iio:dac:ad5686: Add AD5681R/AD5682R/AD5683/AD5683R support

The AD5681R/AD5682R/AD5683/AD5683R are a family of one channel DACs with
12-bit, 14-bit and 16-bit precision respectively. The devices have either
no built-in reference, or built-in 2.5V reference.

These devices are similar to AD5691R/AD5692R/AD5693/AD5693R except
with a few notable differences:
 * they use the SPI interface instead of I2C
 * in the write control register, DB18 and DB17 are used for setting the
   power mode, while DB16 is the REF bit. This is why a new regmap type
   was defined and checked accordingly.
 * the shift register is 24 bits wide, the first four bits are the command
   bits followed by the data bits. As the data comprises of 20-bit, 18-bit
   or 16-bit input code, this means that 4 LSB bits are don't care. This is
   why the data needs to be shifted on the left with four bits. Therefore,
   AD5683_REGMAP is checked inside a switch case in the ad5686_spi_write()
   function. On the other hand, similar devices such as AD5693R family,
   have the 4 MSB command bits followed by 4 don't care bits.

Datasheet:
http://www.analog.com/media/en/technical-documentation/data-sheets/AD5683R_5682R_5681R_5683.pdf

Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
index 1fc0c5642209..e136f0fd38f0 100644
--- a/drivers/iio/dac/ad5686.c
+++ b/drivers/iio/dac/ad5686.c
@@ -83,6 +83,10 @@ static ssize_t ad5686_write_dac_powerdown(struct iio_dev *indio_dev,
 		st->pwr_down_mask &= ~(0x3 << (chan->channel * 2));
 
 	switch (st->chip_info->regmap_type) {
+	case AD5683_REGMAP:
+		shift = 13;
+		ref_bit_msk = AD5683_REF_BIT_MSK;
+		break;
 	case AD5686_REGMAP:
 		shift = 0;
 		ref_bit_msk = 0;
@@ -256,6 +260,29 @@ static const struct ad5686_chip_info ad5686_chip_info_tbl[] = {
 		.num_channels = 8,
 		.regmap_type = AD5686_REGMAP,
 	},
+	[ID_AD5681R] = {
+		.channels = ad5691r_channels,
+		.int_vref_mv = 2500,
+		.num_channels = 1,
+		.regmap_type = AD5683_REGMAP,
+	},
+	[ID_AD5682R] = {
+		.channels = ad5692r_channels,
+		.int_vref_mv = 2500,
+		.num_channels = 1,
+		.regmap_type = AD5683_REGMAP,
+	},
+	[ID_AD5683] = {
+		.channels = ad5693_channels,
+		.num_channels = 1,
+		.regmap_type = AD5683_REGMAP,
+	},
+	[ID_AD5683R] = {
+		.channels = ad5693_channels,
+		.int_vref_mv = 2500,
+		.num_channels = 1,
+		.regmap_type = AD5683_REGMAP,
+	},
 	[ID_AD5684] = {
 		.channels = ad5684_channels,
 		.num_channels = 4,
@@ -385,6 +412,11 @@ int ad5686_probe(struct device *dev,
 	indio_dev->num_channels = st->chip_info->num_channels;
 
 	switch (st->chip_info->regmap_type) {
+	case AD5683_REGMAP:
+		cmd = AD5686_CMD_CONTROL_REG;
+		ref_bit_msk = AD5683_REF_BIT_MSK;
+		st->use_internal_vref = !voltage_uv;
+		break;
 	case AD5686_REGMAP:
 		cmd = AD5686_CMD_INTERNAL_REFER_SETUP;
 		ref_bit_msk = 0;