[libata] Link power management infrastructure

Device Initiated Power Management, which is defined
in SATA 2.5 can be enabled for disks which support it.
This patch enables DIPM when the user sets the link
power management policy to "min_power".

Additionally, libata drivers can define a function
(enable_pm) that will perform hardware specific actions to
enable whatever power management policy the user set up
for Host Initiated Power management (HIPM).
This power management policy will be activated after all
disks have been enumerated and intialized.  Drivers should
also define disable_pm, which will turn off link power
management, but not change link power management policy.

Documentation/scsi/link_power_management_policy.txt has additional
information.

Signed-off-by:  Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

4 files changed, 269 insertions, 1 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 3891cdc6bd3d..513babe6a143 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -620,6 +620,177 @@ void ata_dev_disable(struct ata_device *dev)
         }
 }
 
+static int ata_dev_set_dipm(struct ata_device *dev, enum link_pm policy)
+{
+        struct ata_link *link = dev->link;
+        struct ata_port *ap = link->ap;
+        u32 scontrol;
+        unsigned int err_mask;
+        int rc;
+
+        /*
+         * disallow DIPM for drivers which haven't set
+         * ATA_FLAG_IPM.  This is because when DIPM is enabled,
+         * phy ready will be set in the interrupt status on
+         * state changes, which will cause some drivers to
+         * think there are errors - additionally drivers will
+         * need to disable hot plug.
+         */
+        if (!(ap->flags & ATA_FLAG_IPM) || !ata_dev_enabled(dev)) {
+                ap->pm_policy = NOT_AVAILABLE;
+                return -EINVAL;
+        }
+
+        /*
+         * For DIPM, we will only enable it for the
+         * min_power setting.
+         *
+         * Why?  Because Disks are too stupid to know that
+         * If the host rejects a request to go to SLUMBER
+         * they should retry at PARTIAL, and instead it
+         * just would give up.  So, for medium_power to
+         * work at all, we need to only allow HIPM.
+         */
+        rc = sata_scr_read(link, SCR_CONTROL, &scontrol);
+        if (rc)
+                return rc;
+
+        switch (policy) {
+        case MIN_POWER:
+                /* no restrictions on IPM transitions */
+                scontrol &= ~(0x3 << 8);
+                rc = sata_scr_write(link, SCR_CONTROL, scontrol);
+                if (rc)
+                        return rc;
+
+                /* enable DIPM */
+                if (dev->flags & ATA_DFLAG_DIPM)
+                        err_mask = ata_dev_set_feature(dev,
+                                        SETFEATURES_SATA_ENABLE, SATA_DIPM);
+                break;
+        case MEDIUM_POWER:
+                /* allow IPM to PARTIAL */
+                scontrol &= ~(0x1 << 8);
+                scontrol |= (0x2 << 8);
+                rc = sata_scr_write(link, SCR_CONTROL, scontrol);
+                if (rc)
+                        return rc;
+
+                /* disable DIPM */
+                if (ata_dev_enabled(dev) && (dev->flags & ATA_DFLAG_DIPM))
+                        err_mask = ata_dev_set_feature(dev,
+                                        SETFEATURES_SATA_DISABLE, SATA_DIPM);
+                break;
+        case NOT_AVAILABLE:
+        case MAX_PERFORMANCE:
+                /* disable all IPM transitions */
+                scontrol |= (0x3 << 8);
+                rc = sata_scr_write(link, SCR_CONTROL, scontrol);
+                if (rc)
+                        return rc;
+
+                /* disable DIPM */
+                if (ata_dev_enabled(dev) && (dev->flags & ATA_DFLAG_DIPM))
+                        err_mask = ata_dev_set_feature(dev,
+                                        SETFEATURES_SATA_DISABLE, SATA_DIPM);
+                break;
+        }
+
+        /* FIXME: handle SET FEATURES failure */
+        (void) err_mask;
+
+        return 0;
+}
+
+/**
+ *      ata_dev_enable_pm - enable SATA interface power management
+ *      @device - device to enable ipm for
+ *      @policy - the link power management policy
+ *
+ *      Enable SATA Interface power management.  This will enable
+ *      Device Interface Power Management (DIPM) for min_power
+ *      policy, and then call driver specific callbacks for
+ *      enabling Host Initiated Power management.
+ *
+ *      Locking: Caller.
+ *      Returns: -EINVAL if IPM is not supported, 0 otherwise.
+ */
+void ata_dev_enable_pm(struct ata_device *dev, enum link_pm policy)
+{
+        int rc = 0;
+        struct ata_port *ap = dev->link->ap;
+
+        /* set HIPM first, then DIPM */
+        if (ap->ops->enable_pm)
+                rc = ap->ops->enable_pm(ap, policy);
+        if (rc)
+                goto enable_pm_out;
+        rc = ata_dev_set_dipm(dev, policy);
+
+enable_pm_out:
+        if (rc)
+                ap->pm_policy = MAX_PERFORMANCE;
+        else
+                ap->pm_policy = policy;
+        return /* rc */;        /* hopefully we can use 'rc' eventually */
+}
+
+/**
+ *      ata_dev_disable_pm - disable SATA interface power management
+ *      @device - device to enable ipm for
+ *
+ *      Disable SATA Interface power management.  This will disable
+ *      Device Interface Power Management (DIPM) without changing
+ *      policy,  call driver specific callbacks for disabling Host
+ *      Initiated Power management.
+ *
+ *      Locking: Caller.
+ *      Returns: void
+ */
+static void ata_dev_disable_pm(struct ata_device *dev)
+{
+        struct ata_port *ap = dev->link->ap;
+
+        ata_dev_set_dipm(dev, MAX_PERFORMANCE);
+        if (ap->ops->disable_pm)
+                ap->ops->disable_pm(ap);
+}
+
+void ata_lpm_schedule(struct ata_port *ap, enum link_pm policy)
+{
+        ap->pm_policy = policy;
+        ap->link.eh_info.action |= ATA_EHI_LPM;
+        ap->link.eh_info.flags |= ATA_EHI_NO_AUTOPSY;
+        ata_port_schedule_eh(ap);
+}
+
+static void ata_lpm_enable(struct ata_host *host)
+{
+        struct ata_link *link;
+        struct ata_port *ap;
+        struct ata_device *dev;
+        int i;
+
+        for (i = 0; i < host->n_ports; i++) {
+                ap = host->ports[i];
+                ata_port_for_each_link(link, ap) {
+                        ata_link_for_each_dev(dev, link)
+                                ata_dev_disable_pm(dev);
+                }
+        }
+}
+
+static void ata_lpm_disable(struct ata_host *host)
+{
+        int i;
+
+        for (i = 0; i < host->n_ports; i++) {
+                struct ata_port *ap = host->ports[i];
+                ata_lpm_schedule(ap, ap->pm_policy);
+        }
+}
+
+
 /**
  *      ata_devchk - PATA device presence detection
  *      @ap: ATA channel to examine
@@ -2101,6 +2272,13 @@ int ata_dev_configure(struct ata_device *dev)
         if (dev->flags & ATA_DFLAG_LBA48)
                 dev->max_sectors = ATA_MAX_SECTORS_LBA48;
 
