[PATCH v4 00/10] iio: adc: ad7124: Various fixes

[PATCH v4 00/10] iio: adc: ad7124: Various fixes

[Uwe Kleine-König]

Hello,

this v4 is the follow up to
https://lore.kernel.org/linux-iio/20241122113322.242875-12-u.kleine-koenig@baylibre.com
addressing the comments by Trevor Gamblin, David Lechner and Andy
Shevchenko. Thanks for your feedback.

This series still bases on top of v6.12 + 64612ec9b909 ("iio: adc:
ad7124: Disable all channels at probe time").

Changes include:
 - Expand patch #3 to also extend the dt bindings for the other chips
   making use of the ad_sigma_delta helpers
 - Various code comment and commit log improvements (partly Andy)
 - Check for errors (and other cheap conditions) earlier to reduce
   indentions (Andy)
 - Add error check for gpiod_to_irq() in ad_sd_init()
 - Forward declaration of struct gpio_desc (Andy)
 - Fix a kernel doc descripts (kbuild bot)
 - drop en passant restructuring
 - Use local variable for &st->sd.spi->dev in several functions (Andy)
 - Add a comment about the suspicious bi-polar but still unsigned value
   (David)

In another thread Jonathan asked to maybe reshuffle the series to have
the changes first that should be backported. IMHO all but the last patch
are suitable for such a backport, so no need to reshuffle. Agreed?

Best regards
Uwe

Uwe Kleine-König (10):
  iio: adc: ad7124: Don't create more channels than the driver can
    handle
  iio: adc: ad7124: Refuse invalid input specifiers
  dt-bindings: iio: adc: adi,ad7{124,173,192,780}: Allow specifications
    of a gpio for irq line
  iio: adc: ad_sigma_delta: Add support for reading irq status using a
    GPIO
  iio: adc: ad_sigma_delta: Handle CS assertion as intended in
    ad_sd_read_reg_raw()
  iio: adc: ad_sigma_delta: Fix a race condition
  iio: adc: ad_sigma_delta: Store information about reset sequence
    length
  iio: adc: ad_sigma_delta: Check for previous ready signals
  iio: adc: ad7124: Add error reporting during probe
  iio: adc: ad7124: Implement temperature measurement

 .../bindings/iio/adc/adi,ad7124.yaml          |  13 ++
 .../bindings/iio/adc/adi,ad7173.yaml          |  12 +
 .../bindings/iio/adc/adi,ad7192.yaml          |  15 ++
 .../bindings/iio/adc/adi,ad7780.yaml          |  11 +
 drivers/iio/adc/ad7124.c                      | 220 +++++++++++++-----
 drivers/iio/adc/ad7173.c                      |   1 +
 drivers/iio/adc/ad7192.c                      |   4 +-
 drivers/iio/adc/ad7791.c                      |   1 +
 drivers/iio/adc/ad7793.c                      |   3 +-
 drivers/iio/adc/ad_sigma_delta.c              | 184 ++++++++++++---
 include/linux/iio/adc/ad_sigma_delta.h        |   8 +-
 11 files changed, 384 insertions(+), 88 deletions(-)


base-commit: adc218676eef25575469234709c2d87185ca223a
prerequisite-patch-id: 617af17fc377a984762c61893b9f2a92ae62213a
-- 
2.45.2

[PATCH v4 01/10] iio: adc: ad7124: Don't create more channels than the driver can handle

[Uwe Kleine-König]

The ad7124-4 and ad7124-8 both support 16 channel registers and assigns
each channel defined in dt statically such a register. While the driver
could be a bit more clever about this, it currently isn't and specifying
more than 16 channels yields broken behaviour. So just refuse to bind in
this situation.

Fixes: b3af341bbd96 ("iio: adc: Add ad7124 support")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/iio/adc/ad7124.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 8d94bc2b1cac..5352b26bb391 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -821,6 +821,16 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 	if (!st->num_channels)
 		return dev_err_probe(dev, -ENODEV, "no channel children\n");
 
+	/*
+	 * The driver assigns each logical channel defined in the device tree
+	 * statically one channel register. So only accept 16 such logical
+	 * channels to not treat CONFIG_0 (i.e. the register following
+	 * CHANNEL_15) as an additional channel register. The driver could be
+	 * improved to lift this limitation.
+	 */
+	if (st->num_channels > AD7124_MAX_CHANNELS)
+		return dev_err_probe(dev, -EINVAL, "Too many channels defined\n");
+
 	chan = devm_kcalloc(indio_dev->dev.parent, st->num_channels,
 			    sizeof(*chan), GFP_KERNEL);
 	if (!chan)
-- 
2.45.2

[PATCH v4 02/10] iio: adc: ad7124: Refuse invalid input specifiers

[Uwe Kleine-König]

The ad7124-4 has 8 analog inputs; the input select values 8 to 15 are
reserved and not to be used. These are fine for ad7124-8. For both
ad7124-4 and ad7124-8 values bigger than 15 are internal channels that
might appear as inputs in the channels specified in the device
description according to the description of commit f1794fd7bdf7 ("iio:
adc: ad7124: Remove input number limitation"), values bigger than 31
don't fit into the respective register bit field and the driver masked
them to smaller values.

Check for these invalid input specifiers and fail to probe if one is
found.

Fixes: f1794fd7bdf7 ("iio: adc: ad7124: Remove input number limitation")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/iio/adc/ad7124.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 5352b26bb391..1f3342373f1c 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -807,6 +807,19 @@ static int ad7124_check_chip_id(struct ad7124_state *st)
 	return 0;
 }
 
+/*
+ * Input specifiers 8 - 15 are explicitly reserved for ad7124-4
+ * while they are fine for ad7124-8. Values above 31 don't fit
+ * into the register field and so are invalid for sure.
+ */
+static bool ad7124_valid_input_select(unsigned int ain, const struct ad7124_chip_info *info)
+{
+	if (ain >= info->num_inputs && ain < 16)
+		return false;
+
+	return ain <= FIELD_MAX(AD7124_CHANNEL_AINM_MSK);
+}
+
 static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 				       struct device *dev)
 {
@@ -859,6 +872,11 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 		if (ret)
 			return ret;
 
+		if (!ad7124_valid_input_select(ain[0], st->chip_info) ||
+		    !ad7124_valid_input_select(ain[1], st->chip_info))
+			return dev_err_probe(dev, -EINVAL,
+					     "diff-channels property of %pfwP contains invalid data\n", child);
+
 		st->channels[channel].nr = channel;
 		st->channels[channel].ain = AD7124_CHANNEL_AINP(ain[0]) |
 						  AD7124_CHANNEL_AINM(ain[1]);
-- 
2.45.2

[PATCH v4 03/10] dt-bindings: iio: adc: adi,ad7{124,173,192,780}: Allow specifications of a gpio for irq line

[Uwe Kleine-König]

For the AD7124 chip and some of its cousins the logical irq line (̅R̅D̅Y)
is physically on the same pin as the spi MISO output (DOUT) and so
reading a register might trigger an interrupt. For correct operation
it's critical that the actual state of the pin can be read to judge if
an interrupt event is a real one or just a spurious one triggered by
toggling the line in its MISO mode.

