[PATCH v4 0/4] iio: magnetometer: ak8975: Add gpio reset support

[PATCH v4 0/4] iio: magnetometer: ak8975: Add gpio reset support

[Jonathan Albrieux]

v4:
 - fix some typo
 - use gpio's dt-bindings for more clarity in documentation
 - set compatible properties without vendor prefix as deprecated

v3:
 - fix patch messages style
 - align reset gpio comment to kernel doc reccomendation
 - introduce changelog.
https://lore.kernel.org/linux-iio/20200519124402.26076-1-jonathan.albrieux@gmail.com/

v2:
 - rewording of reset gpio comment and patch messages to better clarify
   reset gpio behaviour.
https://lore.kernel.org/linux-iio/20200518133645.19127-1-jonathan.albrieux@gmail.com/

v1:
 - initial patch submission.
https://lore.kernel.org/linux-iio/20200519065749.4624-1-jonathan.albrieux@gmail.com/

Convert documentation from txt format to yaml. Add documentation about
reset-gpio.

Deassert reset on ak8975_power_on(), assert reset on ak8975_power_off().

Without reset's deassertion during ak8975_power_on(), driver's probe fails
on ak8975_who_i_am() while checking for device identity for AK09911 chip.

AK09911 has an active low reset gpio to handle register's reset.
AK09911 datasheet says that, if not used, reset pin should be connected
to VID. This patch emulates this situation.

Jonathan Albrieux (4):
  dt-bindings: iio: magnetometer: ak8975: convert txt format to yaml
  dt-bindings: iio: magnetometer: ak8975: add gpio reset support
  iio: magnetometer: ak8975: Fix typo, uniform measurement unit style
  iio: magnetometer: ak8975: Add gpio reset support

 .../bindings/iio/magnetometer/ak8975.txt      | 30 --------
 .../bindings/iio/magnetometer/ak8975.yaml     | 77 +++++++++++++++++++
 drivers/iio/magnetometer/ak8975.c             | 22 +++++-
 3 files changed, 97 insertions(+), 32 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
 create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml

-- 
2.17.1

[PATCH v4 1/4] dt-bindings: iio: magnetometer: ak8975: convert txt format to yaml

[Jonathan Albrieux]

Converts documentation from txt format to yaml.

Signed-off-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
---
 .../bindings/iio/magnetometer/ak8975.txt      | 30 --------
 .../bindings/iio/magnetometer/ak8975.yaml     | 71 +++++++++++++++++++
 2 files changed, 71 insertions(+), 30 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
 create mode 100644 Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml

diff --git a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
deleted file mode 100644
index aa67ceb0d4e0..000000000000
--- a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
+++ /dev/null
@@ -1,30 +0,0 @@
-* AsahiKASEI AK8975 magnetometer sensor
-
-Required properties:
-
-  - compatible : should be "asahi-kasei,ak8975"
-  - reg : the I2C address of the magnetometer
-
-Optional properties:
-
-  - gpios : should be device tree identifier of the magnetometer DRDY pin
-  - vdd-supply: an optional regulator that needs to be on to provide VDD
-  - mount-matrix: an optional 3x3 mounting rotation matrix
-
-Example:
-
-ak8975@c {
-        compatible = "asahi-kasei,ak8975";
-        reg = <0x0c>;
-        gpios = <&gpj0 7 0>;
-        vdd-supply = <&ldo_3v3_gnss>;
-        mount-matrix = "-0.984807753012208",  /* x0 */
-                       "0",                   /* y0 */
-                       "-0.173648177666930",  /* z0 */
-                       "0",                   /* x1 */
-                       "-1",                  /* y1 */
-                       "0",                   /* z1 */
-                       "-0.173648177666930",  /* x2 */
-                       "0",                   /* y2 */
-                       "0.984807753012208";   /* z2 */
-};
diff --git a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml
new file mode 100644
index 000000000000..9d5b1e6908d1
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml
@@ -0,0 +1,71 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/magnetometer/ak8975.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: AsahiKASEI AK8975 magnetometer sensor
+
+maintainers:
+  - can't find a maintainer, author is Laxman Dewangan <ldewangan@nvidia.com>
+
+properties:
+  compatible:
+    oneOf:
+      - const: asahi-kasei,ak8975
+      - const: asahi-kasei,ak8963
+      - const: asahi-kasei,ak09911
+      - const: asahi-kasei,ak09912
+      - const: ak8975
+        deprecated: true
+      - const: ak8963
+        deprecated: true
+      - const: ak09911
+        deprecated: true
+      - const: ak09912
+        deprecated: true
+
+  reg:
+    maxItems: 1
+    description: the I2C address of the magnetometer
+
+  gpios:
+    description: should be device tree identifier of the magnetometer DRDY pin
+
+  vdd-supply:
+    maxItems: 1
+    description: |
+      an optional regulator that needs to be on to provide VDD power to
+      the sensor.
+
+  mount-matrix:
+    description: an optional 3x3 mounting rotation matrix
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    i2c@78b7000 {
+        reg = <0x78b6000 0x600>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        magnetometer@c {
+            compatible = "asahi-kasei,ak8975";
+            reg = <0x0c>;
+            gpios = <&gpj0 7 GPIO_ACTIVE_HIGH>;
+            vdd-supply = <&ldo_3v3_gnss>;
+            mount-matrix = "-0.984807753012208",  /* x0 */
+                           "0",                   /* y0 */
+                           "-0.173648177666930",  /* z0 */
+                           "0",                   /* x1 */
+                           "-1",                  /* y1 */
+                           "0",                   /* z1 */
+                           "-0.173648177666930",  /* x2 */
+                           "0",                   /* y2 */
+                           "0.984807753012208";   /* z2 */
+        };
+    };
-- 
2.17.1

