[PATCH v4] mmc: core: select the operation mode with sysfs

[Jaehoon Chung <jh80.chung@samsung.com>]

This patch is support the sysfs for operation mode.

There are two operation modes(open-ended/pre-defined).
Now, operation mode is selected only one at the compile time.

But using this patch, we can change the operation mode with node at runtime.

* pre-defined mode 
echo 1 > /sys/class/mmc_host/mmc0/pre_defined_op  
* open-ended mode
echo 0 > /sys/class/mmc_host/mmc0/pre_defined_op  

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
Changelog V4:
	- Add the explanation in Documentation/mmc/mmc-dev-attrs.txt
Changelog V3:
	- Add the mmc_change_operation_mode()
Changelog v2:
	- Add the check point in mmc_cmd23_store()
	(If host controller didn't support CMD23, need not to change the ops-mode.)

 Documentation/mmc/mmc-dev-attrs.txt |   16 ++++++++++++++
 drivers/mmc/card/block.c            |   19 +++++++++++++++++
 drivers/mmc/core/host.c             |   39 +++++++++++++++++++++++++++++++++++
 include/linux/mmc/card.h            |    1 +
 include/linux/mmc/host.h            |    3 ++
 5 files changed, 78 insertions(+), 0 deletions(-)

diff --git a/Documentation/mmc/mmc-dev-attrs.txt b/Documentation/mmc/mmc-dev-attrs.txt
index 22ae844..e7ba3b6 100644
--- a/Documentation/mmc/mmc-dev-attrs.txt
+++ b/Documentation/mmc/mmc-dev-attrs.txt
@@ -74,3 +74,19 @@ This attribute appears only if CONFIG_MMC_CLKGATE is enabled.
 	clkgate_delay	Tune the clock gating delay with desired value in milliseconds.
 
 echo <desired delay> > /sys/class/mmc_host/mmcX/clkgate_delay
+
+SD and MMC Operation Mode Attribute
+==========================================
+
+SD and MMC can support the two operation mode.
+(Pre-defined(CMD23)/Open-ended operation mode)
+
+This attribute can change the operation mode at runtime if card is supported the CMD23.
+
+	pre_defined_op	Support the pre-defined mode if set 1.
+
+1) Open-ended mode
+echo 0 > /sys/class/mmc_host/mmcX/pre_defined_op
+
+2) Pre-defined mode
+echo 1 > /sys/class/mmc_host/mmcX/pre_defined_op
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index a7c75d8..2c1981c 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -1766,6 +1766,25 @@ static const struct mmc_fixup blk_fixups[] =
 	END_FIXUP
 };
 
+void mmc_change_operation_mode(struct mmc_card *card, int val)
+{
+	struct mmc_blk_data *md = mmc_get_drvdata(card);
+
+	if (mmc_host_cmd23(card->host)) {
+		if (mmc_card_mmc(card) ||
+		    (mmc_card_sd(card) &&
+		     card->scr.cmds & SD_SCR_CMD23_SUPPORT)) {
+			if (val) {
+				md->flags |= MMC_BLK_CMD23;
+				card->host->pre_defined_op = val;
+			} else {
+				md->flags &= ~MMC_BLK_CMD23;
+				card->host->pre_defined_op = val;
+			}
+		}
+	}
+}
+
 static int mmc_blk_probe(struct mmc_card *card)
 {
 	struct mmc_blk_data *md, *part_md;
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 30055f2..7dab0dc 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -293,6 +293,41 @@ static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
 
 #endif
 
+static ssize_t mmc_cmd23_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct mmc_host *host = cls_dev_to_mmc_host(dev);
+	return snprintf(buf, PAGE_SIZE, "%d\n", host->pre_defined_op);
+}
+
+static ssize_t mmc_cmd23_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct mmc_host *host = cls_dev_to_mmc_host(dev);
+	int value;
+	unsigned long flags;
+
+	if (kstrtoint(buf, 0, &value))
+		return -EINVAL;
+
+	spin_lock_irqsave(&host->lock, flags);
+	mmc_change_operation_mode(host->card, value);
+	spin_unlock_irqrestore(&host->lock, flags);
+	return count;
+}
+
+static inline void mmc_host_cmd23_sysfs_init(struct mmc_host *host)
+{
+	host->pre_defined_attr.show = mmc_cmd23_show;
+	host->pre_defined_attr.store = mmc_cmd23_store;
+	sysfs_attr_init(&host->pre_defined_attr.attr);
+	host->pre_defined_attr.attr.name = "pre_defined_op";
+	host->pre_defined_attr.attr.mode = S_IRUGO | S_IWUSR;
+	if (device_create_file(&host->class_dev, &host->pre_defined_attr))
+		pr_err("%s: Failed to create pre_defined_op sysfs entry\n",
+				mmc_hostname(host));
+}
+
 /**
  *	mmc_alloc_host - initialise the per-host structure.
  *	@extra: sizeof private data structure
@@ -381,6 +416,10 @@ int mmc_add_host(struct mmc_host *host)
 #endif
 	mmc_host_clk_sysfs_init(host);
 
+	if (host->caps & MMC_CAP_CMD23)
+		host->pre_defined_op = 1;
+	mmc_host_cmd23_sysfs_init(host);
+
 	mmc_start_host(host);
 	register_pm_notifier(&host->pm_notify);
 
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 1a1ca71..b36d408 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -489,5 +489,6 @@ extern void mmc_unregister_driver(struct mmc_driver *);
 
 extern void mmc_fixup_device(struct mmc_card *card,
 			     const struct mmc_fixup *table);
+extern void mmc_change_operation_mode(struct mmc_card *card, int val);
 
 #endif /* LINUX_MMC_CARD_H */
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 20d7c82..59a30bf 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -259,6 +259,9 @@ struct mmc_host {
 				 MMC_CAP2_HS200_1_2V_SDR)
 #define MMC_CAP2_BROKEN_VOLTAGE	(1 << 7)	/* Use the broken voltage */
 
+	struct device_attribute pre_defined_attr;
+	int			pre_defined_op;	/* CMD23 should be use or not */
+
 	mmc_pm_flag_t		pm_caps;	/* supported pm features */
 	unsigned int        power_notify_type;
 #define MMC_HOST_PW_NOTIFY_NONE		0