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Date: Mon, 27 Dec 2010 18:14:43 +0800
From: Chuanxiao Dong <chuanxiao.dong@...el.com>
To: linux-mmc@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, cjb@...top.org,
akpm@...ux-foundation.org
Subject: [PATCH v6 3/3]mmc: implement hwreset_emmc and reinit_emmc callbacks
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 <chuanxiao.dong@...el.com>
---
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
--
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