[PATCH v1 3/3] scsi - gvp11.c: convert m68k WD33C93 drivers to DMA API

[Michael Schmitz <schmitzmic@gmail.com>]

Use dma_map_single() for gvp11 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
Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
---
 drivers/scsi/gvp11.c | 78 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 65 insertions(+), 13 deletions(-)

diff --git a/drivers/scsi/gvp11.c b/drivers/scsi/gvp11.c
index 2f6c56aabe1d..a793323e008f 100644
--- a/drivers/scsi/gvp11.c
+++ b/drivers/scsi/gvp11.c
@@ -26,8 +26,12 @@
 struct gvp11_hostdata {
 	struct WD33C93_hostdata wh;
 	struct gvp11_scsiregs *regs;
+	struct device *dev;
 };
 
+#define DMA_DIR(d)   ((d == DATA_OUT_DIR) ? DMA_TO_DEVICE : DMA_FROM_DEVICE)
+#define TO_DMA_MASK(m)	((~(m & 0xfffffff0))-1)
+
 static irqreturn_t gvp11_intr(int irq, void *data)
 {
 	struct Scsi_Host *instance = data;
@@ -54,17 +58,33 @@ void gvp11_setup(char *str, int *ints)
 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 gvp11_hostdata *hdata = shost_priv(instance);
 	struct WD33C93_hostdata *wh = &hdata->wh;
 	struct gvp11_scsiregs *regs = hdata->regs;
 	unsigned short cntr = GVP11_DMAC_INT_ENABLE;
-	unsigned long addr = virt_to_bus(scsi_pointer->ptr);
+	dma_addr_t addr;
 	int bank_mask;
 	static int scsi_alloc_out_of_range = 0;
 
+	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;
+
 	/* use bounce buffer if the physical address is bad */
 	if (addr & wh->dma_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;
 
 		if (!scsi_alloc_out_of_range) {
@@ -87,10 +107,21 @@ static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
 			wh->dma_buffer_pool = BUF_CHIP_ALLOCED;
 		}
 
-		/* check if the address of the bounce buffer is OK */
-		addr = virt_to_bus(wh->dma_bounce_buffer);
+		/* may 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;
+		}
 
 		if (addr & wh->dma_xfer_mask) {
+			/* drop useless mapping */
+			dma_unmap_single(hdata->dev, scsi_pointer->dma_handle,
+					 scsi_pointer->this_residual,
+					 DMA_DIR(dir_in));
 			/* fall back to Chip RAM if address out of range */
 			if (wh->dma_buffer_pool == BUF_SCSI_ALLOCED) {
 				kfree(wh->dma_bounce_buffer);
@@ -108,9 +139,19 @@ static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
 				return 1;
 			}
 
-			addr = virt_to_bus(wh->dma_bounce_buffer);
+			/* may 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;
+			}
 			wh->dma_buffer_pool = BUF_CHIP_ALLOCED;
 		}
+		/* finally, have OK mapping (punted for PIO else) */
+		scsi_pointer->dma_handle = addr;
 
 		if (!dir_in) {
 			/* copy to bounce buffer for a write */
@@ -129,13 +170,7 @@ 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 - using coherent memory! */
 
 	bank_mask = (~wh->dma_xfer_mask >> 18) & 0x01c0;
 	if (bank_mask)
@@ -175,6 +210,9 @@ static void dma_stop(struct Scsi_Host *instance, struct scsi_cmnd *SCpnt,
 		wh->dma_bounce_buffer = NULL;
 		wh->dma_bounce_len = 0;
 	}
+	dma_unmap_single(hdata->dev, scsi_pointer->dma_handle,
+			 scsi_pointer->this_residual,
+			 DMA_DIR(wh->dma_dir));
 }
 
 static struct scsi_host_template gvp11_scsi_template = {
@@ -287,6 +325,13 @@ static int gvp11_probe(struct zorro_dev *z, const struct zorro_device_id *ent)
 
 	default_dma_xfer_mask = ent->driver_data;
 
+	if (dma_set_mask_and_coherent(&z->dev,
+		TO_DMA_MASK(default_dma_xfer_mask))) {
+		dev_warn(&z->dev, "cannot use DMA mask %x\n",
+			 TO_DMA_MASK(default_dma_xfer_mask));
+		return -ENODEV;
+	}
+
 	/*
 	 * Rumors state that some GVP ram boards use the same product
 	 * code as the SCSI controllers. Therefore if the board-size
@@ -327,9 +372,16 @@ static int gvp11_probe(struct zorro_dev *z, const struct zorro_device_id *ent)
 	wdregs.SCMD = &regs->SCMD;
 
 	hdata = shost_priv(instance);
-	if (gvp11_xfer_mask)
+	if (gvp11_xfer_mask) {
 		hdata->wh.dma_xfer_mask = gvp11_xfer_mask;
-	else
+		if (dma_set_mask_and_coherent(&z->dev,
+			TO_DMA_MASK(gvp11_xfer_mask))) {
+			dev_warn(&z->dev, "cannot use DMA mask %x\n",
+				 TO_DMA_MASK(gvp11_xfer_mask));
+			error = -ENODEV;
+			goto fail_check_or_alloc;
+		}
+	} else
 		hdata->wh.dma_xfer_mask = default_dma_xfer_mask;
 
 	hdata->wh.no_sync = 0xff;
-- 
2.17.1