Allow specification of an "rdy-gpios" property that references a GPIO
that can be used for that purpose. While this is typically the same GPIO
also used (implicitly) as interrupt source, it is still supposed that
the interrupt is specified as before and usual.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 .../devicetree/bindings/iio/adc/adi,ad7124.yaml   | 13 +++++++++++++
 .../devicetree/bindings/iio/adc/adi,ad7173.yaml   | 12 ++++++++++++
 .../devicetree/bindings/iio/adc/adi,ad7192.yaml   | 15 +++++++++++++++
 .../devicetree/bindings/iio/adc/adi,ad7780.yaml   | 11 +++++++++++
 4 files changed, 51 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7124.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7124.yaml
index 35ed04350e28..9f34a055fdf1 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7124.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7124.yaml
@@ -37,6 +37,17 @@ properties:
     description: IRQ line for the ADC
     maxItems: 1
 
+  rdy-gpios:
+    description: |
+      GPIO reading the ̅̅R̅D̅Y line. Having such a GPIO is technically optional but
+      highly recommended because DOUT/̅R̅D̅Y toggles during SPI transfers (in its
+      DOUT aka MISO role) and so usually triggers a spurious interrupt. The
+      distinction between such a spurious event and a real one can only be done
+      by reading such a GPIO. (There is a register telling the same
+      information, but accessing that one needs a SPI transfer which then
+      triggers another interrupt event.)
+    maxItems: 1
+
   '#address-cells':
     const: 1
 
@@ -111,6 +122,7 @@ unevaluatedProperties: false
 
 examples:
   - |
+    #include <dt-bindings/gpio/gpio.h>
     spi {
       #address-cells = <1>;
       #size-cells = <0>;
@@ -121,6 +133,7 @@ examples:
         spi-max-frequency = <5000000>;
         interrupts = <25 2>;
         interrupt-parent = <&gpio>;
+        rdy-gpios = <&gpio 25 GPIO_ACTIVE_LOW>;
         refin1-supply = <&adc_vref>;
         clocks = <&ad7124_mclk>;
         clock-names = "mclk";
diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml
index 17c5d39cc2c1..c70eb75c6a65 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml
@@ -133,6 +133,17 @@ properties:
   '#clock-cells':
     const: 0
 
+  rdy-gpios:
+    description: |
+      GPIO reading the ̅̅R̅D̅Y line. Having such a GPIO is technically optional but
+      highly recommended because DOUT/̅R̅D̅Y toggles during SPI transfers (in its
+      DOUT aka MISO role) and so usually triggers a spurious interrupt. The
+      distinction between such a spurious event and a real one can only be done
+      by reading such a GPIO. (There is a register telling the same
+      information, but accessing that one needs a SPI transfer which then
+      triggers another interrupt event.)
+    maxItems: 1
+
 patternProperties:
   "^channel@[0-9a-f]$":
     type: object
@@ -440,6 +451,7 @@ examples:
         interrupts = <25 IRQ_TYPE_EDGE_FALLING>;
         interrupt-names = "rdy";
         interrupt-parent = <&gpio>;
+        rdy-gpios = <&gpio 25 GPIO_ACTIVE_LOW>;
         spi-max-frequency = <5000000>;
         gpio-controller;
         #gpio-cells = <2>;
diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7192.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7192.yaml
index 66dd1c549bd3..204766de1e01 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7192.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7192.yaml
@@ -106,6 +106,17 @@ properties:
     description: see Documentation/devicetree/bindings/iio/adc/adc.yaml
     type: boolean
 
+  rdy-gpios:
+    description: |
+      GPIO reading the ̅̅R̅D̅Y line. Having such a GPIO is technically optional but
+      highly recommended because DOUT/̅R̅D̅Y toggles during SPI transfers (in its
+      DOUT aka MISO role) and so usually triggers a spurious interrupt. The
+      distinction between such a spurious event and a real one can only be done
+      by reading such a GPIO. (There is a register telling the same
+      information, but accessing that one needs a SPI transfer which then
+      triggers another interrupt event.)
+    maxItems: 1
+
 patternProperties:
   "^channel@[0-9a-f]+$":
     type: object
@@ -181,6 +192,7 @@ unevaluatedProperties: false
 
 examples:
   - |
+    #include <dt-bindings/gpio/gpio.h>
     spi {
         #address-cells = <1>;
         #size-cells = <0>;
@@ -195,6 +207,7 @@ examples:
             clock-names = "mclk";
             interrupts = <25 0x2>;
             interrupt-parent = <&gpio>;
+            rdy-gpios = <&gpio 25 GPIO_ACTIVE_LOW>;
             aincom-supply = <&aincom>;
             dvdd-supply = <&dvdd>;
             avdd-supply = <&avdd>;
@@ -207,6 +220,7 @@ examples:
         };
     };
   - |
+    #include <dt-bindings/gpio/gpio.h>
     spi {
         #address-cells = <1>;
         #size-cells = <0>;
@@ -224,6 +238,7 @@ examples:
             #clock-cells = <0>;
             interrupts = <25 0x2>;
             interrupt-parent = <&gpio>;
+            rdy-gpios = <&gpio 25 GPIO_ACTIVE_LOW>;
             aincom-supply = <&aincom>;
             dvdd-supply = <&dvdd>;
             avdd-supply = <&avdd>;
diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7780.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7780.yaml
index be2616ff9af6..5f8f59e4e336 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7780.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7780.yaml
@@ -63,6 +63,17 @@ properties:
       marked GPIO_ACTIVE_LOW.
     maxItems: 1
 
+  rdy-gpios:
+    description: |
+      GPIO reading the ̅̅R̅D̅Y line. Having such a GPIO is technically optional but
+      highly recommended because DOUT/̅R̅D̅Y toggles during SPI transfers (in its
+      DOUT aka MISO role) and so usually triggers a spurious interrupt. The
+      distinction between such a spurious event and a real one can only be done
+      by reading such a GPIO. (There is a register telling the same
+      information, but accessing that one needs a SPI transfer which then
+      triggers another interrupt event.)
+    maxItems: 1
+
 required:
   - compatible
   - reg
-- 
2.45.2

[PATCH v4 04/10] iio: adc: ad_sigma_delta: Add support for reading irq status using a GPIO

[Uwe Kleine-König]

Some of the ADCs by Analog signal their irq condition on the MISO line.
So typically that line is connected to an SPI controller and a GPIO. The
GPIO is used as input and the respective interrupt is enabled when the
last SPI transfer is completed.

Depending on the GPIO controller the toggling MISO line might make the
interrupt pending even while it's masked. In that case the irq handler
is called immediately after irq_enable() and so before the device
actually pulls that line low which results in non-sense values being
reported to the upper layers.

The only way to find out if the line was actually pulled low is to read
the GPIO. (There is a flag in AD7124's status register that also signals
if an interrupt was asserted, but reading that register toggles the MISO
line and so might trigger another spurious interrupt.)

Add the possibility to specify an interrupt GPIO in the machine
description in addition to the plain interrupt. This GPIO is used then
to check if the irq line is actually active in the irq handler.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/iio/adc/ad_sigma_delta.c       | 38 ++++++++++++++++++++++----
 include/linux/iio/adc/ad_sigma_delta.h |  2 ++
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index ea4aabd3960a..7f4eae5244dc 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -539,12 +539,29 @@ static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
 {
 	struct ad_sigma_delta *sigma_delta = private;
 
-	complete(&sigma_delta->completion);
-	disable_irq_nosync(irq);
-	sigma_delta->irq_dis = true;
-	iio_trigger_poll(sigma_delta->trig);
+	/*
+	 * AD7124 and a few others use the same physical line for interrupt
+	 * reporting (nRDY) and MISO.
+	 * As MISO toggles when reading a register, this likely results in a
+	 * pending interrupt. This has two consequences: a) The irq might
+	 * trigger immediately after it's enabled even though the conversion
+	 * isn't done yet; and b) checking the STATUS register's nRDY flag is
+	 * off-limits as reading that would trigger another irq event.
+	 *
+	 * So read the MOSI line as GPIO (if available) and only trigger the irq
+	 * if the line is active. Without such a GPIO assume this is a valid
+	 * interrupt.
+	 */
+	if (!sigma_delta->rdy_gpiod || gpiod_get_value(sigma_delta->rdy_gpiod)) {
+		complete(&sigma_delta->completion);
+		disable_irq_nosync(irq);
+		sigma_delta->irq_dis = true;
+		iio_trigger_poll(sigma_delta->trig);
 
-	return IRQ_HANDLED;
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
 }
 
 /**
@@ -679,6 +696,17 @@ int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
 	else
 		sigma_delta->irq_line = spi->irq;
 
