[PATCH libata-dev.git upstream 1/1] ahci: add support for VIA VT8251

[Bastiaan Jacques <b.jacques@planet.nl>]

Adds AHCI support for the VIA VT8251.

Includes a workaround for a hardware bug which requires a Command List
Override before softreset.

Signed-off-by: Bastiaan Jacques <b.jacques@planet.nl>
---

I have been informed that VIA have also made a patch available for the
sata_via driver for this chip. Do you think it would be useful to merge
that patch in addition to the AHCI one, or does AHCI support make the
"native" sata_via driver obsolete?

Below is the latest version of the (AHCI) patch, with a small change to
the error handling in ahci_softreset(): test for "if (rc)" just in case
someone decides to change the error return values of ahci_clo().


This patch is against libata-dev.git upstream[1].

[1] 26ec634c31a11a003040e10b4d650495158632fd


diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 1b8429c..2fe4850 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -73,6 +73,7 @@ enum {
 	RX_FIS_D2H_REG		= 0x40,	/* offset of D2H Register FIS data */
 
 	board_ahci		= 0,
+	board_ahci_vt8251	= 1,
 
 	/* global controller registers */
 	HOST_CAP		= 0x00, /* host capabilities */
@@ -153,6 +154,9 @@ enum {
 
 	/* hpriv->flags bits */
 	AHCI_FLAG_MSI		= (1 << 0),
+
+	/* ap->flags bits */
+	AHCI_FLAG_RESET_NEEDS_CLO	= (1 << 24),
 };
 
 struct ahci_cmd_hdr {
@@ -255,6 +259,16 @@ static const struct ata_port_info ahci_p
 		.udma_mask	= 0x7f, /* udma0-6 ; FIXME */
 		.port_ops	= &ahci_ops,
 	},
+	/* board_ahci_vt8251 */
+	{
+		.sht		= &ahci_sht,
+		.host_flags	= ATA_FLAG_SATA | ATA_FLAG_NO_LEGACY |
+				  ATA_FLAG_MMIO | ATA_FLAG_PIO_DMA |
+				  AHCI_FLAG_RESET_NEEDS_CLO,
+		.pio_mask	= 0x1f, /* pio0-4 */
+		.udma_mask	= 0x7f, /* udma0-6 ; FIXME */
+		.port_ops	= &ahci_ops,
+	},
 };
 
 static const struct pci_device_id ahci_pci_tbl[] = {
@@ -296,6 +310,8 @@ static const struct pci_device_id ahci_p
 	  board_ahci }, /* ATI SB600 non-raid */
 	{ PCI_VENDOR_ID_ATI, 0x4381, PCI_ANY_ID, PCI_ANY_ID, 0, 0,
 	  board_ahci }, /* ATI SB600 raid */
+	{ PCI_VENDOR_ID_VIA, 0x3349, PCI_ANY_ID, PCI_ANY_ID, 0, 0,
+	  board_ahci_vt8251 }, /* VT8251 */
 	{ }	/* terminate list */
 };
 
@@ -516,9 +532,29 @@ static void ahci_fill_cmd_slot(struct ah
 	pp->cmd_slot[0].tbl_addr_hi = cpu_to_le32((pp->cmd_tbl_dma >> 16) >> 16);
 }
 
-static int ahci_softreset(struct ata_port *ap, unsigned int *class)
+static int ahci_clo(struct ata_port *ap)
 {
+	void __iomem *port_mmio = (void __iomem *) ap->ioaddr.cmd_addr;
 	struct ahci_host_priv *hpriv = ap->host_set->private_data;
+	u32 tmp;
+
+	if (!(hpriv->cap & HOST_CAP_CLO))
+		return -EOPNOTSUPP;
+
+	tmp = readl(port_mmio + PORT_CMD);
+	tmp |= PORT_CMD_CLO;
+	writel(tmp, port_mmio + PORT_CMD);
+
+	tmp = ata_wait_register(port_mmio + PORT_CMD,
+				PORT_CMD_CLO, PORT_CMD_CLO, 1, 500);
+	if (tmp & PORT_CMD_CLO)
+		return -EIO;
+
+	return 0;
+}
+
+static int ahci_softreset(struct ata_port *ap, unsigned int *class)
+{
 	struct ahci_port_priv *pp = ap->private_data;
 	void __iomem *mmio = ap->host_set->mmio_base;
 	void __iomem *port_mmio = ahci_port_base(mmio, ap->port_no);
@@ -547,21 +583,13 @@ static int ahci_softreset(struct ata_por
 	/* check BUSY/DRQ, perform Command List Override if necessary */
 	ahci_tf_read(ap, &tf);
 	if (tf.command & (ATA_BUSY | ATA_DRQ)) {
-		if (!(hpriv->cap & HOST_CAP_CLO)) {
-			rc = -EIO;
-			reason = "port busy but no CLO";
-			goto fail_restart;
-		}
-
-		tmp = readl(port_mmio + PORT_CMD);
-		tmp |= PORT_CMD_CLO;
-		writel(tmp, port_mmio + PORT_CMD);
+		rc = ahci_clo(ap);
 
-		tmp = ata_wait_register(port_mmio + PORT_CMD,
-					PORT_CMD_CLO, PORT_CMD_CLO, 1, 500);
-		if (tmp & PORT_CMD_CLO) {
-			rc = -EIO;
-			reason = "CLO failed";
+		if (rc == -EOPNOTSUPP) {
+			reason = "port busy but CLO unavailable";
+			goto fail_restart;
+		} else if (rc) {
+			reason = "port busy but CLO failed";
 			goto fail_restart;
 		}
 	}
@@ -672,6 +700,12 @@ static void ahci_postreset(struct ata_po
 
 static int ahci_probe_reset(struct ata_port *ap, unsigned int *classes)
 {
+	if ((ap->flags & AHCI_FLAG_RESET_NEEDS_CLO) &&
+	    (ata_busy_wait(ap, ATA_BUSY, 1000) & ATA_BUSY)) {
+		/* ATA_BUSY hasn't cleared, so send a CLO */
+		ahci_clo(ap);
+	}
+
 	return ata_drive_probe_reset(ap, ata_std_probeinit,
 				     ahci_softreset, ahci_hardreset,
 				     ahci_postreset, classes);