[SCSI] libsas: Add a sysfs knob to enable/disable a phy

This patch lets a user arbitrarily enable or disable a phy via sysfs.
Potential applications include shutting down a phy to replace one
lane of wide port, and (more importantly) providing a method for the
libata SATL to control the phy.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

3 files changed, 85 insertions, 2 deletions

diff --git a/drivers/scsi/libsas/sas_init.c b/drivers/scsi/libsas/sas_init.c
index 2f0c07fc3f48..90cce34cb6f5 100644
--- a/drivers/scsi/libsas/sas_init.c
+++ b/drivers/scsi/libsas/sas_init.c
@@ -146,6 +146,36 @@ static int sas_get_linkerrors(struct sas_phy *phy)
         return sas_smp_get_phy_events(phy);
 }
 
+int sas_phy_enable(struct sas_phy *phy, int enable)
+{
+        int ret;
+        enum phy_func command;
+
+        if (enable)
+                command = PHY_FUNC_LINK_RESET;
+        else
+                command = PHY_FUNC_DISABLE;
+
+        if (scsi_is_sas_phy_local(phy)) {
+                struct Scsi_Host *shost = dev_to_shost(phy->dev.parent);
+                struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(shost);
+                struct asd_sas_phy *asd_phy = sas_ha->sas_phy[phy->number];
+                struct sas_internal *i =
+                        to_sas_internal(sas_ha->core.shost->transportt);
+
+                if (!enable) {
+                        sas_phy_disconnected(asd_phy);
+                        sas_ha->notify_phy_event(asd_phy, PHYE_LOSS_OF_SIGNAL);
+                }
+                ret = i->dft->lldd_control_phy(asd_phy, command, NULL);
+        } else {
+                struct sas_rphy *rphy = dev_to_rphy(phy->dev.parent);
+                struct domain_device *ddev = sas_find_dev_by_rphy(rphy);
+                ret = sas_smp_phy_control(ddev, phy->number, command, NULL);
+        }
+        return ret;
+}
+
 int sas_phy_reset(struct sas_phy *phy, int hard_reset)
 {
         int ret;
@@ -172,8 +202,8 @@ int sas_phy_reset(struct sas_phy *phy, int hard_reset)
         return ret;
 }
 
-static int sas_set_phy_speed(struct sas_phy *phy,
-                             struct sas_phy_linkrates *rates)
+int sas_set_phy_speed(struct sas_phy *phy,
+                      struct sas_phy_linkrates *rates)
 {
         int ret;
 
@@ -212,6 +242,7 @@ static int sas_set_phy_speed(struct sas_phy *phy,
 }
 
 static struct sas_function_template sft = {
+        .phy_enable = sas_phy_enable,
         .phy_reset = sas_phy_reset,
         .set_phy_speed = sas_set_phy_speed,
         .get_linkerrors = sas_get_linkerrors,
diff --git a/drivers/scsi/libsas/sas_scsi_host.c b/drivers/scsi/libsas/sas_scsi_host.c
index 21bd24775980..7774eb3628ad 100644
--- a/drivers/scsi/libsas/sas_scsi_host.c
+++ b/drivers/scsi/libsas/sas_scsi_host.c
@@ -875,3 +875,4 @@ EXPORT_SYMBOL_GPL(sas_change_queue_type);
 EXPORT_SYMBOL_GPL(sas_bios_param);
 EXPORT_SYMBOL_GPL(sas_task_abort);
 EXPORT_SYMBOL_GPL(sas_phy_reset);
+EXPORT_SYMBOL_GPL(sas_phy_enable);
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index 5c0b75bbfa10..9e38c1894bb2 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -336,6 +336,51 @@ show_sas_device_type(struct class_device *cdev, char *buf)
 }
 static CLASS_DEVICE_ATTR(device_type, S_IRUGO, show_sas_device_type, NULL);
 
+static ssize_t do_sas_phy_enable(struct class_device *cdev,
+                size_t count, int enable)
+{
+        struct sas_phy *phy = transport_class_to_phy(cdev);
+        struct Scsi_Host *shost = dev_to_shost(phy->dev.parent);
+        struct sas_internal *i = to_sas_internal(shost->transportt);
+        int error;
+
+        error = i->f->phy_enable(phy, enable);
+        if (error)
+                return error;
+        phy->enabled = enable;
+        return count;
+};
+
+static ssize_t store_sas_phy_enable(struct class_device *cdev,
+                const char *buf, size_t count)
+{
+        if (count < 1)
+                return -EINVAL;
+
+        switch (buf[0]) {
+        case '0':
+                do_sas_phy_enable(cdev, count, 0);
+                break;
+        case '1':
+                do_sas_phy_enable(cdev, count, 1);
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        return count;
+}
+
+static ssize_t show_sas_phy_enable(struct class_device *cdev, char *buf)
+{
+        struct sas_phy *phy = transport_class_to_phy(cdev);
+
+        return snprintf(buf, 20, "%d", phy->enabled);
+}
+
+static CLASS_DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, show_sas_phy_enable,
+                         store_sas_phy_enable);
+
 static ssize_t do_sas_phy_reset(struct class_device *cdev,
                 size_t count, int hard_reset)
 {
@@ -435,6 +480,7 @@ struct sas_phy *sas_phy_alloc(struct device *parent, int number)
                 return NULL;
 
         phy->number = number;
+        phy->enabled = 1;
 
         device_initialize(&phy->dev);
         phy->dev.parent = get_device(parent);
@@ -1389,6 +1435,10 @@ static int sas_user_scan(struct Scsi_Host *shost, uint channel,
         SETUP_TEMPLATE_RW(phy_attrs, field, S_IRUGO | S_IWUSR, 1,       \
                         !i->f->set_phy_speed, S_IRUGO)
 
+#define SETUP_OPTIONAL_PHY_ATTRIBUTE_RW(field, func)                    \
+        SETUP_TEMPLATE_RW(phy_attrs, field, S_IRUGO | S_IWUSR, 1,       \
+                          !i->f->func, S_IRUGO)
+
 #define SETUP_PORT_ATTRIBUTE(field)                                     \
         SETUP_TEMPLATE(port_attrs, field, S_IRUGO, 1)
 
@@ -1479,6 +1529,7 @@ sas_attach_transport(struct sas_function_template *ft)
         SETUP_PHY_ATTRIBUTE(phy_reset_problem_count);
         SETUP_OPTIONAL_PHY_ATTRIBUTE_WRONLY(link_reset, phy_reset);
         SETUP_OPTIONAL_PHY_ATTRIBUTE_WRONLY(hard_reset, phy_reset);
+        SETUP_OPTIONAL_PHY_ATTRIBUTE_RW(enable, phy_enable);
         i->phy_attrs[count] = NULL;
 
         count = 0;