[V2,1/3] mmc: add support for H/W clock gating of SD controller

Commit Message

Philip Rakity Dec. 7, 2010, 5:56 p.m. UTC

None

Patch

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 6286898..de867d1 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -682,6 +682,28 @@  void mmc_ungate_clock(struct mmc_host *host)
 	}
 }
 
+/*
+ * Let hardware automatically gate the clock when the card becomes idle
+ */
+void mmc_hwgate_clock(struct mmc_host *host)
+{
+	if (host->caps & MMC_CAP_HW_CLOCK_GATING) {
+		host->clk_gated = true;
+		mmc_set_ios(host);
+	}
+}
+
+/*
+ * This ungates the clock by turning off h/w gating
+ */
+void mmc_hwungate_clock(struct mmc_host *host)
+{
+	if (host->caps & MMC_CAP_HW_CLOCK_GATING) {
+		host->clk_gated = false;
+		mmc_set_ios(host);
+	}
+}
+
 void mmc_set_ungated(struct mmc_host *host)
 {
 	unsigned long flags;
@@ -1548,6 +1570,8 @@  void mmc_rescan(struct work_struct *work)
 			mmc_hostname(host), __func__, host->f_init);
 #endif
 		mmc_power_up(host);
+
+		mmc_hwungate_clock(host);
 		sdio_reset(host);
 		mmc_go_idle(host);
 
@@ -1569,6 +1593,10 @@  void mmc_rescan(struct work_struct *work)
 
 				if (mmc_attach_sd(host, ocr))
 					mmc_power_off(host);
+
+				/* hw clock gating is off when we get here */
+				/* do not enable clock gating for sdio cards */
+				/* sdio cards can miss interrupts */
 			}
 			goto out;
 		}
@@ -1580,6 +1608,8 @@  void mmc_rescan(struct work_struct *work)
 		if (!err) {
 			if (mmc_attach_sd(host, ocr))
 				mmc_power_off(host);
+			else
+				mmc_hwgate_clock(host);
 			goto out;
 		}
 
@@ -1590,6 +1620,8 @@  void mmc_rescan(struct work_struct *work)
 		if (!err) {
 			if (mmc_attach_mmc(host, ocr))
 				mmc_power_off(host);
+			else
+				mmc_hwgate_clock(host);
 			goto out;
 		}
 
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index 026c975..3810e28 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -35,6 +35,19 @@  void mmc_set_chip_select(struct mmc_host *host, int mode);
 void mmc_set_clock(struct mmc_host *host, unsigned int hz);
 void mmc_gate_clock(struct mmc_host *host);
 void mmc_ungate_clock(struct mmc_host *host);
+
+#ifdef CONFIG_MMC_CLKGATE
+void mmc_hwgate_clock(struct mmc_host *host);
+void mmc_hwungate_clock(struct mmc_host *host);
+#else
+static inline void mmc_hwgate_clock(struct mmc_host *host)
+{
+}
+
+static inline void mmc_hwungate_clock(struct mmc_host *host)
+{
+}
+#endif
 void mmc_set_ungated(struct mmc_host *host);
 void mmc_set_bus_mode(struct mmc_host *host, unsigned int mode);
 void mmc_set_bus_width(struct mmc_host *host, unsigned int width);
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 92e3370..afadcf4 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -130,6 +130,9 @@  void mmc_host_clk_ungate(struct mmc_host *host)
 {
 	unsigned long flags;
 
+	if (host->caps & MMC_CAP_HW_CLOCK_GATING)
+		return;
+
 	mutex_lock(&host->clk_gate_mutex);
 	spin_lock_irqsave(&host->clk_lock, flags);
 	if (host->clk_gated) {
@@ -178,10 +181,13 @@  void mmc_host_clk_gate(struct mmc_host *host)
 {
 	unsigned long flags;
 
+	if (host->caps & MMC_CAP_HW_CLOCK_GATING)
+		return;
+
 	spin_lock_irqsave(&host->clk_lock, flags);
 	host->clk_requests--;
 	if (mmc_host_may_gate_card(host->card) &&
-	    !host->clk_requests)
+		!host->clk_requests)
 		schedule_work(&host->clk_gate_work);
 	spin_unlock_irqrestore(&host->clk_lock, flags);
 }
@@ -212,6 +218,9 @@  unsigned int mmc_host_clk_rate(struct mmc_host *host)
  */
 static inline void mmc_host_clk_init(struct mmc_host *host)
 {
+	if (host->caps & MMC_CAP_HW_CLOCK_GATING)
+		return;
+
 	host->clk_requests = 0;
 	/* Hold MCI clock for 8 cycles by default */
 	host->clk_delay = 8;
@@ -231,6 +240,9 @@  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 (host->caps & MMC_CAP_HW_CLOCK_GATING)
+		return;
+
 	if (cancel_work_sync(&host->clk_gate_work))
 		mmc_host_clk_gate_delayed(host);
 	if (host->clk_gated)
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 078cff7..243c7ab 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -171,6 +171,7 @@  struct mmc_host {
 #define MMC_CAP_POWER_OFF_CARD	(1 << 13)	/* Can power off after boot */
 
 #define MMC_CAP_BUS_WIDTH_TEST	(1 << 14)	/* CMD14/CMD19 bus width ok */
+#define MMC_CAP_HW_CLOCK_GATING	(1 << 15)	/* h/w supports clock gating */
 	mmc_pm_flag_t		pm_caps;	/* supported pm features */
 
 #ifdef CONFIG_MMC_CLKGATE