libata: reimplement link power management

The current LPM implementation has the following issues.

* Operation order isn't well thought-out.  e.g. HIPM should be
  configured after IPM in SControl is properly configured.  Not the
  other way around.

* Suspend/resume paths call ata_lpm_enable/disable() which must only
  be called from EH context directly.  Also, ata_lpm_enable/disable()
  were called whether LPM was in use or not.

* Implementation is per-port when it should be per-link.  As a result,
  it can't be used for controllers with slave links or PMP.

* LPM state isn't managed consistently.  After a link reset for
  whatever reason including suspend/resume the actual LPM state would
  be reset leaving ap->lpm_policy inconsistent.

* Generic/driver-specific logic boundary isn't clear.  Currently,
  libahci has to mangle stuff which libata EH proper should be
  handling.  This makes the implementation unnecessarily complex and
  fragile.

* Tied to ALPM.  Doesn't consider DIPM only cases and doesn't check
  whether the device allows HIPM.

* Error handling isn't implemented.

Given the extent of mismatch with the rest of libata, I don't think
trying to fix it piecewise makes much sense.  This patch reimplements
LPM support.

* The new implementation is per-link.  The target policy is still
  port-wide (ap->target_lpm_policy) but all the mechanisms and states
  are per-link and integrate well with the rest of link abstraction
  and can work with slave and PMP links.

* Core EH has proper control of LPM state.  LPM state is reconfigured
  when and only when reconfiguration is necessary.  It makes sure that
  LPM state is reset when probing for new device on the link.
  Controller agnostic logic is now implemented in libata EH proper and
  driver implementation only has to deal with controller specifics.

* Proper error handling.  LPM config failure is attributed to the
  device on the link and LPM is disabled for the link if it fails
  repeatedly.

* ops->enable/disable_pm() are replaced with single ops->set_lpm()
  which takes @policy and @hints.  This simplifies driver specific
  implementation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 41 insertions, 117 deletions

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index ed7803f2b4f1..437f92597788 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -56,8 +56,8 @@ MODULE_PARM_DESC(skip_host_reset, "skip global host reset (0=don't skip, 1=skip)
 module_param_named(ignore_sss, ahci_ignore_sss, int, 0444);
 MODULE_PARM_DESC(ignore_sss, "Ignore staggered spinup flag (0=don't ignore, 1=ignore)");
 
-static int ahci_enable_alpm(struct ata_port *ap, enum ata_lpm_policy policy);
-static void ahci_disable_alpm(struct ata_port *ap);
+static int ahci_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
+                        unsigned hints);
 static ssize_t ahci_led_show(struct ata_port *ap, char *buf);
 static ssize_t ahci_led_store(struct ata_port *ap, const char *buf,
                               size_t size);
@@ -163,8 +163,7 @@ struct ata_port_operations ahci_ops = {
         .pmp_attach             = ahci_pmp_attach,
         .pmp_detach             = ahci_pmp_detach,
 
-        .enable_pm              = ahci_enable_alpm,
-        .disable_pm             = ahci_disable_alpm,
+        .set_lpm                = ahci_set_lpm,
         .em_show                = ahci_led_show,
         .em_store               = ahci_led_store,
         .sw_activity_show       = ahci_activity_show,
@@ -641,126 +640,56 @@ static void ahci_power_up(struct ata_port *ap)
         writel(cmd | PORT_CMD_ICC_ACTIVE, port_mmio + PORT_CMD);
 }
 
-static void ahci_disable_alpm(struct ata_port *ap)
+static int ahci_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
+                        unsigned int hints)
 {
+        struct ata_port *ap = link->ap;
         struct ahci_host_priv *hpriv = ap->host->private_data;
-        void __iomem *port_mmio = ahci_port_base(ap);
-        u32 cmd;
         struct ahci_port_priv *pp = ap->private_data;
-
-        /* LPM bits should be disabled by libata-core */
-        /* get the existing command bits */
-        cmd = readl(port_mmio + PORT_CMD);
-
-        /* disable ALPM and ASP */
-        cmd &= ~PORT_CMD_ASP;
-        cmd &= ~PORT_CMD_ALPE;
-
-        /* force the interface back to active */
-        cmd |= PORT_CMD_ICC_ACTIVE;
-
-        /* write out new cmd value */
-        writel(cmd, port_mmio + PORT_CMD);
-        cmd = readl(port_mmio + PORT_CMD);
-
-        /* wait 10ms to be sure we've come out of any low power state */
-        msleep(10);
-
-        /* clear out any PhyRdy stuff from interrupt status */
-        writel(PORT_IRQ_PHYRDY, port_mmio + PORT_IRQ_STAT);
-
-        /* go ahead and clean out PhyRdy Change from Serror too */
-        ahci_scr_write(&ap->link, SCR_ERROR, ((1 << 16) | (1 << 18)));
-
-        /*
-         * Clear flag to indicate that we should ignore all PhyRdy
-         * state changes
-         */
-        hpriv->flags &= ~AHCI_HFLAG_NO_HOTPLUG;
-
-        /*
-         * Enable interrupts on Phy Ready.
-         */
-        pp->intr_mask |= PORT_IRQ_PHYRDY;
-        writel(pp->intr_mask, port_mmio + PORT_IRQ_MASK);
-
-        /*
-         * don't change the link pm policy - we can be called
-         * just to turn of link pm temporarily
-         */
-}
-
-static int ahci_enable_alpm(struct ata_port *ap, enum ata_lpm_policy policy)
-{
-        struct ahci_host_priv *hpriv = ap->host->private_data;
         void __iomem *port_mmio = ahci_port_base(ap);
-        u32 cmd;
-        struct ahci_port_priv *pp = ap->private_data;
-        u32 asp;
-
-        /* Make sure the host is capable of link power management */
-        if (!(hpriv->cap & HOST_CAP_ALPM))
-                return -EINVAL;
 
