iio: dac: ad5504: bindings, cleanups, and scale fixes

The AD5504 output range (0-30V or 0-60V) is determined by the R_SEL pin.

Use standard output-range-microvolt and range-sel-gpios properties to describe the hardware configuration of the R_SEL pin. Ensure mutual exclusivity using the not/required logic. Additionally, add missing vlogic-supply, clr-gpios, ldac-gpios and datasheet links, and provide a complete usage example.

Signed-off-by Taha Ed-Dafili <[email protected]>

Rearrange the include headers in alphabetical order to follow the standard kernel coding style. This is a preparatory cleanup with no functional changes.

Reviewed-by Andy Shevchenko <[email protected]>

Signed-off-by Taha Ed-Dafili <[email protected]>

---
 drivers/iio/dac/ad5504.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

drivers/iio/dac/ad5504.c +8 -8

index 355bcb6a8ba0..03ce37e2c616 100644
@@ -5,21 +5,21 @@
  * Copyright 2011 Analog Devices Inc.
  */
 
-#include <linux/interrupt.h>
-#include <linux/fs.h>
+#include <linux/bitops.h>
 #include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/interrupt.h>
 #include <linux/kernel.h>
-#include <linux/spi/spi.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
 #include <linux/slab.h>
+#include <linux/spi/spi.h>
 #include <linux/sysfs.h>
-#include <linux/regulator/consumer.h>
-#include <linux/module.h>
-#include <linux/bitops.h>
 
+#include <linux/iio/dac/ad5504.h>
+#include <linux/iio/events.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
-#include <linux/iio/events.h>
-#include <linux/iio/dac/ad5504.h>
 
 #define AD5504_RES_MASK			GENMASK(11, 0)
 #define AD5504_CMD_READ			BIT(15)

Update the header inclusions to follow the IWYU principle and ensure they are sorted alphabetically:

- Remove <linux/fs.h>, <linux/slab.h>, and <linux/kernel.h> as they are unused. The driver relies on devm_ managed allocations, so slab is not required.
- Replace <linux/bitops.h> with <linux/bits.h> as only the BIT() and GENMASK() macros are used.
- Add <linux/mod_devicetable.h> for struct spi_device_id.
- Add <linux/errno.h> and <linux/types.h> for error codes and data types.
- Add <asm/byteorder.h> for cpu_to_be16().
- Add <linux/array_size.h> for ARRAY_SIZE().
- Add <linux/kstrtox.h> for string to integer conversions.

Signed-off-by Taha Ed-Dafili <[email protected]>

---
 drivers/iio/dac/ad5504.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

drivers/iio/dac/ad5504.c +0 -0

index 03ce37e2c616..57e6eeed26ef 100644

drivers/iio/dac/ad5504.c +4 -3

-#include <linux/fs.h>
+#include <linux/errno.h>
 #include <linux/interrupt.h>
-#include <linux/kernel.h>
+#include <linux/kstrtox.h>
+#include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/regulator/consumer.h>
-#include <linux/slab.h>
 #include <linux/spi/spi.h>
 #include <linux/sysfs.h>
+#include <linux/types.h>
 
 #include <linux/iio/dac/ad5504.h>
 #include <linux/iio/events.h>

Replace &spi->dev with a local dev pointer to shorten lines, fix alignment, and improve overall readability in the probe function.

Signed-off-by Taha Ed-Dafili <[email protected]>

The AD5504 full-scale range is hardware-determined by the R_SEL pin, not the VCC supply voltage.

Fix the scaling logic by reading the standard 'output-range-microvolt' property from the device tree instead of querying the VCC regulator or relying on legacy platform data (pdata).

As a result of this transition:
- The 'vcc' regulator is now only enabled, not read.
- Legacy pdata support is removed, as it is no longer required for fallback voltage calculations.
- Strict array bounds checking is added for the DT property.

Signed-off-by Taha Ed-Dafili <[email protected]>

---
 drivers/iio/dac/ad5504.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

drivers/iio/dac/ad5504.c +2 -0

index 9e95da6e49d6..040f580b8282 100644
@@ -14,10 +14,12 @@
 #include <linux/kstrtox.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
+#include <linux/property.h>
 #include <linux/regulator/consumer.h>
 #include <linux/spi/spi.h>
 #include <linux/sysfs.h>
 #include <linux/types.h>
+#include <linux/units.h>
 
 #include <linux/iio/dac/ad5504.h>
 #include <linux/iio/events.h>

drivers/iio/dac/ad5504.c +13 -9

 	struct iio_dev *indio_dev;
 	struct ad5504_state *st;
+	u32 range[2];
 	int ret;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));

@@ -285,16 +287,19 @@ static int ad5504_probe(struct spi_device *spi)
 
 	st = iio_priv(indio_dev);
 
