+#ifdef CONFIG_MMC_CLKGATE
+/*
+ * This gates the clock by setting it to 0 Hz.
+ */
+void mmc_gate_clock(struct mmc_host *host)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&host->clk_lock, flags);
+ host->clk_old = host->ios.clock;
+ host->ios.clock = 0;
+ host->clk_gated = true;
+ spin_unlock_irqrestore(&host->clk_lock, flags);
+ mmc_set_ios(host);
+}
+
+/*
+ * This restores the clock from gating by using the cached
+ * clock value.
+ */
+void mmc_ungate_clock(struct mmc_host *host)
+{
+ /*
+ * We should previously have gated the clock, so the clock shall
+ * be 0 here! The clock may however be 0 during initialization,
+ * when some request operations are performed before setting
+ * the frequency. When ungate is requested in that situation
+ * we just ignore the call.
+ */
+ if (host->clk_old) {
+ BUG_ON(host->ios.clock);
+ /* This call will also set host->clk_gated to false */
+ mmc_set_clock(host, host->clk_old);
+ }
+}
+
+void mmc_set_ungated(struct mmc_host *host)
+{
+ unsigned long flags;
+
+ /*
+ * We've been given a new frequency while the clock is gated,
+ * so make sure we regard this as ungating it.
+ */
+ spin_lock_irqsave(&host->clk_lock, flags);
+ host->clk_gated = false;
+ spin_unlock_irqrestore(&host->clk_lock, flags);
+}
+
+#else
+void mmc_set_ungated(struct mmc_host *host)
+{
+}
+#endif
+