hwmon: (occ) Delay hwmon registration until user request

Instead of registering the hwmon device at probe time, use the
existing "occ_active" sysfs file to control when the driver polls
the OCC for sensor data and registers with hwmon. The reason for
this change is that the SBE, which is the device by which the
driver communicates with the OCC, cannot handle communications
during certain system state transitions, resulting in
unrecoverable system errors.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20220427140443.11428-1-eajames@linux.ibm.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/occ/common.c b/drivers/hwmon/occ/common.c
index f00cd59f1d19f7358fceff0f69e4ad6e95c8fdb5..d78f4bebc7189b2200de3dc2128d02514459f8a1 100644 (file)
--- a/drivers/hwmon/occ/common.c
+++ b/drivers/hwmon/occ/common.c
@@ -1149,44 +1149,75 @@ static void occ_parse_poll_response(struct occ *occ)
                sizeof(*header), size + sizeof(*header));
 }
 
-int occ_setup(struct occ *occ, const char *name)
+int occ_active(struct occ *occ, bool active)
 {
-       int rc;
-
-       mutex_init(&occ->lock);
-       occ->groups[0] = &occ->group;
+       int rc = mutex_lock_interruptible(&occ->lock);
 
-       /* no need to lock */
-       rc = occ_poll(occ);
-       if (rc == -ESHUTDOWN) {
-               dev_info(occ->bus_dev, "host is not ready\n");
-               return rc;
-       } else if (rc < 0) {
-               dev_err(occ->bus_dev,
-                       "failed to get OCC poll response=%02x: %d\n",
-                       occ->resp.return_status, rc);
+       if (rc)
                return rc;
-       }
 
-       occ->next_update = jiffies + OCC_UPDATE_FREQUENCY;
-       occ_parse_poll_response(occ);
+       if (active) {
+               if (occ->active) {
+                       rc = -EALREADY;
+                       goto unlock;
+               }
 
-       rc = occ_setup_sensor_attrs(occ);
-       if (rc) {
-               dev_err(occ->bus_dev, "failed to setup sensor attrs: %d\n",
-                       rc);
-               return rc;
-       }
+               occ->error_count = 0;
+               occ->last_safe = 0;
 
-       occ->hwmon = devm_hwmon_device_register_with_groups(occ->bus_dev, name,
-                                                           occ, occ->groups);
-       if (IS_ERR(occ->hwmon)) {
-               rc = PTR_ERR(occ->hwmon);
-               dev_err(occ->bus_dev, "failed to register hwmon device: %d\n",
-                       rc);
-               return rc;
+               rc = occ_poll(occ);
+               if (rc < 0) {
+                       dev_err(occ->bus_dev,
+                               "failed to get OCC poll response=%02x: %d\n",
+                               occ->resp.return_status, rc);
+                       goto unlock;
+               }
+
+               occ->active = true;
+               occ->next_update = jiffies + OCC_UPDATE_FREQUENCY;
+               occ_parse_poll_response(occ);
+
+               rc = occ_setup_sensor_attrs(occ);
+               if (rc) {
+                       dev_err(occ->bus_dev,
+                               "failed to setup sensor attrs: %d\n", rc);
+                       goto unlock;
+               }
+
+               occ->hwmon = hwmon_device_register_with_groups(occ->bus_dev,
+                                                              "occ", occ,
+                                                              occ->groups);
+               if (IS_ERR(occ->hwmon)) {
+                       rc = PTR_ERR(occ->hwmon);
+                       occ->hwmon = NULL;
+                       dev_err(occ->bus_dev,
+                               "failed to register hwmon device: %d\n", rc);
+                       goto unlock;
+               }
+       } else {
+               if (!occ->active) {
+                       rc = -EALREADY;
+                       goto unlock;
+               }
+
+               if (occ->hwmon)
+                       hwmon_device_unregister(occ->hwmon);
+               occ->active = false;
+               occ->hwmon = NULL;
        }
 
+unlock:
+       mutex_unlock(&occ->lock);
+       return rc;
+}
+
+int occ_setup(struct occ *occ)
+{
+       int rc;
+
+       mutex_init(&occ->lock);
+       occ->groups[0] = &occ->group;
+
        rc = occ_setup_sysfs(occ);
        if (rc)
                dev_err(occ->bus_dev, "failed to setup sysfs: %d\n", rc);
@@ -1195,6 +1226,15 @@ int occ_setup(struct occ *occ, const char *name)
 }
 EXPORT_SYMBOL_GPL(occ_setup);
 
+void occ_shutdown(struct occ *occ)
+{
+       occ_shutdown_sysfs(occ);
+
+       if (occ->hwmon)
+               hwmon_device_unregister(occ->hwmon);
+}
+EXPORT_SYMBOL_GPL(occ_shutdown);
+
 MODULE_AUTHOR("Eddie James <eajames@linux.ibm.com>");
 MODULE_DESCRIPTION("Common OCC hwmon code");
 MODULE_LICENSE("GPL");

diff --git a/drivers/hwmon/occ/common.h b/drivers/hwmon/occ/common.h
index 2dd4a4d240c0f775b24cfe5852d72638de725d83..64d5ec7e169b04982951a66cc0c8710ee836de96 100644 (file)
--- a/drivers/hwmon/occ/common.h
+++ b/drivers/hwmon/occ/common.h
@@ -106,6 +106,7 @@ struct occ {
        struct attribute_group group;
        const struct attribute_group *groups[2];
 
