[PATCH v18 3/3] docs: leds: Add MT6370 RGB LED pattern document

ChiaEn Wu
2023-03-10T06:56:46Z

From: ChiYuan Huang <cy_huang@richtek.com>

Document the MT6370 RGB LED pattern trigger.

This simply describe how the pattern works, each timing period, and the
pattern diagram for MT6370 RGB LED.

Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Signed-off-by: ChiaEn Wu <chiaen_wu@richtek.com>
---
v18:
- Revise the text in document title and description.
---
Documentation/leds/leds-mt6370-rgb.rst | 64 ++++++++++++++++++++++++++++++++++
1 file changed, 64 insertions(+)
create mode 100644 Documentation/leds/leds-mt6370-rgb.rst

diff --git a/Documentation/leds/leds-mt6370-rgb.rst b/Documentation/leds/leds-mt6370-rgb.rst
new file mode 100644
index 00000000..abf739e
--- /dev/null
+++ b/Documentation/leds/leds-mt6370-rgb.rst
@@ -0,0 +1,64 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=========================================
+The device for Mediatek MT6370 RGB LED
+=========================================
+
+Description
+-----------
+
+The MT6370 integrates a four-channel RGB LED driver, designed to provide a
+variety of lighting effect for mobile device applications. The RGB LED devices
+includes a smart LED string controller and it can drive 3 channels of LEDs with
+a sink current up to 24mA and a CHG_VIN power good indicator LED with sink
+current up to 6mA. It provides three operation modes for RGB LEDs:
+PWM Dimming mode, breath pattern mode, and constant current mode. The device
+can increase or decrease the brightness of the RGB LED via an I2C interface.
+
+The breath pattern for a channel can be programmed using the "pattern" trigger,
+using the hw_pattern attribute.
+
+/sys/class/leds/<led>/hw_pattern
+--------------------------------
+
+Specify a hardware breath pattern for a MT6370 RGB LED.
+
+The breath pattern is a series of timing pairs, with the hold-time expressed in
+milliseconds. And the brightness is controlled by
+'/sys/class/leds/<led>/brightness'. The pattern doesn't include the brightness
+setting. Hardware pattern only controls the timing for each pattern stage
+depending on the current brightness setting.
+
+Pattern diagram::
+
+ "0 Tr1 0 Tr2 0 Tf1 0 Tf2 0 Ton 0 Toff" --> '0' for dummy brightness code
+
+ ^
+ | ============
+ | / \ /
+Icurr | / \ /
+ | / \ /
+ | / \ / .....repeat
+ | / \ /
+ | --- --- ---
+ |--- --- ---
+ +----------------------------------============------------> Time
+ < Tr1><Tr2>< Ton ><Tf1><Tf2 >< Toff >< Tr1><Tr2>
+
+Timing description::
+
+Tr1: First rising time for duty 0 to 30%.
+Tr2: Second rising time for duty 31% to 100%.
+Ton: On time for duty 100%.
+Tf1: First falling time for duty 100% to 31%.
+Tf2: Second falling time for duty 30% to 0%.
+Toff: Off time for duty 0%.
+
+Tr1/Tr2/Tf1/Tf2/Ton: 125ms to 3125ms, 200ms per step.
+Toff: 250ms to 6250ms, 400ms per step.
+
+Pattern example::
+
+ "0 125 0 125 0 125 0 125 0 625 0 1050"
+
+This Will configure Tr1/Tr2/Tf1/Tf2 to 125m, Ton to 625ms, and Toff to 1050ms.
--
2.7.4