Re: [PATCH v4 1/4] dt-bindings: iio: magnetometer: ak8975: convert txt format to yaml

[Andy Shevchenko]

On Wed, May 20, 2020 at 10:32 AM Jonathan Albrieux
<jonathan.albrieux@gmail.com> wrote:

> +maintainers:
> +  - can't find a maintainer, author is Laxman Dewangan <ldewangan@nvidia.com>

Alas, you'll never go forward with this.
One (easiest way) is to drop this patch completely if you won't be a
maintainer of the binding.


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v4 1/4] dt-bindings: iio: magnetometer: ak8975: convert txt format to yaml

[Jonathan Albrieux]

On Wed, May 20, 2020 at 11:23:18AM +0300, Andy Shevchenko wrote:
> On Wed, May 20, 2020 at 10:32 AM Jonathan Albrieux
> <jonathan.albrieux@gmail.com> wrote:
> 
> > +maintainers:
> > +  - can't find a maintainer, author is Laxman Dewangan <ldewangan@nvidia.com>
> 
> Alas, you'll never go forward with this.
> One (easiest way) is to drop this patch completely if you won't be a
> maintainer of the binding.
>

That's too bad. How can I be a maintainer of the binding?

> 
> -- 
> With Best Regards,
> Andy Shevchenko

Thank you,
Best regards,
Jonathan Albrieux

Re: [PATCH v4 1/4] dt-bindings: iio: magnetometer: ak8975: convert txt format to yaml

[Andy Shevchenko]

On Wed, May 20, 2020 at 03:44:16PM +0200, Jonathan Albrieux wrote:
> On Wed, May 20, 2020 at 11:23:18AM +0300, Andy Shevchenko wrote:
> > On Wed, May 20, 2020 at 10:32 AM Jonathan Albrieux
> > <jonathan.albrieux@gmail.com> wrote:
> > 
> > > +maintainers:
> > > +  - can't find a maintainer, author is Laxman Dewangan <ldewangan@nvidia.com>
> > 
> > Alas, you'll never go forward with this.
> > One (easiest way) is to drop this patch completely if you won't be a
> > maintainer of the binding.
> >
> 
> That's too bad. How can I be a maintainer of the binding?

Put your name there as Jonathan and me suggested. :-)

maintainers:
  - Jonathan Albrieux <jonathan.albrieux@gmail.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v4 1/4] dt-bindings: iio: magnetometer: ak8975: convert txt format to yaml

[Jonathan Albrieux]

On Wed, May 20, 2020 at 04:54:01PM +0300, Andy Shevchenko wrote:
> On Wed, May 20, 2020 at 03:44:16PM +0200, Jonathan Albrieux wrote:
> > On Wed, May 20, 2020 at 11:23:18AM +0300, Andy Shevchenko wrote:
> > > On Wed, May 20, 2020 at 10:32 AM Jonathan Albrieux
> > > <jonathan.albrieux@gmail.com> wrote:
> > > 
> > > > +maintainers:
> > > > +  - can't find a maintainer, author is Laxman Dewangan <ldewangan@nvidia.com>
> > > 
> > > Alas, you'll never go forward with this.
> > > One (easiest way) is to drop this patch completely if you won't be a
> > > maintainer of the binding.
> > >
> > 
> > That's too bad. How can I be a maintainer of the binding?
> 
> Put your name there as Jonathan and me suggested. :-)
> 
> maintainers:
>   - Jonathan Albrieux <jonathan.albrieux@gmail.com>
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
> 

Ok I'll prepare a new patch then :-)

Thank you!!
Best regards,
Jonathan Albrieux

[PATCH v4 2/4] dt-bindings: iio: magnetometer: ak8975: add gpio reset support

[Jonathan Albrieux]

Add reset-gpio support.

Without reset's deassertion during ak8975_power_on(), driver's probe fails
on ak8975_who_i_am() while checking for device identity for AK09911 chip.

AK09911 has an active low reset gpio to handle register's reset.
AK09911 datasheet says that, if not used, reset pin should be connected
to VID. This patch emulates this situation.

