
+ dev->most_iface.poison_channel = poison_channel;
+ dev->most_iface.request_netinfo = request_netinfo;
+
+ INIT_LIST_HEAD(&dev->rx.list);
+ mutex_init(&dev->rx.list_mutex);
+ init_waitqueue_head(&dev->rx.waitq);
+
+ INIT_DELAYED_WORK(&dev->rx.dwork, pending_rx_work);
+
+ dev->client = client;
+ i2c_set_clientdata(client, dev);
+
+ kobj = most_register_interface(&dev->most_iface);
+ if (IS_ERR(kobj)) {
+ pr_err("Failed to register i2c as a MOST interface\n");
+ kfree(dev);
+ return PTR_ERR(kobj);
+ }
+
+ dev->polling_mode = polling_req || client->irq <= 0;
+ if (!dev->polling_mode) {
+ pr_info("Requesting IRQ: %d\n", client->irq);
+ ret = request_irq(client->irq, most_irq_handler, IRQF_SHARED,
+ client->name, dev);
+ if (ret) {
+ pr_info("IRQ request failed: %d, "
+ "falling back to polling\n", ret);
+ dev->polling_mode = true;
+ }
+ }
+
+ if (dev->polling_mode)
+ pr_info("Using polling at rate: %d times/sec\n", scan_rate);
+
+ return 0;
+}
+
+/*
+ * i2c_remove - i2c remove handler
+ * @client: i2c client device structure
+ *
+ * Return 0 on success.
+ *
+ * Unregister the i2c client device as a MOST interface
+ */
+static int i2c_remove(struct i2c_client *client)
+{
+ struct hdm_i2c *dev = i2c_get_clientdata(client);
+ int i;
+
+ if (!dev->polling_mode)
+ free_irq(client->irq, dev);
+
+ most_deregister_interface(&dev->most_iface);
+
+ for (i = 0 ; i < NUM_CHANNELS; i++)
+ if (dev->is_open[i])
+ poison_channel(&dev->most_iface, i);
+ cancel_delayed_work_sync(&dev->rx.dwork);
+ kfree(dev);
+
+ return 0;
+}
+
+static const struct i2c_device_id i2c_id[] = {
+ { "most_i2c", 0 },
+ { }, /* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(i2c, i2c_id);
+
+static struct i2c_driver i2c_driver = {
+ .driver = {
+ .name = "hdm_i2c",
+ .owner = THIS_MODULE,
+ },
+ .probe = i2c_probe,
+ .remove = i2c_remove,
+ .id_table = i2c_id,
+};
+
+/**
+ * hdm_i2c_init - Driver Registration Routine
+ */
+static int __init hdm_i2c_init(void)
+{
+ pr_info("hdm_i2c_init()\n");
+
+ return i2c_add_driver(&i2c_driver);
+}
+
+/**
+ * hdm_i2c_exit - Driver Cleanup Routine
+ **/
+static void __exit hdm_i2c_exit(void)
+{
+ i2c_del_driver(&i2c_driver);
+ pr_info("hdm_i2c_exit()\n");
+}
+
+module_init(hdm_i2c_init);
+module_exit(hdm_i2c_exit);
+
+MODULE_AUTHOR("Jain Roy Ambi <JainRoy.Ambi@microchip.com>");
+MODULE_AUTHOR("Andrey Shvetsov <andrey.shvetsov@k2l.de>");
+MODULE_DESCRIPTION("I2C Hardware Dependent Module");
+MODULE_LICENSE("GPL");
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