iio: adc: mcp3564: use devm_regulator_get_enable_read_voltage()

This makes use of the new devm_regulator_get_enable_read_voltage()
helper function to reduce boilerplate code in the MCP3564 ADC driver.

The error message is slightly changed since there are fewer error
return paths.

Setting adc->vref_mv is consolidated into a single place to make the
logic easier to follow.

A use_internal_vref_attr local variable is added to make it more
obvious what the difference between the two iio info structures is.

The return value of the "Unknown Vref" dev_err_probe() is hard-coded to
-ENODEV instead of ret since it was getting a bit far from where ret
was set and logically that is the only value it could have.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Marius Cristea <marius.cristea@microchip.com>
Link: https://patch.msgid.link/20240723-iio-regulator-refactor-round-3-v2-1-ae9291201785@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/mcp3564.c b/drivers/iio/adc/mcp3564.c
index d83bed0..a68f1cd 100644 (file)
--- a/drivers/iio/adc/mcp3564.c
+++ b/drivers/iio/adc/mcp3564.c
@@ -349,8 +349,6 @@ struct mcp3564_chip_info {
  * struct mcp3564_state - working data for a ADC device
  * @chip_info:         chip specific data
  * @spi:               SPI device structure
- * @vref:              the regulator device used as a voltage reference in case
- *                     external voltage reference is used
  * @vref_mv:           voltage reference value in miliVolts
  * @lock:              synchronize access to driver's state members
  * @dev_addr:          hardware device address
@@ -369,7 +367,6 @@ struct mcp3564_chip_info {
 struct mcp3564_state {
        const struct mcp3564_chip_info  *chip_info;
        struct spi_device               *spi;
-       struct regulator                *vref;
        unsigned short                  vref_mv;
        struct mutex                    lock; /* Synchronize access to driver's state members */
        u8                              dev_addr;
@@ -1085,11 +1082,6 @@ static int mcp3564_parse_fw_children(struct iio_dev *indio_dev)
        return 0;
 }
 
-static void mcp3564_disable_reg(void *reg)
-{
-       regulator_disable(reg);
-}
-
 static void mcp3564_fill_scale_tbls(struct mcp3564_state *adc)
 {
        unsigned int pow = adc->chip_info->resolution - 1;
@@ -1110,7 +1102,7 @@ static void mcp3564_fill_scale_tbls(struct mcp3564_state *adc)
        }
 }
 
-static int mcp3564_config(struct iio_dev *indio_dev)
+static int mcp3564_config(struct iio_dev *indio_dev, bool *use_internal_vref_attr)
 {
        struct mcp3564_state *adc = iio_priv(indio_dev);
        struct device *dev = &adc->spi->dev;
@@ -1119,6 +1111,7 @@ static int mcp3564_config(struct iio_dev *indio_dev)
        enum mcp3564_ids ids;
        int ret = 0;
        unsigned int tmp = 0x01;
+       bool internal_vref;
        bool err = false;
 
        /*
@@ -1218,36 +1211,22 @@ static int mcp3564_config(struct iio_dev *indio_dev)
 
        dev_dbg(dev, "Found %s chip\n", adc->chip_info->name);
 
-       adc->vref = devm_regulator_get_optional(dev, "vref");
-       if (IS_ERR(adc->vref)) {
-               if (PTR_ERR(adc->vref) != -ENODEV)
-                       return dev_err_probe(dev, PTR_ERR(adc->vref),
-                                            "failed to get regulator\n");
+       ret = devm_regulator_get_enable_read_voltage(dev, "vref");
+       if (ret < 0 && ret != -ENODEV)
+               return dev_err_probe(dev, ret, "Failed to get vref voltage\n");
+
+       internal_vref = ret == -ENODEV;
+       adc->vref_mv = internal_vref ? MCP3564R_INT_VREF_MV : ret / MILLI;
+       *use_internal_vref_attr = internal_vref;
 
+       if (internal_vref) {
                /* Check if chip has internal vref */
                if (!adc->have_vref)
-                       return dev_err_probe(dev, PTR_ERR(adc->vref),
-                                            "Unknown Vref\n");
-               adc->vref = NULL;
+                       return dev_err_probe(dev, -ENODEV, "Unknown Vref\n");
+
                dev_dbg(dev, "%s: Using internal Vref\n", __func__);
        } else {
-               ret = regulator_enable(adc->vref);
-               if (ret)
-                       return ret;
-
-               ret = devm_add_action_or_reset(dev, mcp3564_disable_reg,
-                                              adc->vref);
-               if (ret)
-                       return ret;
-
                dev_dbg(dev, "%s: Using External Vref\n", __func__);
-
-               ret = regulator_get_voltage(adc->vref);
-               if (ret < 0)
-                       return dev_err_probe(dev, ret,
-                                            "Failed to read vref regulator\n");
-
-               adc->vref_mv = ret / MILLI;
        }
 
        ret = mcp3564_parse_fw_children(indio_dev);
@@ -1350,10 +1329,8 @@ static int mcp3564_config(struct iio_dev *indio_dev)
        tmp_reg |= FIELD_PREP(MCP3564_CONFIG0_CLK_SEL_MASK, MCP3564_CONFIG0_USE_INT_CLK);
        tmp_reg |= MCP3456_CONFIG0_BIT6_DEFAULT;
 
-       if (!adc->vref) {
+       if (internal_vref)
                tmp_reg |= FIELD_PREP(MCP3456_CONFIG0_VREF_MASK, 1);
-               adc->vref_mv = MCP3564R_INT_VREF_MV;
-       }
 
        ret = mcp3564_write_8bits(adc, MCP3564_CONFIG0_REG, tmp_reg);
 
@@ -1412,6 +1389,7 @@ static int mcp3564_probe(struct spi_device *spi)
        int ret;
        struct iio_dev *indio_dev;
        struct mcp3564_state *adc;
+       bool use_internal_vref_attr;
 
        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
        if (!indio_dev)
@@ -1428,7 +1406,7 @@ static int mcp3564_probe(struct spi_device *spi)
         * enable/disable certain channels
         * change the sampling rate to the requested value
         */
-       ret = mcp3564_config(indio_dev);
+       ret = mcp3564_config(indio_dev, &use_internal_vref_attr);
        if (ret)
                return dev_err_probe(&spi->dev, ret,
                                     "Can't configure MCP356X device\n");
@@ -1440,7 +1418,7 @@ static int mcp3564_probe(struct spi_device *spi)
        indio_dev->name = adc->chip_info->name;
        indio_dev->modes = INDIO_DIRECT_MODE;
 
-       if (!adc->vref)
+       if (use_internal_vref_attr)
                indio_dev->info = &mcp3564r_info;
        else
                indio_dev->info = &mcp3564_info;