avionic design with actual uboot and tooling

submodule of avionic design uboot bootloader and with included tools to
get you started , read readme.md and readme-tk1-loader.md

u-boot/drivers/pwm/Kconfig

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+config DM_PWM
+	bool "Enable support for pulse-width modulation devices (PWM)"
+	depends on DM
+	help
+	  A pulse-width modulator emits a pulse of varying width and provides
+	  control over the duty cycle (high and low time) of the signal. This
+	  is often used to control a voltage level. The more time the PWM
+	  spends in the 'high' state, the higher the voltage. The PWM's
+	  frequency/period can be controlled along with the proportion of that
+	  time that the signal is high.
+
+config PWM_EXYNOS
+	bool "Enable support for the Exynos PWM"
+	depends on DM_PWM
+	help
+	  This PWM is found on Samsung Exynos 5250 and other Samsung SoCs. It
+	  supports a programmable period and duty cycle. A 32-bit counter is
+	  used. It provides 5 channels which can be independently
+	  programmed. Channel 4 (the last) is normally used as a timer.
+
+config PWM_ROCKCHIP
+	bool "Enable support for the Rockchip PWM"
+	depends on DM_PWM
+	help
+	  This PWM is found on RK3288 and other Rockchip SoCs. It supports a
+	  programmable period and duty cycle. A 32-bit counter is used.
+	  Various options provided in the hardware (such as capture mode and
+	  continuous/single-shot) are not supported by the driver.
+
+config PWM_TEGRA
+	bool "Enable support for the Tegra PWM"
+	depends on DM_PWM
+	help
+	  This PWM is found on Tegra 20 and other Nvidia SoCs. It supports
+	  four channels with a programmable period and duty cycle. Only a
+	  32KHz clock is supported by the driver but the duty cycle is
+	  configurable.