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, 51 insertions, 9 deletions

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 8e31a8e..cef763c 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -197,7 +197,7 @@ int pmbus_read_word_data(struct i2c_client *client, u8 page, u8 reg)
 }
 EXPORT_SYMBOL_GPL(pmbus_read_word_data);
 
-static int pmbus_read_byte_data(struct i2c_client *client, u8 page, u8 reg)
+int pmbus_read_byte_data(struct i2c_client *client, u8 page, u8 reg)
 {
 	int rv;
 
@@ -207,6 +207,7 @@ static int pmbus_read_byte_data(struct i2c_client *client, u8 page, u8 reg)
 
 	return i2c_smbus_read_byte_data(client, reg);
 }
+EXPORT_SYMBOL_GPL(pmbus_read_byte_data);
 
 static void pmbus_clear_fault_page(struct i2c_client *client, int page)
 {
@@ -443,15 +444,37 @@ static long pmbus_reg2data_direct(struct pmbus_data *data,
 	return (val - b) / m;
 }
 
+/*
+ * Convert VID sensor values to milli- or micro-units
+ * depending on sensor type.
+ * We currently only support VR11.
+ */
+static long pmbus_reg2data_vid(struct pmbus_data *data,
+			       struct pmbus_sensor *sensor)
+{
+	long val = sensor->data;
+
+	if (val < 0x02 || val > 0xb2)
+		return 0;
+	return DIV_ROUND_CLOSEST(160000 - (val - 2) * 625, 100);
+}
+
 static long pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
 {
 	long val;
 
-	if (data->info->direct[sensor->class])
+	switch (data->info->format[sensor->class]) {
+	case direct:
 		val = pmbus_reg2data_direct(data, sensor);
-	else
+		break;
+	case vid:
+		val = pmbus_reg2data_vid(data, sensor);
+		break;
+	case linear:
+	default:
 		val = pmbus_reg2data_linear(data, sensor);
-
+		break;
+	}
 	return val;
 }
 
@@ -561,16 +584,31 @@ static u16 pmbus_data2reg_direct(struct pmbus_data *data,
 	return val;
 }
 
+static u16 pmbus_data2reg_vid(struct pmbus_data *data,
+			      enum pmbus_sensor_classes class, long val)
+{
+	val = SENSORS_LIMIT(val, 500, 1600);
+
+	return 2 + DIV_ROUND_CLOSEST((1600 - val) * 100, 625);
+}
+
 static u16 pmbus_data2reg(struct pmbus_data *data,
 			  enum pmbus_sensor_classes class, long val)
 {
 	u16 regval;
 
-	if (data->info->direct[class])
+	switch (data->info->format[class]) {
+	case direct:
 		regval = pmbus_data2reg_direct(data, class, val);
-	else
+		break;
+	case vid:
+		regval = pmbus_data2reg_vid(data, class, val);
+		break;
+	case linear:
+	default:
 		regval = pmbus_data2reg_linear(data, class, val);
-
+		break;
+	}
 	return regval;
 }
 
@@ -1380,7 +1418,7 @@ static int pmbus_identify_common(struct i2c_client *client,
 		 */
 		switch (vout_mode >> 5) {
 		case 0:	/* linear mode      */
-			if (data->info->direct[PSC_VOLTAGE_OUT])
+			if (data->info->format[PSC_VOLTAGE_OUT] != linear)
 				return -ENODEV;
 
 			exponent = vout_mode & 0x1f;
@@ -1389,8 +1427,12 @@ static int pmbus_identify_common(struct i2c_client *client,
 				exponent |= ~0x1f;
 			data->exponent = exponent;
 			break;
+		case 1: /* VID mode         */
+			if (data->info->format[PSC_VOLTAGE_OUT] != vid)
+				return -ENODEV;
+			break;
 		case 2:	/* direct mode      */
-			if (!data->info->direct[PSC_VOLTAGE_OUT])
+			if (data->info->format[PSC_VOLTAGE_OUT] != direct)
 				return -ENODEV;
 			break;
 		default: