iio: adc: ad7606: add support for writing registers when using backend

Add the logic for effectively enabling the software mode for the
iio-backend, i.e. enabling the software mode channel configuration and
implementing the register writing functions.

Signed-off-by: Guillaume Stols <gstols@baylibre.com>
Co-developed-by: Angelo Dureghello <adureghello@baylibre.com>
Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
Link: https://patch.msgid.link/20250210-wip-bl-ad7606_add_backend_sw_mode-v4-9-160df18b1da7@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

2 files changed, 63 insertions, 4 deletions

diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
index a35b526f3915..71a30525eaab 100644
--- a/drivers/iio/adc/ad7606.h
+++ b/drivers/iio/adc/ad7606.h
@@ -96,6 +96,21 @@
 		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),  \
 		0, 0, 16)
 
+#define AD7606_BI_SW_CHANNEL(num)			\
+	AD760X_CHANNEL(num,				\
+		/* mask separate */			\
+		BIT(IIO_CHAN_INFO_SCALE),		\
+		/* mask type */				\
+		0,					\
+		/* mask all */				\
+		BIT(IIO_CHAN_INFO_SAMP_FREQ) |		\
+		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		/* mask separate available */		\
+		BIT(IIO_CHAN_INFO_SCALE),		\
+		/* mask all available */		\
+		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		16)
+
 struct ad7606_state;
 
 typedef int (*ad7606_scale_setup_cb_t)(struct iio_dev *indio_dev,
diff --git a/drivers/iio/adc/ad7606_par.c b/drivers/iio/adc/ad7606_par.c
index 64733b607aa8..335fb481bfde 100644
--- a/drivers/iio/adc/ad7606_par.c
+++ b/drivers/iio/adc/ad7606_par.c
@@ -19,6 +19,7 @@
 #include <linux/iio/iio.h>
 
 #include "ad7606.h"
+#include "ad7606_bus_iface.h"
 
 static const struct iio_chan_spec ad7606b_bi_channels[] = {
 	AD7606_BI_CHANNEL(0),
@@ -31,7 +32,19 @@ static const struct iio_chan_spec ad7606b_bi_channels[] = {
 	AD7606_BI_CHANNEL(7),
 };
 
-static int ad7606_bi_update_scan_mode(struct iio_dev *indio_dev, const unsigned long *scan_mask)
+static const struct iio_chan_spec ad7606b_bi_sw_channels[] = {
+	AD7606_BI_SW_CHANNEL(0),
+	AD7606_BI_SW_CHANNEL(1),
+	AD7606_BI_SW_CHANNEL(2),
+	AD7606_BI_SW_CHANNEL(3),
+	AD7606_BI_SW_CHANNEL(4),
+	AD7606_BI_SW_CHANNEL(5),
+	AD7606_BI_SW_CHANNEL(6),
+	AD7606_BI_SW_CHANNEL(7),
+};
+
+static int ad7606_par_bus_update_scan_mode(struct iio_dev *indio_dev,
+					   const unsigned long *scan_mask)
 {
 	struct ad7606_state *st = iio_priv(indio_dev);
 	unsigned int c, ret;
@@ -48,7 +61,8 @@ static int ad7606_bi_update_scan_mode(struct iio_dev *indio_dev, const unsigned
 	return 0;
 }
 
-static int ad7606_bi_setup_iio_backend(struct device *dev, struct iio_dev *indio_dev)
+static int ad7606_par_bus_setup_iio_backend(struct device *dev,
+					    struct iio_dev *indio_dev)
 {
 	struct ad7606_state *st = iio_priv(indio_dev);
 	unsigned int ret, c;
@@ -86,9 +100,39 @@ static int ad7606_bi_setup_iio_backend(struct device *dev, struct iio_dev *indio
 	return 0;
 }
 
+static int ad7606_par_bus_reg_read(struct ad7606_state *st, unsigned int addr)
+{
+	struct ad7606_platform_data *pdata = st->dev->platform_data;
+	int val, ret;
+
+	ret = pdata->bus_reg_read(st->back, addr, &val);
+	if (ret)
+		return ret;
+
+	return val;
+}
+
+static int ad7606_par_bus_reg_write(struct ad7606_state *st, unsigned int addr,
+				    unsigned int val)
+{
+	struct ad7606_platform_data *pdata = st->dev->platform_data;
+
+	return pdata->bus_reg_write(st->back, addr, val);
+}
+
+static int ad7606_par_bus_sw_mode_config(struct iio_dev *indio_dev)
+{
+	indio_dev->channels = ad7606b_bi_sw_channels;
+
+	return 0;
+}
+
 static const struct ad7606_bus_ops ad7606_bi_bops = {
-	.iio_backend_config = ad7606_bi_setup_iio_backend,
-	.update_scan_mode = ad7606_bi_update_scan_mode,
+	.iio_backend_config = ad7606_par_bus_setup_iio_backend,
+	.update_scan_mode = ad7606_par_bus_update_scan_mode,
+	.reg_read = ad7606_par_bus_reg_read,
+	.reg_write = ad7606_par_bus_reg_write,
+	.sw_mode_config = ad7606_par_bus_sw_mode_config,
 };
 
 static int ad7606_par16_read_block(struct device *dev,