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;
+}