[Feature]add MT2731_MP2_MR2_SVN388 baseline version
Change-Id: Ief04314834b31e27effab435d3ca8ba33b499059
diff --git a/src/kernel/linux/v4.14/Documentation/input/devices/rotary-encoder.rst b/src/kernel/linux/v4.14/Documentation/input/devices/rotary-encoder.rst
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+============================================================
+rotary-encoder - a generic driver for GPIO connected devices
+============================================================
+
+:Author: Daniel Mack <daniel@caiaq.de>, Feb 2009
+
+Function
+--------
+
+Rotary encoders are devices which are connected to the CPU or other
+peripherals with two wires. The outputs are phase-shifted by 90 degrees
+and by triggering on falling and rising edges, the turn direction can
+be determined.
+
+Some encoders have both outputs low in stable states, others also have
+a stable state with both outputs high (half-period mode) and some have
+a stable state in all steps (quarter-period mode).
+
+The phase diagram of these two outputs look like this::
+
+ _____ _____ _____
+ | | | | | |
+ Channel A ____| |_____| |_____| |____
+
+ : : : : : : : : : : : :
+ __ _____ _____ _____
+ | | | | | | |
+ Channel B |_____| |_____| |_____| |__
+
+ : : : : : : : : : : : :
+ Event a b c d a b c d a b c d
+
+ |<-------->|
+ one step
+
+ |<-->|
+ one step (half-period mode)
+
+ |<>|
+ one step (quarter-period mode)
+
+For more information, please see
+ https://en.wikipedia.org/wiki/Rotary_encoder
+
+
+Events / state machine
+----------------------
+
+In half-period mode, state a) and c) above are used to determine the
+rotational direction based on the last stable state. Events are reported in
+states b) and d) given that the new stable state is different from the last
+(i.e. the rotation was not reversed half-way).
+
+Otherwise, the following apply:
+
+a) Rising edge on channel A, channel B in low state
+ This state is used to recognize a clockwise turn
+
+b) Rising edge on channel B, channel A in high state
+ When entering this state, the encoder is put into 'armed' state,
+ meaning that there it has seen half the way of a one-step transition.
+
+c) Falling edge on channel A, channel B in high state
+ This state is used to recognize a counter-clockwise turn
+
+d) Falling edge on channel B, channel A in low state
+ Parking position. If the encoder enters this state, a full transition
+ should have happened, unless it flipped back on half the way. The
+ 'armed' state tells us about that.
+
+Platform requirements
+---------------------
+
+As there is no hardware dependent call in this driver, the platform it is
+used with must support gpiolib. Another requirement is that IRQs must be
+able to fire on both edges.
+
+
+Board integration
+-----------------
+
+To use this driver in your system, register a platform_device with the
+name 'rotary-encoder' and associate the IRQs and some specific platform
+data with it. Because the driver uses generic device properties, this can
+be done either via device tree, ACPI, or using static board files, like in
+example below:
+
+::
+
+ /* board support file example */
+
+ #include <linux/input.h>
+ #include <linux/gpio/machine.h>
+ #include <linux/property.h>
+
+ #define GPIO_ROTARY_A 1
+ #define GPIO_ROTARY_B 2
+
+ static struct gpiod_lookup_table rotary_encoder_gpios = {
+ .dev_id = "rotary-encoder.0",
+ .table = {
+ GPIO_LOOKUP_IDX("gpio-0",
+ GPIO_ROTARY_A, NULL, 0, GPIO_ACTIVE_LOW),
+ GPIO_LOOKUP_IDX("gpio-0",
+ GPIO_ROTARY_B, NULL, 1, GPIO_ACTIVE_HIGH),
+ { },
+ },
+ };
+
+ static const struct property_entry rotary_encoder_properties[] __initconst = {
+ PROPERTY_ENTRY_INTEGER("rotary-encoder,steps-per-period", u32, 24),
+ PROPERTY_ENTRY_INTEGER("linux,axis", u32, ABS_X),
+ PROPERTY_ENTRY_INTEGER("rotary-encoder,relative_axis", u32, 0),
+ { },
+ };
+
+ static struct platform_device rotary_encoder_device = {
+ .name = "rotary-encoder",
+ .id = 0,
+ };
+
+ ...
+
+ gpiod_add_lookup_table(&rotary_encoder_gpios);
+ device_add_properties(&rotary_encoder_device, rotary_encoder_properties);
+ platform_device_register(&rotary_encoder_device);
+
+ ...
+
+Please consult device tree binding documentation to see all properties
+supported by the driver.