staging:iio:ad7606: Add support for the ad7605-4

Add support for the AD7605-4 to the AD7606 driver. The AD7605-4 is mostly
interface compatible to the AD7606-6 with the only difference being not
having support for oversampling.

Signed-off-by: Alexandru Ardelean <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/staging/iio/adc/Kconfig

···
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes here to build support for Analog Devices:
-	  ad7606, ad7606-6, ad7606-4 analog to digital converters (ADC).
+	  ad7605-4, ad7606, ad7606-6, ad7606-4 analog to digital converters (ADC).
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad7606.

drivers/staging/iio/adc/ad7606.c

···
 	.attrs = ad7606_attributes_range,
 };
 
-#define AD7606_CHANNEL(num)					\
+#define AD760X_CHANNEL(num, mask)				\
 	{							\
 		.type = IIO_VOLTAGE,				\
 		.indexed = 1,					\
···
 		.address = num,					\
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
-		.info_mask_shared_by_all =			\
-			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		.info_mask_shared_by_all = mask,		\
 		.scan_index = num,				\
 		.scan_type = {					\
 			.sign = 's',				\
···
 			.endianness = IIO_CPU,			\
 		},						\
 	}
+
+#define AD7605_CHANNEL(num)	\
+	AD760X_CHANNEL(num, 0)
+
+#define AD7606_CHANNEL(num)	\
+	AD760X_CHANNEL(num, BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO))
+
+static const struct iio_chan_spec ad7605_channels[] = {
+	IIO_CHAN_SOFT_TIMESTAMP(4),
+	AD7605_CHANNEL(0),
+	AD7605_CHANNEL(1),
+	AD7605_CHANNEL(2),
+	AD7605_CHANNEL(3),
+};
 
 static const struct iio_chan_spec ad7606_channels[] = {
 	IIO_CHAN_SOFT_TIMESTAMP(8),
···
 	/*
 	 * More devices added in future
 	 */
+	[ID_AD7605_4] = {
+		.channels = ad7605_channels,
+		.num_channels = 5,
+	},
 	[ID_AD7606_8] = {
 		.channels = ad7606_channels,
 		.num_channels = 9,
+		.has_oversampling = true,
 	},
 	[ID_AD7606_6] = {
 		.channels = ad7606_channels,
 		.num_channels = 7,
+		.has_oversampling = true,
 	},
 	[ID_AD7606_4] = {
 		.channels = ad7606_channels,
 		.num_channels = 5,
+		.has_oversampling = true,
 	},
 };
 
···
 						    GPIOD_IN);
 	if (IS_ERR(st->gpio_frstdata))
 		return PTR_ERR(st->gpio_frstdata);
+
+	if (!st->chip_info->has_oversampling)
+		return 0;
 
 	st->gpio_os = devm_gpiod_get_array_optional(dev, "oversampling-ratio",
 			GPIOD_OUT_LOW);
···
 		return ret;
 	}
 
+	st->chip_info = &ad7606_chip_info_tbl[id];
+
 	ret = ad7606_request_gpios(st);
 	if (ret)
 		goto error_disable_reg;
-
-	st->chip_info = &ad7606_chip_info_tbl[id];
 
 	indio_dev->dev.parent = dev;
 	if (st->gpio_os) {

drivers/staging/iio/adc/ad7606.h

···
  * struct ad7606_chip_info - chip specific information
  * @channels:		channel specification
  * @num_channels:	number of channels
+ * @has_oversampling:   whether the device has oversampling support
  */
 
 struct ad7606_chip_info {
 	const struct iio_chan_spec	*channels;
 	unsigned int			num_channels;
+	bool				has_oversampling;
 };
 
 /**
···
 int ad7606_remove(struct device *dev, int irq);
 
 enum ad7606_supported_device_ids {
+	ID_AD7605_4,
 	ID_AD7606_8,
 	ID_AD7606_6,
 	ID_AD7606_4

drivers/staging/iio/adc/ad7606_par.c

···
 
 static const struct platform_device_id ad7606_driver_ids[] = {
 	{
+		.name		= "ad7605-4",
+		.driver_data	= ID_AD7605_4,
+	}, {
 		.name		= "ad7606-8",
 		.driver_data	= ID_AD7606_8,
 	}, {

drivers/staging/iio/adc/ad7606_spi.c

···
 }
 
 static const struct spi_device_id ad7606_id[] = {
+	{"ad7605-4", ID_AD7605_4},
 	{"ad7606-8", ID_AD7606_8},
 	{"ad7606-6", ID_AD7606_6},
 	{"ad7606-4", ID_AD7606_4},