libata: use ata_exec_internal() for PMP register access

PMP registers used to be accessed with dedicated accessors ->pmp_read
and ->pmp_write.  During reset, those callbacks are called with the
port frozen so they should be able to run without depending on
interrupt delivery.  To achieve this, they were implemented polling.

However, as resetting the host port makes the PMP to isolate fan-out
ports until SError.X is cleared, resetting fan-out ports while port is
frozen doesn't buy much additional safety.

This patch updates libata PMP support such that PMP registers are
accessed using regular ata_exec_internal() mechanism and kills
->pmp_read/write() callbacks.  The following changes are made.

* PMP access helpers - sata_pmp_read_init_tf(), sata_pmp_read_val(),
  sata_pmp_write_init_tf() are folded into sata_pmp_read/write() which
  are now standalone PMP register access functions.

* sata_pmp_read/write() returns err_mask instead of rc.  This is
  consistent with other functions which issue internal commands and
  allows more detailed error reporting.

* ahci interrupt handler is modified to ignore BAD_PMP and
  spurious/illegal completion IRQs while reset is in progress.  These
  conditions are expected during reset.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/ahci.c

@@ -239,8 +239,6 @@ static void ahci_freeze(struct ata_port *ap);
 static void ahci_thaw(struct ata_port *ap);
 static void ahci_pmp_attach(struct ata_port *ap);
 static void ahci_pmp_detach(struct ata_port *ap);
-static int ahci_pmp_read(struct ata_device *dev, int pmp, int reg, u32 *r_val);
-static int ahci_pmp_write(struct ata_device *dev, int pmp, int reg, u32 val);
 static void ahci_error_handler(struct ata_port *ap);
 static void ahci_vt8251_error_handler(struct ata_port *ap);
 static void ahci_post_internal_cmd(struct ata_queued_cmd *qc);
@@ -297,8 +295,6 @@ static const struct ata_port_operations ahci_ops = {
 
 	.pmp_attach		= ahci_pmp_attach,
 	.pmp_detach		= ahci_pmp_detach,
-	.pmp_read		= ahci_pmp_read,
-	.pmp_write		= ahci_pmp_write,
 
 #ifdef CONFIG_PM
 	.port_suspend		= ahci_port_suspend,
@@ -333,8 +329,6 @@ static const struct ata_port_operations ahci_vt8251_ops = {
 
 	.pmp_attach		= ahci_pmp_attach,
 	.pmp_detach		= ahci_pmp_detach,
-	.pmp_read		= ahci_pmp_read,
-	.pmp_write		= ahci_pmp_write,
 
 #ifdef CONFIG_PM
 	.port_suspend		= ahci_port_suspend,
@@ -1421,12 +1415,17 @@ static void ahci_port_intr(struct ata_port *ap)
 	struct ata_eh_info *ehi = &ap->link.eh_info;
 	struct ahci_port_priv *pp = ap->private_data;
 	struct ahci_host_priv *hpriv = ap->host->private_data;
+	int resetting = !!(ap->pflags & ATA_PFLAG_RESETTING);
 	u32 status, qc_active;
 	int rc, known_irq = 0;
 
 	status = readl(port_mmio + PORT_IRQ_STAT);
 	writel(status, port_mmio + PORT_IRQ_STAT);
 
+	/* ignore BAD_PMP while resetting */
+	if (unlikely(resetting))
+		status &= ~PORT_IRQ_BAD_PMP;
+
 	if (unlikely(status & PORT_IRQ_ERROR)) {
 		ahci_error_intr(ap, status);
 		return;
@@ -1464,6 +1463,13 @@ static void ahci_port_intr(struct ata_port *ap)
 		qc_active = readl(port_mmio + PORT_CMD_ISSUE);
 
 	rc = ata_qc_complete_multiple(ap, qc_active, NULL);
+
+	/* If resetting, spurious or invalid completions are expected,
+	 * return unconditionally.
+	 */
+	if (resetting)
+		return;
+
 	if (rc > 0)
 		return;
 	if (rc < 0) {
@@ -1701,36 +1707,6 @@ static void ahci_pmp_detach(struct ata_port *ap)
 	writel(pp->intr_mask, port_mmio + PORT_IRQ_MASK);
 }
 
-static int ahci_pmp_read(struct ata_device *dev, int pmp, int reg, u32 *r_val)
-{
-	struct ata_port *ap = dev->link->ap;
-	struct ata_taskfile tf;
-	int rc;
-
-	ahci_kick_engine(ap, 0);
-
-	sata_pmp_read_init_tf(&tf, dev, pmp, reg);
-	rc = ahci_exec_polled_cmd(ap, SATA_PMP_CTRL_PORT, &tf, 1, 0,
-				  SATA_PMP_SCR_TIMEOUT);
-	if (rc == 0) {
-		ahci_tf_read(ap, &tf);
-		*r_val = sata_pmp_read_val(&tf);
-	}
-	return rc;
-}
-
-static int ahci_pmp_write(struct ata_device *dev, int pmp, int reg, u32 val)
-{
-	struct ata_port *ap = dev->link->ap;
-	struct ata_taskfile tf;
-
-	ahci_kick_engine(ap, 0);
-
-	sata_pmp_write_init_tf(&tf, dev, pmp, reg, val);
-	return ahci_exec_polled_cmd(ap, SATA_PMP_CTRL_PORT, &tf, 1, 0,
-				    SATA_PMP_SCR_TIMEOUT);
-}
-
 static int ahci_port_resume(struct ata_port *ap)
 {
 	ahci_power_up(ap);

drivers/ata/libata-core.c

@@ -7354,9 +7354,6 @@ EXPORT_SYMBOL_GPL(ata_pci_clear_simplex);
 #endif /* CONFIG_PCI */
 
 EXPORT_SYMBOL_GPL(sata_pmp_qc_defer_cmd_switch);
-EXPORT_SYMBOL_GPL(sata_pmp_read_init_tf);
-EXPORT_SYMBOL_GPL(sata_pmp_read_val);
-EXPORT_SYMBOL_GPL(sata_pmp_write_init_tf);
 EXPORT_SYMBOL_GPL(sata_pmp_std_prereset);
 EXPORT_SYMBOL_GPL(sata_pmp_std_hardreset);
 EXPORT_SYMBOL_GPL(sata_pmp_std_postreset);

drivers/ata/libata-eh.c

@@ -2557,7 +2557,11 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
 
 	/* reset */
 	if (reset) {
-		ata_eh_freeze_port(ap);
+		/* if PMP is attached, this function only deals with
+		 * downstream links, port should stay thawed.
+		 */
+		if (!ap->nr_pmp_links)
+			ata_eh_freeze_port(ap);
 
 		ata_port_for_each_link(link, ap) {
 			struct ata_eh_context *ehc = &link->eh_context;
@@ -2575,7 +2579,8 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
 			}
 		}
 
-		ata_eh_thaw_port(ap);
+		if (!ap->nr_pmp_links)
+			ata_eh_thaw_port(ap);
 	}
 
 	/* the rest */
@@ -2610,8 +2615,14 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
 		if (ata_eh_handle_dev_fail(dev, rc))
 			nr_disabled_devs++;
 
-		if (ap->pflags & ATA_PFLAG_FROZEN)
+		if (ap->pflags & ATA_PFLAG_FROZEN) {
+			/* PMP reset requires working host port.
+			 * Can't retry if it's frozen.
+			 */
+			if (ap->nr_pmp_links)
+				goto out;
 			break;
+		}
 	}
 
 	if (nr_failed_devs) {