[PATCH v1 4/4] scsi - convert mvme147_scsi driver to DMA API

[Michael Schmitz <schmitzmic@gmail.com>]

Convert mvme147_scsi to DMA API to eliminate one of the last
usages of virt_to_bus().

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/mvme147.c | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/mvme147.c b/drivers/scsi/mvme147.c
index aa6476c3e70c..6ffd15f08629 100644
--- a/drivers/scsi/mvme147.c
+++ b/drivers/scsi/mvme147.c
@@ -21,6 +21,8 @@
 #include "wd33c93.h"
 #include "mvme147.h"
 
+#define DMA_DIR(d)   ((d == DATA_OUT_DIR) ? DMA_TO_DEVICE : DMA_FROM_DEVICE)
+
 static irqreturn_t mvme147_intr(int irq, void *data)
 {
 	struct Scsi_Host *instance = data;
@@ -35,10 +37,20 @@ static irqreturn_t mvme147_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 WD33C93_hostdata *hdata = shost_priv(instance);
 	unsigned char flags = 0x01;
-	unsigned long addr = virt_to_bus(scsi_pointer->ptr);
+	dma_addr_t addr;
+
+	addr = dma_map_single(instance->dma_dev, scsi_pointer->ptr,
+			      len, DMA_DIR(dir_in));
+	if (dma_mapping_error(instance->dma_dev, addr)) {
+		dev_warn(instance->dma_dev, "cannot map SCSI data block %p\n",
+			 scsi_pointer->ptr);
+		return 1;
+	}
+	scsi_pointer->dma_handle = addr;
 
 	/* setup dma direction */
 	if (!dir_in)
@@ -47,14 +59,6 @@ static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
 	/* remember direction */
 	hdata->dma_dir = dir_in;
 
-	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);
-	}
-
 	/* start DMA */
 	m147_pcc->dma_bcr = scsi_pointer->this_residual | (1 << 24);
 	m147_pcc->dma_dadr = addr;
@@ -67,7 +71,13 @@ static int dma_setup(struct scsi_cmnd *cmd, int dir_in)
 static void dma_stop(struct Scsi_Host *instance, struct scsi_cmnd *SCpnt,
 		     int status)
 {
+	struct scsi_pointer *scsi_pointer = WD33C93_scsi_pointer(SCpnt);
+	struct WD33C93_hostdata *hdata = shost_priv(instance);
+
 	m147_pcc->dma_cntrl = 0;
+	dma_unmap_single(instance->dma_dev, scsi_pointer->dma_handle,
+			 scsi_pointer->this_residual,
+			 DMA_DIR(hdata->dma_dir));
 }
 
 static struct scsi_host_template mvme147_host_template = {
@@ -94,6 +104,11 @@ static int __init mvme147_scsi_probe(struct platform_device *pdev)
 	struct WD33C93_hostdata *hdata;
 	int error = -ENOMEM;
 
+	if (dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32))) {
+		dev_warn(&pdev->dev, "cannot use 32 bit DMA\n");
+		return -ENODEV;
+	}
+
 	mres = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!mres)
 		return -ENODEV;
-- 
2.17.1