iio: adc: ad7606: Add support for AD7606B ADC

The AD7606B is a 16-bit ADC that supports simultaneous sampling of 8
channels. It is pin compatible to AD7606, but adds extra modes by
writing to the register map.

The AD7606B can be configured to work in software mode by setting all
oversampling pins to high. This mode is selected by default.
The oversampling ratio is configured from the OS_MODE register (address
0x08) with the addition of OS=128 and OS=256 that were not available in
hardware mode.

The device is configured to output data on a single spi channel, but this
configuration must be done right after restart. That is why the delay was
removed for devices which doesn't require it.

Moreover, in software mode, the range gpio has no longer its function.
Instead, the scale can be configured individually for each channel from
the RANGE_CH registers (address 0x03 to 0x06). Besides the already
supported ±10 V and ±5 V ranges, software mode can also accommodate the
±2.5 V range.
Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Co-developed-by: Beniamin Bia <beniamin.bia@analog.com>
Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7606.c

@@ -410,12 +410,19 @@ static const struct ad7606_chip_info ad7606_chip_info_tbl[] = {
 		.oversampling_avail = ad7606_oversampling_avail,
 		.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
 	},
+	[ID_AD7606B] = {
+		.channels = ad7606_channels,
+		.num_channels = 9,
+		.oversampling_avail = ad7606_oversampling_avail,
+		.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
+	},
 	[ID_AD7616] = {
 		.channels = ad7616_channels,
 		.num_channels = 17,
 		.oversampling_avail = ad7616_oversampling_avail,
 		.oversampling_num = ARRAY_SIZE(ad7616_oversampling_avail),
 		.os_req_reset = true,
+		.init_delay_ms = 15,
 	},
 };
 
@@ -631,8 +638,10 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
 		dev_warn(st->dev, "failed to RESET: no RESET GPIO specified\n");
 
 	/* AD7616 requires al least 15ms to reconfigure after a reset */
-	if (msleep_interruptible(15))
+	if (st->chip_info->init_delay_ms) {
+		if (msleep_interruptible(st->chip_info->init_delay_ms))
 			return -ERESTARTSYS;
+	}
 
 	st->write_scale = ad7606_write_scale_hw;
 	st->write_os = ad7606_write_os_hw;

drivers/iio/adc/ad7606.h

@@ -46,6 +46,8 @@
  *			oversampling ratios.
  * @oversampling_num	number of elements stored in oversampling_avail array
  * @os_req_reset	some devices require a reset to update oversampling
+ * @init_delay_ms	required delay in miliseconds for initialization
+ *			after a restart
  */
 struct ad7606_chip_info {
 	const struct iio_chan_spec	*channels;
@@ -53,6 +55,7 @@ struct ad7606_chip_info {
 	const unsigned int		*oversampling_avail;
 	unsigned int			oversampling_num;
 	bool				os_req_reset;
+	unsigned long			init_delay_ms;
 };
 
 /**
@@ -155,6 +158,7 @@ enum ad7606_supported_device_ids {
 	ID_AD7606_8,
 	ID_AD7606_6,
 	ID_AD7606_4,
+	ID_AD7606B,
 	ID_AD7616,
 };
 

drivers/iio/adc/ad7606_spi.c

@@ -28,9 +28,23 @@
  * an offset of 2 for register address.
  */
 #define AD7616_RANGE_CH_ADDR(ch)	((ch) >> 2)
-/* The range of the channel is stored on 2 bits*/
+/* The range of the channel is stored in 2 bits */
 #define AD7616_RANGE_CH_MSK(ch)		(0b11 << (((ch) & 0b11) * 2))
 #define AD7616_RANGE_CH_MODE(ch, mode)	((mode) << ((((ch) & 0b11)) * 2))
+
+#define AD7606_CONFIGURATION_REGISTER	0x02
+#define AD7606_SINGLE_DOUT		0x00
+
+/*
+ * Range for AD7606B channels are stored in registers starting with address 0x3.
+ * Each register stores range for 2 channels(4 bits per channel).
+ */
+#define AD7606_RANGE_CH_MSK(ch)		(GENMASK(3, 0) << (4 * ((ch) & 0x1)))
+#define AD7606_RANGE_CH_MODE(ch, mode)	\
+	((GENMASK(3, 0) & mode) << (4 * ((ch) & 0x1)))
+#define AD7606_RANGE_CH_ADDR(ch)	(0x03 + ((ch) >> 1))
+#define AD7606_OS_MODE			0x08
+
 static const struct iio_chan_spec ad7616_sw_channels[] = {
 	IIO_CHAN_SOFT_TIMESTAMP(16),
 	AD7616_CHANNEL(0),
@@ -51,6 +65,22 @@ static const struct iio_chan_spec ad7616_sw_channels[] = {
 	AD7616_CHANNEL(15),
 };
 
+static const struct iio_chan_spec ad7606b_sw_channels[] = {
+	IIO_CHAN_SOFT_TIMESTAMP(8),
+	AD7616_CHANNEL(0),
+	AD7616_CHANNEL(1),
+	AD7616_CHANNEL(2),
+	AD7616_CHANNEL(3),
+	AD7616_CHANNEL(4),
+	AD7616_CHANNEL(5),
+	AD7616_CHANNEL(6),
+	AD7616_CHANNEL(7),
+};
+
+static const unsigned int ad7606B_oversampling_avail[9] = {
+	1, 2, 4, 8, 16, 32, 64, 128, 256
+};
+
 static u16 ad7616_spi_rd_wr_cmd(int addr, char isWriteOp)
 {
 	/*
@@ -60,6 +90,16 @@ static u16 ad7616_spi_rd_wr_cmd(int addr, char isWriteOp)
 	return ((addr & 0x7F) << 1) | ((isWriteOp & 0x1) << 7);
 }
 
