diff options
| -rw-r--r-- | Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt | 25 | ||||
| -rw-r--r-- | drivers/mmc/core/Makefile | 2 | ||||
| -rw-r--r-- | drivers/mmc/core/pwrseq.c | 3 | ||||
| -rw-r--r-- | drivers/mmc/core/pwrseq.h | 1 | ||||
| -rw-r--r-- | drivers/mmc/core/pwrseq_emmc.c | 101 |
5 files changed, 131 insertions, 1 deletions
diff --git a/Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt new file mode 100644 index 000000000000..0cb827bf9435 --- /dev/null +++ b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt @@ -0,0 +1,25 @@ +* The simple eMMC hardware reset provider + +The purpose of this driver is to perform standard eMMC hw reset +procedure, as descibed by Jedec 4.4 specification. This procedure is +performed just after MMC core enabled power to the given mmc host (to +fix possible issues if bootloader has left eMMC card in initialized or +unknown state), and before performing complete system reboot (also in +case of emergency reboot call). The latter is needed on boards, which +doesn't have hardware reset logic connected to emmc card and (limited or +broken) ROM bootloaders are unable to read second stage from the emmc +card if the card is left in unknown or already initialized state. + +Required properties: +- compatible : contains "mmc-pwrseq-emmc". +- reset-gpios : contains a GPIO specifier. The reset GPIO is asserted + and then deasserted to perform eMMC card reset. To perform + reset procedure as described in Jedec 4.4 specification, the + gpio line should be defined as GPIO_ACTIVE_LOW. + +Example: + + sdhci0_pwrseq { + compatible = "mmc-pwrseq-emmc"; + reset-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>; + } diff --git a/drivers/mmc/core/Makefile b/drivers/mmc/core/Makefile index b39cbd2f830b..2c25138f28b7 100644 --- a/drivers/mmc/core/Makefile +++ b/drivers/mmc/core/Makefile @@ -8,5 +8,5 @@ mmc_core-y := core.o bus.o host.o \ sdio.o sdio_ops.o sdio_bus.o \ sdio_cis.o sdio_io.o sdio_irq.o \ quirks.o slot-gpio.o -mmc_core-$(CONFIG_OF) += pwrseq.o pwrseq_simple.o +mmc_core-$(CONFIG_OF) += pwrseq.o pwrseq_simple.o pwrseq_emmc.o mmc_core-$(CONFIG_DEBUG_FS) += debugfs.o diff --git a/drivers/mmc/core/pwrseq.c b/drivers/mmc/core/pwrseq.c index 2cea00ed4e65..862356123d78 100644 --- a/drivers/mmc/core/pwrseq.c +++ b/drivers/mmc/core/pwrseq.c @@ -26,6 +26,9 @@ static struct mmc_pwrseq_match pwrseq_match[] = { { .compatible = "mmc-pwrseq-simple", .alloc = mmc_pwrseq_simple_alloc, + }, { + .compatible = "mmc-pwrseq-emmc", + .alloc = mmc_pwrseq_emmc_alloc, }, }; diff --git a/drivers/mmc/core/pwrseq.h b/drivers/mmc/core/pwrseq.h index bd860d88f116..aba3409e8d6e 100644 --- a/drivers/mmc/core/pwrseq.h +++ b/drivers/mmc/core/pwrseq.h @@ -28,6 +28,7 @@ void mmc_pwrseq_power_off(struct mmc_host *host); void mmc_pwrseq_free(struct mmc_host *host); int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev); +int mmc_pwrseq_emmc_alloc(struct mmc_host *host, struct device *dev); #else diff --git a/drivers/mmc/core/pwrseq_emmc.c b/drivers/mmc/core/pwrseq_emmc.c new file mode 100644 index 000000000000..a2d545904fbf --- /dev/null +++ b/drivers/mmc/core/pwrseq_emmc.c @@ -0,0 +1,101 @@ +/* + * Copyright (C) 2015, Samsung Electronics Co., Ltd. + * + * Author: Marek Szyprowski <m.szyprowski@samsung.com> + * + * License terms: GNU General Public License (GPL) version 2 + * + * Simple eMMC hardware reset provider + */ +#include <linux/delay.h> +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/gpio/consumer.h> +#include <linux/reboot.h> + +#include <linux/mmc/host.h> + +#include "pwrseq.h" + +struct mmc_pwrseq_emmc { + struct mmc_pwrseq pwrseq; + struct notifier_block reset_nb; + struct gpio_desc *reset_gpio; +}; + +static void __mmc_pwrseq_emmc_reset(struct mmc_pwrseq_emmc *pwrseq) +{ + gpiod_set_value(pwrseq->reset_gpio, 1); + udelay(1); + gpiod_set_value(pwrseq->reset_gpio, 0); + udelay(200); +} + +static void mmc_pwrseq_emmc_reset(struct mmc_host *host) +{ + struct mmc_pwrseq_emmc *pwrseq = container_of(host->pwrseq, + struct mmc_pwrseq_emmc, pwrseq); + + __mmc_pwrseq_emmc_reset(pwrseq); +} + +static void mmc_pwrseq_emmc_free(struct mmc_host *host) +{ + struct mmc_pwrseq_emmc *pwrseq = container_of(host->pwrseq, + struct mmc_pwrseq_emmc, pwrseq); + + unregister_restart_handler(&pwrseq->reset_nb); + gpiod_put(pwrseq->reset_gpio); + kfree(pwrseq); + host->pwrseq = NULL; +} + +static struct mmc_pwrseq_ops mmc_pwrseq_emmc_ops = { + .post_power_on = mmc_pwrseq_emmc_reset, + .free = mmc_pwrseq_emmc_free, +}; + +static int mmc_pwrseq_emmc_reset_nb(struct notifier_block *this, + unsigned long mode, void *cmd) +{ + struct mmc_pwrseq_emmc *pwrseq = container_of(this, + struct mmc_pwrseq_emmc, reset_nb); + + __mmc_pwrseq_emmc_reset(pwrseq); + return NOTIFY_DONE; +} + +int mmc_pwrseq_emmc_alloc(struct mmc_host *host, struct device *dev) +{ + struct mmc_pwrseq_emmc *pwrseq; + int ret = 0; + + pwrseq = kzalloc(sizeof(struct mmc_pwrseq_emmc), GFP_KERNEL); + if (!pwrseq) + return -ENOMEM; + + pwrseq->reset_gpio = gpiod_get_index(dev, "reset", 0, GPIOD_OUT_LOW); + if (IS_ERR(pwrseq->reset_gpio)) { + ret = PTR_ERR(pwrseq->reset_gpio); + goto free; + } + + /* + * register reset handler to ensure emmc reset also from + * emergency_reboot(), priority 129 schedules it just before + * system reboot + */ + pwrseq->reset_nb.notifier_call = mmc_pwrseq_emmc_reset_nb; + pwrseq->reset_nb.priority = 129; + register_restart_handler(&pwrseq->reset_nb); + + pwrseq->pwrseq.ops = &mmc_pwrseq_emmc_ops; + host->pwrseq = &pwrseq->pwrseq; + + return 0; +free: + kfree(pwrseq); + return ret; +} |