regulator (max5970): Add hwmon support

Utilize the integrated 10-bit ADC in Max5970/Max5978 to enable voltage
and current monitoring. This feature is seamlessly integrated through
the hwmon subsystem.

Signed-off-by: Naresh Solanki <naresh.solanki@9elements.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20231027152830.1269895-1-naresh.solanki@9elements.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/regulator/max5970-regulator.c b/drivers/regulator/max5970-regulator.c
index b56a174cde3df140a041507786a94b8266d4a184..56cc56ae63b73e6e455b2fdd699e29538893308c 100644 (file)
--- a/drivers/regulator/max5970-regulator.c
+++ b/drivers/regulator/max5970-regulator.c
@@ -10,6 +10,7 @@
 #include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/hwmon.h>
 #include <linux/module.h>
 #include <linux/io.h>
 #include <linux/of.h>
@@ -32,6 +33,132 @@ enum max597x_regulator_id {
        MAX597X_SW1,
 };
 
+static int max5970_read_adc(struct regmap *regmap, int reg, long *val)
+{
+       u8 reg_data[2];
+       int ret;
+
+       ret = regmap_bulk_read(regmap, reg, &reg_data[0], 2);
+       if (ret < 0)
+               return ret;
+
+       *val = (reg_data[0] << 2) | (reg_data[1] & 3);
+
+       return 0;
+}
+
+static int max5970_read(struct device *dev, enum hwmon_sensor_types type,
+                       u32 attr, int channel, long *val)
+{
+       struct regulator_dev **rdevs = dev_get_drvdata(dev);
+       struct max5970_regulator *ddata = rdev_get_drvdata(rdevs[channel]);
+       struct regmap *regmap = ddata->regmap;
+       int ret;
+
+       switch (type) {
+       case hwmon_curr:
+               switch (attr) {
+               case hwmon_curr_input:
+                       ret = max5970_read_adc(regmap, MAX5970_REG_CURRENT_H(channel), val);
+                       if (ret < 0)
+                               return ret;
+                       /*
+                        * Calculate current from ADC value, IRNG range & shunt resistor value.
+                        * ddata->irng holds the voltage corresponding to the maximum value the
+                        * 10-bit ADC can measure.
+                        * To obtain the output, multiply the ADC value by the IRNG range (in
+                        * millivolts) and then divide it by the maximum value of the 10-bit ADC.
+                        */
+                       *val = (*val * ddata->irng) >> 10;
+                       /* Convert the voltage meansurement across shunt resistor to current */
+                       *val = (*val * 1000) / ddata->shunt_micro_ohms;
+                       return 0;
+               default:
+                       return -EOPNOTSUPP;
+               }
+
+       case hwmon_in:
+               switch (attr) {
+               case hwmon_in_input:
+                       ret = max5970_read_adc(regmap, MAX5970_REG_VOLTAGE_H(channel), val);
+                       if (ret < 0)
+                               return ret;
+                       /*
+                        * Calculate voltage from ADC value and MON range.
+                        * ddata->mon_rng holds the voltage corresponding to the maximum value the
+                        * 10-bit ADC can measure.
+                        * To obtain the output, multiply the ADC value by the MON range (in
+                        * microvolts) and then divide it by the maximum value of the 10-bit ADC.
+                        */
+                       *val = mul_u64_u32_shr(*val, ddata->mon_rng, 10);
+                       /* uV to mV */
+                       *val = *val / 1000;
+                       return 0;
+               default:
+                       return -EOPNOTSUPP;
+               }
+       default:
+               return -EOPNOTSUPP;
+       }
+}
+
+static umode_t max5970_is_visible(const void *data,
+                                 enum hwmon_sensor_types type,
+                                 u32 attr, int channel)
+{
+       struct regulator_dev **rdevs = (struct regulator_dev **)data;
+       struct max5970_regulator *ddata;
+
+       if (channel >= MAX5970_NUM_SWITCHES || !rdevs[channel])
+               return 0;
+
+       ddata = rdev_get_drvdata(rdevs[channel]);
+
+       if (channel >= ddata->num_switches)
+               return 0;
+
+       switch (type) {
+       case hwmon_in:
+               switch (attr) {
+               case hwmon_in_input:
+                       return 0444;
+               default:
+                       break;
+               }
+               break;
+       case hwmon_curr:
+               switch (attr) {
+               case hwmon_curr_input:
+                       /* Current measurement requires knowledge of the shunt resistor value. */
+                       if (ddata->shunt_micro_ohms)
+                               return 0444;
+                       break;
+               default:
+                       break;
+               }
+               break;
+       default:
+               break;
+       }
+       return 0;
+}
+
+static const struct hwmon_ops max5970_hwmon_ops = {
+       .is_visible = max5970_is_visible,
+       .read = max5970_read,
+};
+
+static const struct hwmon_channel_info *max5970_info[] = {
+       HWMON_CHANNEL_INFO(in, HWMON_I_INPUT, HWMON_I_INPUT),
+       HWMON_CHANNEL_INFO(curr, HWMON_C_INPUT, HWMON_C_INPUT),
+       NULL
+};
+
+static const struct hwmon_chip_info max5970_chip_info = {
+       .ops = &max5970_hwmon_ops,
+       .info = max5970_info,
+};
+
 static int max597x_uvp_ovp_check_mode(struct regulator_dev *rdev, int severity)
 {
        int ret, reg;
@@ -431,7 +558,8 @@ static int max597x_regulator_probe(struct platform_device *pdev)
        struct i2c_client *i2c = to_i2c_client(pdev->dev.parent);
        struct regulator_config config = { };
        struct regulator_dev *rdev;
-       struct regulator_dev *rdevs[MAX5970_NUM_SWITCHES];
+       struct regulator_dev **rdevs = NULL;
+       struct device *hwmon_dev;
        int num_switches;
        int ret, i;
 
@@ -442,6 +570,11 @@ static int max597x_regulator_probe(struct platform_device *pdev)
        if (!max597x)
                return -ENOMEM;
 
+       rdevs = devm_kcalloc(&i2c->dev, MAX5970_NUM_SWITCHES, sizeof(struct regulator_dev *),
+                            GFP_KERNEL);
+       if (!rdevs)
+               return -ENOMEM;
+
        i2c_set_clientdata(i2c, max597x);
 
        if (of_device_is_compatible(i2c->dev.of_node, "maxim,max5978"))
@@ -485,6 +618,15 @@ static int max597x_regulator_probe(struct platform_device *pdev)
                max597x->shunt_micro_ohms[i] = data->shunt_micro_ohms;
        }
 
+       if (IS_REACHABLE(CONFIG_HWMON)) {
+               hwmon_dev = devm_hwmon_device_register_with_info(&i2c->dev, "max5970", rdevs,
+                                                                &max5970_chip_info, NULL);
+               if (IS_ERR(hwmon_dev)) {
+                       return dev_err_probe(&i2c->dev, PTR_ERR(hwmon_dev),
+                                            "Unable to register hwmon device\n");
+               }
+       }
+
        if (i2c->irq) {
                ret =
                    max597x_setup_irq(&i2c->dev, i2c->irq, rdevs, num_switches,