+       bool active;
        int error;                      /* final transfer error after retry */
        int last_error;                 /* latest transfer error */
        unsigned int error_count;       /* number of xfr errors observed */
@@ -123,9 +124,11 @@ struct occ {
        u8 prev_mode;
 };
 
-int occ_setup(struct occ *occ, const char *name);
+int occ_active(struct occ *occ, bool active);
+int occ_setup(struct occ *occ);
 int occ_setup_sysfs(struct occ *occ);
 void occ_shutdown(struct occ *occ);
+void occ_shutdown_sysfs(struct occ *occ);
 void occ_sysfs_poll_done(struct occ *occ);
 int occ_update_response(struct occ *occ);
 

diff --git a/drivers/hwmon/occ/p8_i2c.c b/drivers/hwmon/occ/p8_i2c.c
index 9e61e1fb5142cfeb398ebb1dd5d634cc76d39a1e..da39ea28df3122652a744454785c03c5e498e97f 100644 (file)
--- a/drivers/hwmon/occ/p8_i2c.c
+++ b/drivers/hwmon/occ/p8_i2c.c
@@ -223,7 +223,7 @@ static int p8_i2c_occ_probe(struct i2c_client *client)
        occ->poll_cmd_data = 0x10;              /* P8 OCC poll data */
        occ->send_cmd = p8_i2c_occ_send_cmd;
 
-       return occ_setup(occ, "p8_occ");
+       return occ_setup(occ);
 }
 
 static int p8_i2c_occ_remove(struct i2c_client *client)

diff --git a/drivers/hwmon/occ/p9_sbe.c b/drivers/hwmon/occ/p9_sbe.c
index 49b13cc01073a51e6d7aa1a77859899237634ec8..42fc7b97bb34b55ed5dc4ea73e31ff8b2a7a1af4 100644 (file)
--- a/drivers/hwmon/occ/p9_sbe.c
+++ b/drivers/hwmon/occ/p9_sbe.c
@@ -145,7 +145,7 @@ static int p9_sbe_occ_probe(struct platform_device *pdev)
        occ->poll_cmd_data = 0x20;              /* P9 OCC poll data */
        occ->send_cmd = p9_sbe_occ_send_cmd;
 
-       rc = occ_setup(occ, "p9_occ");
+       rc = occ_setup(occ);
        if (rc == -ESHUTDOWN)
                rc = -ENODEV;   /* Host is shutdown, don't spew errors */
 

diff --git a/drivers/hwmon/occ/sysfs.c b/drivers/hwmon/occ/sysfs.c
index b2f788a777469367676fb63f20788cd6005d089a..2317301fc1e9f62cd367a51d5c256bf95e09b1eb 100644 (file)
--- a/drivers/hwmon/occ/sysfs.c
+++ b/drivers/hwmon/occ/sysfs.c
@@ -6,13 +6,13 @@
 #include <linux/export.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/kernel.h>
+#include <linux/kstrtox.h>
 #include <linux/sysfs.h>
 
 #include "common.h"
 
 /* OCC status register */
 #define OCC_STAT_MASTER                        BIT(7)
-#define OCC_STAT_ACTIVE                        BIT(0)
 
 /* OCC extended status register */
 #define OCC_EXT_STAT_DVFS_OT           BIT(7)
@@ -22,6 +22,25 @@
 #define OCC_EXT_STAT_DVFS_VDD          BIT(3)
 #define OCC_EXT_STAT_GPU_THROTTLE      GENMASK(2, 0)
 
+static ssize_t occ_active_store(struct device *dev,
+                               struct device_attribute *attr,
+                               const char *buf, size_t count)
+{
+       int rc;
+       bool active;
+       struct occ *occ = dev_get_drvdata(dev);
+
+       rc = kstrtobool(buf, &active);
+       if (rc)
+               return rc;
+
+       rc = occ_active(occ, active);
+       if (rc)
+               return rc;
+
+       return count;
+}
+
 static ssize_t occ_sysfs_show(struct device *dev,
                              struct device_attribute *attr, char *buf)
 {
@@ -31,54 +50,64 @@ static ssize_t occ_sysfs_show(struct device *dev,
        struct occ_poll_response_header *header;
        struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
 
-       rc = occ_update_response(occ);
-       if (rc)
-               return rc;
+       if (occ->active) {
+               rc = occ_update_response(occ);
+               if (rc)
+                       return rc;
 