-	ret = devm_regulator_get_enable_read_voltage(dev, "vcc");
-	if (ret < 0 && ret != -ENODEV)
+	ret = devm_regulator_get_enable(dev, "vcc");
+	if (ret && ret != -ENODEV)
 		return ret;
-	if (ret == -ENODEV) {
-		if (pdata->vref_mv)
-			st->vref_mv = pdata->vref_mv;
-		else
-			dev_warn(dev, "reference voltage unspecified\n");
-	} else {
-		st->vref_mv = ret / 1000;
+
+	st->vref_mv = 60 * MILLI;
+	ret = device_property_read_u32_array(dev, "output-range-microvolt",
+					     range, ARRAY_SIZE(range));
+	if (!ret) {
+		if (range[0] != 0 || (range[1] != 30 * MICRO && range[1] != 60 * MICRO))
+			return -EINVAL;
+
+		if (range[1] == 30 * MICRO)
+			st->vref_mv = 30 * MILLI;
 	}
 
 	st->spi = spi;

The AD5504 full-scale range is hardware-determined by the R_SEL pin, not the VCC supply voltage.

Fix the scaling logic by reading the standard 'output-range-microvolt' property from the device tree instead of querying the VCC regulator or relying on legacy platform data (pdata).

As a result of this transition:
- The 'vcc' regulator is now only enabled, not read.
- Legacy pdata support is removed, as it is no longer required for fallback voltage calculations.
- Strict array bounds checking is added for the DT property.

Signed-off-by Taha Ed-Dafili <[email protected]>

---
 drivers/iio/dac/ad5504.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

drivers/iio/dac/ad5504.c +3 -1

index 9e95da6e49d6..040f580b8282 100644
@@ -14,10 +14,12 @@
 #include <linux/kstrtox.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
+#include <linux/property.h>
 #include <linux/regulator/consumer.h>
 #include <linux/spi/spi.h>
 #include <linux/sysfs.h>
 #include <linux/types.h>
+#include <linux/units.h>
 
 #include <linux/iio/dac/ad5504.h>
 #include <linux/iio/events.h>

@@ -274,9 +276,9 @@ static const struct iio_chan_spec ad5504_channels[] = {
 static int ad5504_probe(struct spi_device *spi)
 {
 	struct device *dev = &spi->dev;
-	const struct ad5504_platform_data *pdata = dev_get_platdata(dev);
 	struct iio_dev *indio_dev;
 	struct ad5504_state *st;
+	u32 range[2];
 	int ret;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));

drivers/iio/dac/ad5504.c +12 -7

+	ret = devm_regulator_get_enable(dev, "vcc");
+	if (ret && ret != -ENODEV)
 		return ret;
-	if (ret == -ENODEV) {
-		if (pdata->vref_mv)
-			st->vref_mv = pdata->vref_mv;
-		else
-			dev_warn(dev, "reference voltage unspecified\n");
-	} else {
-		st->vref_mv = ret / 1000;
+
+	st->vref_mv = 60 * MILLI;
+	ret = device_property_read_u32_array(dev, "output-range-microvolt",
+					     range, ARRAY_SIZE(range));
+	if (!ret) {
+		if (range[0] != 0 || (range[1] != 30 * MICRO && range[1] != 60 * MICRO))
+			return -EINVAL;
+
+		if (range[1] == 30 * MICRO)
+			st->vref_mv = 30 * MILLI;
 	}
 
 	st->spi = spi;

Hi everyone,

First, I want to sincerely apologize for the long delay between v2 and v3. I had to step away to focus on finishing my last year studies, but I am back now to get this series over the finish line!

This v3 series addresses the feedbacks from the v2 review, specifically focusing on strict DT validation, dropping unnecessary driver code, and making sure the driver works perfectly at every individual commit.

Testing & Hardware Proof:
The series has been physically verified on an ARM64 Raspberry Pi 5 using a custom Device Tree overlay.

The AD5504 is a 12-bit DAC. The hardware scale outputs now perfectly match the DT inputs:

Testing the 60V path (output-range-microvolt = <0 60000000>):

$ cat /sys/bus/iio/devices/iio:device0/out_voltage_scale
14.648437500  (60000mV / 4096)

Testing the 30V path (output-range-microvolt = <0 30000000>):

$ cat /sys/bus/iio/devices/iio:device0/out_voltage_scale
7.324218750   (30000mV / 4096)

Additionally, providing invalid DT configurations (e.g., 70V) successfully triggers the strict bounds checking and cleanly aborts the probe with -EINVAL.

Changes in v3:

* Dropped the patch adding GPIO control for /CLR and /LDAC. As pointed out by Nuno Sá, since the driver does not actively handle or toggle these pins, requesting them in the driver is dead code. They remain documented in the bindings.
* Combined the pdata removal, regulator _enable swap, and DT parsing into a single atomic commit (Patch 5) so the driver compiles and runs cleanly at every step of the git history.

* Restored the -ENODEV check for the regulator to maintain ACPI compatibility.

* Implemented strict min/max array bounds validation for the 'output-range-microvolt' property.
* Included missing <linux/array_size.h>, <asm/byteorder.h>, and <linux/kstrtox.h> headers for full IWYU compliance.
* Reordered commits to group cleanups before functional changes.
* Dropped Suggested-by tags for standard review feedback.