+	sigma_delta->rdy_gpiod = devm_gpiod_get_optional(&spi->dev, "rdy", GPIOD_IN);
+	if (IS_ERR(sigma_delta->rdy_gpiod))
+		return dev_err_probe(&spi->dev, PTR_ERR(sigma_delta->rdy_gpiod),
+				     "Failed to find rdy gpio\n");
+
+	if (sigma_delta->rdy_gpiod && !sigma_delta->irq_line) {
+		sigma_delta->irq_line = gpiod_to_irq(sigma_delta->rdy_gpiod);
+		if (sigma_delta->irq_line < 0)
+			return sigma_delta->irq_line;
+	}
+
 	iio_device_set_drvdata(indio_dev, sigma_delta);
 
 	return 0;
diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h
index f8c1d2505940..126b187d70e9 100644
--- a/include/linux/iio/adc/ad_sigma_delta.h
+++ b/include/linux/iio/adc/ad_sigma_delta.h
@@ -29,6 +29,7 @@ struct ad_sd_calib_data {
 
 struct ad_sigma_delta;
 struct device;
+struct gpio_desc;
 struct iio_dev;
 
 /**
@@ -96,6 +97,7 @@ struct ad_sigma_delta {
 	unsigned int		active_slots;
 	unsigned int		current_slot;
 	unsigned int		num_slots;
+	struct gpio_desc	*rdy_gpiod;
 	int		irq_line;
 	bool			status_appended;
 	/* map slots to channels in order to know what to expect from devices */
-- 
2.45.2

[PATCH v4 05/10] iio: adc: ad_sigma_delta: Handle CS assertion as intended in ad_sd_read_reg_raw()

[Uwe Kleine-König]

When struct ad_sigma_delta::keep_cs_asserted was introduced only
register writing was adapted to honor this new flag. Also respect it
when reading a register.

Fixes: df1d80aee963 ("iio: ad_sigma_delta: Properly handle SPI bus locking vs CS assertion")
Reviewed-by: Trevor Gamblin <tgamblin@baylibre.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/iio/adc/ad_sigma_delta.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index 7f4eae5244dc..a2efd2145373 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -109,7 +109,7 @@ static int ad_sd_read_reg_raw(struct ad_sigma_delta *sigma_delta,
 		}, {
 			.rx_buf = val,
 			.len = size,
-			.cs_change = sigma_delta->bus_locked,
+			.cs_change = sigma_delta->keep_cs_asserted,
 		},
 	};
 	struct spi_message m;
-- 
2.45.2

[PATCH v4 06/10] iio: adc: ad_sigma_delta: Fix a race condition

[Uwe Kleine-König]

The ad_sigma_delta driver helper uses irq_disable_nosync(). With that
one it is possible that the irq handler still runs after the
irq_disable_nosync() function call returns. Also to properly synchronize
irq disabling in the different threads proper locking is needed and
because it's unclear if the irq handler's irq_disable_nosync() call
comes first or the one in the enabler's error path, all code locations
that disable the irq must check for .irq_dis first to ensure there is
exactly one disable call per enable call.

So add a spinlock to the struct ad_sigma_delta and use it to synchronize
irq enabling and disabling. Also only act in the irq handler if the irq
is still enabled.

Fixes: af3008485ea0 ("iio:adc: Add common code for ADI Sigma Delta devices")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/iio/adc/ad_sigma_delta.c       | 56 ++++++++++++++++----------
 include/linux/iio/adc/ad_sigma_delta.h |  1 +
 2 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index a2efd2145373..9abde276cd17 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -202,6 +202,27 @@ int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
 }
 EXPORT_SYMBOL_NS_GPL(ad_sd_reset, IIO_AD_SIGMA_DELTA);
 
+static bool ad_sd_disable_irq(struct ad_sigma_delta *sigma_delta)
+{
+	guard(spinlock_irqsave)(&sigma_delta->irq_lock);
+
+	/* It's already off, return false to indicate nothing was changed */
+	if (sigma_delta->irq_dis)
+		return false;
+
+	sigma_delta->irq_dis = true;
+	disable_irq_nosync(sigma_delta->irq_line);
+	return true;
+}
+
+static void ad_sd_enable_irq(struct ad_sigma_delta *sigma_delta)
+{
+	guard(spinlock_irqsave)(&sigma_delta->irq_lock);
+
+	sigma_delta->irq_dis = false;
+	enable_irq(sigma_delta->irq_line);
+}
+
 int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
 	unsigned int mode, unsigned int channel)
 {
@@ -221,12 +242,10 @@ int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
 	if (ret < 0)
 		goto out;
 
-	sigma_delta->irq_dis = false;
-	enable_irq(sigma_delta->irq_line);
+	ad_sd_enable_irq(sigma_delta);
 	time_left = wait_for_completion_timeout(&sigma_delta->completion, 2 * HZ);
 	if (time_left == 0) {
-		sigma_delta->irq_dis = true;
-		disable_irq_nosync(sigma_delta->irq_line);
+		ad_sd_disable_irq(sigma_delta);
 		ret = -EIO;
 	} else {
 		ret = 0;
@@ -294,8 +313,7 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
 
 	ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE);
 
-	sigma_delta->irq_dis = false;
-	enable_irq(sigma_delta->irq_line);
+	ad_sd_enable_irq(sigma_delta);
 	ret = wait_for_completion_interruptible_timeout(
 			&sigma_delta->completion, HZ);
 
@@ -314,10 +332,7 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
 		&raw_sample);
 
 out:
-	if (!sigma_delta->irq_dis) {
-		disable_irq_nosync(sigma_delta->irq_line);
-		sigma_delta->irq_dis = true;
-	}
+	ad_sd_disable_irq(sigma_delta);
 
 	sigma_delta->keep_cs_asserted = false;
 	ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
@@ -396,8 +411,7 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
 	if (ret)
 		goto err_unlock;
 
-	sigma_delta->irq_dis = false;
-	enable_irq(sigma_delta->irq_line);
+	ad_sd_enable_irq(sigma_delta);
 
 	return 0;
 
@@ -414,10 +428,7 @@ static int ad_sd_buffer_postdisable(struct iio_dev *indio_dev)
 	reinit_completion(&sigma_delta->completion);
 	wait_for_completion_timeout(&sigma_delta->completion, HZ);
 
-	if (!sigma_delta->irq_dis) {
-		disable_irq_nosync(sigma_delta->irq_line);
-		sigma_delta->irq_dis = true;
-	}
+	ad_sd_disable_irq(sigma_delta);
 
 	sigma_delta->keep_cs_asserted = false;
 	ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
@@ -516,8 +527,7 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
 
 irq_handled:
 	iio_trigger_notify_done(indio_dev->trig);
-	sigma_delta->irq_dis = false;
-	enable_irq(sigma_delta->irq_line);
+	ad_sd_enable_irq(sigma_delta);
 
 	return IRQ_HANDLED;
 }
@@ -551,11 +561,13 @@ static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
 	 * So read the MOSI line as GPIO (if available) and only trigger the irq
 	 * if the line is active. Without such a GPIO assume this is a valid
 	 * interrupt.
+	 *
+	 * Also as disable_irq_nosync() is used to disable the irq, only act if
+	 * the irq wasn't disabled before.
 	 */
-	if (!sigma_delta->rdy_gpiod || gpiod_get_value(sigma_delta->rdy_gpiod)) {
+	if ((!sigma_delta->rdy_gpiod || gpiod_get_value(sigma_delta->rdy_gpiod)) &&
+	    ad_sd_disable_irq(sigma_delta)) {
 		complete(&sigma_delta->completion);
-		disable_irq_nosync(irq);
-		sigma_delta->irq_dis = true;
 		iio_trigger_poll(sigma_delta->trig);
 
 		return IRQ_HANDLED;
@@ -691,6 +703,8 @@ int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
 		}
 	}
 
+	spin_lock_init(&sigma_delta->irq_lock);
+
 	if (info->irq_line)
 		sigma_delta->irq_line = info->irq_line;
 	else
diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h
index 126b187d70e9..f86eca6126b4 100644
--- a/include/linux/iio/adc/ad_sigma_delta.h
+++ b/include/linux/iio/adc/ad_sigma_delta.h
@@ -86,6 +86,7 @@ struct ad_sigma_delta {
 
 /* private: */
 	struct completion	completion;
+	spinlock_t		irq_lock; /* protects .irq_dis and irq en/disable state */
 	bool			irq_dis;
 
 	bool			bus_locked;
-- 
2.45.2

[PATCH v4 07/10] iio: adc: ad_sigma_delta: Store information about reset sequence length

[Uwe Kleine-König]

The various chips can be reset using a sequence of SPI transfers with
MOSI = 1. The length of such a sequence varies from chip to chip. Store
that length in struct ad_sigma_delta_info and replace the respective
parameter to ad_sd_reset() with it.

