linux-kernel - [PATCH v7 3/5] dt-bindings: iio: magnetometer: ak8975: add gpio reset support

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Date:   Thu, 28 May 2020 16:59:28 +0200
From:   Jonathan Albrieux <jonathan.albrieux@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     ~postmarketos/upstreaming@...ts.sr.ht,
        Jonathan Albrieux <jonathan.albrieux@...il.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Rob Herring <robh+dt@...nel.org>,
        linux-iio@...r.kernel.org (open list:IIO SUBSYSTEM AND DRIVERS),
        devicetree@...r.kernel.org (open list:OPEN FIRMWARE AND FLATTENED
        DEVICE TREE BINDINGS)
Subject: [PATCH v7 3/5] dt-bindings: iio: magnetometer: ak8975: add gpio reset support

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@...il.com>
Reviewed-by: Rob Herring <robh@...nel.org>
---
 .../bindings/iio/magnetometer/asahi-kasei,ak8975.yaml      | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/magnetometer/asahi-kasei,ak8975.yaml b/Documentation/devicetree/bindings/iio/magnetometer/asahi-kasei,ak8975.yaml
index 55b18784e503..e8af53d60759 100644
--- a/Documentation/devicetree/bindings/iio/magnetometer/asahi-kasei,ak8975.yaml
+++ b/Documentation/devicetree/bindings/iio/magnetometer/asahi-kasei,ak8975.yaml
@@ -47,6 +47,11 @@ properties:
   mount-matrix:
     description: an optional 3x3 mounting rotation matrix.
 
+  reset-gpios:
+    description: |
+      an optional pin needed for AK09911 to set the reset state. This should
+      be usually active low
+
 required:
   - compatible
   - reg
@@ -54,6 +59,7 @@ required:
 examples:
   - |
     #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/gpio/gpio.h>
     i2c {
         #address-cells = <1>;
         #size-cells = <0>;
@@ -64,6 +70,7 @@ examples:
             interrupt-parent = <&gpio6>;
             interrupts = <15 IRQ_TYPE_EDGE_RISING>;
             vdd-supply = <&ldo_3v3_gnss>;
+            reset-gpios = <&msmgpio 111 GPIO_ACTIVE_LOW>;
             mount-matrix = "-0.984807753012208",  /* x0 */
                            "0",                   /* y0 */
                            "-0.173648177666930",  /* z0 */
-- 
2.17.1