iio: adc: ad7616: Add support for AD7616 ADC

The AD7616 is a 12-bit ADC with 16 channels.

The AD7616 can be configured to work in hardware mode by controlling it via
gpio pins and read data via spi. No support for software mode yet, but it
is a work in progress.

This device requires a reset in order to update oversampling, so chip info
has got a new attribute to mark this.

The current assumption that this driver makes for AD7616, is that it's
working in Hardware Mode with Serial, Burst and Sequencer modes activated.
To activate them, following pins must be pulled high:
	-SER/PAR
	-SEQEN
And following must be pulled low:
	-WR/BURST
	-DB4/SEQEN

Datasheets:
Link: https://www.analog.com/media/en/technical-documentation/data-sheets/ad7616.pdf

Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7606.c

@@ -39,6 +39,10 @@ static const unsigned int ad7606_oversampling_avail[7] = {
 	1, 2, 4, 8, 16, 32, 64,
 };
 
+static const unsigned int ad7616_oversampling_avail[8] = {
+	1, 2, 4, 8, 16, 32, 64, 128,
+};
+
 static int ad7606_reset(struct ad7606_state *st)
 {
 	if (st->gpio_reset) {
@@ -220,6 +224,11 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
 		mutex_lock(&st->lock);
 		gpiod_set_array_value(ARRAY_SIZE(values), st->gpio_os->desc,
 				      st->gpio_os->info, values);
+
+		/* AD7616 requires a reset to update value */
+		if (st->chip_info->os_req_reset)
+			ad7606_reset(st);
+
 		st->oversampling = st->oversampling_avail[i];
 		mutex_unlock(&st->lock);
 
@@ -314,6 +323,36 @@ static const struct iio_chan_spec ad7606_channels[] = {
 	AD7606_CHANNEL(7),
 };
 
+/*
+ * The current assumption that this driver makes for AD7616, is that it's
+ * working in Hardware Mode with Serial, Burst and Sequencer modes activated.
+ * To activate them, following pins must be pulled high:
+ *	-SER/PAR
+ *	-SEQEN
+ * And following pins must be pulled low:
+ *	-WR/BURST
+ *	-DB4/SER1W
+ */
+static const struct iio_chan_spec ad7616_channels[] = {
+	IIO_CHAN_SOFT_TIMESTAMP(16),
+	AD7606_CHANNEL(0),
+	AD7606_CHANNEL(1),
+	AD7606_CHANNEL(2),
+	AD7606_CHANNEL(3),
+	AD7606_CHANNEL(4),
+	AD7606_CHANNEL(5),
+	AD7606_CHANNEL(6),
+	AD7606_CHANNEL(7),
+	AD7606_CHANNEL(8),
+	AD7606_CHANNEL(9),
+	AD7606_CHANNEL(10),
+	AD7606_CHANNEL(11),
+	AD7606_CHANNEL(12),
+	AD7606_CHANNEL(13),
+	AD7606_CHANNEL(14),
+	AD7606_CHANNEL(15),
+};
+
 static const struct ad7606_chip_info ad7606_chip_info_tbl[] = {
 	/* More devices added in future */
 	[ID_AD7605_4] = {
@@ -338,6 +377,13 @@ static const struct ad7606_chip_info ad7606_chip_info_tbl[] = {
 		.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,
+	},
 };
 
 static int ad7606_request_gpios(struct ad7606_state *st)

drivers/iio/adc/ad7606.h

@@ -15,12 +15,14 @@
  * @oversampling_avail	pointer to the array which stores the available
  *			oversampling ratios.
  * @oversampling_num	number of elements stored in oversampling_avail array
+ * @os_req_reset	some devices require a reset to update oversampling
  */
 struct ad7606_chip_info {
 	const struct iio_chan_spec	*channels;
 	unsigned int			num_channels;
 	const unsigned int		*oversampling_avail;
 	unsigned int			oversampling_num;
+	bool				os_req_reset;
 };
 
 /**
@@ -76,9 +78,9 @@ struct ad7606_state {
 	/*
 	 * DMA (thus cache coherency maintenance) requires the
 	 * transfer buffers to live in their own cache lines.
-	 * 8 * 16-bit samples + 64-bit timestamp
+	 * 16 * 16-bit samples + 64-bit timestamp
 	 */
-	unsigned short			data[12] ____cacheline_aligned;
+	unsigned short			data[20] ____cacheline_aligned;
 };
 
 /**
@@ -98,7 +100,8 @@ enum ad7606_supported_device_ids {
 	ID_AD7605_4,
 	ID_AD7606_8,
 	ID_AD7606_6,
-	ID_AD7606_4
+	ID_AD7606_4,
+	ID_AD7616,
 };
 
 #ifdef CONFIG_PM_SLEEP

drivers/iio/adc/ad7606_spi.c

@@ -53,6 +53,7 @@ static const struct spi_device_id ad7606_id_table[] = {
 	{ "ad7606-4", ID_AD7606_4 },
 	{ "ad7606-6", ID_AD7606_6 },
 	{ "ad7606-8", ID_AD7606_8 },
+	{ "ad7616",   ID_AD7616 },
 	{}
 };
 MODULE_DEVICE_TABLE(spi, ad7606_id_table);
@@ -62,6 +63,7 @@ static const struct of_device_id ad7606_of_match[] = {
 	{ .compatible = "adi,ad7606-4" },
 	{ .compatible = "adi,ad7606-6" },
 	{ .compatible = "adi,ad7606-8" },
+	{ .compatible = "adi,ad7616" },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, ad7606_of_match);