Note the ad7192 used to pass 48 as length but the documentation
specifies 40 as the required length. Assuming the latter is right.
(Using a too long sequence doesn't hurt apart from using a longer spi
transfer than necessary, so this is no relevant fix.)

The motivation for storing this information is that this is useful to
clear a pending RDY signal in the next change.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/iio/adc/ad7124.c               | 3 ++-
 drivers/iio/adc/ad7173.c               | 1 +
 drivers/iio/adc/ad7192.c               | 4 +++-
 drivers/iio/adc/ad7791.c               | 1 +
 drivers/iio/adc/ad7793.c               | 3 ++-
 drivers/iio/adc/ad_sigma_delta.c       | 5 ++---
 include/linux/iio/adc/ad_sigma_delta.h | 5 +++--
 7 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 1f3342373f1c..b17c3dbeaeba 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -571,6 +571,7 @@ static const struct ad_sigma_delta_info ad7124_sigma_delta_info = {
 	.data_reg = AD7124_DATA,
 	.num_slots = 8,
 	.irq_flags = IRQF_TRIGGER_FALLING,
+	.num_resetclks = 64,
 };
 
 static int ad7124_read_raw(struct iio_dev *indio_dev,
@@ -756,7 +757,7 @@ static int ad7124_soft_reset(struct ad7124_state *st)
 	unsigned int readval, timeout;
 	int ret;
 
-	ret = ad_sd_reset(&st->sd, 64);
+	ret = ad_sd_reset(&st->sd);
 	if (ret < 0)
 		return ret;
 
diff --git a/drivers/iio/adc/ad7173.c b/drivers/iio/adc/ad7173.c
index 0702ec71aa29..2550194efee8 100644
--- a/drivers/iio/adc/ad7173.c
+++ b/drivers/iio/adc/ad7173.c
@@ -744,6 +744,7 @@ static struct ad_sigma_delta_info ad7173_sigma_delta_info = {
 	.read_mask = BIT(6),
 	.status_ch_mask = GENMASK(3, 0),
 	.data_reg = AD7173_REG_DATA,
+	.num_resetclks = 64,
 };
 
 static int ad7173_setup(struct iio_dev *indio_dev)
diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
index 7042ddfdfc03..c4dd48edd8d9 100644
--- a/drivers/iio/adc/ad7192.c
+++ b/drivers/iio/adc/ad7192.c
@@ -361,6 +361,7 @@ static const struct ad_sigma_delta_info ad7192_sigma_delta_info = {
 	.status_ch_mask = GENMASK(3, 0),
 	.num_slots = 4,
 	.irq_flags = IRQF_TRIGGER_FALLING,
+	.num_resetclks = 40,
 };
 
 static const struct ad_sigma_delta_info ad7194_sigma_delta_info = {
@@ -373,6 +374,7 @@ static const struct ad_sigma_delta_info ad7194_sigma_delta_info = {
 	.read_mask = BIT(6),
 	.status_ch_mask = GENMASK(3, 0),
 	.irq_flags = IRQF_TRIGGER_FALLING,
+	.num_resetclks = 40,
 };
 
 static const struct ad_sd_calib_data ad7192_calib_arr[8] = {
@@ -565,7 +567,7 @@ static int ad7192_setup(struct iio_dev *indio_dev, struct device *dev)
 	int i, ret, id;
 
 	/* reset the serial interface */
-	ret = ad_sd_reset(&st->sd, 48);
+	ret = ad_sd_reset(&st->sd);
 	if (ret < 0)
 		return ret;
 	usleep_range(500, 1000); /* Wait for at least 500us */
diff --git a/drivers/iio/adc/ad7791.c b/drivers/iio/adc/ad7791.c
index 86effe8501b4..c7509b911835 100644
--- a/drivers/iio/adc/ad7791.c
+++ b/drivers/iio/adc/ad7791.c
@@ -254,6 +254,7 @@ static const struct ad_sigma_delta_info ad7791_sigma_delta_info = {
 	.addr_shift = 4,
 	.read_mask = BIT(3),
 	.irq_flags = IRQF_TRIGGER_FALLING,
+	.num_resetclks = 32,
 };
 
 static int ad7791_read_raw(struct iio_dev *indio_dev,
diff --git a/drivers/iio/adc/ad7793.c b/drivers/iio/adc/ad7793.c
index abebd519cafa..0767c56bb442 100644
--- a/drivers/iio/adc/ad7793.c
+++ b/drivers/iio/adc/ad7793.c
@@ -206,6 +206,7 @@ static const struct ad_sigma_delta_info ad7793_sigma_delta_info = {
 	.addr_shift = 3,
 	.read_mask = BIT(6),
 	.irq_flags = IRQF_TRIGGER_FALLING,
+	.num_resetclks = 32,
 };
 
 static const struct ad_sd_calib_data ad7793_calib_arr[6] = {
@@ -265,7 +266,7 @@ static int ad7793_setup(struct iio_dev *indio_dev,
 		return ret;
 
 	/* reset the serial interface */
-	ret = ad_sd_reset(&st->sd, 32);
+	ret = ad_sd_reset(&st->sd);
 	if (ret < 0)
 		goto out;
 	usleep_range(500, 2000); /* Wait for at least 500us */
diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index 9abde276cd17..9891346c2d73 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -178,13 +178,12 @@ EXPORT_SYMBOL_NS_GPL(ad_sd_read_reg, IIO_AD_SIGMA_DELTA);
  * ad_sd_reset() - Reset the serial interface
  *
  * @sigma_delta: The sigma delta device
- * @reset_length: Number of SCLKs with DIN = 1
  *
  * Returns 0 on success, an error code otherwise.
  **/
-int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
-	unsigned int reset_length)
+int ad_sd_reset(struct ad_sigma_delta *sigma_delta)
 {
+	unsigned int reset_length = sigma_delta->info->num_resetclks;
 	uint8_t *buf;
 	unsigned int size;
 	int ret;
diff --git a/include/linux/iio/adc/ad_sigma_delta.h b/include/linux/iio/adc/ad_sigma_delta.h
index f86eca6126b4..eef87d04eb6b 100644
--- a/include/linux/iio/adc/ad_sigma_delta.h
+++ b/include/linux/iio/adc/ad_sigma_delta.h
@@ -54,6 +54,7 @@ struct iio_dev;
  * @irq_flags: flags for the interrupt used by the triggered buffer
  * @num_slots: Number of sequencer slots
  * @irq_line: IRQ for reading conversions. If 0, spi->irq will be used
+ * @num_resetclks: Number of SPI clk cycles with MOSI=1 to reset the chip.
  */
 struct ad_sigma_delta_info {
 	int (*set_channel)(struct ad_sigma_delta *, unsigned int channel);
@@ -70,6 +71,7 @@ struct ad_sigma_delta_info {
 	unsigned long irq_flags;
 	unsigned int num_slots;
 	int irq_line;
+	unsigned int num_resetclks;
 };
 
 /**
@@ -181,8 +183,7 @@ int ad_sd_write_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg,
 int ad_sd_read_reg(struct ad_sigma_delta *sigma_delta, unsigned int reg,
 	unsigned int size, unsigned int *val);
 
-int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
-	unsigned int reset_length);
+int ad_sd_reset(struct ad_sigma_delta *sigma_delta);
 
 int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, int *val);
-- 
2.45.2

[PATCH v4 08/10] iio: adc: ad_sigma_delta: Check for previous ready signals

[Uwe Kleine-König]

It can happen if a previous conversion was aborted the ADC pulls down
the ̅R̅D̅Y line but the event wasn't handled before. In that case enabling
the irq might immediately fire (depending on the irq controller's
capabilities) and even with a rdy-gpio isn't identified as an unrelated
one.

