[PATCH v2] iio: dac: ad5593r: Dynamically set AD5593R channel modes

[William Sung]

To use ad5593r more flexibly, we use the module parameter to setting the
channel modes dynamically whenever the module probe up. Users can pass
the channel modes to the module parameter for allocating the
functionality of channels as desired.

For example:
* Use in the kernel command line:
Users can add the module parameter in the kernel command line such as

    "ad5593r.ch_mode=88001122"

"88001122" means the channel mode setting for each channel. The most
left side indicates the mode of channel 7, and the most right side
indicates the mode of channel 0.

* Use when manually probe the module:
Similar to the kernel command line usage, users can enter

    "modprobe ad5593r ch_mode=88001122"

to start the ad5593r module with the desired channel mode setting.

v2: Fix the patch description and remove redundant for loop

Signed-off-by: William Sung <william.sung@xxxxxxxxxxxxxxxx>
---
 drivers/iio/dac/ad5592r-base.c | 33 ++++++++++++++++++++---
 drivers/iio/dac/ad5592r-base.h |  4 +++
 drivers/iio/dac/ad5593r.c      | 48 ++++++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-base.c
index cc4875660a69..cd69a34fa21e 100644
--- a/drivers/iio/dac/ad5592r-base.c
+++ b/drivers/iio/dac/ad5592r-base.c
@@ -21,6 +21,10 @@
 
 #include "ad5592r-base.h"
 
+/* Parameters for dynamic channel mode setting */
+static u8 update_channel_mode;
+static u8 new_channel_modes[AD559XR_CHANNEL_NR];
+
 static int ad5592r_gpio_get(struct gpio_chip *chip, unsigned offset)
 {
 	struct ad5592r_state *st = gpiochip_get_data(chip);
@@ -132,7 +136,7 @@ static int ad5592r_gpio_init(struct ad5592r_state *st)
 
 	st->gpiochip.label = dev_name(st->dev);
 	st->gpiochip.base = -1;
-	st->gpiochip.ngpio = 8;
+	st->gpiochip.ngpio = AD559XR_CHANNEL_NR;
 	st->gpiochip.parent = st->dev;
 	st->gpiochip.can_sleep = true;
 	st->gpiochip.direction_input = ad5592r_gpio_direction_input;
@@ -287,6 +291,14 @@ static int ad5592r_set_channel_modes(struct ad5592r_state *st)
 	return ret;
 }
 
+static void ad5592r_set_def_channel_modes(struct ad5592r_state *st)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(st->channel_modes); i++)
+		st->channel_modes[i] = new_channel_modes[i];
+}
+
 static int ad5592r_reset_channel_modes(struct ad5592r_state *st)
 {
 	int i;
@@ -532,6 +544,10 @@ static int ad5592r_alloc_channels(struct iio_dev *iio_dev)
 			st->channel_offstate[reg] = tmp;
 	}
 
+	/* Update default channel modes set by external module */
+	if (update_channel_mode == 1)
+		ad5592r_set_def_channel_modes(st);
+
 	channels = devm_kcalloc(st->dev,
 			1 + 2 * num_channels, sizeof(*channels),
 			GFP_KERNEL);
@@ -567,7 +583,7 @@ static int ad5592r_alloc_channels(struct iio_dev *iio_dev)
 	}
 
 	channels[curr_channel].type = IIO_TEMP;
-	channels[curr_channel].channel = 8;
+	channels[curr_channel].channel = AD559XR_CHANNEL_NR;
 	channels[curr_channel].info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 				   BIT(IIO_CHAN_INFO_SCALE) |
 				   BIT(IIO_CHAN_INFO_OFFSET);
@@ -589,6 +605,17 @@ static void ad5592r_init_scales(struct ad5592r_state *st, int vref_mV)
 		div_s64_rem(tmp * 2, 1000000000LL, &st->scale_avail[1][1]);
 }
 