-       header = (struct occ_poll_response_header *)occ->resp.data;
-
-       switch (sattr->index) {
-       case 0:
-               val = !!(header->status & OCC_STAT_MASTER);
-               break;
-       case 1:
-               val = !!(header->status & OCC_STAT_ACTIVE);
-               break;
-       case 2:
-               val = !!(header->ext_status & OCC_EXT_STAT_DVFS_OT);
-               break;
-       case 3:
-               val = !!(header->ext_status & OCC_EXT_STAT_DVFS_POWER);
-               break;
-       case 4:
-               val = !!(header->ext_status & OCC_EXT_STAT_MEM_THROTTLE);
-               break;
-       case 5:
-               val = !!(header->ext_status & OCC_EXT_STAT_QUICK_DROP);
-               break;
-       case 6:
-               val = header->occ_state;
-               break;
-       case 7:
-               if (header->status & OCC_STAT_MASTER)
-                       val = hweight8(header->occs_present);
-               else
+               header = (struct occ_poll_response_header *)occ->resp.data;
+
+               switch (sattr->index) {
+               case 0:
+                       val = !!(header->status & OCC_STAT_MASTER);
+                       break;
+               case 1:
                        val = 1;
-               break;
-       case 8:
-               val = header->ips_status;
-               break;
-       case 9:
-               val = header->mode;
-               break;
-       case 10:
-               val = !!(header->ext_status & OCC_EXT_STAT_DVFS_VDD);
-               break;
-       case 11:
-               val = header->ext_status & OCC_EXT_STAT_GPU_THROTTLE;
-               break;
-       default:
-               return -EINVAL;
+                       break;
+               case 2:
+                       val = !!(header->ext_status & OCC_EXT_STAT_DVFS_OT);
+                       break;
+               case 3:
+                       val = !!(header->ext_status & OCC_EXT_STAT_DVFS_POWER);
+                       break;
+               case 4:
+                       val = !!(header->ext_status &
+                                OCC_EXT_STAT_MEM_THROTTLE);
+                       break;
+               case 5:
+                       val = !!(header->ext_status & OCC_EXT_STAT_QUICK_DROP);
+                       break;
+               case 6:
+                       val = header->occ_state;
+                       break;
+               case 7:
+                       if (header->status & OCC_STAT_MASTER)
+                               val = hweight8(header->occs_present);
+                       else
+                               val = 1;
+                       break;
+               case 8:
+                       val = header->ips_status;
+                       break;
+               case 9:
+                       val = header->mode;
+                       break;
+               case 10:
+                       val = !!(header->ext_status & OCC_EXT_STAT_DVFS_VDD);
+                       break;
+               case 11:
+                       val = header->ext_status & OCC_EXT_STAT_GPU_THROTTLE;
+                       break;
+               default:
+                       return -EINVAL;
+               }
+       } else {
+               if (sattr->index == 1)
+                       val = 0;
+               else if (sattr->index <= 11)
+                       val = -ENODATA;
+               else
+                       return -EINVAL;
        }
 
        return sysfs_emit(buf, "%d\n", val);
@@ -95,7 +124,8 @@ static ssize_t occ_error_show(struct device *dev,
 }
 
 static SENSOR_DEVICE_ATTR(occ_master, 0444, occ_sysfs_show, NULL, 0);
-static SENSOR_DEVICE_ATTR(occ_active, 0444, occ_sysfs_show, NULL, 1);
+static SENSOR_DEVICE_ATTR(occ_active, 0644, occ_sysfs_show, occ_active_store,
+                         1);
 static SENSOR_DEVICE_ATTR(occ_dvfs_overtemp, 0444, occ_sysfs_show, NULL, 2);
 static SENSOR_DEVICE_ATTR(occ_dvfs_power, 0444, occ_sysfs_show, NULL, 3);
 static SENSOR_DEVICE_ATTR(occ_mem_throttle, 0444, occ_sysfs_show, NULL, 4);
@@ -139,7 +169,7 @@ void occ_sysfs_poll_done(struct occ *occ)
         * On the first poll response, we haven't yet created the sysfs
         * attributes, so don't make any notify calls.
         */
-       if (!occ->hwmon)
+       if (!occ->active)
                goto done;
 
        if ((header->status & OCC_STAT_MASTER) !=
@@ -148,12 +178,6 @@ void occ_sysfs_poll_done(struct occ *occ)
                sysfs_notify(&occ->bus_dev->kobj, NULL, name);
        }
 
-       if ((header->status & OCC_STAT_ACTIVE) !=
-           (occ->prev_stat & OCC_STAT_ACTIVE)) {
-               name = sensor_dev_attr_occ_active.dev_attr.attr.name;
-               sysfs_notify(&occ->bus_dev->kobj, NULL, name);
-       }
-
        if ((header->ext_status & OCC_EXT_STAT_DVFS_OT) !=
            (occ->prev_ext_stat & OCC_EXT_STAT_DVFS_OT)) {
                name = sensor_dev_attr_occ_dvfs_overtemp.dev_attr.attr.name;
@@ -227,8 +251,7 @@ int occ_setup_sysfs(struct occ *occ)
        return sysfs_create_group(&occ->bus_dev->kobj, &occ_sysfs);
 }
 
-void occ_shutdown(struct occ *occ)
+void occ_shutdown_sysfs(struct occ *occ)
 {
        sysfs_remove_group(&occ->bus_dev->kobj, &occ_sysfs);
 }
-EXPORT_SYMBOL_GPL(occ_shutdown);