+        if (!(dev->horkage & ATA_HORKAGE_IPM)) {
+                if (ata_id_has_hipm(dev->id))
+                        dev->flags |= ATA_DFLAG_HIPM;
+                if (ata_id_has_dipm(dev->id))
+                        dev->flags |= ATA_DFLAG_DIPM;
+        }
+
         if (dev->horkage & ATA_HORKAGE_DIAGNOSTIC) {
                 /* Let the user know. We don't want to disallow opens for
                    rescue purposes, or in case the vendor is just a blithering
@@ -2126,6 +2304,13 @@ int ata_dev_configure(struct ata_device *dev)
                 dev->max_sectors = min_t(unsigned int, ATA_MAX_SECTORS_128,
                                          dev->max_sectors);
 
+        if (ata_dev_blacklisted(dev) & ATA_HORKAGE_IPM) {
+                dev->horkage |= ATA_HORKAGE_IPM;
+
+                /* reset link pm_policy for this port to no pm */
+                ap->pm_policy = MAX_PERFORMANCE;
+        }
+
         if (ap->ops->dev_config)
                 ap->ops->dev_config(dev);
 
@@ -6361,6 +6546,12 @@ int ata_host_suspend(struct ata_host *host, pm_message_t mesg)
 {
         int rc;
 
+        /*
+         * disable link pm on all ports before requesting
+         * any pm activity
+         */
+        ata_lpm_enable(host);
+
         rc = ata_host_request_pm(host, mesg, 0, ATA_EHI_QUIET, 1);
         if (rc == 0)
                 host->dev->power.power_state = mesg;
@@ -6383,6 +6574,9 @@ void ata_host_resume(struct ata_host *host)
         ata_host_request_pm(host, PMSG_ON, ATA_EH_SOFTRESET,
                             ATA_EHI_NO_AUTOPSY | ATA_EHI_QUIET, 0);
         host->dev->power.power_state = PMSG_ON;
+
+        /* reenable link pm */
+        ata_lpm_disable(host);
 }
 #endif
 
