ahci: Add functions to manage runtime PM of AHCI ports

Add new functions ahci_rpm_get_port()/ahci_rpm_put_port() that change
runtime PM status of AHCI ports. Depending if the AHCI host has runtime PM
enabled or disabled calling these may trigger runtime suspend/resume of the
host controller.

We also call these functions in appropriate places to make sure host
controller registers are available before using them.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 8cdf0afd551d8b345e3dcd83b230b239e0f12c7d..2d21b46db714d63de6ba393ead298a02de1e4924 100644 (file)
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -225,6 +225,31 @@ static void ahci_enable_ahci(void __iomem *mmio)
        WARN_ON(1);
 }
 
+/**
+ *     ahci_rpm_get_port - Make sure the port is powered on
+ *     @ap: Port to power on
+ *
+ *     Whenever there is need to access the AHCI host registers outside of
+ *     normal execution paths, call this function to make sure the host is
+ *     actually powered on.
+ */
+static int ahci_rpm_get_port(struct ata_port *ap)
+{
+       return pm_runtime_get_sync(ap->dev);
+}
+
+/**
+ *     ahci_rpm_put_port - Undoes ahci_rpm_get_port()
+ *     @ap: Port to power down
+ *
+ *     Undoes ahci_rpm_get_port() and possibly powers down the AHCI host
+ *     if it has no more active users.
+ */
+static void ahci_rpm_put_port(struct ata_port *ap)
+{
+       pm_runtime_put(ap->dev);
+}
+
 static ssize_t ahci_show_host_caps(struct device *dev,
                                   struct device_attribute *attr, char *buf)
 {
@@ -261,8 +286,13 @@ static ssize_t ahci_show_port_cmd(struct device *dev,
        struct Scsi_Host *shost = class_to_shost(dev);
        struct ata_port *ap = ata_shost_to_port(shost);
        void __iomem *port_mmio = ahci_port_base(ap);
+       ssize_t ret;
 
-       return sprintf(buf, "%x\n", readl(port_mmio + PORT_CMD));
+       ahci_rpm_get_port(ap);
+       ret = sprintf(buf, "%x\n", readl(port_mmio + PORT_CMD));
+       ahci_rpm_put_port(ap);
+
+       return ret;
 }
 
 static ssize_t ahci_read_em_buffer(struct device *dev,
@@ -278,17 +308,20 @@ static ssize_t ahci_read_em_buffer(struct device *dev,
        size_t count;
        int i;
 
+       ahci_rpm_get_port(ap);
        spin_lock_irqsave(ap->lock, flags);
 
        em_ctl = readl(mmio + HOST_EM_CTL);
        if (!(ap->flags & ATA_FLAG_EM) || em_ctl & EM_CTL_XMT ||
            !(hpriv->em_msg_type & EM_MSG_TYPE_SGPIO)) {
                spin_unlock_irqrestore(ap->lock, flags);
+               ahci_rpm_put_port(ap);
                return -EINVAL;
        }
 
        if (!(em_ctl & EM_CTL_MR)) {
                spin_unlock_irqrestore(ap->lock, flags);
+               ahci_rpm_put_port(ap);
                return -EAGAIN;
        }
 
@@ -316,6 +349,7 @@ static ssize_t ahci_read_em_buffer(struct device *dev,
        }
 
        spin_unlock_irqrestore(ap->lock, flags);
+       ahci_rpm_put_port(ap);
 
        return i;
 }
@@ -340,11 +374,13 @@ static ssize_t ahci_store_em_buffer(struct device *dev,
            size % 4 || size > hpriv->em_buf_sz)
                return -EINVAL;
 
+       ahci_rpm_get_port(ap);
        spin_lock_irqsave(ap->lock, flags);
 
        em_ctl = readl(mmio + HOST_EM_CTL);
        if (em_ctl & EM_CTL_TM) {
                spin_unlock_irqrestore(ap->lock, flags);
+               ahci_rpm_put_port(ap);
                return -EBUSY;
        }
 
@@ -357,6 +393,7 @@ static ssize_t ahci_store_em_buffer(struct device *dev,
        writel(em_ctl | EM_CTL_TM, mmio + HOST_EM_CTL);
 
        spin_unlock_irqrestore(ap->lock, flags);
+       ahci_rpm_put_port(ap);
 
        return size;
 }
@@ -370,7 +407,9 @@ static ssize_t ahci_show_em_supported(struct device *dev,
        void __iomem *mmio = hpriv->mmio;
        u32 em_ctl;
 
+       ahci_rpm_get_port(ap);
        em_ctl = readl(mmio + HOST_EM_CTL);
+       ahci_rpm_put_port(ap);
 
        return sprintf(buf, "%s%s%s%s\n",
                       em_ctl & EM_CTL_LED ? "led " : "",
@@ -1014,6 +1053,7 @@ static ssize_t ahci_transmit_led_message(struct ata_port *ap, u32 state,
        else
                return -EINVAL;
 
+       ahci_rpm_get_port(ap);
        spin_lock_irqsave(ap->lock, flags);
 
        /*
@@ -1023,6 +1063,7 @@ static ssize_t ahci_transmit_led_message(struct ata_port *ap, u32 state,
        em_ctl = readl(mmio + HOST_EM_CTL);
        if (em_ctl & EM_CTL_TM) {
                spin_unlock_irqrestore(ap->lock, flags);
+               ahci_rpm_put_port(ap);
                return -EBUSY;
        }
 
@@ -1050,6 +1091,8 @@ static ssize_t ahci_transmit_led_message(struct ata_port *ap, u32 state,
        emp->led_state = state;
 
        spin_unlock_irqrestore(ap->lock, flags);
+       ahci_rpm_put_port(ap);
+
        return size;
 }
 
@@ -2216,6 +2259,8 @@ static void ahci_pmp_detach(struct ata_port *ap)
 
 int ahci_port_resume(struct ata_port *ap)
 {
+       ahci_rpm_get_port(ap);
+
        ahci_power_up(ap);
        ahci_start_port(ap);
 
@@ -2242,6 +2287,7 @@ static int ahci_port_suspend(struct ata_port *ap, pm_message_t mesg)
                ata_port_freeze(ap);
        }
 
+       ahci_rpm_put_port(ap);
        return rc;
 }
 #endif