1 files changed, 138 insertions, 0 deletions
diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
index d66afdc33d54..34852fced999 100644
--- a/drivers/ata/libata-sata.c
+++ b/drivers/ata/libata-sata.c
@@ -197,6 +197,144 @@ void ata_tf_from_fis(const u8 *fis, struct ata_taskfile *tf)
 EXPORT_SYMBOL_GPL(ata_tf_from_fis);
 
 /**
+ *	sata_link_debounce - debounce SATA phy status
+ *	@link: ATA link to debounce SATA phy status for
+ *	@params: timing parameters { interval, duration, timeout } in msec
+ *	@deadline: deadline jiffies for the operation
+ *
+ *	Make sure SStatus of @link reaches stable state, determined by
+ *	holding the same value where DET is not 1 for @duration polled
+ *	every @interval, before @timeout.  Timeout constraints the
+ *	beginning of the stable state.  Because DET gets stuck at 1 on
+ *	some controllers after hot unplugging, this functions waits
+ *	until timeout then returns 0 if DET is stable at 1.
+ *
+ *	@timeout is further limited by @deadline.  The sooner of the
+ *	two is used.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+int sata_link_debounce(struct ata_link *link, const unsigned long *params,
+		       unsigned long deadline)
+{
+	unsigned long interval = params[0];
+	unsigned long duration = params[1];
+	unsigned long last_jiffies, t;
+	u32 last, cur;
+	int rc;
+
+	t = ata_deadline(jiffies, params[2]);
+	if (time_before(t, deadline))
+		deadline = t;
+
+	if ((rc = sata_scr_read(link, SCR_STATUS, &cur)))
+		return rc;
+	cur &= 0xf;
+
+	last = cur;
+	last_jiffies = jiffies;
+
+	while (1) {
+		ata_msleep(link->ap, interval);
+		if ((rc = sata_scr_read(link, SCR_STATUS, &cur)))
+			return rc;
+		cur &= 0xf;
+
+		/* DET stable? */
+		if (cur == last) {
+			if (cur == 1 && time_before(jiffies, deadline))
+				continue;
+			if (time_after(jiffies,
+				       ata_deadline(last_jiffies, duration)))
+				return 0;
+			continue;
+		}
+
+		/* unstable, start over */
+		last = cur;
+		last_jiffies = jiffies;
+
+		/* Check deadline.  If debouncing failed, return
+		 * -EPIPE to tell upper layer to lower link speed.
+		 */
+		if (time_after(jiffies, deadline))
+			return -EPIPE;
+	}
+}
+EXPORT_SYMBOL_GPL(sata_link_debounce);
+
+/**
+ *	sata_link_resume - resume SATA link
+ *	@link: ATA link to resume SATA
+ *	@params: timing parameters { interval, duration, timeout } in msec
+ *	@deadline: deadline jiffies for the operation
+ *
+ *	Resume SATA phy @link and debounce it.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep)
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+int sata_link_resume(struct ata_link *link, const unsigned long *params,
+		     unsigned long deadline)
+{
+	int tries = ATA_LINK_RESUME_TRIES;
+	u32 scontrol, serror;
+	int rc;
+
+	if ((rc = sata_scr_read(link, SCR_CONTROL, &scontrol)))
+		return rc;
+
+	/*
+	 * Writes to SControl sometimes get ignored under certain
+	 * controllers (ata_piix SIDPR).  Make sure DET actually is
+	 * cleared.
+	 */
+	do {
+		scontrol = (scontrol & 0x0f0) | 0x300;
+		if ((rc = sata_scr_write(link, SCR_CONTROL, scontrol)))
+			return rc;
+		/*
+		 * Some PHYs react badly if SStatus is pounded
+		 * immediately after resuming.  Delay 200ms before
+		 * debouncing.
+		 */
+		if (!(link->flags & ATA_LFLAG_NO_DB_DELAY))
+			ata_msleep(link->ap, 200);
+
+		/* is SControl restored correctly? */
+		if ((rc = sata_scr_read(link, SCR_CONTROL, &scontrol)))
+			return rc;
+	} while ((scontrol & 0xf0f) != 0x300 && --tries);
+
+	if ((scontrol & 0xf0f) != 0x300) {
+		ata_link_warn(link, "failed to resume link (SControl %X)\n",
+			     scontrol);
+		return 0;
+	}
+
+	if (tries < ATA_LINK_RESUME_TRIES)
+		ata_link_warn(link, "link resume succeeded after %d retries\n",
+			      ATA_LINK_RESUME_TRIES - tries);
+
+	if ((rc = sata_link_debounce(link, params, deadline)))
+		return rc;
+
+	/* clear SError, some PHYs require this even for SRST to work */
+	if (!(rc = sata_scr_read(link, SCR_ERROR, &serror)))
+		rc = sata_scr_write(link, SCR_ERROR, serror);
+
+	return rc != -EINVAL ? rc : 0;
+}
+EXPORT_SYMBOL_GPL(sata_link_resume);
+
+/**
  *	sata_link_scr_lpm - manipulate SControl IPM and SPM fields
  *	@link: ATA link to manipulate SControl for
  *	@policy: LPM policy to configure