+void ad5592r_update_default_channel_modes(u8 *new_modes)
+{
+	int idx = 0;
+
+	update_channel_mode = 1;
+	for (idx = 0; idx < AD559XR_CHANNEL_NR; idx++)
+		new_channel_modes[idx] = new_modes[idx];
+
+}
+EXPORT_SYMBOL_GPL(ad5592r_update_default_channel_modes);
+
 int ad5592r_probe(struct device *dev, const char *name,
 		const struct ad5592r_rw_ops *ops)
 {
@@ -603,7 +630,7 @@ int ad5592r_probe(struct device *dev, const char *name,
 	st = iio_priv(iio_dev);
 	st->dev = dev;
 	st->ops = ops;
-	st->num_channels = 8;
+	st->num_channels = AD559XR_CHANNEL_NR;
 	dev_set_drvdata(dev, iio_dev);
 
 	st->reg = devm_regulator_get_optional(dev, "vref");
diff --git a/drivers/iio/dac/ad5592r-base.h b/drivers/iio/dac/ad5592r-base.h
index 23dac2f1ff8a..40ad6369e660 100644
--- a/drivers/iio/dac/ad5592r-base.h
+++ b/drivers/iio/dac/ad5592r-base.h
@@ -39,6 +39,9 @@ enum ad5592r_registers {
 #define AD5592R_REG_CTRL_ADC_RANGE	BIT(5)
 #define AD5592R_REG_CTRL_DAC_RANGE	BIT(4)
 
+/* Define quantity of channels of AD5592R/AD5593R */
+#define AD559XR_CHANNEL_NR		8
+
 struct ad5592r_rw_ops {
 	int (*write_dac)(struct ad5592r_state *st, unsigned chan, u16 value);
 	int (*read_adc)(struct ad5592r_state *st, unsigned chan, u16 *value);
@@ -69,6 +72,7 @@ struct ad5592r_state {
 	__be16 spi_msg_nop;
 };
 
+void ad5592r_update_default_channel_modes(u8 *new_modes);
 int ad5592r_probe(struct device *dev, const char *name,
 		const struct ad5592r_rw_ops *ops);
 int ad5592r_remove(struct device *dev);
diff --git a/drivers/iio/dac/ad5593r.c b/drivers/iio/dac/ad5593r.c
index 1fbe9c019c7f..a19331d91406 100644
--- a/drivers/iio/dac/ad5593r.c
+++ b/drivers/iio/dac/ad5593r.c
@@ -21,6 +21,10 @@
 #define AD5593R_MODE_GPIO_READBACK	(6 << 4)
 #define AD5593R_MODE_REG_READBACK	(7 << 4)
 
+/* Parameters for dynamic channel mode setting */
+static char *ch_mode = "";
+module_param(ch_mode, charp, 0400);
+
 static int ad5593r_write_dac(struct ad5592r_state *st, unsigned chan, u16 value)
 {
 	struct i2c_client *i2c = to_i2c_client(st->dev);
@@ -92,9 +96,53 @@ static const struct ad5592r_rw_ops ad5593r_rw_ops = {
 	.gpio_read = ad5593r_gpio_read,
 };
 
+static void ad5593r_check_new_channel_mode(void)
+{
+	char *new_mode = NULL, tmp[2];
+	u8 new_ch_modes[AD559XR_CHANNEL_NR];
+	int idx = 0;
+
+	if (strlen(ch_mode) != AD559XR_CHANNEL_NR)
+		return;
+
+	new_mode = ch_mode;
+
+	/* Check if all channel modes are valid */
+	for (idx = 0; idx < AD559XR_CHANNEL_NR; idx++) {
+		switch (new_mode[idx]) {
+		case '0':
+		case '1':
+		case '2':
+		case '3':
+		case '8':
+			continue;
+		default:
+			/* There is invalid mode exist, ignore the settings */
+			pr_err("%s: invalid(%c) in index(%d)\n",
+				__func__, new_mode[idx], idx);
+			return;
+		}
+	}
+
+	/* Set the new modes to ad5592r-base driver to setup the new channel modes */
+	memset(tmp, 0, 2);
+	for (idx = 0; idx < AD559XR_CHANNEL_NR; idx++) {
+		tmp[0] = new_mode[idx];
+		if (kstrtou8(tmp, 10, &new_ch_modes[AD559XR_CHANNEL_NR - idx - 1])) {
+			/* Something error when converting the string to integer */
+			/* Ignore this settings */
+			pr_err("%s: kstr error idx(%d)\n", __func__, idx);
+			return;
+		}
+	}
+
+	ad5592r_update_default_channel_modes(new_ch_modes);
+}
+
 static int ad5593r_i2c_probe(struct i2c_client *i2c,
 		const struct i2c_device_id *id)
 {
+	ad5593r_check_new_channel_mode();
 	return ad5592r_probe(&i2c->dev, id->name, &ad5593r_rw_ops);
 }
 
-- 
2.17.1