iio: adc: Improve the MAX22531 ADC driver

Add device entries for MAX22530 and MAX22532.
Retrieve logic and DC-DC power supplies post fixes in DT overlay.
Add chip_info structure for the device.
Fix regmap_config for SPI read/write commands as per the datasheet.
Implement scale in max22531_read_raw function.
Add boilerplate text to Kconfig for the driver.

Signed-off-by: Abhinav Jain <jain.abhinav177@gmail.com>

Author: psychild

drivers/iio/adc/Kconfig

@@ -1130,7 +1130,11 @@ config MAX22531
         tristate "Analog Devices MAX22531 ADC Driver"
         depends on SPI
         help
-          Say yes here to build support for this driver.
+          Say yes here to build support for field-side self-powered 12-bit
+	  isolated Maxim ADCs. (max22530, max22531, max22532).
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called max22531.
 
 config MAX77541_ADC
 	tristate "Analog Devices MAX77541 ADC driver"

drivers/iio/adc/max22531.c

@@ -26,15 +26,36 @@
 #define MAX22531_REG_INTERRUPT_ENABLE	0x13
 #define MAX22531_REG_CONTROL		0x14
 
+#define MAX22531_VREF_MV		1800 
+
+
 enum max22531_id {
+	max22530,
 	max22531,
+	max22532,
+};
+
+struct max22531_chip_info {
+	const char* name;
+};
+
+static struct max22531_chip_info max22531_chip_info_tbl[] = {
+	[max22530] = {
+		.name = "max22530",
+	},
+	[max22531] = {
+		.name = "max22531",
+	},
+	[max22532] = {
+		.name = "max22532",
+	}.
 };
 
 struct max22531 {
 	struct spi_device *spi_dev;
-	struct regulator *vref;
+	const struct max22531_chip_info *chip_info;
 	struct regulator *vddl;
-	struct regulator *vddf;
+	struct regulator *vddpl;
 	struct regmap *regmap;
 };
 
@@ -46,111 +67,156 @@ struct max22531 {
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
 		.scan_index = ch,					\
-		.output = 0,						\
 	}
 
 static const struct iio_chan_spec max22531_channels[] = {
 	MAX22531_CHANNEL(0),
 	MAX22531_CHANNEL(1),
 	MAX22531_CHANNEL(2),
 	MAX22531_CHANNEL(3),
-	IIO_CHAN_SOFT_TIMESTAMP(2),
 };
 
 static const struct regmap_config regmap_config = {
-	.reg_bits = 16,
-	.val_bits = 16,
-	.max_register = 0x14,
+	.reg_bits = 6,
+	.val_bits = 6,
+	.write_flag_mask = BIT(1),
+	.pad_bits = 1,
+	.max_register = MAX22531_REG_CONTROL,
 };
 
 static int max22531_read_raw(struct iio_dev *indio_dev,
 			 struct iio_chan_spec const *chan,
 			 int *val, int *val2, long mask)
 {
-	struct regmap **regmap = iio_priv(indio_dev);
+	struct max22531 *adc = iio_priv(indio_dev);
 	int ret; 
 
-	/* mock for now */
 	switch(mask) {
 	case IIO_CHAN_INFO_RAW:
-		ret = regmap_read(*regmap, chan->address, val);
-		if (ret) 
-			return ret;
-		return IIO_VAL_INT;
+		switch(chan->channel) {
+		case 0:
+			reg = MAX22531_REG_ADC1;
+			break;
+		case 1:
+			reg = MAX22531_REG_ADC2;
+			break;
+		case 2:
+			reg = MAX22531_REG_ADC3;
+			break;
+		case 3:
+			reg = MAX22531_REG_ADC3;
+			break;
+		default:
+			return -EINVAL;
+	}
+	ret = regmap_read(adc->regmap, reg, val);
+	if (ret) 
+		return ret;
+	return IIO_VAL_INT;
+	
+	case IIO_CHAN_INFO_SCALE:
+		switch(chan->channel) {
+		case 0:
+			reg = MAX22531_REG_FADC1;
+			break;
+		case 1:
+			reg = MAX22531_REG_FADC2;
+			break;
+		case 2:
+			reg = MAX22531_REG_FADC3;
+			break;
+		case 3:
+			reg = MAX22531_REG_FADC4;
+			break;
+		default:
+			return -EINVAL;
+	}
+	
+	reg = regmap_read(adc->regmap, reg, val);
+	if (ret)
+		return ret;
+	return IIO_VAL_INT;
+
 	case IIO_CHAN_INFO_SCALE:
-		return IIO_VAL_INT;
+		*val = MAX22531_VREF_MV;
+		*val2 = 12;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+	
 	default:
 		return -EINVAL;
+	
 	}
 }
 
 static const struct iio_info max22531_info = {
 	.read_raw = max22531_read_raw,
 };
 
