ata: libata: Move sata_down_spd_limit() to libata-sata.c

Move the definition of the function sata_down_spd_limit() to
libata-sata.c where it belongs, together with sata_set_spd().
The helper function ata_sstatus_online() is also changed to be an
inline function defined in drivers/ata/libata.h.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>

1 files changed, 80 insertions, 0 deletions

diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
index ea6126c139af..124e2b2ea3c0 100644
--- a/drivers/ata/libata-sata.c
+++ b/drivers/ata/libata-sata.c
@@ -518,6 +518,86 @@ int sata_set_spd(struct ata_link *link)
 EXPORT_SYMBOL_GPL(sata_set_spd);
 
 /**
+ *	sata_down_spd_limit - adjust SATA spd limit downward
+ *	@link: Link to adjust SATA spd limit for
+ *	@spd_limit: Additional limit
+ *
+ *	Adjust SATA spd limit of @link downward.  Note that this
+ *	function only adjusts the limit.  The change must be applied
+ *	using sata_set_spd().
+ *
+ *	If @spd_limit is non-zero, the speed is limited to equal to or
+ *	lower than @spd_limit if such speed is supported.  If
+ *	@spd_limit is slower than any supported speed, only the lowest
+ *	supported speed is allowed.
+ *
+ *	LOCKING:
+ *	Inherited from caller.
+ *
+ *	RETURNS:
+ *	0 on success, negative errno on failure
+ */
+int sata_down_spd_limit(struct ata_link *link, u32 spd_limit)
+{
+	u32 sstatus, spd, mask;
+	int rc, bit;
+
+	if (!sata_scr_valid(link))
+		return -EOPNOTSUPP;
+
+	/* If SCR can be read, use it to determine the current SPD.
+	 * If not, use cached value in link->sata_spd.
+	 */
+	rc = sata_scr_read(link, SCR_STATUS, &sstatus);
+	if (rc == 0 && ata_sstatus_online(sstatus))
+		spd = (sstatus >> 4) & 0xf;
+	else
+		spd = link->sata_spd;
+
+	mask = link->sata_spd_limit;
+	if (mask <= 1)
+		return -EINVAL;
+
+	/* unconditionally mask off the highest bit */
+	bit = fls(mask) - 1;
+	mask &= ~(1 << bit);
+
+	/*
+	 * Mask off all speeds higher than or equal to the current one.  At
+	 * this point, if current SPD is not available and we previously
+	 * recorded the link speed from SStatus, the driver has already
+	 * masked off the highest bit so mask should already be 1 or 0.
+	 * Otherwise, we should not force 1.5Gbps on a link where we have
+	 * not previously recorded speed from SStatus.  Just return in this
+	 * case.
+	 */
+	if (spd > 1)
+		mask &= (1 << (spd - 1)) - 1;
+	else if (link->sata_spd)
+		return -EINVAL;
+
+	/* were we already at the bottom? */
+	if (!mask)
+		return -EINVAL;
+
+	if (spd_limit) {
+		if (mask & ((1 << spd_limit) - 1))
+			mask &= (1 << spd_limit) - 1;
+		else {
+			bit = ffs(mask) - 1;
+			mask = 1 << bit;
+		}
+	}
+
+	link->sata_spd_limit = mask;
+
+	ata_link_warn(link, "limiting SATA link speed to %s\n",
+		      sata_spd_string(fls(mask)));
+
+	return 0;
+}
+
+/**
  *	sata_link_hardreset - reset link via SATA phy reset
  *	@link: link to reset
  *	@timing: timing parameters { interval, duration, timeout } in msec