hwmon: (pmbus) Add support for VID output voltage mode

In VID mode, output voltages are measured and reported as VID values, and
have to be converted to voltages using VID conversion tables or functions.
Support is added for VR11 only at this time.

This patch enables support for PMBus devices supporting VID VR11 based output
voltage selection such as NCP4200 and NCP4208.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Reviewed-by: Robert Coulson <robert.coulson@ericsson.com>

1 files changed, 31 insertions, 3 deletions

diff --git a/drivers/hwmon/pmbus/pmbus.c b/drivers/hwmon/pmbus/pmbus.c
index 9b1f0c37ef77..4d8e31bcd7a3 100644
--- a/drivers/hwmon/pmbus/pmbus.c
+++ b/drivers/hwmon/pmbus/pmbus.c
@@ -96,6 +96,8 @@ static void pmbus_find_sensor_groups(struct i2c_client *client,
 static int pmbus_identify(struct i2c_client *client,
                           struct pmbus_driver_info *info)
 {
+        int ret = 0;
+
         if (!info->pages) {
                 /*
                  * Check if the PAGE command is supported. If it is,
@@ -117,6 +119,27 @@ static int pmbus_identify(struct i2c_client *client,
                 }
         }
 
+        if (pmbus_check_byte_register(client, 0, PMBUS_VOUT_MODE)) {
+                int vout_mode;
+
+                vout_mode = pmbus_read_byte_data(client, 0, PMBUS_VOUT_MODE);
+                if (vout_mode >= 0 && vout_mode != 0xff) {
+                        switch (vout_mode >> 5) {
+                        case 0:
+                                break;
+                        case 1:
+                                info->format[PSC_VOLTAGE_OUT] = vid;
+                                break;
+                        case 2:
+                                info->format[PSC_VOLTAGE_OUT] = direct;
+                                break;
+                        default:
+                                ret = -ENODEV;
+                                goto abort;
+                        }
+                }
+        }
+
         /*
          * We should check if the COEFFICIENTS register is supported.
          * If it is, and the chip is configured for direct mode, we can read
@@ -125,13 +148,18 @@ static int pmbus_identify(struct i2c_client *client,
          *
          * To do this, we will need access to a chip which actually supports the
          * COEFFICIENTS command, since the command is too complex to implement
-         * without testing it.
+         * without testing it. Until then, abort if a chip configured for direct
+         * mode was detected.
          */
+        if (info->format[PSC_VOLTAGE_OUT] == direct) {
+                ret = -ENODEV;
+                goto abort;
+        }
 
         /* Try to find sensor groups  */
         pmbus_find_sensor_groups(client, info);
-
-        return 0;
+abort:
+        return ret;
 }
 
 static int pmbus_probe(struct i2c_client *client,