-        switch (policy) {
-        case ATA_LPM_MAX_POWER:
-        case ATA_LPM_UNKNOWN:
+        if (policy != ATA_LPM_MAX_POWER) {
                 /*
-                 * if we came here with ATA_LPM_UNKNOWN,
-                 * it just means this is the first time we
-                 * have tried to enable - default to max performance,
-                 * and let the user go to lower power modes on request.
+                 * Disable interrupts on Phy Ready. This keeps us from
+                 * getting woken up due to spurious phy ready
+                 * interrupts.
                  */
-                ahci_disable_alpm(ap);
-                return 0;
-        case ATA_LPM_MIN_POWER:
-                /* configure HBA to enter SLUMBER */
-                asp = PORT_CMD_ASP;
-                break;
-        case ATA_LPM_MED_POWER:
-                /* configure HBA to enter PARTIAL */
-                asp = 0;
-                break;
-        default:
-                return -EINVAL;
+                pp->intr_mask &= ~PORT_IRQ_PHYRDY;
+                writel(pp->intr_mask, port_mmio + PORT_IRQ_MASK);
+
+                sata_link_scr_lpm(link, policy, false);
         }
 
-        /*
-         * Disable interrupts on Phy Ready. This keeps us from
-         * getting woken up due to spurious phy ready interrupts
-         * TBD - Hot plug should be done via polling now, is
-         * that even supported?
-         */
-        pp->intr_mask &= ~PORT_IRQ_PHYRDY;
-        writel(pp->intr_mask, port_mmio + PORT_IRQ_MASK);
+        if (hpriv->cap & HOST_CAP_ALPM) {
+                u32 cmd = readl(port_mmio + PORT_CMD);
 
-        /*
-         * Set a flag to indicate that we should ignore all PhyRdy
-         * state changes since these can happen now whenever we
-         * change link state
-         */
-        hpriv->flags |= AHCI_HFLAG_NO_HOTPLUG;
+                if (policy == ATA_LPM_MAX_POWER || !(hints & ATA_LPM_HIPM)) {
+                        cmd &= ~(PORT_CMD_ASP | PORT_CMD_ALPE);
+                        cmd |= PORT_CMD_ICC_ACTIVE;
 
-        /* get the existing command bits */
-        cmd = readl(port_mmio + PORT_CMD);
+                        writel(cmd, port_mmio + PORT_CMD);
+                        readl(port_mmio + PORT_CMD);
 
-        /*
-         * Set ASP based on Policy
-         */
-        cmd |= asp;
+                        /* wait 10ms to be sure we've come out of LPM state */
+                        msleep(10);
+                } else {
+                        cmd |= PORT_CMD_ALPE;
+                        if (policy == ATA_LPM_MIN_POWER)
+                                cmd |= PORT_CMD_ASP;
 
-        /*
-         * Setting this bit will instruct the HBA to aggressively
-         * enter a lower power link state when it's appropriate and
-         * based on the value set above for ASP
-         */
-        cmd |= PORT_CMD_ALPE;
+                        /* write out new cmd value */
+                        writel(cmd, port_mmio + PORT_CMD);
+                }
+        }
 
-        /* write out new cmd value */
-        writel(cmd, port_mmio + PORT_CMD);
-        cmd = readl(port_mmio + PORT_CMD);
+        if (policy == ATA_LPM_MAX_POWER) {
+                sata_link_scr_lpm(link, policy, false);
+
+                /* turn PHYRDY IRQ back on */
+                pp->intr_mask |= PORT_IRQ_PHYRDY;
+                writel(pp->intr_mask, port_mmio + PORT_IRQ_MASK);
+        }
 
-        /* LPM bits should be set by libata-core */
         return 0;
 }
 
@@ -1658,15 +1587,10 @@ static void ahci_port_intr(struct ata_port *ap)
         if (unlikely(resetting))
                 status &= ~PORT_IRQ_BAD_PMP;
 
-        /* If we are getting PhyRdy, this is
-         * just a power state change, we should
-         * clear out this, plus the PhyRdy/Comm
-         * Wake bits from Serror
-         */
-        if ((hpriv->flags & AHCI_HFLAG_NO_HOTPLUG) &&
-                (status & PORT_IRQ_PHYRDY)) {
+        /* if LPM is enabled, PHYRDY doesn't mean anything */
+        if (ap->link.lpm_policy > ATA_LPM_MAX_POWER) {
                 status &= ~PORT_IRQ_PHYRDY;
-                ahci_scr_write(&ap->link, SCR_ERROR, ((1 << 16) | (1 << 18)));
+                ahci_scr_write(&ap->link, SCR_ERROR, SERR_PHYRDY_CHG);
         }
 
         if (unlikely(status & PORT_IRQ_ERROR)) {