ahci: implement aggressive SATA device sleep support

Device Sleep is a feature as described in AHCI 1.3.1 Technical Proposal.
This feature enables an HBA and SATA storage device to enter the DevSleep
interface state, enabling lower power SATA-based systems.

Aggressive Device Sleep enables the HBA to assert the DEVSLP signal as
soon as there are no commands outstanding to the device and the port
specific Device Sleep idle timer has expired. This enables autonomous
entry into the DevSleep interface state without waiting for software
in power sensitive systems.

This patch enables Aggressive Device Sleep only if both host controller
and device support it.

Tested on AMD reference board together with Device Sleep supported device
sample.

Signed-off-by: Shane Huang <shane.huang@amd.com>
Reviewed-by: Aaron Lu <aaron.lwe@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 96 insertions, 1 deletions

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 555c07afa05..4201e535a8c 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -45,6 +45,7 @@
 #include <scsi/scsi_cmnd.h>
 #include <linux/libata.h>
 #include "ahci.h"
+#include "libata.h"
 
 static int ahci_skip_host_reset;
 int ahci_ignore_sss;
@@ -76,6 +77,7 @@ static void ahci_qc_prep(struct ata_queued_cmd *qc);
 static int ahci_pmp_qc_defer(struct ata_queued_cmd *qc);
 static void ahci_freeze(struct ata_port *ap);
 static void ahci_thaw(struct ata_port *ap);
+static void ahci_set_aggressive_devslp(struct ata_port *ap, bool sleep);
 static void ahci_enable_fbs(struct ata_port *ap);
 static void ahci_disable_fbs(struct ata_port *ap);
 static void ahci_pmp_attach(struct ata_port *ap);
@@ -193,6 +195,10 @@ module_param(ahci_em_messages, int, 0444);
 MODULE_PARM_DESC(ahci_em_messages,
 	"AHCI Enclosure Management Message control (0 = off, 1 = on)");
 
+int devslp_idle_timeout = 1000;	/* device sleep idle timeout in ms */
+module_param(devslp_idle_timeout, int, 0644);
+MODULE_PARM_DESC(devslp_idle_timeout, "device sleep idle timeout");
+
 static void ahci_enable_ahci(void __iomem *mmio)
 {
 	int i;
@@ -702,6 +708,16 @@ static int ahci_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
 		}
 	}
 
+	/* set aggressive device sleep */
+	if ((hpriv->cap2 & HOST_CAP2_SDS) &&
+	    (hpriv->cap2 & HOST_CAP2_SADM) &&
+	    (link->device->flags & ATA_DFLAG_DEVSLP)) {
+		if (policy == ATA_LPM_MIN_POWER)
+			ahci_set_aggressive_devslp(ap, true);
+		else
+			ahci_set_aggressive_devslp(ap, false);
+	}
+
 	if (policy == ATA_LPM_MAX_POWER) {
 		sata_link_scr_lpm(link, policy, false);
 
@@ -1890,6 +1906,81 @@ static void ahci_post_internal_cmd(struct ata_queued_cmd *qc)
 		ahci_kick_engine(ap);
 }
 
+static void ahci_set_aggressive_devslp(struct ata_port *ap, bool sleep)
+{
+	void __iomem *port_mmio = ahci_port_base(ap);
+	struct ata_device *dev = ap->link.device;
+	u32 devslp, dm, dito, mdat, deto;
+	int rc;
+	unsigned int err_mask;
+
+	devslp = readl(port_mmio + PORT_DEVSLP);
+	if (!(devslp & PORT_DEVSLP_DSP)) {
+		dev_err(ap->host->dev, "port does not support device sleep\n");
+		return;
+	}
+
+	/* disable device sleep */
+	if (!sleep) {
+		if (devslp & PORT_DEVSLP_ADSE) {
+			writel(devslp & ~PORT_DEVSLP_ADSE,
+			       port_mmio + PORT_DEVSLP);
+			err_mask = ata_dev_set_feature(dev,
+						       SETFEATURES_SATA_DISABLE,
+						       SATA_DEVSLP);
+			if (err_mask && err_mask != AC_ERR_DEV)
+				ata_dev_warn(dev, "failed to disable DEVSLP\n");
+		}
+		return;
+	}
+
+	/* device sleep was already enabled */
+	if (devslp & PORT_DEVSLP_ADSE)
+		return;
+
+	/* set DITO, MDAT, DETO and enable DevSlp, need to stop engine first */
+	rc = ahci_stop_engine(ap);
+	if (rc)
+		return;
+
+	dm = (devslp & PORT_DEVSLP_DM_MASK) >> PORT_DEVSLP_DM_OFFSET;
+	dito = devslp_idle_timeout / (dm + 1);
+	if (dito > 0x3ff)
+		dito = 0x3ff;
+
+	/* Use the nominal value 10 ms if the read MDAT is zero,
+	 * the nominal value of DETO is 20 ms.
+	 */
+	if (dev->sata_settings[ATA_LOG_DEVSLP_VALID] &
+	    ATA_LOG_DEVSLP_VALID_MASK) {
+		mdat = dev->sata_settings[ATA_LOG_DEVSLP_MDAT] &
+		       ATA_LOG_DEVSLP_MDAT_MASK;
+		if (!mdat)
+			mdat = 10;
+		deto = dev->sata_settings[ATA_LOG_DEVSLP_DETO];
+		if (!deto)
+			deto = 20;
+	} else {
+		mdat = 10;
+		deto = 20;
+	}
+
+	devslp |= ((dito << PORT_DEVSLP_DITO_OFFSET) |
+		   (mdat << PORT_DEVSLP_MDAT_OFFSET) |
+		   (deto << PORT_DEVSLP_DETO_OFFSET) |
+		   PORT_DEVSLP_ADSE);
+	writel(devslp, port_mmio + PORT_DEVSLP);
+
+	ahci_start_engine(ap);
+
+	/* enable device sleep feature for the drive */
+	err_mask = ata_dev_set_feature(dev,
+				       SETFEATURES_SATA_ENABLE,
+				       SATA_DEVSLP);
+	if (err_mask && err_mask != AC_ERR_DEV)
+		ata_dev_warn(dev, "failed to enable DEVSLP\n");
+}
+
 static void ahci_enable_fbs(struct ata_port *ap)
 {
 	struct ahci_port_priv *pp = ap->private_data;
@@ -2164,7 +2255,8 @@ void ahci_print_info(struct ata_host *host, const char *scc_s)
 		"flags: "
 		"%s%s%s%s%s%s%s"
 		"%s%s%s%s%s%s%s"
-		"%s%s%s%s%s%s\n"
+		"%s%s%s%s%s%s%s"
+		"%s%s\n"
 		,
 
 		cap & HOST_CAP_64 ? "64bit " : "",
@@ -2184,6 +2276,9 @@ void ahci_print_info(struct ata_host *host, const char *scc_s)
 		cap & HOST_CAP_CCC ? "ccc " : "",
 		cap & HOST_CAP_EMS ? "ems " : "",
 		cap & HOST_CAP_SXS ? "sxs " : "",
+		cap2 & HOST_CAP2_DESO ? "deso " : "",
+		cap2 & HOST_CAP2_SADM ? "sadm " : "",
+		cap2 & HOST_CAP2_SDS ? "sds " : "",
 		cap2 & HOST_CAP2_APST ? "apst " : "",
 		cap2 & HOST_CAP2_NVMHCI ? "nvmp " : "",
 		cap2 & HOST_CAP2_BOH ? "boh " : ""