hwmon: (pmbus/ltc2978) Set voltage resolution

The LTC2977 regulator does not set the regulator_desc .n_voltages value
which is needed in order to let the regulator core list the regulator
voltage range.

This patch defines a regulator_desc with a voltage range, and uses it
for defining voltage resolution for regulators LTC2972/LTC2974/LTC2975/
LTC2977/LTC2978/LTC2979/LTC2980/LTM2987 based on that they all have a 16
bit ADC with the same stepwise 122.07uV resolution. It also scales the
resolution to a 1mV resolution which is easier to handle.

Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
Link: https://lore.kernel.org/r/20220614095144.3472305-1-marten.lindahl@axis.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

2 files changed, 46 insertions, 6 deletions

diff --git a/drivers/hwmon/pmbus/ltc2978.c b/drivers/hwmon/pmbus/ltc2978.c
index 531aa674a928..6d2592731ba3 100644
--- a/drivers/hwmon/pmbus/ltc2978.c
+++ b/drivers/hwmon/pmbus/ltc2978.c
@@ -562,7 +562,24 @@ static const struct i2c_device_id ltc2978_id[] = {
 MODULE_DEVICE_TABLE(i2c, ltc2978_id);
 
 #if IS_ENABLED(CONFIG_SENSORS_LTC2978_REGULATOR)
+#define LTC2978_ADC_RES	0xFFFF
+#define LTC2978_N_ADC	122
+#define LTC2978_MAX_UV	(LTC2978_ADC_RES * LTC2978_N_ADC)
+#define LTC2978_UV_STEP	1000
+#define LTC2978_N_VOLTAGES	((LTC2978_MAX_UV / LTC2978_UV_STEP) + 1)
+
 static const struct regulator_desc ltc2978_reg_desc[] = {
+	PMBUS_REGULATOR_STEP("vout", 0, LTC2978_N_VOLTAGES, LTC2978_UV_STEP),
+	PMBUS_REGULATOR_STEP("vout", 1, LTC2978_N_VOLTAGES, LTC2978_UV_STEP),
+	PMBUS_REGULATOR_STEP("vout", 2, LTC2978_N_VOLTAGES, LTC2978_UV_STEP),
+	PMBUS_REGULATOR_STEP("vout", 3, LTC2978_N_VOLTAGES, LTC2978_UV_STEP),
+	PMBUS_REGULATOR_STEP("vout", 4, LTC2978_N_VOLTAGES, LTC2978_UV_STEP),
+	PMBUS_REGULATOR_STEP("vout", 5, LTC2978_N_VOLTAGES, LTC2978_UV_STEP),
+	PMBUS_REGULATOR_STEP("vout", 6, LTC2978_N_VOLTAGES, LTC2978_UV_STEP),
+	PMBUS_REGULATOR_STEP("vout", 7, LTC2978_N_VOLTAGES, LTC2978_UV_STEP),
+};
+
+static const struct regulator_desc ltc2978_reg_desc_default[] = {
 	PMBUS_REGULATOR("vout", 0),
 	PMBUS_REGULATOR("vout", 1),
 	PMBUS_REGULATOR("vout", 2),
@@ -839,10 +856,29 @@ static int ltc2978_probe(struct i2c_client *client)
 
 #if IS_ENABLED(CONFIG_SENSORS_LTC2978_REGULATOR)
 	info->num_regulators = info->pages;
-	info->reg_desc = ltc2978_reg_desc;
-	if (info->num_regulators > ARRAY_SIZE(ltc2978_reg_desc)) {
-		dev_err(&client->dev, "num_regulators too large!");
-		info->num_regulators = ARRAY_SIZE(ltc2978_reg_desc);
+	switch (data->id) {
+	case ltc2972:
+	case ltc2974:
+	case ltc2975:
+	case ltc2977:
+	case ltc2978:
+	case ltc2979:
+	case ltc2980:
+	case ltm2987:
+		info->reg_desc = ltc2978_reg_desc;
+		if (info->num_regulators > ARRAY_SIZE(ltc2978_reg_desc)) {
+			dev_warn(&client->dev, "num_regulators too large!");
+			info->num_regulators = ARRAY_SIZE(ltc2978_reg_desc);
+		}
+		break;
+	default:
+		info->reg_desc = ltc2978_reg_desc_default;
+		if (info->num_regulators > ARRAY_SIZE(ltc2978_reg_desc_default)) {
+			dev_warn(&client->dev, "num_regulators too large!");
+			info->num_regulators =
+			    ARRAY_SIZE(ltc2978_reg_desc_default);
+		}
+		break;
 	}
 #endif
 
diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
index c708b60c1b48..7daaf0caf4d3 100644
--- a/drivers/hwmon/pmbus/pmbus.h
+++ b/drivers/hwmon/pmbus/pmbus.h
@@ -463,8 +463,8 @@ struct pmbus_driver_info {
 
 extern const struct regulator_ops pmbus_regulator_ops;
 
-/* Macro for filling in array of struct regulator_desc */
-#define PMBUS_REGULATOR(_name, _id)				\
+/* Macros for filling in array of struct regulator_desc */
+#define PMBUS_REGULATOR_STEP(_name, _id, _voltages, _step)  \
 	[_id] = {						\
 		.name = (_name # _id),				\
 		.supply_name = "vin",				\
@@ -474,8 +474,12 @@ extern const struct regulator_ops pmbus_regulator_ops;
 		.ops = &pmbus_regulator_ops,			\
 		.type = REGULATOR_VOLTAGE,			\
 		.owner = THIS_MODULE,				\
+		.n_voltages = _voltages,			\
+		.uV_step = _step,				\
 	}
 
+#define PMBUS_REGULATOR(_name, _id)	PMBUS_REGULATOR_STEP(_name, _id, 0, 0)
+
 /* Function declarations */
 
 void pmbus_clear_cache(struct i2c_client *client);