+static u16 ad7606B_spi_rd_wr_cmd(int addr, char is_write_op)
+{
+	/*
+	 * The address of register consists of one bit which
+	 * specifies a read command placed in bit 6, followed by
+	 * 6 bits of address.
+	 */
+	return (addr & 0x3F) | (((~is_write_op) & 0x1) << 6);
+}
+
 static int ad7606_spi_read_block(struct device *dev,
 				 int count, void *buf)
 {
@@ -169,6 +209,23 @@ static int ad7616_write_os_sw(struct iio_dev *indio_dev, int val)
 				     AD7616_OS_MASK, val << 2);
 }
 
+static int ad7606_write_scale_sw(struct iio_dev *indio_dev, int ch, int val)
+{
+	struct ad7606_state *st = iio_priv(indio_dev);
+
+	return ad7606_spi_write_mask(st,
+				     AD7606_RANGE_CH_ADDR(ch),
+				     AD7606_RANGE_CH_MSK(ch),
+				     AD7606_RANGE_CH_MODE(ch, val));
+}
+
+static int ad7606_write_os_sw(struct iio_dev *indio_dev, int val)
+{
+	struct ad7606_state *st = iio_priv(indio_dev);
+
+	return ad7606_spi_reg_write(st, AD7606_OS_MODE, val);
+}
+
 static int ad7616_sw_mode_config(struct iio_dev *indio_dev)
 {
 	struct ad7606_state *st = iio_priv(indio_dev);
@@ -189,6 +246,42 @@ static int ad7616_sw_mode_config(struct iio_dev *indio_dev)
 			      AD7616_BURST_MODE | AD7616_SEQEN_MODE);
 }
 
+static int ad7606B_sw_mode_config(struct iio_dev *indio_dev)
+{
+	struct ad7606_state *st = iio_priv(indio_dev);
+	unsigned long os[3] = {1};
+
+	/*
+	 * Software mode is enabled when all three oversampling
+	 * pins are set to high. If oversampling gpios are defined
+	 * in the device tree, then they need to be set to high,
+	 * otherwise, they must be hardwired to VDD
+	 */
+	if (st->gpio_os) {
+		gpiod_set_array_value(ARRAY_SIZE(os),
+				      st->gpio_os->desc, st->gpio_os->info, os);
+	}
+	/* OS of 128 and 256 are available only in software mode */
+	st->oversampling_avail = ad7606B_oversampling_avail;
+	st->num_os_ratios = ARRAY_SIZE(ad7606B_oversampling_avail);
+
+	st->write_scale = ad7606_write_scale_sw;
+	st->write_os = &ad7606_write_os_sw;
+
+	/* Configure device spi to output on a single channel */
+	st->bops->reg_write(st,
+			    AD7606_CONFIGURATION_REGISTER,
+			    AD7606_SINGLE_DOUT);
+
+	/*
+	 * Scale can be configured individually for each channel
+	 * in software mode.
+	 */
+	indio_dev->channels = ad7606b_sw_channels;
+
+	return 0;
+}
+
 static const struct ad7606_bus_ops ad7606_spi_bops = {
 	.read_block = ad7606_spi_read_block,
 };
@@ -202,6 +295,15 @@ static const struct ad7606_bus_ops ad7616_spi_bops = {
 	.sw_mode_config = ad7616_sw_mode_config,
 };
 
+static const struct ad7606_bus_ops ad7606B_spi_bops = {
+	.read_block = ad7606_spi_read_block,
+	.reg_read = ad7606_spi_reg_read,
+	.reg_write = ad7606_spi_reg_write,
+	.write_mask = ad7606_spi_write_mask,
+	.rd_wr_cmd = ad7606B_spi_rd_wr_cmd,
+	.sw_mode_config = ad7606B_sw_mode_config,
+};
+
 static int ad7606_spi_probe(struct spi_device *spi)
 {
 	const struct spi_device_id *id = spi_get_device_id(spi);
@@ -211,6 +313,9 @@ static int ad7606_spi_probe(struct spi_device *spi)
 	case ID_AD7616:
 		bops = &ad7616_spi_bops;
 		break;
+	case ID_AD7606B:
+		bops = &ad7606B_spi_bops;
+		break;
 	default:
 		bops = &ad7606_spi_bops;
 		break;
@@ -226,6 +331,7 @@ static const struct spi_device_id ad7606_id_table[] = {
 	{ "ad7606-4", ID_AD7606_4 },
 	{ "ad7606-6", ID_AD7606_6 },
 	{ "ad7606-8", ID_AD7606_8 },
+	{ "ad7606b",  ID_AD7606B },
 	{ "ad7616",   ID_AD7616 },
 	{}
 };
@@ -236,6 +342,7 @@ static const struct of_device_id ad7606_of_match[] = {
 	{ .compatible = "adi,ad7606-4" },
 	{ .compatible = "adi,ad7606-6" },
 	{ .compatible = "adi,ad7606-8" },
+	{ .compatible = "adi,ad7606b" },
 	{ .compatible = "adi,ad7616" },
 	{ },
 };