libata: implement LPM support for port multipliers

Port multipliers can do DIPM on fan-out links fine.  Implement support
for it.  Tested w/ SIMG 57xx and marvell PMPs.  Both the host and
fan-out links enter power save modes nicely.

SIMG 37xx and 47xx report link offline on SStatus causing EH to detach
the devices.  Blacklisted.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-eh.c

@@ -3232,7 +3232,7 @@ static int ata_eh_maybe_retry_flush(struct ata_device *dev)
 static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 			  struct ata_device **r_failed_dev)
 {
-	struct ata_port *ap = link->ap;
+	struct ata_port *ap = ata_is_host_link(link) ? link->ap : NULL;
 	struct ata_eh_context *ehc = &link->eh_context;
 	struct ata_device *dev, *link_dev = NULL, *lpm_dev = NULL;
 	unsigned int hints = ATA_LPM_EMPTY | ATA_LPM_HIPM;
@@ -3278,9 +3278,12 @@ static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 		}
 	}
 
-	rc = ap->ops->set_lpm(link, policy, hints);
-	if (!rc && ap->slave_link)
-		rc = ap->ops->set_lpm(ap->slave_link, policy, hints);
+	if (ap) {
+		rc = ap->ops->set_lpm(link, policy, hints);
+		if (!rc && ap->slave_link)
+			rc = ap->ops->set_lpm(ap->slave_link, policy, hints);
+	} else
+		rc = sata_pmp_set_lpm(link, policy, hints);
 
 	/*
 	 * Attribute link config failure to the first (LPM) enabled
@@ -3412,8 +3415,14 @@ static int ata_eh_schedule_probe(struct ata_device *dev)
 	ehc->saved_ncq_enabled &= ~(1 << dev->devno);
 
 	/* the link maybe in a deep sleep, wake it up */
-	if (link->lpm_policy > ATA_LPM_MAX_POWER)
-		link->ap->ops->set_lpm(link, ATA_LPM_MAX_POWER, ATA_LPM_EMPTY);
+	if (link->lpm_policy > ATA_LPM_MAX_POWER) {
+		if (ata_is_host_link(link))
+			link->ap->ops->set_lpm(link, ATA_LPM_MAX_POWER,
+					       ATA_LPM_EMPTY);
+		else
+			sata_pmp_set_lpm(link, ATA_LPM_MAX_POWER,
+					 ATA_LPM_EMPTY);
+	}
 
 	/* Record and count probe trials on the ering.  The specific
 	 * error mask used is irrelevant.  Because a successful device

drivers/ata/libata-pmp.c

@@ -185,6 +185,27 @@ int sata_pmp_scr_write(struct ata_link *link, int reg, u32 val)
 	return 0;
 }
 
+/**
+ *	sata_pmp_set_lpm - configure LPM for a PMP link
+ *	@link: PMP link to configure LPM for
+ *	@policy: target LPM policy
+ *	@hints: LPM hints
+ *
+ *	Configure LPM for @link.  This function will contain any PMP
+ *	specific workarounds if necessary.
+ *
+ *	LOCKING:
+ *	EH context.
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+int sata_pmp_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
+		     unsigned hints)
+{
+	return sata_link_scr_lpm(link, policy, true);
+}
+
 /**
  *	sata_pmp_read_gscr - read GSCR block of SATA PMP
  *	@dev: PMP device
@@ -365,6 +386,9 @@ static void sata_pmp_quirks(struct ata_port *ap)
 	if (vendor == 0x1095 && devid == 0x3726) {
 		/* sil3726 quirks */
 		ata_for_each_link(link, ap, EDGE) {
+			/* link reports offline after LPM */
+			link->flags |= ATA_LFLAG_NO_LPM;
+
 			/* Class code report is unreliable and SRST
 			 * times out under certain configurations.
 			 */
@@ -380,6 +404,9 @@ static void sata_pmp_quirks(struct ata_port *ap)
 	} else if (vendor == 0x1095 && devid == 0x4723) {
 		/* sil4723 quirks */
 		ata_for_each_link(link, ap, EDGE) {
+			/* link reports offline after LPM */
+			link->flags |= ATA_LFLAG_NO_LPM;
+
 			/* class code report is unreliable */
 			if (link->pmp < 2)
 				link->flags |= ATA_LFLAG_ASSUME_ATA;
@@ -392,6 +419,9 @@ static void sata_pmp_quirks(struct ata_port *ap)
 	} else if (vendor == 0x1095 && devid == 0x4726) {
 		/* sil4726 quirks */
 		ata_for_each_link(link, ap, EDGE) {
+			/* link reports offline after LPM */
+			link->flags |= ATA_LFLAG_NO_LPM;
+
 			/* Class code report is unreliable and SRST
 			 * times out under certain configurations.
 			 * Config device can be at port 0 or 5 and
@@ -952,15 +982,25 @@ static int sata_pmp_eh_recover(struct ata_port *ap)
 	if (rc)
 		goto link_fail;
 
-	/* Connection status might have changed while resetting other
-	 * links, check SATA_PMP_GSCR_ERROR before returning.
-	 */
-
 	/* clear SNotification */
 	rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
 	if (rc == 0)
 		sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);
 
+	/*
+	 * If LPM is active on any fan-out port, hotplug wouldn't
+	 * work.  Return w/ PHY event notification disabled.
+	 */
+	ata_for_each_link(link, ap, EDGE)
+		if (link->lpm_policy > ATA_LPM_MAX_POWER)
+			return 0;
+
+	/*
+	 * Connection status might have changed while resetting other
+	 * links, enable notification and check SATA_PMP_GSCR_ERROR
+	 * before returning.
+	 */
+
 	/* enable notification */
 	if (pmp_dev->flags & ATA_DFLAG_AN) {
 		gscr[SATA_PMP_GSCR_FEAT_EN] |= SATA_PMP_FEAT_NOTIFY;

drivers/ata/libata.h

@@ -176,6 +176,8 @@ extern int ata_ering_map(struct ata_ering *ering,
 #ifdef CONFIG_SATA_PMP
 extern int sata_pmp_scr_read(struct ata_link *link, int reg, u32 *val);
 extern int sata_pmp_scr_write(struct ata_link *link, int reg, u32 val);
+extern int sata_pmp_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
+			    unsigned hints);
 extern int sata_pmp_attach(struct ata_device *dev);
 #else /* CONFIG_SATA_PMP */
 static inline int sata_pmp_scr_read(struct ata_link *link, int reg, u32 *val)
@@ -188,6 +190,12 @@ static inline int sata_pmp_scr_write(struct ata_link *link, int reg, u32 val)
 	return -EINVAL;
 }
 
+static inline int sata_pmp_set_lpm(struct ata_link *link,
+				   enum ata_lpm_policy policy, unsigned hints)
+{
+	return -EINVAL;
+}
+
 static inline int sata_pmp_attach(struct ata_device *dev)
 {
 	return -EINVAL;