To cure that problem check for a pending event before the measurement is
started and clear it if needed.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/iio/adc/ad_sigma_delta.c | 89 ++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index 9891346c2d73..164a4d0b571d 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -29,8 +29,11 @@
 #define AD_SD_COMM_CHAN_MASK	0x3
 
 #define AD_SD_REG_COMM		0x00
+#define AD_SD_REG_STATUS	0x00
 #define AD_SD_REG_DATA		0x03
 
+#define AD_SD_REG_STATUS_RDY	0x80
+
 /**
  * ad_sd_set_comm() - Set communications register
  *
@@ -222,6 +225,80 @@ static void ad_sd_enable_irq(struct ad_sigma_delta *sigma_delta)
 	enable_irq(sigma_delta->irq_line);
 }
 
+/* Called with `sigma_delta->bus_locked == true` only.  */
+static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta)
+{
+	bool pending_event;
+	unsigned int data_read_len = BITS_TO_BYTES(sigma_delta->info->num_resetclks);
+	u8 data[9];
+	struct spi_transfer t[] = {
+		{
+			.tx_buf = data,
+			.len = 1,
+		}, {
+			.tx_buf = data + 1,
+			.len = data_read_len,
+		}
+	};
+	struct spi_message m;
+
+	/*
+	 * read RDY pin (if possible) or status register to check if there is an
+	 * old event.
+	 */
+	if (sigma_delta->rdy_gpiod) {
+		pending_event = gpiod_get_value(sigma_delta->rdy_gpiod);
+	} else {
+		int ret;
+		unsigned status_reg;
+
+		ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_STATUS, 1, &status_reg);
+		if (ret)
+			return ret;
+
+		pending_event = !(status_reg & AD_SD_REG_STATUS_RDY);
+	}
+
+	if (!pending_event)
+		return 0;
+
+	/*
+	 * In general the size of the data register is unknown. It varies from
+	 * device to device, might be one byte longer if CONTROL.DATA_STATUS is
+	 * set and even varies on some devices depending on which input is
+	 * selected. So send one byte to start reading the data register and
+	 * then just clock for some bytes with DIN (aka MOSI) high to not
+	 * confuse the register access state machine after the data register was
+	 * completely read. Note however that the sequence length must be
+	 * shorter than the reset procedure.
+	 */
+
+	/* Oh, back out instead of overflowing data[] */
+	if (data_read_len > sizeof(data) - 1)
+		return -EINVAL;
+
+	spi_message_init(&m);
+	if (sigma_delta->info->has_registers) {
+		unsigned int data_reg = sigma_delta->info->data_reg ?: AD_SD_REG_DATA;
+
+		data[0] = data_reg << sigma_delta->info->addr_shift;
+		data[0] |= sigma_delta->info->read_mask;
+		data[0] |= sigma_delta->comm;
+		spi_message_add_tail(&t[0], &m);
+	}
+
+	/*
+	 * The first transferred byte is part of the real data register,
+	 * so this doesn't need to be 0xff. In the remaining
+	 * `data_read_len - 1` bytes are less than $num_resetclks ones.
+	 */
+	data[1] = 0x00;
+	memset(data + 2, 0xff, data_read_len - 1);
+	spi_message_add_tail(&t[1], &m);
+
+	return spi_sync_locked(sigma_delta->spi, &m);
+}
+
 int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
 	unsigned int mode, unsigned int channel)
 {
@@ -237,6 +314,10 @@ int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
 	sigma_delta->keep_cs_asserted = true;
 	reinit_completion(&sigma_delta->completion);
 
+	ret = ad_sigma_delta_clear_pending_event(sigma_delta);
+	if (ret)
+		return ret;
+
 	ret = ad_sigma_delta_set_mode(sigma_delta, mode);
 	if (ret < 0)
 		goto out;
@@ -310,6 +391,10 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
 	sigma_delta->keep_cs_asserted = true;
 	reinit_completion(&sigma_delta->completion);
 
+	ret = ad_sigma_delta_clear_pending_event(sigma_delta);
+	if (ret)
+		return ret;
+
 	ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE);
 
 	ad_sd_enable_irq(sigma_delta);
@@ -406,6 +491,10 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
 	sigma_delta->bus_locked = true;
 	sigma_delta->keep_cs_asserted = true;
 
+	ret = ad_sigma_delta_clear_pending_event(sigma_delta);
+	if (ret)
+		return ret;
+
 	ret = ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_CONTINUOUS);
 	if (ret)
 		goto err_unlock;
-- 
2.45.2

[PATCH v4 09/10] iio: adc: ad7124: Add error reporting during probe

[Uwe Kleine-König]

A driver that silently fails to probe is annoying and hard to debug. So
add messages in the error paths of the probe function.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/iio/adc/ad7124.c | 79 ++++++++++++++++++++++------------------
 1 file changed, 43 insertions(+), 36 deletions(-)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index b17c3dbeaeba..50b8ffa2dbe5 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -360,20 +360,21 @@ static int ad7124_find_free_config_slot(struct ad7124_state *st)
 	return free_cfg_slot;
 }
 
+/* Only called during probe, so dev_err_probe() can be used */
 static int ad7124_init_config_vref(struct ad7124_state *st, struct ad7124_channel_config *cfg)
 {
+	struct device *dev = &st->sd.spi->dev;
 	unsigned int refsel = cfg->refsel;
 
 	switch (refsel) {
 	case AD7124_REFIN1:
 	case AD7124_REFIN2:
 	case AD7124_AVDD_REF:
-		if (IS_ERR(st->vref[refsel])) {
-			dev_err(&st->sd.spi->dev,
-				"Error, trying to use external voltage reference without a %s regulator.\n",
-				ad7124_ref_names[refsel]);
-			return PTR_ERR(st->vref[refsel]);
-		}
+		if (IS_ERR(st->vref[refsel]))
+			return dev_err_probe(dev, PTR_ERR(st->vref[refsel]),
+					     "Error, trying to use external voltage reference without a %s regulator.\n",
+					     ad7124_ref_names[refsel]);
+
 		cfg->vref_mv = regulator_get_voltage(st->vref[refsel]);
 		/* Conversion from uV to mV */
 		cfg->vref_mv /= 1000;
@@ -384,8 +385,7 @@ static int ad7124_init_config_vref(struct ad7124_state *st, struct ad7124_channe
 		st->adc_control |= AD7124_ADC_CTRL_REF_EN(1);
 		return 0;
 	default:
-		dev_err(&st->sd.spi->dev, "Invalid reference %d\n", refsel);
-		return -EINVAL;
+		return dev_err_probe(dev, -EINVAL, "Invalid reference %d\n", refsel);
 	}
 }
 
@@ -752,8 +752,10 @@ static const struct iio_info ad7124_info = {
 	.attrs = &ad7124_attrs_group,
 };
 
+/* Only called during probe, so dev_err_probe() can be used */
 static int ad7124_soft_reset(struct ad7124_state *st)
 {
+	struct device *dev = &st->sd.spi->dev;
 	unsigned int readval, timeout;
 	int ret;
 
@@ -766,7 +768,7 @@ static int ad7124_soft_reset(struct ad7124_state *st)
 	do {
 		ret = ad_sd_read_reg(&st->sd, AD7124_STATUS, 1, &readval);
 		if (ret < 0)
-			return ret;
+			return dev_err_probe(dev, ret, "Error reading status register\n");
 
 		if (!(readval & AD7124_STATUS_POR_FLAG_MSK))
 			return 0;
@@ -775,35 +777,30 @@ static int ad7124_soft_reset(struct ad7124_state *st)
 		usleep_range(100, 2000);
 	} while (--timeout);
 
-	dev_err(&st->sd.spi->dev, "Soft reset failed\n");
-
-	return -EIO;
+	return dev_err_probe(dev, -EIO, "Soft reset failed\n");
 }
 
 static int ad7124_check_chip_id(struct ad7124_state *st)
 {
+	struct device *dev = &st->sd.spi->dev;
 	unsigned int readval, chip_id, silicon_rev;
 	int ret;
 
 	ret = ad_sd_read_reg(&st->sd, AD7124_ID, 1, &readval);
 	if (ret < 0)
-		return ret;
+		return dev_err_probe(dev, ret, "Failure to read ID register\n");
 
 	chip_id = AD7124_DEVICE_ID_GET(readval);
 	silicon_rev = AD7124_SILICON_REV_GET(readval);
 
