imx: system counter driver for imx7d and mx6ul

Add system counter driver for imx7d and mx6ul
imx7 and imx6ul supports system counter timer as well as
GPT timer (arch/arm/imx-common/timer.c); The default for
imx7 is systemcounter timer.

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

arch/arm/imx-common/syscounter.c

+/*
+ * Copyright (C) 2015 Freescale Semiconductor, Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ *
+ * The file use ls102xa/timer.c as a reference.
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <div64.h>
+#include <asm/arch/imx-regs.h>
+#include <asm/arch/sys_proto.h>
+#include <asm/imx-common/syscounter.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/*
+ * This function is intended for SHORT delays only.
+ * It will overflow at around 10 seconds @ 400MHz,
+ * or 20 seconds @ 200MHz.
+ */
+unsigned long usec2ticks(unsigned long usec)
+{
+	ulong ticks;
+
+	if (usec < 1000)
+		ticks = ((usec * (get_tbclk()/1000)) + 500) / 1000;
+	else
+		ticks = ((usec / 10) * (get_tbclk() / 100000));
+
+	return ticks;
+}
+
+static inline unsigned long long tick_to_time(unsigned long long tick)
+{
+	unsigned long freq;
+
+	asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (freq));
+
+	tick *= CONFIG_SYS_HZ;
+	do_div(tick, freq);
+
+	return tick;
+}
+
+static inline unsigned long long us_to_tick(unsigned long long usec)
+{
+	unsigned long freq;
+
+	asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (freq));
+
+	usec = usec * freq  + 999999;
+	do_div(usec, 1000000);
+
+	return usec;
+}
+
+int timer_init(void)
+{
+	struct sctr_regs *sctr = (struct sctr_regs *)SCTR_BASE_ADDR;
+	unsigned long val, freq;
+
+	freq = CONFIG_SC_TIMER_CLK;
+	asm("mcr p15, 0, %0, c14, c0, 0" : : "r" (freq));
+
+	writel(freq, &sctr->cntfid0);
+
+	/* Enable system counter */
+	val = readl(&sctr->cntcr);
+	val &= ~(SC_CNTCR_FREQ0 | SC_CNTCR_FREQ1);
+	val |= SC_CNTCR_FREQ0 | SC_CNTCR_ENABLE | SC_CNTCR_HDBG;
+	writel(val, &sctr->cntcr);
+
+	gd->arch.tbl = 0;
+	gd->arch.tbu = 0;
+
+	return 0;
+}
+
+unsigned long long get_ticks(void)
+{
+	unsigned long long now;
+
+	asm("mrrc p15, 0, %Q0, %R0, c14" : "=r" (now));
+
+	gd->arch.tbl = (unsigned long)(now & 0xffffffff);
+	gd->arch.tbu = (unsigned long)(now >> 32);
+
+	return now;
+}
+
+ulong get_timer_masked(void)
+{
+	return tick_to_time(get_ticks());
+}
+
+ulong get_timer(ulong base)
+{
+	return get_timer_masked() - base;
+}
+
+void __udelay(unsigned long usec)
+{
+	unsigned long long tmp;
+	ulong tmo;
+
+	tmo = us_to_tick(usec);
+	tmp = get_ticks() + tmo;	/* get current timestamp */
+
+	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)
+{
+	unsigned long freq;
+
+	asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (freq));
+
+	return freq;
+}

arch/arm/include/asm/imx-common/syscounter.h

+/*
+ * Copyright (C) 2015 Freescale Semiconductor, Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _ASM_ARCH_SYSTEM_COUNTER_H
+#define _ASM_ARCH_SYSTEM_COUNTER_H
+
+/* System Counter */
+struct sctr_regs {
+	u32 cntcr;
+	u32 cntsr;
+	u32 cntcv1;
+	u32 cntcv2;
+	u32 resv1[4];
+	u32 cntfid0;
+	u32 cntfid1;
+	u32 cntfid2;
+	u32 resv2[1001];
+	u32 counterid[1];
+};
+
+#define SC_CNTCR_ENABLE		(1 << 0)
+#define SC_CNTCR_HDBG		(1 << 1)
+#define SC_CNTCR_FREQ0		(1 << 8)
+#define SC_CNTCR_FREQ1		(1 << 9)
+
+#endif