1 files changed, 68 insertions, 0 deletions

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 *))
 {