-	if (chip_id != st->chip_info->chip_id) {
-		dev_err(&st->sd.spi->dev,
-			"Chip ID mismatch: expected %u, got %u\n",
-			st->chip_info->chip_id, chip_id);
-		return -ENODEV;
-	}
+	if (chip_id != st->chip_info->chip_id)
+		return dev_err_probe(dev, -ENODEV,
+				     "Chip ID mismatch: expected %u, got %u\n",
+				     st->chip_info->chip_id, chip_id);
 
-	if (silicon_rev == 0) {
-		dev_err(&st->sd.spi->dev,
-			"Silicon revision empty. Chip may not be present\n");
-		return -ENODEV;
-	}
+	if (silicon_rev == 0)
+		return dev_err_probe(dev, -ENODEV,
+				     "Silicon revision empty. Chip may not be present\n");
 
 	return 0;
 }
@@ -862,16 +859,18 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 	device_for_each_child_node_scoped(dev, child) {
 		ret = fwnode_property_read_u32(child, "reg", &channel);
 		if (ret)
-			return ret;
+			return dev_err_probe(dev, ret,
+					     "Failed to parse reg property of %pfwP\n", child);
 
 		if (channel >= indio_dev->num_channels)
 			return dev_err_probe(dev, -EINVAL,
-				"Channel index >= number of channels\n");
+					     "Channel index >= number of channels in %pfwP\n", child);
 
 		ret = fwnode_property_read_u32_array(child, "diff-channels",
 						     ain, 2);
 		if (ret)
-			return ret;
+			return dev_err_probe(dev, ret,
+					     "Failed to parse diff-channels property of %pfwP\n", child);
 
 		if (!ad7124_valid_input_select(ain[0], st->chip_info) ||
 		    !ad7124_valid_input_select(ain[1], st->chip_info))
@@ -908,12 +907,13 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 
 static int ad7124_setup(struct ad7124_state *st)
 {
+	struct device *dev = &st->sd.spi->dev;
 	unsigned int fclk, power_mode;
 	int i, ret;
 
 	fclk = clk_get_rate(st->mclk);
 	if (!fclk)
-		return -EINVAL;
+		return dev_err_probe(dev, -EINVAL, "Failed to get mclk rate\n");
 
 	/* The power mode changes the master clock frequency */
 	power_mode = ad7124_find_closest_match(ad7124_master_clk_freq_hz,
@@ -922,7 +922,7 @@ static int ad7124_setup(struct ad7124_state *st)
 	if (fclk != ad7124_master_clk_freq_hz[power_mode]) {
 		ret = clk_set_rate(st->mclk, fclk);
 		if (ret)
-			return ret;
+			return dev_err_probe(dev, ret, "Failed to set mclk rate\n");
 	}
 
 	/* Set the power mode */
@@ -953,7 +953,7 @@ static int ad7124_setup(struct ad7124_state *st)
 
 	ret = ad_sd_write_reg(&st->sd, AD7124_ADC_CONTROL, 2, st->adc_control);
 	if (ret < 0)
-		return ret;
+		return dev_err_probe(dev, ret, "Failed to setup CONTROL register\n");
 
 	return ret;
 }
@@ -966,13 +966,14 @@ static void ad7124_reg_disable(void *r)
 static int ad7124_probe(struct spi_device *spi)
 {
 	const struct ad7124_chip_info *info;
+	struct device *dev = &spi->dev;
 	struct ad7124_state *st;
 	struct iio_dev *indio_dev;
 	int i, ret;
 
 	info = spi_get_device_match_data(spi);
 	if (!info)
-		return -ENODEV;
+		return dev_err_probe(dev, -ENODEV, "Failed to get match data\n");
 
 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 	if (!indio_dev)
@@ -1007,36 +1008,42 @@ static int ad7124_probe(struct spi_device *spi)
 
 		ret = regulator_enable(st->vref[i]);
 		if (ret)
-			return ret;
+			return dev_err_probe(dev, ret, "Failed to enable regulator #%d\n", i);
 
 		ret = devm_add_action_or_reset(&spi->dev, ad7124_reg_disable,
 					       st->vref[i]);
 		if (ret)
-			return ret;
+			return dev_err_probe(dev, ret, "Failed to register disable handler for regulator #%d\n", i);
 	}
 
 	st->mclk = devm_clk_get_enabled(&spi->dev, "mclk");
 	if (IS_ERR(st->mclk))
-		return PTR_ERR(st->mclk);
+		return dev_err_probe(dev, PTR_ERR(st->mclk), "Failed to get mclk\n");
 
 	ret = ad7124_soft_reset(st);
 	if (ret < 0)
+		/* ad7124_soft_reset() already emitted an error message */
 		return ret;
 
 	ret = ad7124_check_chip_id(st);
 	if (ret)
+		/* ad7124_check_chip_id() already emitted an error message */
 		return ret;
 
 	ret = ad7124_setup(st);
 	if (ret < 0)
+		/* ad7124_setup() already emitted an error message */
 		return ret;
 
 	ret = devm_ad_sd_setup_buffer_and_trigger(&spi->dev, indio_dev);
 	if (ret < 0)
-		return ret;
+		return dev_err_probe(dev, ret, "Failed to setup triggers\n");
 
-	return devm_iio_device_register(&spi->dev, indio_dev);
+	ret = devm_iio_device_register(&spi->dev, indio_dev);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to register iio device\n");
 
+	return 0;
 }
 
 static const struct of_device_id ad7124_of_match[] = {
-- 
2.45.2

[PATCH v4 10/10] iio: adc: ad7124: Implement temperature measurement

[Uwe Kleine-König]

If the maximal count of channels the driver supports isn't fully
utilized, add an attribute providing the internal temperature.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
---
 drivers/iio/adc/ad7124.c | 112 +++++++++++++++++++++++++++++++--------
 1 file changed, 91 insertions(+), 21 deletions(-)

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 50b8ffa2dbe5..3b95e5a22473 100644
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -95,6 +95,10 @@
 #define AD7124_MAX_CONFIGS	8
 #define AD7124_MAX_CHANNELS	16
 
+/* AD7124 input sources */
+#define AD7124_INPUT_TEMPSENSOR	16
+#define AD7124_INPUT_AVSS	17
+
 enum ad7124_ids {
 	ID_AD7124_4,
 	ID_AD7124_8,
@@ -589,26 +593,59 @@ static int ad7124_read_raw(struct iio_dev *indio_dev,
 
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
-		mutex_lock(&st->cfgs_lock);
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			mutex_lock(&st->cfgs_lock);
 
-		idx = st->channels[chan->address].cfg.pga_bits;
-		*val = st->channels[chan->address].cfg.vref_mv;
-		if (st->channels[chan->address].cfg.bipolar)
-			*val2 = chan->scan_type.realbits - 1 + idx;
-		else
-			*val2 = chan->scan_type.realbits + idx;
+			idx = st->channels[chan->address].cfg.pga_bits;
+			*val = st->channels[chan->address].cfg.vref_mv;
+			if (st->channels[chan->address].cfg.bipolar)
+				*val2 = chan->scan_type.realbits - 1 + idx;
+			else
+				*val2 = chan->scan_type.realbits + idx;
+
+			mutex_unlock(&st->cfgs_lock);
+			return IIO_VAL_FRACTIONAL_LOG2;
+
+		case IIO_TEMP:
+			/*
+			 * According to the data sheet
+			 *   Temperature (°C)
+			 * = ((Conversion − 0x800000)/13584) − 272.5
+			 * = (Conversion − 0x800000 - 13584 * 272.5) / 13584
+			 * = (Conversion − 12090248) / 13584
+			 * So scale with 1000/13584 to yield °mC. Reduce by 8 to
+			 * 125/1698.
+			 */
+			*val = 125;
+			*val2 = 1698;
+			return IIO_VAL_FRACTIONAL;
+
+		default:
+			return -EINVAL;
+		}
 
