[RFC linux dev-4.10 3/3] drivers/hwmon/pmbus: Add sensor status to pmbus attributes

[Eddie James <eajames@linux.vnet.ibm.com>]

From: "Edward A. James" <eajames@us.ibm.com>

Extend the pmbus core to provide status registers for attributes.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/hwmon/pmbus/pmbus_core.c | 51 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index fc88cae..d319f94 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -87,6 +87,14 @@ struct pmbus_label {
 #define to_pmbus_label(_attr) \
 	container_of(_attr, struct pmbus_label, attribute)
 
+struct pmbus_status {
+	char name[PMBUS_NAME_SIZE];	/* sysfs status name */
+	struct device_attribute attribute;
+	int reg;
+};
+#define to_pmbus_status(_attr) \
+	container_of(_attr, struct pmbus_status, attribute)
+
 struct pmbus_data {
 	struct device *dev;
 	struct device *hwmon_dev;
@@ -993,6 +1001,16 @@ static ssize_t pmbus_show_label(struct device *dev,
 	return snprintf(buf, PAGE_SIZE, "%s\n", label->label);
 }
 
+static ssize_t pmbus_show_status(struct device *dev,
+				 struct device_attribute *da, char *buf)
+{
+	struct pmbus_status *status = to_pmbus_status(da);
+	struct pmbus_data *data = pmbus_update_device(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%02x\n",
+			pmbus_get_status(data, status->reg) & 0xFF);
+}
+
 static int pmbus_add_attribute(struct pmbus_data *data, struct attribute *attr)
 {
 	if (data->num_attributes >= data->max_attributes - 1) {
@@ -1131,6 +1149,25 @@ static int pmbus_add_label(struct pmbus_data *data,
 	return pmbus_add_attribute(data, &a->attr);
 }
 
+static int pmbus_add_status(struct pmbus_data *data, const char *name, int seq,
+			    int reg)
+{
+	struct pmbus_status *status;
+	struct device_attribute *a;
+
+	status = devm_kzalloc(data->dev, sizeof(*status), GFP_KERNEL);
+	if (!status)
+		return -ENOMEM;
+
+	a = &status->attribute;
+
+	snprintf(status->name, sizeof(status->name), "%s%d_status", name, seq);
+	status->reg = reg;
+
+	pmbus_dev_attr_init(a, status->name, S_IRUGO, pmbus_show_status, NULL);
+	return pmbus_add_attribute(data, &a->attr);
+}
+
 /*
  * Search for attributes. Allocate sensors, booleans, and labels as needed.
  */
@@ -1253,6 +1290,16 @@ static int pmbus_add_sensor_attrs_one(struct i2c_client *client,
 				return ret;
 		}
 	}
+	if (attr->sbase > 0 && attr->sbase < PB_STATUS_VMON_BASE) {
+		/* Add "status" attribute for physical status registers to dump
+		 * the contents. This is pretty useful for hardware diagnostic
+		 * purposes, as an alarm or fault bit doesn't necessarily
+		 * provide all the info available.
+		 */
+		ret = pmbus_add_status(data, name, index, attr->sbase + page);
+		if (ret)
+			return ret;
+	}
 	return 0;
 }
 
@@ -1885,6 +1932,10 @@ static int pmbus_add_fan_attributes(struct i2c_client *client,
 					PB_FAN_FAN1_FAULT >> (f & 1));
 				if (ret)
 					return ret;
+				ret = pmbus_add_status(data, "fan", index,
+						       base);
+				if (ret)
+					return ret;
 			}
 			index++;
 		}
-- 
1.8.3.1