MX5/MX6: add missing get_ticks() and get_tbclk()

commit f31a911fe (arm, post: add missing post_time_ms for arm)
enables get_ticks and get_tbclk for all arm based boards,
MX5/MX6 have not yet implemented.

Signed-off-by: Stefano Babic <sbabic@denx.de>
CC: Dirk Behme <dirk.behme@de.bosch.com>
CC: Jason Liu <jason.hui@linaro.org>
CC: Marek Vasut <marek.vasut@gmail.com>

arch/arm/cpu/armv7/imx-common/timer.c

@@ -25,6 +25,7 @@
 
 #include <common.h>
 #include <asm/io.h>
+#include <div64.h>
 #include <asm/arch/imx-regs.h>
 
 /* General purpose timers registers */
@@ -50,6 +51,22 @@ DECLARE_GLOBAL_DATA_PTR;
 #define timestamp (gd->tbl)
 #define lastinc (gd->lastinc)
 
+static inline unsigned long long tick_to_time(unsigned long long tick)
+{
+	tick *= CONFIG_SYS_HZ;
+	do_div(tick, CLK_32KHZ);
+
+	return tick;
+}
+
+static inline unsigned long long us_to_tick(unsigned long long usec)
+{
+	usec *= CLK_32KHZ;
+	do_div(usec, 1000000);
+
+	return usec;
+}
+
 int timer_init(void)
 {
 	int i;
@@ -75,36 +92,58 @@ int timer_init(void)
 	return 0;
 }
 
-ulong get_timer_masked(void)
+unsigned long long get_ticks(void)
 {
-	ulong val = __raw_readl(&cur_gpt->counter);
-	val /= (CLK_32KHZ / CONFIG_SYS_HZ);
-	if (val >= lastinc)
-		timestamp += (val - lastinc);
-	else
-		timestamp += ((0xFFFFFFFF / (CLK_32KHZ / CONFIG_SYS_HZ))
-				- lastinc) + val;
-	lastinc = val;
+	ulong now = __raw_readl(&cur_gpt->counter); /* current tick value */
+
+	if (now >= lastinc) {
+		/*
+		 * normal mode (non roll)
+		 * move stamp forward with absolut diff ticks
+		 */
+		timestamp += (now - lastinc);
+	} else {
+		/* we have rollover of incrementer */
+		timestamp += (0xFFFFFFFF - lastinc) + now;
+	}
+	lastinc = now;
 	return timestamp;
 }
 
+ulong get_timer_masked(void)
+{
+	/*
+	 * get_ticks() returns a long long (64 bit), it wraps in
+	 * 2^64 / CONFIG_MX25_CLK32 = 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.
+	 */
+	return tick_to_time(get_ticks());
+}
+
 ulong get_timer(ulong base)
 {
 	return get_timer_masked() - base;
 }
 
-/* delay x useconds AND preserve advance timestamp value */
+/* delay x useconds AND preserve advance timstamp value */
 void __udelay(unsigned long usec)
 {
-	unsigned long now, start, tmo;
-	tmo = usec * (CLK_32KHZ / 1000) / 1000;
-
-	if (!tmo)
-		tmo = 1;
+	unsigned long long tmp;
+	ulong tmo;
 
-	now = start = readl(&cur_gpt->counter);
+	tmo = us_to_tick(usec);
+	tmp = get_ticks() + tmo;	/* get current timestamp */
 
-	while ((now - start) < tmo)
-		now = readl(&cur_gpt->counter);
+	while (get_ticks() < tmp)	/* loop till event */
+		 /*NOP*/;
+}
 
+/*
+ * This function is derived from PowerPC code (timebase clock frequency).
+ * On ARM it returns the number of timer ticks per second.
+ */
+ulong get_tbclk(void)
+{
+	return CLK_32KHZ;
 }