mmc: dw_mmc: add reset support to dwmmc host controller
Dwmmc host controller may in unknown state when entering kernel boot. One example is when booting from eMMC, bootloader need initialize MMC host controller into some state so it can read. In order to make sure MMC host controller in a clean initial state, this reset support is added. With this patch, a 'resets' property can be added into dw_mmc device tree node. The hardware logic is: dwmmc host controller IP receives a reset signal from a 'reset provider' (eg. power management unit). The 'resets' property points to this reset signal. So, during dwmmc driver probe, it can use this signal to reset itself. Refer to [1] for more information. [1] Documentation/devicetree/bindings/reset/reset.txt Signed-off-by: Guodong Xu <guodong.xu@linaro.org> Signed-off-by: Xinwei Kong <kong.kongxinwei@hisilicon.com> Signed-off-by: Zhangfei Gao <zhangfei.gao@linaro.org> Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
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