hwreset_emmc: used for host to trigger a RST_n signal as eMMC4.4 spec recommanded to reset eMMC card. It is useful when eMMC card cannot response any command.
reinit_emmc: reinitialize eMMC card after HW reset occurs. Signed-off-by: Chuanxiao Dong <[email protected]> --- drivers/mmc/core/mmc.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++ include/linux/mmc/host.h | 2 + 2 files changed, 85 insertions(+), 0 deletions(-) diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index ebb5748..8c82b9d 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -12,6 +12,7 @@ #include <linux/err.h> #include <linux/slab.h> +#include <linux/gpio.h> #include <linux/mmc/host.h> #include <linux/mmc/card.h> @@ -745,6 +746,84 @@ static int mmc_awake(struct mmc_host *host) return err; } +/** + * mmc_reinit_card - reinitialize eMMC card after HW reset + * @host: mmc host structure + * + * this callback is used to reinitialize card after a HW + * reset occurs. + * mmc_claim_host should be called before using this callback and + * mmc_release_host should be called after. + * + * Return value: + * 0 - successfully reinitialize + * other - failed to reinitialize + */ +static int mmc_reinit_card(struct mmc_host *host) +{ + int err; + /* + * Before init card, set the clock to be + * the init frequency + */ + host->ios.clock = host->f_init; + mmc_set_clock(host, host->ios.clock); + + err = mmc_init_card(host, host->ocr, host->card); + if (err) + pr_err("%s: Error %d while reinit card\n", + mmc_hostname(host), err); + + return err; +} + +/** + * mmc_reset_card - reset eMMC card + * + * this callback is used to trigger RST_n signal by using GPIO to reset eMMC + * card. The RST_n signal is defined in eMMC4.4 spec + * + * Return value: + * 0 - successfully reset eMMC card + * -ENODEV - no valid GPIO line to be used + * -ENOSYS - GPIO functions is not implemented + * other - failed to reset eMMC card + */ +static int mmc_hwreset_emmc(struct mmc_host *host) +{ + int gpio = host->rst_gpio; + int ret; + if (gpio <= 0) + return -ENODEV; + + /* request reset pin for eMMC */ + ret = gpio_request(gpio, "eMMC_rst_pin"); + if (ret < 0) { + pr_err("gpio %d request failed, err %d\n", + gpio, ret); + return ret; + } + /* set to be output and to be low state */ + ret = gpio_direction_output(gpio, 0); + if (ret < 0) { + pr_err("gpio %d direction output failed, err %d\n", + gpio, ret); + gpio_free(gpio); + return ret; + } + /* delay 10us for tRSTW */ + udelay(10); + /* set to be high and delay 300us */ + gpio_set_value(gpio, 1); + udelay(300); + /* set to be output and to be low state */ + gpio_direction_output(gpio, 0); + /* free reset gpio pin */ + gpio_free(gpio); + + return 0; +} + static const struct mmc_bus_ops mmc_ops = { .awake = mmc_awake, .sleep = mmc_sleep, @@ -753,6 +832,8 @@ static const struct mmc_bus_ops mmc_ops = { .suspend = NULL, .resume = NULL, .power_restore = mmc_power_restore, + .reinit_emmc = mmc_reinit_card, + .hwreset_emmc = mmc_hwreset_emmc, }; static const struct mmc_bus_ops mmc_ops_unsafe = { @@ -763,6 +844,8 @@ static const struct mmc_bus_ops mmc_ops_unsafe = { .suspend = mmc_suspend, .resume = mmc_resume, .power_restore = mmc_power_restore, + .reinit_emmc = mmc_reinit_card, + .hwreset_emmc = mmc_hwreset_emmc, }; static void mmc_attach_bus_ops(struct mmc_host *host) diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index bcb793e..d2b3bf6 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -243,6 +243,8 @@ struct mmc_host { struct dentry *debugfs_root; + unsigned int rst_gpio; /* gpio pin to reset eMMC card */ + unsigned long private[0] ____cacheline_aligned; }; -- 1.6.6.1 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
