1 files changed, 53 insertions, 4 deletions

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index d31c78b72b0f..817a76039743 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);