[PATCH] sil24: implement proper TF register reading & caching

03_sil24_add-tf-reading.patch

	This patch implements proper TF register reading back and
	caching and bumps up version to 0.22.  This is taken from
	Edward's driver.
Signed-off-by: Tejun Heo <htejun@gmail.com>

 sata_sil24.c |   50 +++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 5 deletions(-)
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/scsi/sata_sil24.c

@@ -41,7 +41,7 @@
 #include <asm/io.h>
 
 #define DRV_NAME	"sata_sil24"
-#define DRV_VERSION	"0.21"	/* Silicon Image's preview driver was 0.10 */
+#define DRV_VERSION	"0.22"	/* Silicon Image's preview driver was 0.10 */
 
 #define NR_PORTS	4
 
@@ -216,6 +216,7 @@ struct sil24_cmd_block {
 struct sil24_port_priv {
 	struct sil24_cmd_block *cmd_block;	/* 32 cmd blocks */
 	dma_addr_t cmd_block_dma;		/* DMA base addr for them */
+	struct ata_taskfile tf;			/* Cached taskfile registers */
 };
 
 /* ap->host_set->private_data */
@@ -322,14 +323,25 @@ static struct ata_port_info sil24_port_info[] = {
 	},
 };
 
+static inline void sil24_update_tf(struct ata_port *ap)
+{
+	struct sil24_port_priv *pp = ap->private_data;
+	void *port = (void *)ap->ioaddr.cmd_addr;
+	struct sil24_prb *prb = port;
+
+	ata_tf_from_fis(prb->fis, &pp->tf);
+}
+
 static u8 sil24_check_status(struct ata_port *ap)
 {
-	return ATA_DRDY;
+	struct sil24_port_priv *pp = ap->private_data;
+	return pp->tf.command;
 }
 
 static u8 sil24_check_err(struct ata_port *ap)
 {
-	return 0;
+	struct sil24_port_priv *pp = ap->private_data;
+	return pp->tf.feature;
 }
 
 static int sil24_scr_map[] = {
@@ -485,6 +497,7 @@ static void sil24_eng_timeout(struct ata_port *ap)
 static void sil24_error_intr(struct ata_port *ap, u32 slot_stat)
 {
 	struct ata_queued_cmd *qc = ata_qc_from_tag(ap, ap->active_tag);
+	struct sil24_port_priv *pp = ap->private_data;
 	void *port = (void *)ap->ioaddr.cmd_addr;
 	u32 irq_stat, cmd_err, sstatus, serror;
 
@@ -509,8 +522,22 @@ static void sil24_error_intr(struct ata_port *ap, u32 slot_stat)
 	       "  stat=0x%x irq=0x%x cmd_err=%d sstatus=0x%x serror=0x%x\n",
 	       ap->id, ap->port_no, slot_stat, irq_stat, cmd_err, sstatus, serror);
 
+	if (cmd_err == PORT_CERR_DEV || cmd_err == PORT_CERR_SDB) {
+		/*
+		 * Device is reporting error, tf registers are valid.
+		 */
+		sil24_update_tf(ap);
+	} else {
+		/*
+		 * Other errors.  libata currently doesn't have any
+		 * mechanism to report these errors.  Just turn on
+		 * ATA_ERR.
+		 */
+		pp->tf.command = ATA_ERR;
+	}
+
 	if (qc)
-		ata_qc_complete(qc, ATA_ERR);
+		ata_qc_complete(qc, pp->tf.command);
 
 	sil24_reset_controller(ap);
 }
@@ -523,8 +550,19 @@ static inline void sil24_host_intr(struct ata_port *ap)
 
 	slot_stat = readl(port + PORT_SLOT_STAT);
 	if (!(slot_stat & HOST_SSTAT_ATTN)) {
+		struct sil24_port_priv *pp = ap->private_data;
+		/*
+		 * !HOST_SSAT_ATTN guarantees successful completion,
+		 * so reading back tf registers is unnecessary for
+		 * most commands.  TODO: read tf registers for
+		 * commands which require these values on successful
+		 * completion (EXECUTE DEVICE DIAGNOSTIC, CHECK POWER,
+		 * DEVICE RESET and READ PORT MULTIPLIER (any more?).
+		 */
+		sil24_update_tf(ap);
+
 		if (qc)
-			ata_qc_complete(qc, 0);
+			ata_qc_complete(qc, pp->tf.command);
 	} else
 		sil24_error_intr(ap, slot_stat);
 }
@@ -579,6 +617,8 @@ static int sil24_port_start(struct ata_port *ap)
 		return -ENOMEM;
 	memset(pp, 0, sizeof(*pp));
 
+	pp->tf.command = ATA_DRDY;
+
 	cb = dma_alloc_coherent(dev, cb_size, &cb_dma, GFP_KERNEL);
 	if (!cb) {
 		kfree(pp);