libata: implement sata_link_scr_lpm() and make ata_dev_set_feature() global

Link power management is about to be reimplemented.  Prepare for it.

* Implement sata_link_scr_lpm().

* Drop static from ata_dev_set_feature() and make it available to
  other libata files.

* Trivial whitespace adjustments.

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

3 files changed, 74 insertions, 5 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 380ceb000aad..b8024451234c 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -91,8 +91,6 @@ const struct ata_port_operations sata_port_ops = {
 static unsigned int ata_dev_init_params(struct ata_device *dev,
                                         u16 heads, u16 sectors);
 static unsigned int ata_dev_set_xfermode(struct ata_device *dev);
-static unsigned int ata_dev_set_feature(struct ata_device *dev,
-                                        u8 enable, u8 feature);
 static void ata_dev_xfermask(struct ata_device *dev);
 static unsigned long ata_dev_blacklisted(const struct ata_device *dev);
 
@@ -3628,7 +3626,7 @@ int ata_wait_after_reset(struct ata_link *link, unsigned long deadline,
  *      @params: timing parameters { interval, duratinon, timeout } in msec
  *      @deadline: deadline jiffies for the operation
  *
-*       Make sure SStatus of @link reaches stable state, determined by
+ *      Make sure SStatus of @link reaches stable state, determined by
  *      holding the same value where DET is not 1 for @duration polled
  *      every @interval, before @timeout.  Timeout constraints the
  *      beginning of the stable state.  Because DET gets stuck at 1 on
@@ -3760,6 +3758,72 @@ int sata_link_resume(struct ata_link *link, const unsigned long *params,
 }
 
 /**
+ *      sata_link_scr_lpm - manipulate SControl IPM and SPM fields
+ *      @link: ATA link to manipulate SControl for
+ *      @policy: LPM policy to configure
+ *      @spm_wakeup: initiate LPM transition to active state
+ *
+ *      Manipulate the IPM field of the SControl register of @link
+ *      according to @policy.  If @policy is ATA_LPM_MAX_POWER and
+ *      @spm_wakeup is %true, the SPM field is manipulated to wake up
+ *      the link.  This function also clears PHYRDY_CHG before
+ *      returning.
+ *
+ *      LOCKING:
+ *      EH context.
+ *
+ *      RETURNS:
+ *      0 on succes, -errno otherwise.
+ */
+int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
+                      bool spm_wakeup)
+{
+        struct ata_eh_context *ehc = &link->eh_context;
+        bool woken_up = false;
+        u32 scontrol;
+        int rc;
+
+        rc = sata_scr_read(link, SCR_CONTROL, &scontrol);
+        if (rc)
+                return rc;
+
+        switch (policy) {
+        case ATA_LPM_MAX_POWER:
+                /* disable all LPM transitions */
+                scontrol |= (0x3 << 8);
+                /* initiate transition to active state */
+                if (spm_wakeup) {
+                        scontrol |= (0x4 << 12);
+                        woken_up = true;
+                }
+                break;
+        case ATA_LPM_MED_POWER:
+                /* allow LPM to PARTIAL */
+                scontrol &= ~(0x1 << 8);
+                scontrol |= (0x2 << 8);
+                break;
+        case ATA_LPM_MIN_POWER:
+                /* no restrictions on LPM transitions */
+                scontrol &= ~(0x3 << 8);
+                break;
+        default:
+                WARN_ON(1);
+        }
+
+        rc = sata_scr_write(link, SCR_CONTROL, scontrol);
+        if (rc)
+                return rc;
+
+        /* give the link time to transit out of LPM state */
+        if (woken_up)
+                msleep(10);
+
+        /* clear PHYRDY_CHG from SError */
+        ehc->i.serror &= ~SERR_PHYRDY_CHG;
+        return sata_scr_write(link, SCR_ERROR, SERR_PHYRDY_CHG);
+}
+
+/**
  *      ata_std_prereset - prepare for reset
  *      @link: ATA link to be reset
  *      @deadline: deadline jiffies for the operation
@@ -4551,6 +4615,7 @@ static unsigned int ata_dev_set_xfermode(struct ata_device *dev)
         DPRINTK("EXIT, err_mask=%x\n", err_mask);
         return err_mask;
 }
+
 /**
  *      ata_dev_set_feature - Issue SET FEATURES - SATA FEATURES
  *      @dev: Device to which command will be sent
@@ -4566,8 +4631,7 @@ static unsigned int ata_dev_set_xfermode(struct ata_device *dev)
  *      RETURNS:
  *      0 on success, AC_ERR_* mask otherwise.
  */
-static unsigned int ata_dev_set_feature(struct ata_device *dev, u8 enable,
-                                        u8 feature)
+unsigned int ata_dev_set_feature(struct ata_device *dev, u8 enable, u8 feature)
 {
         struct ata_taskfile tf;
         unsigned int err_mask;
@@ -6732,6 +6796,7 @@ EXPORT_SYMBOL_GPL(sata_set_spd);
 EXPORT_SYMBOL_GPL(ata_wait_after_reset);
 EXPORT_SYMBOL_GPL(sata_link_debounce);
 EXPORT_SYMBOL_GPL(sata_link_resume);
+EXPORT_SYMBOL_GPL(sata_link_scr_lpm);
 EXPORT_SYMBOL_GPL(ata_std_prereset);
 EXPORT_SYMBOL_GPL(sata_link_hardreset);
 EXPORT_SYMBOL_GPL(sata_std_hardreset);
diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
index 1471462e3e3c..65b6a73c3ac7 100644
--- a/drivers/ata/libata.h
+++ b/drivers/ata/libata.h
@@ -86,6 +86,8 @@ extern int ata_dev_revalidate(struct ata_device *dev, unsigned int new_class,
 extern int ata_dev_configure(struct ata_device *dev);
 extern int sata_down_spd_limit(struct ata_link *link, u32 spd_limit);
 extern int ata_down_xfermask_limit(struct ata_device *dev, unsigned int sel);
+extern unsigned int ata_dev_set_feature(struct ata_device *dev,
+                                        u8 enable, u8 feature);
 extern void ata_sg_clean(struct ata_queued_cmd *qc);
 extern void ata_qc_free(struct ata_queued_cmd *qc);
 extern void ata_qc_issue(struct ata_queued_cmd *qc);
diff --git a/include/linux/libata.h b/include/linux/libata.h
index c5bdc90fd319..7770eeb21039 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -952,6 +952,8 @@ extern int sata_link_debounce(struct ata_link *link,
                         const unsigned long *params, unsigned long deadline);
 extern int sata_link_resume(struct ata_link *link, const unsigned long *params,
                             unsigned long deadline);
+extern int sata_link_scr_lpm(struct ata_link *link, enum ata_lpm_policy policy,
+                             bool spm_wakeup);
 extern int sata_link_hardreset(struct ata_link *link,
                         const unsigned long *timing, unsigned long deadline,
                         bool *online, int (*check_ready)(struct ata_link *));