-static void max22531_regulator_disable(void *reg)
-{
-	regulator_disable(reg);
-}
-
 static int max22531_probe(struct spi_device *spi)
 {
 	dev_info(&spi->dev, "MAX22531: probing ADC\n");
 
 	unsigned int ret, prod_id;
+	const struct max22531_chip_info *info;
 	struct max22531 *adc;
 	struct iio_dev *indio_dev;
 
 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
-	if (!indio_dev) {
-		dev_err(&spi->dev, "MAX22531: Failed to allocate memory"
-			       "for IIO device.\n");
-		return -ENOMEM;
-	}
+	if (!indio_dev)
+		dev_err_probe(&spi->dev, -ENODEV,
+				"MAX22531: Failed to allocate memory or IIO device.\n");
 
 	adc = iio_priv(indio_dev);
 	adc->spi_dev = spi;
-	
-	indio_dev->name = "max22531";
+	adc->chip_info = info;
+
+	indio_dev->name = adc->chip_info->name;
 	indio_dev->info = &max22531_info;
 	indio_dev->channels = max22531_channels;
 	indio_dev->num_channels = ARRAY_SIZE(max22531_channels);
 
 	adc->regmap = devm_regmap_init_spi(spi, &regmap_config);
 	if (IS_ERR(adc->regmap))
-		dev_err(&spi->dev, "regmap init failure\n");
+		return dev_err_probe(&spi->dev, PTR_ERR(adc->regmap),
+				"regmap init failure\n");
 
 	ret = regmap_read(adc->regmap, MAX22531_REG_PROD_ID, &prod_id);
 	if (ret)
-		dev_err(&spi->dev, "Failed to read PROD_ID\n");
+		return dev_err_probe(&spi->dev, PTR_ERR(adc->regmap),
+				"Failed to read PROD_ID\n");
 	else
 		dev_info(&spi->dev, "MAX22531: Successfully read PROD_ID"
 				": %d from the driver.\n", ret);
 
-	adc->vref = devm_regulator_get(&spi->dev, "vref");
-	if (IS_ERR(adc->vref))
-		dev_err(&spi->dev, "Failed to retrieve vref\n");
-
-	ret = regulator_enable(adc->vref);
-	if (ret)
-		return ret;
+	adc->vddl = devm_regulator_get_enable(&spi->dev, "vddl");
+	if (IS_ERR(adc->vddl))
+		return dev_err_probe(&spi->dev, PTR_ERR(adc->vddl),
+				"Failed to retrieve power logic supply\n");
 
-	ret = devm_add_action_or_reset(&spi->dev, max22531_regulator_disable,
-					adc->vref);
-	if (ret)
-		return ret;
+	adc->vddpl = devm_regulator_get_enable(&spi->dev, "vddpl");
+	if (IS_ERR(adc->vddpl))
+		return dev_err_probe(&spi->dev, PTR_ERR(adc->vddpl),
+		       "Failed to retrieve isolated DC-DC supply\n");
 
 	return devm_iio_device_register(&spi->dev, indio_dev);
 }
 
 static const struct spi_device_id max22531_id[] = {
-	{ "max22531" },
+	{ "max22530", (kernel_ulong_t)&max22531_chip_info_tbl[max22530] },
+	{ "max22531", (kernel_ulong_t)&max22531_chip_info_tbl[max22531] },
+	{ "max22532", (kernel_ulong_t)&max22531_chip_info_tbl[max22532] },
 	{ }
 };
 MODULE_DEVICE_TABLE(spi, max22531_id);
 
 static const struct of_device_id max22531_spi_of_id[] = {
-	{ .compatible = "adi,max22531" },
+	{ .compatible = "adi,max22530",
+		.data = &max22531_chip_info_tbl[max22530], },
+	{ .compatible = "adi,max22531",
+		.data = &max22531_chip_info_tbl[max22531], },
+	{ .compatible = "adi,max22532",
+		.data = &max22531_chip_info_tbl[max22532], },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, max22531_spi_of_id);