[PATCH 1/2 v6] dt-bindings: leds: Add DT binding for Richtek RT8515

[PATCH 1/2 v6] dt-bindings: leds: Add DT binding for Richtek RT8515

[Linus Walleij]

Add a YAML devicetree binding for the Richtek RT8515
dual channel flash/torch LED driver.

Cc: Sakari Ailus <sakari.ailus@iki.fi>
Cc: newbytee@protonmail.com
Cc: Stephan Gerhold <stephan@gerhold.net>
Cc: phone-devel@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ChangeLog v5->v6:
- Use the suffix -ohms for the resistor values as this gets
  recognized by default by dtschema and is nominal.
ChangeLog v4->v5:
- Fix the RFS/RTS resistors to reference the u32 schema.
- Fix resisitor speling error.
ChangeLog v3->v4:
- Add DT attributes for the RFS and RTS resistors, so that
  the hardware-defined maximum current can be determined.
- Add torch-max-microamp to the common bindings so we can
  set an attribute for the max microamp in torch mode.
- Add flash-max-microamp and torch-max-microamp as optional
  to the LED node.
- Slot in some elabortative descriptions of the new
  properties and describe what the hardware is doing.
- Cc phone-devel@vger.kernel.org
ChangeLog v2->v3:
- Add Sakari to CC
- Resend
ChangeLog v1->v2:
- Explicitly inherit function, color and flash-max-timeout-us
  from common.yaml
- Add "led" node as required.
---
 .../devicetree/bindings/leds/common.yaml      |   6 +
 .../bindings/leds/richtek,rt8515.yaml         | 109 ++++++++++++++++++
 2 files changed, 115 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/richtek,rt8515.yaml

diff --git a/Documentation/devicetree/bindings/leds/common.yaml b/Documentation/devicetree/bindings/leds/common.yaml
index f1211e7045f1..92fa90b4a671 100644
--- a/Documentation/devicetree/bindings/leds/common.yaml
+++ b/Documentation/devicetree/bindings/leds/common.yaml
@@ -151,6 +151,12 @@ properties:
       Maximum flash LED supply current in microamperes. Required for flash LED
       nodes with configurable current.
 
+  torch-max-microamp:
+    description:
+      Maximum flash LED supply current in microamperes, when the flash LED is
+      used as a torch (flashlight). This is usually lower than the flash mode
+      maximum current, if the LED supports torch mode.
+
   flash-max-timeout-us:
     description:
       Maximum timeout in microseconds after which the flash LED is turned off.
diff --git a/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml b/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml
new file mode 100644
index 000000000000..b2022cb3ee1c
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml
@@ -0,0 +1,109 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/richtek,rt8515.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Richtek RT8515 1.5A dual channel LED driver
+
+maintainers:
+  - Linus Walleij <linus.walleij@linaro.org>
+
+description: |
+  The Richtek RT8515 is a dual channel (two mode) LED driver that
+  supports driving a white LED in flash or torch mode. The maximum
+  current for each mode is defined in hardware using two resistors
+  RFS and RTS.
+
+properties:
+  compatible:
+    const: richtek,rt8515
+
+  enf-gpios:
+    maxItems: 1
+    description: A connection to the 'ENF' (enable flash) pin.
+
+  ent-gpios:
+    maxItems: 1
+    description: A connection to the 'ENT' (enable torch) pin.
+
+  richtek,rfs-ohms:
+    minimum: 7680
+    maximum: 367000
+    description: The resistance value of the RFS resistor. This
+      resistors limits the maximum flash current. This must be set
+      for the property flash-max-microamp to work, the RFS resistor
+      defines the range of the dimmer setting (brightness) of the
+      flash LED.
+
+  richtek,rts-ohms:
+    minimum: 7680
+    maximum: 367000
+    description: The resistance value of the RTS resistor. This
+      resistors limits the maximum torch current. This must be set
+      for the property torch-max-microamp to work, the RTS resistor
+      defines the range of the dimmer setting (brightness) of the
+      torch LED.
+
+  led:
+    type: object
+    $ref: common.yaml#
+    properties:
+      function: true
+      color: true
+      flash-max-timeout-us: true
+
+      flash-max-microamp:
+        maximum: 700000
+        description: The maximum current for flash mode
+          is hardwired to the component using the RFS resistor to
+          ground. The maximum hardware current setting is calculated
+          according to the formula Imax = 5500 / RFS. The lowest
+          allowed resistance value is 7.86 kOhm giving an absolute
+          maximum current of 700mA. By setting this attribute in
+          the device tree, you can further restrict the maximum
+          current below the hardware limit. This requires the RFS
+          to be defined as it defines the maximum range.
+
+      torch-max-microamp:
+        maximum: 700000
+        description: The maximum current for torch mode
+          is hardwired to the component using the RTS resistor to
+          ground. The maximum hardware current setting is calculated
+          according to the formula Imax = 5500 / RTS. The lowest
+          allowed resistance value is 7.86 kOhm giving an absolute
+          maximum current of 700mA. By setting this attribute in
+          the device tree, you can further restrict the maximum
+          current below the hardware limit. This requires the RTS
+          to be defined as it defines the maximum range.
+
+required:
+  - compatible
+  - ent-gpios
+  - enf-gpios
+  - led
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/leds/common.h>
+
+    led-controller {
+        compatible = "richtek,rt8515";
+        enf-gpios = <&gpio4 12 GPIO_ACTIVE_HIGH>;
+        ent-gpios = <&gpio4 13 GPIO_ACTIVE_HIGH>;
+        richtek,rfs-ohms = <16000>;
+        richtek,rts-ohms = <100000>;
+
+        led {
+            function = LED_FUNCTION_FLASH;
+            color = <LED_COLOR_ID_WHITE>;
+            flash-max-timeout-us = <250000>;
+            flash-max-microamp = <150000>;
+            torch-max-microamp = <25000>;
+        };
+    };
+
+...
-- 
2.26.2

