[PATCH 2/4] add two new callback to use HW reset feature

[Chuanxiao Dong]

HW reset will reset eMMC card. So after reset, card should
also be reinitialized. Add two new callbacks to implement
reset and reinitialize. MMC core layer will check whether
occures a timeout error in the new added routine
mmc_handle_timeout_error

mmc_handle_timeout_error: check whether occures a timeout error.
If occures, use HW reset callbacks to do reset and reinitialize

hardware_reset: trigger a RST_n signal for host to reset card.
This callback was just defined in header file, not implemented in
this patch.

Signed-off-by: Chuanxiao Dong <chuanxiao.dong@xxxxxxxxx>
---
 drivers/mmc/core/core.c  |   45 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/mmc/core/core.h  |    9 +++++++++
 drivers/mmc/core/mmc.c   |   31 +++++++++++++++++++++++++++++++
 include/linux/mmc/core.h |    1 +
 include/linux/mmc/host.h |   13 +++++++++++++
 5 files changed, 99 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 6286898..530fc35 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -82,6 +82,51 @@ static void mmc_flush_scheduled_work(void)
 }
 
 /**
+ *	mmc_handle_timeout_error - handle command and data timeout
+ *	errors.
+ *	@host: MMC host used to handle error
+ *	@error: error condition
+ *
+ *	check whether there is a command or data timeout error occured,
+ *	if so, reset and reinit eMMC card if card has such capbility.
+ *	1. let host controller do a specific hardware reset for eMMC
+ *	   card (trigger RST_n signal).
+ *	2. after reset done, reinit eMMC card.
+ */
+void mmc_handle_timeout_error(struct mmc_host *host, int error)
+{
+	struct mmc_card *card = host->card;
+
+	/*
+	 * If error condition is not timeout, do nothing
+	 */
+	if (error != -ETIMEDOUT)
+		return;
+	/*
+	 * make sure mmc_reqeust is not NULL
+	 * make sure mmc_card has HW reset capbility
+	 */
+	if (!card || !card->ext_csd.rst)
+		return;
+
+	/* check whether host has such callback */
+	if (!host->ops->hardware_reset ||
+			!host->bus_ops->reinit)
+		return;
+
+	/*
+	 * if there occurs any timeout error, HW reset
+	 * eMMC card and reinit again.
+	 */
+	if (host->ops->hardware_reset(host))
+		pr_warn("MMC card reset failed\n");
+	else
+		if (host->bus_ops->reinit(host))
+			pr_warn("MMC card reinit failed\n");
+}
+EXPORT_SYMBOL(mmc_handle_timeout_error);
+
+/**
  *	mmc_request_done - finish processing an MMC request
  *	@host: MMC host which completed request
  *	@mrq: MMC request which request
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index 026c975..4980e2f 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -24,6 +24,15 @@ struct mmc_bus_ops {
 	int (*resume)(struct mmc_host *);
 	int (*power_save)(struct mmc_host *);
 	int (*power_restore)(struct mmc_host *);
+	/*
+	 * New added callback
+	 * Used to reinit card when HW reset occurs
+	 *
+	 * return value:
+	 * 0: successfully reinit card.
+	 * negative value: failed to reinit
+	 */
+	int (*reinit)(struct mmc_host *);
 };
 
 void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops);
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 85cc7f6..bc4611a 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -732,6 +732,35 @@ static int mmc_awake(struct mmc_host *host)
 	return err;
 }
 
+/**
+ * mmc_reinit_card - reinitialize card after HW reset
+ *
+ * this callback is used to reinitialize card after a HW
+ * reset occurs.
+ * Reture value:
+ * 0: successfully reinitialize
+ * other: failed to reinitialize
+ *
+ * claim_host should be called before using this callback.
+ */
+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;
+}
+
 static const struct mmc_bus_ops mmc_ops = {
 	.awake = mmc_awake,
 	.sleep = mmc_sleep,
@@ -740,6 +769,7 @@ static const struct mmc_bus_ops mmc_ops = {
 	.suspend = NULL,
 	.resume = NULL,
 	.power_restore = mmc_power_restore,
+	.reinit = mmc_reinit_card,
 };
 
 static const struct mmc_bus_ops mmc_ops_unsafe = {
@@ -750,6 +780,7 @@ static const struct mmc_bus_ops mmc_ops_unsafe = {
 	.suspend = mmc_suspend,
 	.resume = mmc_resume,
 	.power_restore = mmc_power_restore,
+	.reinit = mmc_reinit_card,
 };
 
 static void mmc_attach_bus_ops(struct mmc_host *host)
diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
index 64e013f..115d589 100644
--- a/include/linux/mmc/core.h
+++ b/include/linux/mmc/core.h
@@ -131,6 +131,7 @@ struct mmc_request {
 struct mmc_host;
 struct mmc_card;
 
+extern void mmc_handle_timeout_error(struct mmc_host *, int);
 extern void mmc_wait_for_req(struct mmc_host *, struct mmc_request *);
 extern int mmc_wait_for_cmd(struct mmc_host *, struct mmc_command *, int);
 extern int mmc_wait_for_app_cmd(struct mmc_host *, struct mmc_card *,
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 381c77f..3a7008d 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -117,6 +117,19 @@ struct mmc_host_ops {
 
 	/* optional callback for HC quirks */
 	void	(*init_card)(struct mmc_host *host, struct mmc_card *card);
+
+	/*
+	 * eMMC4.4 HW reset feature callback
+	 *
+	 * eMMC4.4 card can be reset if host triggers a RST_n signal
+	 * This callback will be used to for host to trigger such
+	 * signal.
+	 *
+	 * return value:
+	 * 0: successfully reset the eMMC card.
+	 * -ENODEV: no valid hardware to do so.
+	 */
+	int (*hardware_reset)(struct mmc_host *host);
 };
 
 struct mmc_card;
-- 
1.6.6.1

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