] mmc: add support for H/W clock gating of SD controller

Commit Message

Philip Rakity Jan. 21, 2011, 7:34 p.m. UTC

None

Patch

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 198f70b..281c7d9 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -683,10 +683,35 @@  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;
 
+	if (host->caps & MMC_CAP_HW_CLOCK_GATING)
+		return;
 	/*
 	 * We've been given a new frequency while the clock is gated,
 	 * so make sure we regard this as ungating it.
@@ -1487,6 +1512,7 @@  EXPORT_SYMBOL(mmc_set_blocklen);
 
 static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
 {
+	int ret;
 	host->f_init = freq;
 
 #ifdef CONFIG_MMC_DEBUG
@@ -1496,19 +1522,30 @@  static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
 	mmc_power_up(host);
 	sdio_reset(host);
 	mmc_go_idle(host);
+	mmc_hwungate_clock(host);
 
 	mmc_send_if_cond(host, host->ocr_avail);
 
 	/* Order's important: probe SDIO, then SD, then MMC */
 	if (!mmc_attach_sdio(host))
-		return 0;
-	if (!mmc_attach_sd(host))
-		return 0;
-	if (!mmc_attach_mmc(host))
-		return 0;
+		ret = 0;
+	else if (!mmc_attach_sd(host))
+		ret = 0;
+	else if (!mmc_attach_mmc(host))
+		ret = 0;
+	else
+		ret = -EIO;
 
-	mmc_power_off(host);
-	return -EIO;
+	if (ret == 0) {
+#ifdef CONFIG_MMC_CLKGATE
+		if (mmc_host_may_gate_card(host->card))
+			mmc_hwgate_clock(host);
+		else
+			mmc_hwungate_clock(host);
+#endif
+	} else
+		mmc_power_off(host);
+	return ret;
 }
 
 void mmc_rescan(struct work_struct *work)
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index ca1fdde..1972a38 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 b3ac6c5..04a269d 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) {
@@ -147,7 +150,7 @@  void mmc_host_clk_ungate(struct mmc_host *host)
  *	mmc_host_may_gate_card - check if this card may be gated
  *	@card: card to check.
  */
-static bool mmc_host_may_gate_card(struct mmc_card *card)
+bool mmc_host_may_gate_card(struct mmc_card *card)
 {
 	/* If there is no card we may gate it */
 	if (!card)
@@ -178,6 +181,9 @@  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) &&
@@ -198,7 +204,10 @@  unsigned int mmc_host_clk_rate(struct mmc_host *host)
 	unsigned long flags;
 
 	spin_lock_irqsave(&host->clk_lock, flags);
-	if (host->clk_gated)
+		freq = host->ios.clock;
+	if (host->caps & MMC_CAP_HW_CLOCK_GATING)
+		freq = host->ios.clock;
+	else if (host->clk_gated)
 		freq = host->clk_old;
 	else
 		freq = host->ios.clock;
@@ -212,6 +221,9 @@  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;
@@ -227,6 +239,9 @@  static inline void mmc_host_clk_init(struct mmc_host *host)
  */
 static inline void mmc_host_clk_exit(struct mmc_host *host)
 {
+	if (host->caps & MMC_CAP_HW_CLOCK_GATING)
+		return;
+
 	/*
 	 * Wait for any outstanding gate and then make sure we're
 	 * ungated before exiting.
diff --git a/drivers/mmc/core/host.h b/drivers/mmc/core/host.h
index de199f9..db9d407 100644
--- a/drivers/mmc/core/host.h
+++ b/drivers/mmc/core/host.h
@@ -19,6 +19,7 @@  void mmc_unregister_host_class(void);
 void mmc_host_clk_ungate(struct mmc_host *host);
 void mmc_host_clk_gate(struct mmc_host *host);
 unsigned int mmc_host_clk_rate(struct mmc_host *host);
+bool mmc_host_may_gate_card(struct mmc_card *card);
 
 #else
 static inline void mmc_host_clk_ungate(struct mmc_host *host)
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 359924c..f51b1b2 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -174,6 +174,7 @@  struct mmc_host {
 						/* DDR mode at 1.2V */
 #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 */