scsi: mac_scsi: Enable PDMA on Mac IIfx

Add support for Apple's custom "SCSI DMA" chip. This patch doesn't make use
of its DMA capability. Just the PDMA capability is sufficient to improve
sequential read throughput by a factor of 5.

Cc: Michael Schmitz <schmitzmic@gmail.com>
Cc: Joshua Thompson <funaho@jurai.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Stan Johnson <userm57@yahoo.com>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 39 insertions, 8 deletions

diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index 27364b71e833..8fbec1768bbf 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -24,6 +24,7 @@
 
 #include <asm/hwtest.h>
 #include <asm/io.h>
+#include <asm/macintosh.h>
 #include <asm/macints.h>
 #include <asm/setup.h>
 
@@ -262,11 +263,22 @@ out:
 	return addr - start;
 }
 
+/* The "SCSI DMA" chip on the IIfx implements this register. */
+#define CTRL_REG                0x8
+#define CTRL_INTERRUPTS_ENABLE  BIT(1)
+#define CTRL_HANDSHAKE_MODE     BIT(3)
+
+static inline void write_ctrl_reg(struct NCR5380_hostdata *hostdata, u32 value)
+{
+	out_be32(hostdata->io + (CTRL_REG << 4), value);
+}
+
 static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
                                 unsigned char *dst, int len)
 {
 	u8 __iomem *s = hostdata->pdma_io + (INPUT_DATA_REG << 4);
 	unsigned char *d = dst;
+	int result = 0;
 
 	hostdata->pdma_residual = len;
 
@@ -275,6 +287,10 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
 		int bytes;
 
+		if (macintosh_config->ident == MAC_MODEL_IIFX)
+			write_ctrl_reg(hostdata, CTRL_HANDSHAKE_MODE |
+			                         CTRL_INTERRUPTS_ENABLE);
+
 		bytes = mac_pdma_recv(s, d, min(hostdata->pdma_residual, 512));
 
 		if (bytes > 0) {
@@ -283,7 +299,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 		}
 
 		if (hostdata->pdma_residual == 0)
-			return 0;
+			goto out;
 
 		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
 		                           BUS_AND_STATUS_REG, BASR_ACK,
@@ -291,7 +307,7 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 			scmd_printk(KERN_DEBUG, hostdata->connected,
 			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
-			return 0;
+			goto out;
 
 		if (bytes == 0)
 			udelay(MAC_PDMA_DELAY);
@@ -302,13 +318,18 @@ static inline int macscsi_pread(struct NCR5380_hostdata *hostdata,
 		dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
 		         "%s: bus error (%d/%d)\n", __func__, d - dst, len);
 		NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
-		return -1;
+		result = -1;
+		goto out;
 	}
 
 	scmd_printk(KERN_ERR, hostdata->connected,
 	            "%s: phase mismatch or !DRQ\n", __func__);
 	NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
-	return -1;
+	result = -1;
+out:
+	if (macintosh_config->ident == MAC_MODEL_IIFX)
+		write_ctrl_reg(hostdata, CTRL_INTERRUPTS_ENABLE);
+	return result;
 }
 
 static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
@@ -316,6 +337,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 {
 	unsigned char *s = src;
 	u8 __iomem *d = hostdata->pdma_io + (OUTPUT_DATA_REG << 4);
+	int result = 0;
 
 	hostdata->pdma_residual = len;
 
@@ -324,6 +346,10 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 	                              BASR_DRQ | BASR_PHASE_MATCH, HZ / 64)) {
 		int bytes;
 
+		if (macintosh_config->ident == MAC_MODEL_IIFX)
+			write_ctrl_reg(hostdata, CTRL_HANDSHAKE_MODE |
+			                         CTRL_INTERRUPTS_ENABLE);
+
 		bytes = mac_pdma_send(s, d, min(hostdata->pdma_residual, 512));
 
 		if (bytes > 0) {
@@ -337,7 +363,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 			                          TCR_LAST_BYTE_SENT, HZ / 64) < 0)
 				scmd_printk(KERN_ERR, hostdata->connected,
 				            "%s: Last Byte Sent timeout\n", __func__);
-			return 0;
+			goto out;
 		}
 
 		if (NCR5380_poll_politely2(hostdata, STATUS_REG, SR_REQ, SR_REQ,
@@ -346,7 +372,7 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 			scmd_printk(KERN_DEBUG, hostdata->connected,
 			            "%s: !REQ and !ACK\n", __func__);
 		if (!(NCR5380_read(BUS_AND_STATUS_REG) & BASR_PHASE_MATCH))
-			return 0;
+			goto out;
 
 		if (bytes == 0)
 			udelay(MAC_PDMA_DELAY);
@@ -357,13 +383,18 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 		dsprintk(NDEBUG_PSEUDO_DMA, hostdata->host,
 		         "%s: bus error (%d/%d)\n", __func__, s - src, len);
 		NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
-		return -1;
+		result = -1;
+		goto out;
 	}
 
 	scmd_printk(KERN_ERR, hostdata->connected,
 	            "%s: phase mismatch or !DRQ\n", __func__);
 	NCR5380_dprint(NDEBUG_PSEUDO_DMA, hostdata->host);
-	return -1;
+	result = -1;
+out:
+	if (macintosh_config->ident == MAC_MODEL_IIFX)
+		write_ctrl_reg(hostdata, CTRL_INTERRUPTS_ENABLE);
+	return result;
 }
 
 static int macscsi_dma_xfer_len(struct NCR5380_hostdata *hostdata,