@@ -6925,6 +7119,7 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
                 struct ata_port *ap = host->ports[i];
 
                 ata_scsi_scan_host(ap, 1);
+                ata_lpm_schedule(ap, ap->pm_policy);
         }
 
         return 0;
@@ -7321,7 +7516,6 @@ const struct ata_port_info ata_dummy_port_info = {
  * likely to change as new drivers are added and updated.
  * Do not depend on ABI/API stability.
  */
-
 EXPORT_SYMBOL_GPL(sata_deb_timing_normal);
 EXPORT_SYMBOL_GPL(sata_deb_timing_hotplug);
 EXPORT_SYMBOL_GPL(sata_deb_timing_long);
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index ec55d63cf20e..fefea7470e51 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2628,6 +2628,10 @@ int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
                         ehc->i.flags &= ~ATA_EHI_SETMODE;
                 }
 
+                if (ehc->i.action & ATA_EHI_LPM)
+                        ata_link_for_each_dev(dev, link)
+                                ata_dev_enable_pm(dev, ap->pm_policy);
+
                 /* this link is okay now */
                 ehc->i.flags = 0;
                 continue;
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index f752eddc19ed..93bd36c19690 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -110,6 +110,74 @@ static struct scsi_transport_template ata_scsi_transport_template = {
 };
 
 
+static const struct {
+        enum link_pm    value;
+        const char      *name;
+} link_pm_policy[] = {
+        { NOT_AVAILABLE, "max_performance" },
+        { MIN_POWER, "min_power" },
+        { MAX_PERFORMANCE, "max_performance" },
+        { MEDIUM_POWER, "medium_power" },
+};
+
+const char *ata_scsi_lpm_get(enum link_pm policy)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(link_pm_policy); i++)
+                if (link_pm_policy[i].value == policy)
+                        return link_pm_policy[i].name;
+
+        return NULL;
+}
+
+static ssize_t ata_scsi_lpm_put(struct class_device *class_dev,
+        const char *buf, size_t count)
+{
+        struct Scsi_Host *shost = class_to_shost(class_dev);
+        struct ata_port *ap = ata_shost_to_port(shost);
+        enum link_pm policy = 0;
+        int i;
+
+        /*
+         * we are skipping array location 0 on purpose - this
+         * is because a value of NOT_AVAILABLE is displayed
+         * to the user as max_performance, but when the user
+         * writes "max_performance", they actually want the
+         * value to match MAX_PERFORMANCE.
+         */
+        for (i = 1; i < ARRAY_SIZE(link_pm_policy); i++) {
+                const int len = strlen(link_pm_policy[i].name);
+                if (strncmp(link_pm_policy[i].name, buf, len) == 0 &&
+                   buf[len] == '\n') {
+                        policy = link_pm_policy[i].value;
+                        break;
+                }
+        }
+        if (!policy)
+                return -EINVAL;
+
+        ata_lpm_schedule(ap, policy);
+        return count;
+}
+
+static ssize_t
+ata_scsi_lpm_show(struct class_device *class_dev, char *buf)
+{
+        struct Scsi_Host *shost = class_to_shost(class_dev);
+        struct ata_port *ap = ata_shost_to_port(shost);
+        const char *policy =
+                ata_scsi_lpm_get(ap->pm_policy);
+
+        if (!policy)
+                return -EINVAL;
+
+        return snprintf(buf, 23, "%s\n", policy);
+}
+CLASS_DEVICE_ATTR(link_power_management_policy, S_IRUGO | S_IWUSR,
+                ata_scsi_lpm_show, ata_scsi_lpm_put);
+EXPORT_SYMBOL_GPL(class_device_attr_link_power_management_policy);
+
 static void ata_scsi_invalid_field(struct scsi_cmnd *cmd,
                                    void (*done)(struct scsi_cmnd *))
 {
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 90df58a3edc9..0e6cf3a484dc 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -101,6 +101,8 @@ extern int sata_link_init_spd(struct ata_link *link);
 extern int ata_task_ioctl(struct scsi_device *scsidev, void __user *arg);
 extern int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg);
 extern struct ata_port *ata_port_alloc(struct ata_host *host);
+extern void ata_dev_enable_pm(struct ata_device *dev, enum link_pm policy);
+extern void ata_lpm_schedule(struct ata_port *ap, enum link_pm);
 
 /* libata-acpi.c */
 #ifdef CONFIG_ATA_ACPI