[PATCH] libata: implement ata_drive_probe_reset()

Most low level drivers share supported reset/classify actions and
sequence.  This patch implements ata_drive_probe_reset() which helps
constructing ->probe_reset from three component operations -
softreset, hardreset and postreset.  This minimizes duplicate code and
yet allows flexibility if needed. The three component operations can
also be shared by EH later.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 89 insertions, 0 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 147e1461062d..cf91fdc08ef6 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -2233,6 +2233,94 @@ err_out:
         DPRINTK("EXIT\n");
 }
 
+static int do_probe_reset(struct ata_port *ap, ata_reset_fn_t reset,
+                          ata_postreset_fn_t postreset,
+                          unsigned int *classes)
+{
+        int i, rc;
+
+        for (i = 0; i < ATA_MAX_DEVICES; i++)
+                classes[i] = ATA_DEV_UNKNOWN;
+
+        rc = reset(ap, 0, classes);
+        if (rc)
+                return rc;
+
+        /* If any class isn't ATA_DEV_UNKNOWN, consider classification
+         * is complete and convert all ATA_DEV_UNKNOWN to
+         * ATA_DEV_NONE.
+         */
+        for (i = 0; i < ATA_MAX_DEVICES; i++)
+                if (classes[i] != ATA_DEV_UNKNOWN)
+                        break;
+
+        if (i < ATA_MAX_DEVICES)
+                for (i = 0; i < ATA_MAX_DEVICES; i++)
+                        if (classes[i] == ATA_DEV_UNKNOWN)
+                                classes[i] = ATA_DEV_NONE;
+
+        if (postreset)
+                postreset(ap, classes);
+
+        return classes[0] != ATA_DEV_UNKNOWN ? 0 : -ENODEV;
+}
+
+/**
+ *      ata_drive_probe_reset - Perform probe reset with given methods
+ *      @ap: port to reset
+ *      @softreset: softreset method (can be NULL)
+ *      @hardreset: hardreset method (can be NULL)
+ *      @postreset: postreset method (can be NULL)
+ *      @classes: resulting classes of attached devices
+ *
+ *      Reset the specified port and classify attached devices using
+ *      given methods.  This function prefers softreset but tries all
+ *      possible reset sequences to reset and classify devices.  This
+ *      function is intended to be used for constructing ->probe_reset
+ *      callback by low level drivers.
+ *
+ *      Reset methods should follow the following rules.
+ *
+ *      - Return 0 on sucess, -errno on failure.
+ *      - If classification is supported, fill classes[] with
+ *        recognized class codes.
+ *      - If classification is not supported, leave classes[] alone.
+ *      - If verbose is non-zero, print error message on failure;
+ *        otherwise, shut up.
+ *
+ *      LOCKING:
+ *      Kernel thread context (may sleep)
+ *
+ *      RETURNS:
+ *      0 on success, -EINVAL if no reset method is avaliable, -ENODEV
+ *      if classification fails, and any error code from reset
+ *      methods.
+ */
+int ata_drive_probe_reset(struct ata_port *ap,
+                          ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
+                          ata_postreset_fn_t postreset, unsigned int *classes)
+{
+        int rc = -EINVAL;
+
+        if (softreset) {
+                rc = do_probe_reset(ap, softreset, postreset, classes);
+                if (rc == 0)
+                        return 0;
+        }
+
+        if (!hardreset)
+                return rc;
+
+        rc = do_probe_reset(ap, hardreset, postreset, classes);
+        if (rc == 0 || rc != -ENODEV)
+                return rc;
+
+        if (softreset)
+                rc = do_probe_reset(ap, softreset, postreset, classes);
+
+        return rc;
+}
+
 static void ata_pr_blacklisted(const struct ata_port *ap,
                                const struct ata_device *dev)
 {
@@ -5180,6 +5268,7 @@ EXPORT_SYMBOL_GPL(ata_port_probe);
 EXPORT_SYMBOL_GPL(sata_phy_reset);
 EXPORT_SYMBOL_GPL(__sata_phy_reset);
 EXPORT_SYMBOL_GPL(ata_bus_reset);
+EXPORT_SYMBOL_GPL(ata_drive_probe_reset);
 EXPORT_SYMBOL_GPL(ata_port_disable);
 EXPORT_SYMBOL_GPL(ata_ratelimit);
 EXPORT_SYMBOL_GPL(ata_busy_sleep);