scsi: a3000: Convert m68k WD33C93 drivers to DMA API

Use dma_map_single() for a3000 driver (leave bounce buffer logic
unchanged).

Use dma_set_mask_and_coherent() to avoid explicit cache flushes.

Compile-tested only.

CC: linux-scsi@vger.kernel.org
Link: https://lore.kernel.org/r/6d1d88ee-1cf6-c735-1e6d-bafd2096e322@gmail.com
Link: https://lore.kernel.org/r/20220630033302.3183-2-schmitzmic@gmail.com
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
--

Changes from v1:

- restore bounce buffer allocation (dropped in v1)

Arnd Bergmann:
- reorder dma mapping and bounce buffer copy

diff --git a/drivers/scsi/a3000.c b/drivers/scsi/a3000.c
index dd16188..2c5cb1a 100644 (file)
--- a/drivers/scsi/a3000.c
+++ b/drivers/scsi/a3000.c
@@ -7,6 +7,7 @@
 #include <linux/spinlock.h>
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
 #include <linux/module.h>
 
 #include <asm/page.h>
@@ -25,8 +26,11 @@
 struct a3000_hostdata {
        struct WD33C93_hostdata wh;
        struct a3000_scsiregs *regs;
+       struct device *dev;
 };
 
+#define DMA_DIR(d)   ((d == DATA_OUT_DIR) ? DMA_TO_DEVICE : DMA_FROM_DEVICE)
+
 static irqreturn_t a3000_intr(int irq, void *data)
 {
        struct Scsi_Host *instance = data;
@@ -49,20 +53,38 @@ static irqreturn_t a3000_intr(int irq, void *data)
 static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
 {
        struct scsi_pointer *scsi_pointer = WD33C93_scsi_pointer(cmd);
+       unsigned long len = scsi_pointer->this_residual;
        struct Scsi_Host *instance = cmd->device->host;
        struct a3000_hostdata *hdata = shost_priv(instance);
        struct WD33C93_hostdata *wh = &hdata->wh;
        struct a3000_scsiregs *regs = hdata->regs;
        unsigned short cntr = CNTR_PDMD | CNTR_INTEN;
-       unsigned long addr = virt_to_bus(scsi_pointer->ptr);
+       dma_addr_t addr;
+
+       addr = dma_map_single(hdata->dev, scsi_pointer->ptr,
+                             len, DMA_DIR(dir_in));
+       if (dma_mapping_error(hdata->dev, addr)) {
+               dev_warn(hdata->dev, "cannot map SCSI data block %p\n",
+                        scsi_pointer->ptr);
+               return 1;
+       }
+       scsi_pointer->dma_handle = addr;
 
        /*
         * if the physical address has the wrong alignment, or if
         * physical address is bad, or if it is a write and at the
         * end of a physical memory chunk, then allocate a bounce
         * buffer
+        * MSch 20220629 - only wrong alignment tested - bounce
+        * buffer returned by kmalloc is guaranteed to be aligned
         */
        if (addr & A3000_XFER_MASK) {
+               WARN_ONCE(1, "Invalid alignment for DMA!");
+               /* drop useless mapping */
+               dma_unmap_single(hdata->dev, scsi_pointer->dma_handle,
+                                scsi_pointer->this_residual,
+                                DMA_DIR(dir_in));
+
                wh->dma_bounce_len = (scsi_pointer->this_residual + 511) & ~0x1ff;
                wh->dma_bounce_buffer = kmalloc(wh->dma_bounce_len,
                                                GFP_KERNEL);
@@ -70,6 +92,7 @@ static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
                /* can't allocate memory; use PIO */
                if (!wh->dma_bounce_buffer) {
                        wh->dma_bounce_len = 0;
+                       scsi_pointer->dma_handle = (dma_addr_t) NULL;
                        return 1;
                }
 
@@ -79,7 +102,15 @@ static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
                               scsi_pointer->this_residual);
                }
 
-               addr = virt_to_bus(wh->dma_bounce_buffer);
+               addr = dma_map_single(hdata->dev, scsi_pointer->ptr,
+                                     len, DMA_DIR(dir_in));
+               if (dma_mapping_error(hdata->dev, addr)) {
+                       dev_warn(hdata->dev,
+                                "cannot map SCSI data block %p\n",
+                                scsi_pointer->ptr);
+                       return 1;
+               }
+               scsi_pointer->dma_handle = addr;
        }
 
        /* setup dma direction */
@@ -94,13 +125,7 @@ static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
        /* setup DMA *physical* address */
        regs->ACR = addr;
 
-       if (dir_in) {
-               /* invalidate any cache */
-               cache_clear(addr, scsi_pointer->this_residual);
-       } else {
-               /* push any dirty cache */
-               cache_push(addr, scsi_pointer->this_residual);
-       }
+       /* no more cache flush here - dma_map_single() takes care */
 
        /* start DMA */
        mb();                   /* make sure setup is completed */
@@ -151,6 +176,10 @@ static void dma_stop(struct Scsi_Host *instance, struct scsi_cmnd *SCpnt,
        regs->CNTR = CNTR_PDMD | CNTR_INTEN;
        mb();                   /* make sure CNTR is updated before next IO */
 
+       dma_unmap_single(hdata->dev, scsi_pointer->dma_handle,
+                        scsi_pointer->this_residual,
+                        DMA_DIR(wh->dma_dir));
+
        /* copy from a bounce buffer, if necessary */
        if (status && wh->dma_bounce_buffer) {
                if (SCpnt) {
@@ -193,6 +222,11 @@ static int __init amiga_a3000_scsi_probe(struct platform_device *pdev)
        wd33c93_regs wdregs;
        struct a3000_hostdata *hdata;
 
+       if (dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32))) {
+               dev_warn(&pdev->dev, "cannot use 32 bit DMA\n");
+               return -ENODEV;
+       }
+
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENODEV;
@@ -216,6 +250,7 @@ static int __init amiga_a3000_scsi_probe(struct platform_device *pdev)
        wdregs.SCMD = &regs->SCMD;
 
        hdata = shost_priv(instance);
+       hdata->dev = &pdev->dev;
        hdata->wh.no_sync = 0xff;
        hdata->wh.fast = 0;
        hdata->wh.dma_mode = CTRL_DMA;