Hello, This patchset adds new mmc power sequence driver, which performs eMMC card hardware reset. Such power sequence, involving resetting emmc card, is required on some boards to properly perform system reboot procedure. This patchset originates from fixes for the reboot hang issue on Hardkernel's Odroid boards with eMMC card. Those boards are designed in such a way, that the eMMC nreset signal is routed to SoC GPIO line instead of the board reset logic. To properly restard system and let ROM bootloader to read next bootloader from eMMC, one need to reset emmc card before performing reboot. The initial patches consisted of a complete reset/power off driver, but after further analysis, it turned out that only eMMC nreset line control logic is specific for those boards. Everything else can be done by the MMC code. Sjoerd Simons and Jaehoon Chung suggested that such feature is something generic, not really specific to the MMC host controller used on Odroid boards, so it should be implemented in MMC core. Then, Ulf Hansson suggested to use recently introduced power sequences driver for implementing this feature. This patches provides a simple mmc-pwrseq-emmc driver, which controls single gpio line and performs eMMC reset procedure just after card power on and just before turning it off or performing system reboot. This driver has been instantiated on Odroid X2/U3 and XU3 boards. Patches are prepared on top of linux-next. Best regards Marek Szyprowski Samsung R&D Institute Poland Changelog: v2: - moved all code to separate mmc-prwseq-emmc driver v1: https://www.mail-archive.com/linux-samsung-soc@xxxxxxxxxxxxxxx/msg41641.html - moved all the code and logic to mmc core (slot-gpio.c), so it is available to all mmc drivers, which uses device tree v0: http://thread.gmane.org/gmane.linux.kernel.samsung-soc/42477/ - separated emmc reset logic from other code and moved to exynos dw-mmc driver initial version: http://thread.gmane.org/gmane.linux.power-management.general/51855/ - separate reset driver implementing all the logic Patch summary: Marek Szyprowski (3): mmc: pwrseq: add driver for emmc hardware reset ARM: dts: exynos4412-odroid*: add eMMC reset line ARM: dts: exynos5422-odroidxu3: add eMMC reset line .../devicetree/bindings/mmc/mmc-pwrseq-emmc.txt | 25 +++++ arch/arm/boot/dts/exynos4412-odroid-common.dtsi | 14 +++ arch/arm/boot/dts/exynos5422-odroidxu3.dts | 17 ++++ drivers/mmc/core/Makefile | 2 +- drivers/mmc/core/pwrseq.c | 3 + drivers/mmc/core/pwrseq.h | 1 + drivers/mmc/core/pwrseq_emmc.c | 108 +++++++++++++++++++++ 7 files changed, 169 insertions(+), 1 deletion(-) create mode 100644 Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt create mode 100644 drivers/mmc/core/pwrseq_emmc.c -- 1.9.2 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
