hwmon: (max6650) Add support for alarms

Export the alarm flags provided by the MAX6650/MAX6651 fan-speed regulator
and monitor chips via sysfs.

Signed-off-by: Christian Engelmayer <christian.engelmayer@frequentis.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 85 insertions, 1 deletions

diff --git a/drivers/hwmon/max6650.c b/drivers/hwmon/max6650.c
index f27af6a9da41..86142a858238 100644
--- a/drivers/hwmon/max6650.c
+++ b/drivers/hwmon/max6650.c
@@ -12,7 +12,7 @@
  * also work with the MAX6651. It does not distinguish max6650 and max6651
  * chips.
  *
- * Tha datasheet was last seen at:
+ * The datasheet was last seen at:
  *
  *        http://pdfserv.maxim-ic.com/en/ds/MAX6650-MAX6651.pdf
  *
@@ -98,6 +98,16 @@ I2C_CLIENT_INSMOD_1(max6650);
 #define MAX6650_CFG_MODE_OPEN_LOOP      0x30
 #define MAX6650_COUNT_MASK              0x03
 
+/*
+ * Alarm status register bits
+ */
+
+#define MAX6650_ALRM_MAX        0x01
+#define MAX6650_ALRM_MIN        0x02
+#define MAX6650_ALRM_TACH       0x04
+#define MAX6650_ALRM_GPIO1      0x08
+#define MAX6650_ALRM_GPIO2      0x10
+
 /* Minimum and maximum values of the FAN-RPM */
 #define FAN_RPM_MIN 240
 #define FAN_RPM_MAX 30000
@@ -151,6 +161,7 @@ struct max6650_data
         u8 tach[4];
         u8 count;
         u8 dac;
+        u8 alarm;
 };
 
 static ssize_t get_fan(struct device *dev, struct device_attribute *devattr,
@@ -418,6 +429,33 @@ static ssize_t set_div(struct device *dev, struct device_attribute *devattr,
         return count;
 }
 
+/*
+ * Get alarm stati:
+ * Possible values:
+ * 0 = no alarm
+ * 1 = alarm
+ */
+
+static ssize_t get_alarm(struct device *dev, struct device_attribute *devattr,
+                         char *buf)
+{
+        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
+        struct max6650_data *data = max6650_update_device(dev);
+        struct i2c_client *client = to_i2c_client(dev);
+        int alarm = 0;
+
+        if (data->alarm & attr->index) {
+                mutex_lock(&data->update_lock);
+                alarm = 1;
+                data->alarm &= ~attr->index;
+                data->alarm |= i2c_smbus_read_byte_data(client,
+                                                        MAX6650_REG_ALARM);
+                mutex_unlock(&data->update_lock);
+        }
+
+        return sprintf(buf, "%d\n", alarm);
+}
+
 static SENSOR_DEVICE_ATTR(fan1_input, S_IRUGO, get_fan, NULL, 0);
 static SENSOR_DEVICE_ATTR(fan2_input, S_IRUGO, get_fan, NULL, 1);
 static SENSOR_DEVICE_ATTR(fan3_input, S_IRUGO, get_fan, NULL, 2);
@@ -426,7 +464,41 @@ static DEVICE_ATTR(fan1_target, S_IWUSR | S_IRUGO, get_target, set_target);
 static DEVICE_ATTR(fan1_div, S_IWUSR | S_IRUGO, get_div, set_div);
 static DEVICE_ATTR(pwm1_enable, S_IWUSR | S_IRUGO, get_enable, set_enable);
 static DEVICE_ATTR(pwm1, S_IWUSR | S_IRUGO, get_pwm, set_pwm);
+static SENSOR_DEVICE_ATTR(fan1_max_alarm, S_IRUGO, get_alarm, NULL,
+                          MAX6650_ALRM_MAX);
+static SENSOR_DEVICE_ATTR(fan1_min_alarm, S_IRUGO, get_alarm, NULL,
+                          MAX6650_ALRM_MIN);
+static SENSOR_DEVICE_ATTR(fan1_fault, S_IRUGO, get_alarm, NULL,
+                          MAX6650_ALRM_TACH);
+static SENSOR_DEVICE_ATTR(gpio1_alarm, S_IRUGO, get_alarm, NULL,
+                          MAX6650_ALRM_GPIO1);
+static SENSOR_DEVICE_ATTR(gpio2_alarm, S_IRUGO, get_alarm, NULL,
+                          MAX6650_ALRM_GPIO2);
+
+static mode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
+                                    int n)
+{
+        struct device *dev = container_of(kobj, struct device, kobj);
+        struct i2c_client *client = to_i2c_client(dev);
+        u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
+        struct device_attribute *devattr;
 
+        /*
+         * Hide the alarms that have not been enabled by the firmware
+         */
+
+        devattr = container_of(a, struct device_attribute, attr);
+        if (devattr == &sensor_dev_attr_fan1_max_alarm.dev_attr
+         || devattr == &sensor_dev_attr_fan1_min_alarm.dev_attr
+         || devattr == &sensor_dev_attr_fan1_fault.dev_attr
+         || devattr == &sensor_dev_attr_gpio1_alarm.dev_attr
+         || devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
+                if (!(alarm_en & to_sensor_dev_attr(devattr)->index))
+                        return 0;
+        }
+
+        return a->mode;
+}
 
 static struct attribute *max6650_attrs[] = {
         &sensor_dev_attr_fan1_input.dev_attr.attr,
@@ -437,11 +509,17 @@ static struct attribute *max6650_attrs[] = {
         &dev_attr_fan1_div.attr,
         &dev_attr_pwm1_enable.attr,
         &dev_attr_pwm1.attr,
+        &sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
+        &sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
+        &sensor_dev_attr_fan1_fault.dev_attr.attr,
+        &sensor_dev_attr_gpio1_alarm.dev_attr.attr,
+        &sensor_dev_attr_gpio2_alarm.dev_attr.attr,
         NULL
 };
 
 static struct attribute_group max6650_attr_grp = {
         .attrs = max6650_attrs,
+        .is_visible = max6650_attrs_visible,
 };
 
 /*
@@ -659,6 +737,12 @@ static struct max6650_data *max6650_update_device(struct device *dev)
                                                         MAX6650_REG_COUNT);
                 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
 
+                /* Alarms are cleared on read in case the condition that
+                 * caused the alarm is removed. Keep the value latched here
+                 * for providing the register through different alarm files. */
+                data->alarm |= i2c_smbus_read_byte_data(client,
+                                                        MAX6650_REG_ALARM);
+
                 data->last_updated = jiffies;
                 data->valid = 1;
         }