-		mutex_unlock(&st->cfgs_lock);
-		return IIO_VAL_FRACTIONAL_LOG2;
 	case IIO_CHAN_INFO_OFFSET:
-		mutex_lock(&st->cfgs_lock);
-		if (st->channels[chan->address].cfg.bipolar)
-			*val = -(1 << (chan->scan_type.realbits - 1));
-		else
-			*val = 0;
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			mutex_lock(&st->cfgs_lock);
+			if (st->channels[chan->address].cfg.bipolar)
+				*val = -(1 << (chan->scan_type.realbits - 1));
+			else
+				*val = 0;
+
+			mutex_unlock(&st->cfgs_lock);
+			return IIO_VAL_INT;
+
+		case IIO_TEMP:
+			/* see calculation above */
+			*val = -12090248;
+			return IIO_VAL_INT;
+
+		default:
+			return -EINVAL;
+		}
 
-		mutex_unlock(&st->cfgs_lock);
-		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		mutex_lock(&st->cfgs_lock);
 		*val = st->channels[chan->address].cfg.odr;
@@ -826,11 +863,10 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 	struct ad7124_channel *channels;
 	struct iio_chan_spec *chan;
 	unsigned int ain[2], channel = 0, tmp;
+	unsigned int num_channels;
 	int ret;
 
-	st->num_channels = device_get_child_node_count(dev);
-	if (!st->num_channels)
-		return dev_err_probe(dev, -ENODEV, "no channel children\n");
+	num_channels = device_get_child_node_count(dev);
 
 	/*
 	 * The driver assigns each logical channel defined in the device tree
@@ -839,9 +875,12 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 	 * CHANNEL_15) as an additional channel register. The driver could be
 	 * improved to lift this limitation.
 	 */
-	if (st->num_channels > AD7124_MAX_CHANNELS)
+	if (num_channels > AD7124_MAX_CHANNELS)
 		return dev_err_probe(dev, -EINVAL, "Too many channels defined\n");
 
+	/* Add one for temperature */
+	st->num_channels = min(num_channels + 1, AD7124_MAX_CHANNELS);
+
 	chan = devm_kcalloc(indio_dev->dev.parent, st->num_channels,
 			    sizeof(*chan), GFP_KERNEL);
 	if (!chan)
@@ -862,7 +901,7 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 			return dev_err_probe(dev, ret,
 					     "Failed to parse reg property of %pfwP\n", child);
 
-		if (channel >= indio_dev->num_channels)
+		if (channel >= num_channels)
 			return dev_err_probe(dev, -EINVAL,
 					     "Channel index >= number of channels in %pfwP\n", child);
 
@@ -902,6 +941,37 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
 		chan[channel].channel2 = ain[1];
 	}
 
+	if (num_channels < AD7124_MAX_CHANNELS) {
+		st->channels[num_channels] = (struct ad7124_channel) {
+			.nr = num_channels,
+			.ain = AD7124_CHANNEL_AINP(AD7124_INPUT_TEMPSENSOR) |
+				AD7124_CHANNEL_AINM(AD7124_INPUT_AVSS),
+			.cfg = {
+				.bipolar = true,
+			},
+		};
+
+		chan[num_channels] = (struct iio_chan_spec) {
+			.type = IIO_TEMP,
+			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET) |
+				BIT(IIO_CHAN_INFO_SAMP_FREQ),
+			.scan_type = {
+				/*
+				 * You might find it strange that a bipolar
+				 * measurement yields an unsigned value, but
+				 * this matches the device's manual.
+				 */
+				.sign = 'u',
+				.realbits = 24,
+				.storagebits = 32,
+				.endianness = IIO_BE,
+			},
+			.address = num_channels,
+			.scan_index = num_channels,
+		};
+	};
+
 	return 0;
 }
 
-- 
2.45.2

Re: [PATCH v4 03/10] dt-bindings: iio: adc: adi,ad7{124,173,192,780}: Allow specifications of a gpio for irq line

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 2575 bytes --]

On Wed, Nov 27, 2024 at 03:59:32PM +0100, Uwe Kleine-König wrote:
> For the AD7124 chip and some of its cousins the logical irq line (̅R̅D̅Y)
> is physically on the same pin as the spi MISO output (DOUT) and so
> reading a register might trigger an interrupt. For correct operation
> it's critical that the actual state of the pin can be read to judge if
> an interrupt event is a real one or just a spurious one triggered by
> toggling the line in its MISO mode.
> 
> Allow specification of an "rdy-gpios" property that references a GPIO
> that can be used for that purpose. While this is typically the same GPIO
> also used (implicitly) as interrupt source, it is still supposed that
> the interrupt is specified as before and usual.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
> ---
>  .../devicetree/bindings/iio/adc/adi,ad7124.yaml   | 13 +++++++++++++
>  .../devicetree/bindings/iio/adc/adi,ad7173.yaml   | 12 ++++++++++++
>  .../devicetree/bindings/iio/adc/adi,ad7192.yaml   | 15 +++++++++++++++
>  .../devicetree/bindings/iio/adc/adi,ad7780.yaml   | 11 +++++++++++
>  4 files changed, 51 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7124.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7124.yaml
> index 35ed04350e28..9f34a055fdf1 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7124.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7124.yaml
> @@ -37,6 +37,17 @@ properties:
>      description: IRQ line for the ADC
>      maxItems: 1
>  
> +  rdy-gpios:
> +    description: |
> +      GPIO reading the ̅̅R̅D̅Y line. Having such a GPIO is technically optional but
> +      highly recommended because DOUT/̅R̅D̅Y toggles during SPI transfers (in its
> +      DOUT aka MISO role) and so usually triggers a spurious interrupt. The
> +      distinction between such a spurious event and a real one can only be done
> +      by reading such a GPIO. (There is a register telling the same
> +      information, but accessing that one needs a SPI transfer which then
> +      triggers another interrupt event.)
> +    maxItems: 1

Rob commented to v2 which I missed to pickup:

	Don't need '|'.

	Otherwise,

	Reviewed-by: Rob Hering (Arm) <robh@kernel.org>

Dropped the | now in my tree in case we need a v5. Otherwise I'd ask
Jonathan to drop the |s when applying. I probably would have dropped the
R-b tag given the changes here (i.e. adding the property to several more
bindings).

Best regards and sorry,
Uwe

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH v4 08/10] iio: adc: ad_sigma_delta: Check for previous ready signals

[Jonathan Cameron]

On Wed, 27 Nov 2024 15:59:37 +0100
Uwe Kleine-König <u.kleine-koenig@baylibre.com> wrote:

> It can happen if a previous conversion was aborted the ADC pulls down
> the ̅R̅D̅Y line but the event wasn't handled before. In that case enabling
> the irq might immediately fire (depending on the irq controller's
> capabilities) and even with a rdy-gpio isn't identified as an unrelated
> one.
> 
> To cure that problem check for a pending event before the measurement is
> started and clear it if needed.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Hi Uwe,

I think there is a DMA buffer safety issue hiding in the new code. Other than
that this looks good to me.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/ad_sigma_delta.c | 89 ++++++++++++++++++++++++++++++++
>  1 file changed, 89 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
> index 9891346c2d73..164a4d0b571d 100644
> --- a/drivers/iio/adc/ad_sigma_delta.c
> +++ b/drivers/iio/adc/ad_sigma_delta.c
> @@ -29,8 +29,11 @@
>  #define AD_SD_COMM_CHAN_MASK	0x3
>  
>  #define AD_SD_REG_COMM		0x00
> +#define AD_SD_REG_STATUS	0x00
>  #define AD_SD_REG_DATA		0x03
>  
> +#define AD_SD_REG_STATUS_RDY	0x80
> +
>  /**
>   * ad_sd_set_comm() - Set communications register
>   *
> @@ -222,6 +225,80 @@ static void ad_sd_enable_irq(struct ad_sigma_delta *sigma_delta)
>  	enable_irq(sigma_delta->irq_line);
>  }
>  
> +/* Called with `sigma_delta->bus_locked == true` only.  */

Trivial but bonus space before */

> +static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta)
> +{
> +	bool pending_event;
> +	unsigned int data_read_len = BITS_TO_BYTES(sigma_delta->info->num_resetclks);
> +	u8 data[9];

SPI requires DMA safe buffers.  Either play games to get one in iio_priv via
__aligned(IIO_DMA_MINALIGN) or just kzalloc() this here.
Probably do that after the !pending_event check though so we only allocate
when there is a need for it.


