ahci: Workaround HW bug for SB600/700 SATA controller PMP support

There is one bug in ATI SATA PMP of SB600 and SB700 old revision, which leads
to soft reset failure. This patch can fix the bug.
Signed-off-by: Shane Huang <shane.huang@amd.com>
Acked-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/ahci.c

@@ -255,6 +255,8 @@ static void ahci_pmp_attach(struct ata_port *ap);
 static void ahci_pmp_detach(struct ata_port *ap);
 static int ahci_softreset(struct ata_link *link, unsigned int *class,
 			  unsigned long deadline);
+static int ahci_sb600_softreset(struct ata_link *link, unsigned int *class,
+			  unsigned long deadline);
 static int ahci_hardreset(struct ata_link *link, unsigned int *class,
 			  unsigned long deadline);
 static int ahci_vt8251_hardreset(struct ata_link *link, unsigned int *class,
@@ -331,6 +333,12 @@ static struct ata_port_operations ahci_p5wdh_ops = {
 	.hardreset		= ahci_p5wdh_hardreset,
 };
 
+static struct ata_port_operations ahci_sb600_ops = {
+	.inherits		= &ahci_ops,
+	.softreset		= ahci_sb600_softreset,
+	.pmp_softreset		= ahci_sb600_softreset,
+};
+
 #define AHCI_HFLAGS(flags)	.private_data	= (void *)(flags)
 
 static const struct ata_port_info ahci_port_info[] = {
@@ -361,11 +369,11 @@ static const struct ata_port_info ahci_port_info[] = {
 	{
 		AHCI_HFLAGS	(AHCI_HFLAG_IGN_SERR_INTERNAL |
 				 AHCI_HFLAG_32BIT_ONLY | AHCI_HFLAG_NO_MSI |
-				 AHCI_HFLAG_SECT255 | AHCI_HFLAG_NO_PMP),
+				 AHCI_HFLAG_SECT255),
 		.flags		= AHCI_FLAG_COMMON,
 		.pio_mask	= 0x1f, /* pio0-4 */
 		.udma_mask	= ATA_UDMA6,
-		.port_ops	= &ahci_ops,
+		.port_ops	= &ahci_sb600_ops,
 	},
 	/* board_ahci_mv */
 	{
@@ -379,12 +387,11 @@ static const struct ata_port_info ahci_port_info[] = {
 	},
 	/* board_ahci_sb700 */
 	{
-		AHCI_HFLAGS	(AHCI_HFLAG_IGN_SERR_INTERNAL |
-				 AHCI_HFLAG_NO_PMP),
+		AHCI_HFLAGS	(AHCI_HFLAG_IGN_SERR_INTERNAL),
 		.flags		= AHCI_FLAG_COMMON,
 		.pio_mask	= 0x1f, /* pio0-4 */
 		.udma_mask	= ATA_UDMA6,
-		.port_ops	= &ahci_ops,
+		.port_ops	= &ahci_sb600_ops,
 	},
 	/* board_ahci_mcp65 */
 	{
@@ -1278,19 +1285,11 @@ static int ahci_exec_polled_cmd(struct ata_port *ap, int pmp,
 	return 0;
 }
 
-static int ahci_check_ready(struct ata_link *link)
-{
-	void __iomem *port_mmio = ahci_port_base(link->ap);
-	u8 status = readl(port_mmio + PORT_TFDATA) & 0xFF;
-
-	return ata_check_ready(status);
-}
-
-static int ahci_softreset(struct ata_link *link, unsigned int *class,
-			  unsigned long deadline)
+static int ahci_do_softreset(struct ata_link *link, unsigned int *class,
+			     int pmp, unsigned long deadline,
+			     int (*check_ready)(struct ata_link *link))
 {
 	struct ata_port *ap = link->ap;
-	int pmp = sata_srst_pmp(link);
 	const char *reason = NULL;
 	unsigned long now, msecs;
 	struct ata_taskfile tf;
@@ -1328,7 +1327,7 @@ static int ahci_softreset(struct ata_link *link, unsigned int *class,
 	ahci_exec_polled_cmd(ap, pmp, &tf, 0, 0, 0);
 
 	/* wait for link to become ready */
-	rc = ata_wait_after_reset(link, deadline, ahci_check_ready);
+	rc = ata_wait_after_reset(link, deadline, check_ready);
 	/* link occupied, -ENODEV too is an error */
 	if (rc) {
 		reason = "device not ready";
@@ -1344,6 +1343,72 @@ static int ahci_softreset(struct ata_link *link, unsigned int *class,
 	return rc;
 }
 
+static int ahci_check_ready(struct ata_link *link)
+{
+	void __iomem *port_mmio = ahci_port_base(link->ap);
+	u8 status = readl(port_mmio + PORT_TFDATA) & 0xFF;
+
+	return ata_check_ready(status);
+}
+
+static int ahci_softreset(struct ata_link *link, unsigned int *class,
+			  unsigned long deadline)
+{
+	int pmp = sata_srst_pmp(link);
+
+	DPRINTK("ENTER\n");
+
+	return ahci_do_softreset(link, class, pmp, deadline, ahci_check_ready);
+}
+
+static int ahci_sb600_check_ready(struct ata_link *link)
+{
+	void __iomem *port_mmio = ahci_port_base(link->ap);
+	u8 status = readl(port_mmio + PORT_TFDATA) & 0xFF;
+	u32 irq_status = readl(port_mmio + PORT_IRQ_STAT);
+
+	/*
+	 * There is no need to check TFDATA if BAD PMP is found due to HW bug,
+	 * which can save timeout delay.
+	 */
+	if (irq_status & PORT_IRQ_BAD_PMP)
+		return -EIO;
+
+	return ata_check_ready(status);
+}
+
+static int ahci_sb600_softreset(struct ata_link *link, unsigned int *class,
+				unsigned long deadline)
+{
+	struct ata_port *ap = link->ap;
+	void __iomem *port_mmio = ahci_port_base(ap);
+	int pmp = sata_srst_pmp(link);
+	int rc;
+	u32 irq_sts;
+
+	DPRINTK("ENTER\n");
+
+	rc = ahci_do_softreset(link, class, pmp, deadline,
+			       ahci_sb600_check_ready);
+
+	/*
+	 * Soft reset fails on some ATI chips with IPMS set when PMP
+	 * is enabled but SATA HDD/ODD is connected to SATA port,
+	 * do soft reset again to port 0.
+	 */
+	if (rc == -EIO) {
+		irq_sts = readl(port_mmio + PORT_IRQ_STAT);
+		if (irq_sts & PORT_IRQ_BAD_PMP) {
+			ata_link_printk(link, KERN_WARNING,
+					"failed due to HW bug, retry pmp=0\n");
+			rc = ahci_do_softreset(link, class, 0, deadline,
+					       ahci_check_ready);
+		}
+	}
+
+	return rc;
+}
+
 static int ahci_hardreset(struct ata_link *link, unsigned int *class,
 			  unsigned long deadline)
 {