Signed-off-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
---
 .../devicetree/bindings/iio/magnetometer/ak8975.yaml        | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml
index 9d5b1e6908d1..d83f7e212658 100644
--- a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml
+++ b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.yaml
@@ -41,6 +41,11 @@ properties:
   mount-matrix:
     description: an optional 3x3 mounting rotation matrix
 
+  reset-gpio:
+    description: |
+      an optional pin needed for AK09911 to set the reset state. This should
+      be usually active low
+
 required:
   - compatible
   - reg
@@ -58,6 +63,7 @@ examples:
             reg = <0x0c>;
             gpios = <&gpj0 7 GPIO_ACTIVE_HIGH>;
             vdd-supply = <&ldo_3v3_gnss>;
+            reset-gpio = <&msmgpio 111 GPIO_ACTIVE_LOW>;
             mount-matrix = "-0.984807753012208",  /* x0 */
                            "0",                   /* y0 */
                            "-0.173648177666930",  /* z0 */
-- 
2.17.1

[PATCH v4 3/4] iio: magnetometer: ak8975: Fix typo, uniform measurement unit style

[Jonathan Albrieux]

Minor comment style edits.

Signed-off-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/iio/magnetometer/ak8975.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index 3c881541ae72..fd368455cd7b 100644
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -385,9 +385,9 @@ static int ak8975_power_on(const struct ak8975_data *data)
 		return ret;
 	}
 	/*
-	 * According to the datasheet the power supply rise time i 200us
+	 * According to the datasheet the power supply rise time is 200us
 	 * and the minimum wait time before mode setting is 100us, in
-	 * total 300 us. Add some margin and say minimum 500us here.
+	 * total 300us. Add some margin and say minimum 500us here.
 	 */
 	usleep_range(500, 1000);
 	return 0;
-- 
2.17.1

[PATCH v4 4/4] iio: magnetometer: ak8975: Add gpio reset support

[Jonathan Albrieux]

According to AK09911 datasheet, if reset gpio is provided then
deassert reset on ak8975_power_on() and assert reset on ak8975_power_off().

Without reset's deassertion during ak8975_power_on(), driver's probe fails
on ak8975_who_i_am() while checking for device identity for AK09911 chip.

AK09911 has an active low reset gpio to handle register's reset.
AK09911 datasheet says that, if not used, reset pin should be connected
to VID. This patch emulates this situation.

Signed-off-by: Jonathan Albrieux <jonathan.albrieux@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
---
 drivers/iio/magnetometer/ak8975.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index fd368455cd7b..a23422aad97d 100644
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -358,6 +358,7 @@ struct ak8975_data {
 	u8			asa[3];
 	long			raw_to_gauss[3];
 	struct gpio_desc	*eoc_gpiod;
+	struct gpio_desc	*reset_gpiod;
 	int			eoc_irq;
 	wait_queue_head_t	data_ready_queue;
 	unsigned long		flags;
@@ -384,6 +385,9 @@ static int ak8975_power_on(const struct ak8975_data *data)
 			 "Failed to enable specified Vid supply\n");
 		return ret;
 	}
+
+	gpiod_set_value_cansleep(data->reset_gpiod, 0);
+
 	/*
 	 * According to the datasheet the power supply rise time is 200us
 	 * and the minimum wait time before mode setting is 100us, in
@@ -396,6 +400,8 @@ static int ak8975_power_on(const struct ak8975_data *data)
 /* Disable attached power regulator if any. */
 static void ak8975_power_off(const struct ak8975_data *data)
 {
+	gpiod_set_value_cansleep(data->reset_gpiod, 1);
+
 	regulator_disable(data->vid);
 	regulator_disable(data->vdd);
 }
@@ -839,6 +845,7 @@ static int ak8975_probe(struct i2c_client *client,
 	struct ak8975_data *data;
 	struct iio_dev *indio_dev;
 	struct gpio_desc *eoc_gpiod;
+	struct gpio_desc *reset_gpiod;
 	const void *match;
 	unsigned int i;
 	int err;
@@ -856,6 +863,16 @@ static int ak8975_probe(struct i2c_client *client,
 	if (eoc_gpiod)
 		gpiod_set_consumer_name(eoc_gpiod, "ak_8975");
 
+	/*
+	 * According to AK09911 datasheet, if reset GPIO is provided then
+	 * deassert reset on ak8975_power_on() and assert reset on
+	 * ak8975_power_off().
+	 */
+	reset_gpiod = devm_gpiod_get_optional(&client->dev,
+					      "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(reset_gpiod))
+		return PTR_ERR(reset_gpiod);
+
 	/* Register with IIO */
 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (indio_dev == NULL)
@@ -866,6 +883,7 @@ static int ak8975_probe(struct i2c_client *client,
 
 	data->client = client;
 	data->eoc_gpiod = eoc_gpiod;
+	data->reset_gpiod = reset_gpiod;
 	data->eoc_irq = 0;
 
 	err = iio_read_mount_matrix(&client->dev, "mount-matrix", &data->orientation);
-- 
2.17.1