> +	struct spi_transfer t[] = {
> +		{
> +			.tx_buf = data,
> +			.len = 1,
> +		}, {
> +			.tx_buf = data + 1,
> +			.len = data_read_len,
> +		}
> +	};
> +	struct spi_message m;
> +
> +	/*
> +	 * read RDY pin (if possible) or status register to check if there is an

* Read RDY...

> +	 * old event.
> +	 */
> +	if (sigma_delta->rdy_gpiod) {
> +		pending_event = gpiod_get_value(sigma_delta->rdy_gpiod);
> +	} else {
> +		int ret;
> +		unsigned status_reg;
> +
> +		ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_STATUS, 1, &status_reg);
> +		if (ret)
> +			return ret;
> +
> +		pending_event = !(status_reg & AD_SD_REG_STATUS_RDY);
> +	}
> +
> +	if (!pending_event)
> +		return 0;
> +
> +	/*
> +	 * In general the size of the data register is unknown. It varies from
> +	 * device to device, might be one byte longer if CONTROL.DATA_STATUS is
> +	 * set and even varies on some devices depending on which input is
> +	 * selected. So send one byte to start reading the data register and
> +	 * then just clock for some bytes with DIN (aka MOSI) high to not
> +	 * confuse the register access state machine after the data register was
> +	 * completely read. Note however that the sequence length must be
> +	 * shorter than the reset procedure.
> +	 */
> +
> +	/* Oh, back out instead of overflowing data[] */
> +	if (data_read_len > sizeof(data) - 1)
> +		return -EINVAL;
> +
> +	spi_message_init(&m);
> +	if (sigma_delta->info->has_registers) {
> +		unsigned int data_reg = sigma_delta->info->data_reg ?: AD_SD_REG_DATA;
> +
> +		data[0] = data_reg << sigma_delta->info->addr_shift;
> +		data[0] |= sigma_delta->info->read_mask;
> +		data[0] |= sigma_delta->comm;
> +		spi_message_add_tail(&t[0], &m);
> +	}
> +
> +	/*
> +	 * The first transferred byte is part of the real data register,
> +	 * so this doesn't need to be 0xff. In the remaining
> +	 * `data_read_len - 1` bytes are less than $num_resetclks ones.
> +	 */
> +	data[1] = 0x00;
> +	memset(data + 2, 0xff, data_read_len - 1);
> +	spi_message_add_tail(&t[1], &m);
> +
> +	return spi_sync_locked(sigma_delta->spi, &m);
> +}
> +
>  int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
>  	unsigned int mode, unsigned int channel)
>  {
> @@ -237,6 +314,10 @@ int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
>  	sigma_delta->keep_cs_asserted = true;
>  	reinit_completion(&sigma_delta->completion);
>  
> +	ret = ad_sigma_delta_clear_pending_event(sigma_delta);
> +	if (ret)
> +		return ret;
> +
>  	ret = ad_sigma_delta_set_mode(sigma_delta, mode);
>  	if (ret < 0)
>  		goto out;
> @@ -310,6 +391,10 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
>  	sigma_delta->keep_cs_asserted = true;
>  	reinit_completion(&sigma_delta->completion);
>  
> +	ret = ad_sigma_delta_clear_pending_event(sigma_delta);
> +	if (ret)
> +		return ret;
> +
>  	ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE);
>  
>  	ad_sd_enable_irq(sigma_delta);
> @@ -406,6 +491,10 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
>  	sigma_delta->bus_locked = true;
>  	sigma_delta->keep_cs_asserted = true;
>  
> +	ret = ad_sigma_delta_clear_pending_event(sigma_delta);
> +	if (ret)
> +		return ret;
> +
>  	ret = ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_CONTINUOUS);
>  	if (ret)
>  		goto err_unlock;

Re: [PATCH v4 09/10] iio: adc: ad7124: Add error reporting during probe

[Jonathan Cameron]

On Wed, 27 Nov 2024 15:59:38 +0100
Uwe Kleine-König <u.kleine-koenig@baylibre.com> wrote:

> A driver that silently fails to probe is annoying and hard to debug. So
> add messages in the error paths of the probe function.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>

Probably worth calling out in this patch description that you also
replace some dev_err() calls with dev_err_probe()

One comment inline.

Thanks,

Jonathan

> @@ -1007,36 +1008,42 @@ static int ad7124_probe(struct spi_device *spi)
>  
>  		ret = regulator_enable(st->vref[i]);
>  		if (ret)
> -			return ret;
> +			return dev_err_probe(dev, ret, "Failed to enable regulator #%d\n", i);
>  
>  		ret = devm_add_action_or_reset(&spi->dev, ad7124_reg_disable,
>  					       st->vref[i]);
>  		if (ret)
> -			return ret;
> +			return dev_err_probe(dev, ret, "Failed to register disable handler for regulator #%d\n", i);
>  	}
>  
>  	st->mclk = devm_clk_get_enabled(&spi->dev, "mclk");
>  	if (IS_ERR(st->mclk))
> -		return PTR_ERR(st->mclk);
> +		return dev_err_probe(dev, PTR_ERR(st->mclk), "Failed to get mclk\n");
>  
>  	ret = ad7124_soft_reset(st);
>  	if (ret < 0)
> +		/* ad7124_soft_reset() already emitted an error message */
I'd not bother adding these already emitted comments.
The only time we'd care is if someone else comes along and adds them. Hopefully we'd
catch that anyway in review, but even if don't it wouldn't matter a lot.
>  		return ret;
>  
>  	ret = ad7124_check_chip_id(st);
>  	if (ret)
> +		/* ad7124_check_chip_id() already emitted an error message */
>  		return ret;
>  
>  	ret = ad7124_setup(st);
>  	if (ret < 0)
> +		/* ad7124_setup() already emitted an error message */
>  		return ret;
>  
>  	ret = devm_ad_sd_setup_buffer_and_trigger(&spi->dev, indio_dev);
>  	if (ret < 0)
> -		return ret;
> +		return dev_err_probe(dev, ret, "Failed to setup triggers\n");
>  
> -	return devm_iio_device_register(&spi->dev, indio_dev);
> +	ret = devm_iio_device_register(&spi->dev, indio_dev);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to register iio device\n");
>  
> +	return 0;
>  }
>  
>  static const struct of_device_id ad7124_of_match[] = {

Re: [PATCH v4 10/10] iio: adc: ad7124: Implement temperature measurement

[Jonathan Cameron]

On Wed, 27 Nov 2024 15:59:39 +0100
Uwe Kleine-König <u.kleine-koenig@baylibre.com> wrote:

> If the maximal count of channels the driver supports isn't fully
> utilized, add an attribute providing the internal temperature.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
LGTM

For the whole series, I would ideally like an additional review from someone more
familiar with these parts than I am.

Thanks,

Jonathan


> @@ -902,6 +941,37 @@ static int ad7124_parse_channel_config(struct iio_dev *indio_dev,
>  		chan[channel].channel2 = ain[1];
>  	}
>  
> +	if (num_channels < AD7124_MAX_CHANNELS) {
> +		st->channels[num_channels] = (struct ad7124_channel) {
> +			.nr = num_channels,
> +			.ain = AD7124_CHANNEL_AINP(AD7124_INPUT_TEMPSENSOR) |
> +				AD7124_CHANNEL_AINM(AD7124_INPUT_AVSS),
> +			.cfg = {
> +				.bipolar = true,
> +			},
> +		};
> +
> +		chan[num_channels] = (struct iio_chan_spec) {
> +			.type = IIO_TEMP,
> +			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET) |
> +				BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +			.scan_type = {
> +				/*
> +				 * You might find it strange that a bipolar
> +				 * measurement yields an unsigned value, but
> +				 * this matches the device's manual.

I did indeed ;)  So good comment.

> +				 */
> +				.sign = 'u',
> +				.realbits = 24,
> +				.storagebits = 32,
> +				.endianness = IIO_BE,
> +			},
> +			.address = num_channels,
> +			.scan_index = num_channels,
> +		};
> +	};
> +
>  	return 0;
>  }
>