diff --git a/Documentation/mmc/mmc-dev-attrs.txt b/Documentation/mmc/mmc-dev-attrs.txt
index 8898a95b41e5ee1b277cd64697870726b11bc2fa..b0245565875ac05e944da0a150cb295fd05e0650 100644
--- a/Documentation/mmc/mmc-dev-attrs.txt
+++ b/Documentation/mmc/mmc-dev-attrs.txt
@@ -64,3 +64,13 @@ Note on Erase Size and Preferred Erase Size:
size specified by the card.
"preferred_erase_size" is in bytes.
+
+SD/MMC/SDIO Clock Gating Attribute
+==================================
+
+Read and write access is provided to following attribute.
+This attribute appears only if CONFIG_MMC_CLKGATE is enabled.
+
+ clkgate_delay Tune the clock gating delay with desired value in milli seconds.
+
+echo <desired delay> > /sys/class/mmc_host/mmcX/clkgate_delay
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index d31c78b72b0fd8d1e53adb2f403454790896fafe..817a760397434e71f752440de71ad6c3a3729b95 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -54,6 +54,31 @@ static DEFINE_IDR(mmc_host_idr);
static DEFINE_SPINLOCK(mmc_host_lock);
#ifdef CONFIG_MMC_CLKGATE
+static ssize_t clkgate_delay_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, "%lu millisecs\n",
+ host->clkgate_delay);
+}
+
+static ssize_t clkgate_delay_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct mmc_host *host = cls_dev_to_mmc_host(dev);
+ unsigned long flags, value;
+
+ if (kstrtoul(buf, 0, &value))
+ return -EINVAL;
+
+ spin_lock_irqsave(&host->clk_lock, flags);
+ host->clkgate_delay = value;
+ spin_unlock_irqrestore(&host->clk_lock, flags);
+
+ pr_info("%s: clock gate delay set to %lu ms\n",
+ mmc_hostname(host), value);
+ return count;
+}
/*
* Enabling clock gating will make the core call out to the host
@@ -114,7 +139,7 @@ static void mmc_host_clk_gate_delayed(struct mmc_host *host)
static void mmc_host_clk_gate_work(struct work_struct *work)
{
struct mmc_host *host = container_of(work, struct mmc_host,
- clk_gate_work);
+ clk_gate_work.work);
mmc_host_clk_gate_delayed(host);
}
@@ -131,6 +156,8 @@ void mmc_host_clk_hold(struct mmc_host *host)
{
unsigned long flags;
+ /* cancel any clock gating work scheduled by mmc_host_clk_release() */
+ cancel_delayed_work_sync(&host->clk_gate_work);
mutex_lock(&host->clk_gate_mutex);
spin_lock_irqsave(&host->clk_lock, flags);
if (host->clk_gated) {
@@ -180,7 +207,8 @@ void mmc_host_clk_release(struct mmc_host *host)
host->clk_requests--;
if (mmc_host_may_gate_card(host->card) &&
!host->clk_requests)
- queue_work(system_nrt_wq, &host->clk_gate_work);
+ queue_delayed_work(system_nrt_wq, &host->clk_gate_work,
+ msecs_to_jiffies(host->clkgate_delay));
spin_unlock_irqrestore(&host->clk_lock, flags);
}
@@ -213,8 +241,13 @@ static inline void mmc_host_clk_init(struct mmc_host *host)
host->clk_requests = 0;
/* Hold MCI clock for 8 cycles by default */
host->clk_delay = 8;
+ /*
+ * Default clock gating delay is 200ms.
+ * This value can be tuned by writing into sysfs entry.
+ */
+ host->clkgate_delay = 200;
host->clk_gated = false;
- INIT_WORK(&host->clk_gate_work, mmc_host_clk_gate_work);
+ INIT_DELAYED_WORK(&host->clk_gate_work, mmc_host_clk_gate_work);
spin_lock_init(&host->clk_lock);
mutex_init(&host->clk_gate_mutex);
}
@@ -229,7 +262,7 @@ static inline void mmc_host_clk_exit(struct mmc_host *host)
* Wait for any outstanding gate and then make sure we're
* ungated before exiting.
*/
- if (cancel_work_sync(&host->clk_gate_work))
+ if (cancel_delayed_work_sync(&host->clk_gate_work))
mmc_host_clk_gate_delayed(host);
if (host->clk_gated)
mmc_host_clk_hold(host);
@@ -237,6 +270,17 @@ static inline void mmc_host_clk_exit(struct mmc_host *host)
WARN_ON(host->clk_requests > 1);
}
+static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
+{
+ host->clkgate_delay_attr.show = clkgate_delay_show;
+ host->clkgate_delay_attr.store = clkgate_delay_store;
+ sysfs_attr_init(&host->clkgate_delay_attr.attr);
+ host->clkgate_delay_attr.attr.name = "clkgate_delay";
+ host->clkgate_delay_attr.attr.mode = S_IRUGO | S_IWUSR;
+ if (device_create_file(&host->class_dev, &host->clkgate_delay_attr))
+ pr_err("%s: Failed to create clkgate_delay sysfs entry\n",
+ mmc_hostname(host));
+}
#else
static inline void mmc_host_clk_init(struct mmc_host *host)
@@ -247,6 +291,10 @@ static inline void mmc_host_clk_exit(struct mmc_host *host)
{
}
+static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
+{
+}
+
#endif
/**
@@ -335,6 +383,7 @@ int mmc_add_host(struct mmc_host *host)
#ifdef CONFIG_DEBUG_FS
mmc_add_host_debugfs(host);
#endif
+ mmc_host_clk_sysfs_init(host);
mmc_start_host(host);
register_pm_notifier(&host->pm_notify);
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index cea064f73514bd118b4c5e1e48d44cd2711e4b9d..706f72279a17a67e210f153110225addc61c6e6e 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -253,10 +253,12 @@ struct mmc_host {
int clk_requests; /* internal reference counter */
unsigned int clk_delay; /* number of MCI clk hold cycles */
bool clk_gated; /* clock gated */
- struct work_struct clk_gate_work; /* delayed clock gate */
+ struct delayed_work clk_gate_work; /* delayed clock gate */
unsigned int clk_old; /* old clock value cache */
spinlock_t clk_lock; /* lock for clk fields */
struct mutex clk_gate_mutex; /* mutex for clock gating */
+ struct device_attribute clkgate_delay_attr;
+ unsigned long clkgate_delay;
#endif
/* host specific block data */