scsi: a2091: Convert m68k WD33C93 drivers to DMA API

Use dma_map_single() for a2091 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/20220630033302.3183-3-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:

Arnd Bergmann:
- reorder mapping and bounce buffer copy

diff --git a/drivers/scsi/a2091.c b/drivers/scsi/a2091.c
index cf703a1ecddae65994f911e8dd946f915c8ba991..74312400468ba6617899f71822f8ae6d088f8530 100644 (file)
--- a/drivers/scsi/a2091.c
+++ b/drivers/scsi/a2091.c
@@ -24,8 +24,11 @@
 struct a2091_hostdata {
        struct WD33C93_hostdata wh;
        struct a2091_scsiregs *regs;
+       struct device *dev;
 };
 
+#define DMA_DIR(d)   ((d == DATA_OUT_DIR) ? DMA_TO_DEVICE : DMA_FROM_DEVICE)
+
 static irqreturn_t a2091_intr(int irq, void *data)
 {
        struct Scsi_Host *instance = data;
@@ -45,15 +48,31 @@ static irqreturn_t a2091_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 a2091_hostdata *hdata = shost_priv(instance);
        struct WD33C93_hostdata *wh = &hdata->wh;
        struct a2091_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;
 
        /* don't allow DMA if the physical address is bad */
        if (addr & A2091_XFER_MASK) {
+               /* drop useless mapping */
+               dma_unmap_single(hdata->dev, scsi_pointer->dma_handle,
+                                scsi_pointer->this_residual,
+                                DMA_DIR(dir_in));
+               scsi_pointer->dma_handle = (dma_addr_t) NULL;
+
                wh->dma_bounce_len = (scsi_pointer->this_residual + 511) & ~0x1ff;
                wh->dma_bounce_buffer = kmalloc(wh->dma_bounce_len,
                                                GFP_KERNEL);
@@ -64,8 +83,21 @@ static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
                        return 1;
                }
 
-               /* get the physical address of the bounce buffer */
-               addr = virt_to_bus(wh->dma_bounce_buffer);
+               if (!dir_in) {
+                       /* copy to bounce buffer for a write */
+                       memcpy(wh->dma_bounce_buffer, scsi_pointer->ptr,
+                              scsi_pointer->this_residual);
+               }
+
+               /* will flush/invalidate cache for us */
+               addr = dma_map_single(hdata->dev, wh->dma_bounce_buffer,
+                                     wh->dma_bounce_len, DMA_DIR(dir_in));
+               /* can't map buffer; use PIO */
+               if (dma_mapping_error(hdata->dev, addr)) {
+                       dev_warn(hdata->dev, "cannot map bounce buffer %p\n",
+                                wh->dma_bounce_buffer);
+                       return 1;
+               }
 
                /* the bounce buffer may not be in the first 16M of physmem */
                if (addr & A2091_XFER_MASK) {
@@ -76,11 +108,7 @@ static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
                        return 1;
                }
 
-               if (!dir_in) {
-                       /* copy to bounce buffer for a write */
-                       memcpy(wh->dma_bounce_buffer, scsi_pointer->ptr,
-                              scsi_pointer->this_residual);
-               }
+               scsi_pointer->dma_handle = addr;
        }
 
        /* setup dma direction */
@@ -95,13 +123,8 @@ 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 */
        regs->ST_DMA = 1;
 
@@ -142,6 +165,10 @@ static void dma_stop(struct Scsi_Host *instance, struct scsi_cmnd *SCpnt,
        /* restore the CONTROL bits (minus the direction flag) */
        regs->CNTR = CNTR_PDMD | CNTR_INTEN;
 
+       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 (wh->dma_dir)
@@ -178,6 +205,11 @@ static int a2091_probe(struct zorro_dev *z, const struct zorro_device_id *ent)
        wd33c93_regs wdregs;
        struct a2091_hostdata *hdata;
 
+       if (dma_set_mask_and_coherent(&z->dev, DMA_BIT_MASK(24))) {
+               dev_warn(&z->dev, "cannot use 24 bit DMA\n");
+               return -ENODEV;
+       }
+
        if (!request_mem_region(z->resource.start, 256, "wd33c93"))
                return -EBUSY;
 
@@ -198,6 +230,7 @@ static int a2091_probe(struct zorro_dev *z, const struct zorro_device_id *ent)
        wdregs.SCMD = &regs->SCMD;
 
        hdata = shost_priv(instance);
+       hdata->dev = &z->dev;
        hdata->wh.no_sync = 0xff;
        hdata->wh.fast = 0;
        hdata->wh.dma_mode = CTRL_DMA;