ARM: mxs: Use a proper timeout mechanism

Introduce a function for checking the busy bits of CLKCTRL register that
uses a proper timeout mechanism.

Remove parts of code that use busy loops and replace them with the
mxs_clkctrl_timeout() function.

Tested on a mx28evk by performing audio playback.

Suggested-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
diff --git a/arch/arm/mach-mxs/system.c b/arch/arm/mach-mxs/system.c
index 54f91ad..7aa5ac5 100644
--- a/arch/arm/mach-mxs/system.c
+++ b/arch/arm/mach-mxs/system.c
@@ -37,6 +37,8 @@
 #define MXS_MODULE_CLKGATE		(1 << 30)
 #define MXS_MODULE_SFTRST		(1 << 31)
 
+#define CLKCTRL_TIMEOUT		10	/* 10 ms */
+
 static void __iomem *mxs_clkctrl_reset_addr;
 
 /*
@@ -137,3 +139,17 @@
 	return -ETIMEDOUT;
 }
 EXPORT_SYMBOL(mxs_reset_block);
+
+int mxs_clkctrl_timeout(unsigned int reg_offset, unsigned int mask)
+{
+	unsigned long timeout = jiffies + msecs_to_jiffies(CLKCTRL_TIMEOUT);
+	while (readl_relaxed(MXS_IO_ADDRESS(MXS_CLKCTRL_BASE_ADDR)
+						+ reg_offset) & mask) {
+		if (time_after(jiffies, timeout)) {
+			pr_err("Timeout at CLKCTRL + 0x%x\n", reg_offset);
+			return -ETIMEDOUT;
+		}
+	}
+
+	return 0;
+}