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1b9ee2882e
This PWM is used in rk3399-gru-bob and rk3399-gru-kevin to control
the display brightness. We can only change the duty cycle, so on
set_config() we just try to match the duty cycle that dividing duty_ns
by period_ns gives us. To disable, we set the duty cycle to zero while
keeping the old value for when we want to re-enable it.
The cros_ec_set_pwm_duty() function is taken from Depthcharge's
cros_ec_set_bl_pwm_duty() but modified to use the generic pwm type.
The driver itself is very loosely based on rk_pwm.c for the general pwm
driver structure.
The devicetree binding file is from Linux, before it was converted to
YAML at 5df5a577a6b4 ("dt-bindings: pwm: Convert google,cros-ec-pwm.txt
to YAML format") in their repo.
Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
93 lines
3.1 KiB
Text
93 lines
3.1 KiB
Text
config DM_PWM
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bool "Enable support for pulse-width modulation devices (PWM)"
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depends on DM
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help
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A pulse-width modulator emits a pulse of varying width and provides
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control over the duty cycle (high and low time) of the signal. This
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is often used to control a voltage level. The more time the PWM
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spends in the 'high' state, the higher the voltage. The PWM's
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frequency/period can be controlled along with the proportion of that
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time that the signal is high.
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config PWM_CROS_EC
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bool "Enable support for the Chrome OS EC PWM"
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depends on DM_PWM
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help
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This PWM is found on several Chrome OS devices and controlled by
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the Chrome OS embedded controller. It may be used to control the
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screen brightness and/or the keyboard backlight depending on the
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device.
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config PWM_EXYNOS
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bool "Enable support for the Exynos PWM"
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depends on DM_PWM
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help
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This PWM is found on Samsung Exynos 5250 and other Samsung SoCs. It
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supports a programmable period and duty cycle. A 32-bit counter is
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used. It provides 5 channels which can be independently
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programmed. Channel 4 (the last) is normally used as a timer.
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config PWM_IMX
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bool "Enable support for i.MX27 and later PWM"
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help
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This PWM is found i.MX27 and later i.MX SoCs.
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config PWM_MESON
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bool "Enable support for Amlogic Meson SoCs PWM"
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depends on DM_PWM
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help
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This PWM is found on Amlogic Meson SoCs. It supports a
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programmable period and duty cycle for 2 independant channels.
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config PWM_MTK
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bool "Enable support for MediaTek PWM"
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depends on DM_PWM
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help
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This PWM is found on MT7622, MT7623, and MT7629. It supports a
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programmable period and duty cycle.
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config PWM_ROCKCHIP
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bool "Enable support for the Rockchip PWM"
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depends on DM_PWM
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help
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This PWM is found on RK3288 and other Rockchip SoCs. It supports a
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programmable period and duty cycle. A 32-bit counter is used.
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Various options provided in the hardware (such as capture mode and
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continuous/single-shot) are not supported by the driver.
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config PWM_SANDBOX
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bool "Enable support for the sandbox PWM"
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help
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This is a sandbox PWM used for testing. It provides 3 channels and
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records the settings passed into it, but otherwise does nothing
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useful. The PWM can be enabled but is not connected to any outputs
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so this is not very useful.
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config PWM_SIFIVE
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bool "Enable support for SiFive PWM"
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depends on DM_PWM
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help
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This PWM is found SiFive's FU540 and other SoCs.
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config PWM_TEGRA
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bool "Enable support for the Tegra PWM"
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depends on DM_PWM
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help
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This PWM is found on Tegra 20 and other Nvidia SoCs. It supports
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four channels with a programmable period and duty cycle. Only a
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32KHz clock is supported by the driver but the duty cycle is
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configurable.
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config PWM_SUNXI
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bool "Enable support for the Allwinner Sunxi PWM"
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depends on DM_PWM
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help
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This PWM is found on H3, A64 and other Allwinner SoCs. It supports a
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programmable period and duty cycle. A 16-bit counter is used.
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config PWM_TI_EHRPWM
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bool "Enable support for EHRPWM PWM"
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depends on DM_PWM && ARCH_OMAP2PLUS
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default y
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help
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PWM driver support for the EHRPWM controller found on TI SOCs.
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