Re: [PATCH 1/2 v6] dt-bindings: leds: Add DT binding for Richtek RT8515

[Sakari Ailus]

Hi Linus,

On Mon, Nov 23, 2020 at 10:44:38PM +0100, Linus Walleij wrote:
> diff --git a/Documentation/devicetree/bindings/leds/common.yaml b/Documentation/devicetree/bindings/leds/common.yaml
> index f1211e7045f1..92fa90b4a671 100644
> --- a/Documentation/devicetree/bindings/leds/common.yaml
> +++ b/Documentation/devicetree/bindings/leds/common.yaml
> @@ -151,6 +151,12 @@ properties:
>        Maximum flash LED supply current in microamperes. Required for flash LED
>        nodes with configurable current.
>  
> +  torch-max-microamp:
> +    description:
> +      Maximum flash LED supply current in microamperes, when the flash LED is
> +      used as a torch (flashlight). This is usually lower than the flash mode
> +      maximum current, if the LED supports torch mode.

Thanks for the update.

One more thing. The other flash LED DT bindings are using led-max-microamp
for the torch mode --- for it's what the non-flash LEDs do.

Could you use the same here?

With that, for the set:

Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com>

-- 
Kind regards,

Sakari Ailus

Re: [PATCH 1/2 v6] dt-bindings: leds: Add DT binding for Richtek RT8515

[Rob Herring]

On Tue, Nov 24, 2020 at 12:45:43AM +0200, Sakari Ailus wrote:
> Hi Linus,
> 
> On Mon, Nov 23, 2020 at 10:44:38PM +0100, Linus Walleij wrote:
> > diff --git a/Documentation/devicetree/bindings/leds/common.yaml b/Documentation/devicetree/bindings/leds/common.yaml
> > index f1211e7045f1..92fa90b4a671 100644
> > --- a/Documentation/devicetree/bindings/leds/common.yaml
> > +++ b/Documentation/devicetree/bindings/leds/common.yaml
> > @@ -151,6 +151,12 @@ properties:
> >        Maximum flash LED supply current in microamperes. Required for flash LED
> >        nodes with configurable current.
> >  
> > +  torch-max-microamp:
> > +    description:
> > +      Maximum flash LED supply current in microamperes, when the flash LED is
> > +      used as a torch (flashlight). This is usually lower than the flash mode
> > +      maximum current, if the LED supports torch mode.
> 
> Thanks for the update.
> 
> One more thing. The other flash LED DT bindings are using led-max-microamp
> for the torch mode --- for it's what the non-flash LEDs do.
> 
> Could you use the same here?

Good point. Seems like it as led-max-microamp should be the max steady 
state current whereas flash-max-microamp is the max for a limited time.

Rob