hwmon: (w83795) Add support for dynamic in0-2 limits

The W83795G can be configured to set the in0, in1 and/or in2 voltage
limits dynamically based on VID input pins. Switch the respective
sysfs attributes to read-only.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 56 insertions, 0 deletions

diff --git a/drivers/hwmon/w83795.c b/drivers/hwmon/w83795.c
index 24e44245e548..458fb297f696 100644
--- a/drivers/hwmon/w83795.c
+++ b/drivers/hwmon/w83795.c
@@ -316,6 +316,7 @@ struct w83795_data {
         u8 bank;
 
         u32 has_in;             /* Enable monitor VIN or not */
+        u8 has_dyn_in;          /* Only in2-0 can have this */
         u16 in[21][3];          /* Register value, read/high/low */
         u8 in_lsb[10][3];       /* LSB Register value, high/low */
         u8 has_gain;            /* has gain: in17-20 * 8 */
@@ -450,6 +451,23 @@ static struct w83795_data *w83795_update_device(struct device *dev)
                 data->in[i][IN_READ] = tmp;
         }
 
+        /* in0-2 can have dynamic limits (W83795G only) */
+        if (data->has_dyn_in) {
+                u8 lsb_max = w83795_read(client, IN_LSB_REG(0, IN_MAX));
+                u8 lsb_low = w83795_read(client, IN_LSB_REG(0, IN_LOW));
+
+                for (i = 0; i < 3; i++) {
+                        if (!(data->has_dyn_in & (1 << i)))
+                                continue;
+                        data->in[i][IN_MAX] =
+                                w83795_read(client, W83795_REG_IN[i][IN_MAX]);
+                        data->in[i][IN_LOW] =
+                                w83795_read(client, W83795_REG_IN[i][IN_LOW]);
+                        data->in_lsb[i][IN_MAX] = (lsb_max >> (2 * i)) & 0x03;
+                        data->in_lsb[i][IN_LOW] = (lsb_low >> (2 * i)) & 0x03;
+                }
+        }
+
         /* Update fan */
         for (i = 0; i < ARRAY_SIZE(data->fan); i++) {
                 if (!(data->has_fan & (1 << i)))
@@ -1450,6 +1468,8 @@ store_sf_setup(struct device *dev, struct device_attribute *attr,
 
 #define NOT_USED                        -1
 
+/* Don't change the attribute order, _max and _min are accessed by index
+ * somewhere else in the code */
 #define SENSOR_ATTR_IN(index) {                                         \
         SENSOR_ATTR_2(in##index##_input, S_IRUGO, show_in, NULL,        \
                 IN_READ, index), \
@@ -1844,6 +1864,39 @@ static int device_remove_file_wrapper(struct device *dev,
         return 0;
 }
 
+static void w83795_check_dynamic_in_limits(struct i2c_client *client)
+{
+        struct w83795_data *data = i2c_get_clientdata(client);
+        u8 vid_ctl;
+        int i, err_max, err_min;
+
+        vid_ctl = w83795_read(client, W83795_REG_VID_CTRL);
+
+        /* Return immediately if VRM isn't configured */
+        if ((vid_ctl & 0x07) == 0x00 || (vid_ctl & 0x07) == 0x07)
+                return;
+
+        data->has_dyn_in = (vid_ctl >> 3) & 0x07;
+        for (i = 0; i < 2; i++) {
+                if (!(data->has_dyn_in & (1 << i)))
+                        continue;
+
+                /* Voltage limits in dynamic mode, switch to read-only */
+                err_max = sysfs_chmod_file(&client->dev.kobj,
+                                           &w83795_in[i][2].dev_attr.attr,
+                                           S_IRUGO);
+                err_min = sysfs_chmod_file(&client->dev.kobj,
+                                           &w83795_in[i][3].dev_attr.attr,
+                                           S_IRUGO);
+                if (err_max || err_min)
+                        dev_warn(&client->dev, "Failed to set in%d limits "
+                                 "read-only (%d, %d)\n", i, err_max, err_min);
+                else
+                        dev_info(&client->dev, "in%d limits set dynamically "
+                                 "from VID\n", i);
+        }
+}
+
 /* Check pins that can be used for either temperature or voltage monitoring */
 static void w83795_apply_temp_config(struct w83795_data *data, u8 config,
                                      int temp_chan, int in_chan)
@@ -2049,6 +2102,9 @@ static int w83795_probe(struct i2c_client *client,
         if (err)
                 goto exit_remove;
 
+        if (data->chip_type == w83795g)
+                w83795_check_dynamic_in_limits(client);
+
         data->hwmon_dev = hwmon_device_register(dev);
         if (IS_ERR(data->hwmon_dev)) {
                 err = PTR_ERR(data->hwmon_dev);