imx: gpt: Add High frequency clock source support for GPT

Introduce a new configuration "CONFIG_MXC_GPT_HCLK". When it is set,
the GPT will select a high frequency clock as clock source.
Otherwise, the GPT will stay to use 32Khz OSC as clock source.

In the implementation, since only the GPT on i.MX6 series provide the
clock source option for 24Mhz OSC. For others (only i.MX5 and i.MX6
compile the driver), if the configuration is set, the perclk will be
selected as clock source.
MX6Q/D Rev 1.0 and MX6SL are special in the implementation, because they
don't have the 24Mhz OSC clock source option, so also select the perclk
for them. For MX6SL, we will set the OSC 24Mhz to perclk in CCM, so
eventually the clock comes from OSC 24Mhz.

Signed-off-by: Ye.Li <B37916@freescale.com>

arch/arm/imx-common/timer.c

@@ -12,6 +12,7 @@
 #include <div64.h>
 #include <asm/arch/imx-regs.h>
 #include <asm/arch/clock.h>
+#include <asm/arch/sys_proto.h>
 
 /* General purpose timers registers */
 struct mxc_gpt {
@@ -26,23 +27,59 @@ static struct mxc_gpt *cur_gpt = (struct mxc_gpt *)GPT1_BASE_ADDR;
 
 /* General purpose timers bitfields */
 #define GPTCR_SWR		(1 << 15)	/* Software reset */
+#define GPTCR_24MEN	    (1 << 10)	/* Enable 24MHz clock input */
 #define GPTCR_FRR		(1 << 9)	/* Freerun / restart */
-#define GPTCR_CLKSOURCE_32	(4 << 6)	/* Clock source */
+#define GPTCR_CLKSOURCE_32	(4 << 6)	/* Clock source 32khz */
+#define GPTCR_CLKSOURCE_OSC	(5 << 6)	/* Clock source OSC */
+#define GPTCR_CLKSOURCE_PRE	(1 << 6)	/* Clock source PRECLK */
+#define GPTCR_CLKSOURCE_MASK (0x7 << 6)
 #define GPTCR_TEN		1		/* Timer enable */
 
+#define GPTPR_PRESCALER24M_SHIFT 12
+#define GPTPR_PRESCALER24M_MASK (0xF << GPTPR_PRESCALER24M_SHIFT)
+
 DECLARE_GLOBAL_DATA_PTR;
 
+static inline int gpt_has_clk_source_osc(void)
+{
+#if defined(CONFIG_MX6)
+	if (((is_cpu_type(MXC_CPU_MX6Q) || is_cpu_type(MXC_CPU_MX6D)) &&
+	     (is_soc_rev(CHIP_REV_1_0) > 0)) || is_cpu_type(MXC_CPU_MX6DL) ||
+	      is_cpu_type(MXC_CPU_MX6SOLO) || is_cpu_type(MXC_CPU_MX6SX))
+		return 1;
+
+	return 0;
+#else
+	return 0;
+#endif
+}
+
+static inline ulong gpt_get_clk(void)
+{
+#ifdef CONFIG_MXC_GPT_HCLK
+	if (gpt_has_clk_source_osc())
+		return MXC_HCLK >> 3;
+	else
+		return mxc_get_clock(MXC_IPG_PERCLK);
+#else
+	return MXC_CLK32;
+#endif
+}
 static inline unsigned long long tick_to_time(unsigned long long tick)
 {
+	ulong gpt_clk = gpt_get_clk();
+
 	tick *= CONFIG_SYS_HZ;
-	do_div(tick, MXC_CLK32);
+	do_div(tick, gpt_clk);
 
 	return tick;
 }
 
 static inline unsigned long long us_to_tick(unsigned long long usec)
 {
-	usec = usec * MXC_CLK32 + 999999;
+	ulong gpt_clk = gpt_get_clk();
+
+	usec = usec * gpt_clk + 999999;
 	do_div(usec, 1000000);
 
 	return usec;
@@ -59,11 +96,31 @@ int timer_init(void)
 	for (i = 0; i < 100; i++)
 		__raw_writel(0, &cur_gpt->control);
 
-	__raw_writel(0, &cur_gpt->prescaler); /* 32Khz */
-
-	/* Freerun Mode, PERCLK1 input */
 	i = __raw_readl(&cur_gpt->control);
-	__raw_writel(i | GPTCR_CLKSOURCE_32 | GPTCR_TEN, &cur_gpt->control);
+	i &= ~GPTCR_CLKSOURCE_MASK;
+
+#ifdef CONFIG_MXC_GPT_HCLK
+	if (gpt_has_clk_source_osc()) {
+		i |= GPTCR_CLKSOURCE_OSC | GPTCR_TEN;
+
+		/* For DL/S, SX, set 24Mhz OSC Enable bit and prescaler */
+		if (is_cpu_type(MXC_CPU_MX6DL) ||
+		    is_cpu_type(MXC_CPU_MX6SOLO) ||
+		    is_cpu_type(MXC_CPU_MX6SX)) {
+			i |= GPTCR_24MEN;
+
+			/* Produce 3Mhz clock */
+			__raw_writel((7 << GPTPR_PRESCALER24M_SHIFT),
+				     &cur_gpt->prescaler);
+		}
+	} else {
+		i |= GPTCR_CLKSOURCE_PRE | GPTCR_TEN;
+	}
+#else
+	__raw_writel(0, &cur_gpt->prescaler); /* 32Khz */
+	i |= GPTCR_CLKSOURCE_32 | GPTCR_TEN;
+#endif
+	__raw_writel(i, &cur_gpt->control);
 
 	gd->arch.tbl = __raw_readl(&cur_gpt->counter);
 	gd->arch.tbu = 0;
@@ -86,7 +143,7 @@ ulong get_timer_masked(void)
 {
 	/*
 	 * get_ticks() returns a long long (64 bit), it wraps in
-	 * 2^64 / MXC_CLK32 = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
+	 * 2^64 / GPT_CLK = 2^64 / 2^15 = 2^49 ~ 5 * 10^14 (s) ~
 	 * 5 * 10^9 days... and get_ticks() * CONFIG_SYS_HZ wraps in
 	 * 5 * 10^6 days - long enough.
 	 */
@@ -117,5 +174,5 @@ void __udelay(unsigned long usec)
  */
 ulong get_tbclk(void)
 {
-	return MXC_CLK32;
+	return gpt_get_clk();
 }