[ARM] 4461/1: MXC platform and i.MX31ADS core support

This patch adds the foundation pieces for
the Freescale MXC platforms, including
i.MX2 and i.MX3 based systems.

The bare-bones MX31 support in this patch
boots to the rootdev panic with 8250 serial
console configured "console=ttyS0,115200".
It assumes that Redboot is the boot loader.

Signed-off-by: Quinn Jensen <quinn.jensen@freescale.com>
Acked-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 152 insertions, 0 deletions

diff --git a/arch/arm/mach-mx3/time.c b/arch/arm/mach-mx3/time.c
new file mode 100644
index 000000000000..e81fb5c5d7c3
--- /dev/null
+++ b/arch/arm/mach-mx3/time.c
@@ -0,0 +1,152 @@
+/*
+ * System Timer Interrupt reconfigured to run in free-run mode.
+ * Author: Vitaly Wool
+ * Copyright 2004 MontaVista Software Inc.
+ * Copyright 2004-2007 Freescale Semiconductor, Inc. All Rights Reserved.
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*!
+ * @file time.c
+ * @brief This file contains OS tick and wdog timer implementations.
+ *
+ * This file contains OS tick and wdog timer implementations.
+ *
+ * @ingroup Timers
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <asm/hardware.h>
+#include <asm/mach/time.h>
+#include <asm/io.h>
+#include <asm/arch/common.h>
+
+/*!
+ * This is the timer interrupt service routine to do required tasks.
+ * It also services the WDOG timer at the frequency of twice per WDOG
+ * timeout value. For example, if the WDOG's timeout value is 4 (2
+ * seconds since the WDOG runs at 0.5Hz), it will be serviced once
+ * every 2/2=1 second.
+ *
+ * @param  irq          GPT interrupt source number (not used)
+ * @param  dev_id       this parameter is not used
+ * @return always returns \b IRQ_HANDLED as defined in
+ *         include/linux/interrupt.h.
+ */
+static irqreturn_t mxc_timer_interrupt(int irq, void *dev_id)
+{
+	unsigned int next_match;
+
+	write_seqlock(&xtime_lock);
+
+	if (__raw_readl(MXC_GPT_GPTSR) & GPTSR_OF1) {
+		do {
+			timer_tick();
+			next_match = __raw_readl(MXC_GPT_GPTOCR1) + LATCH;
+			__raw_writel(GPTSR_OF1, MXC_GPT_GPTSR);
+			__raw_writel(next_match, MXC_GPT_GPTOCR1);
+		} while ((signed long)(next_match -
+				       __raw_readl(MXC_GPT_GPTCNT)) <= 0);
+	}
+
+	write_sequnlock(&xtime_lock);
+
+	return IRQ_HANDLED;
+}
+
+/*!
+ * This function is used to obtain the number of microseconds since the last
+ * timer interrupt. Note that interrupts is disabled by do_gettimeofday().
+ *
+ * @return the number of microseconds since the last timer interrupt.
+ */
+static unsigned long mxc_gettimeoffset(void)
+{
+	unsigned long ticks_to_match, elapsed, usec, tick_usec, i;
+
+	/* Get ticks before next timer match */
+	ticks_to_match =
+	    __raw_readl(MXC_GPT_GPTOCR1) - __raw_readl(MXC_GPT_GPTCNT);
+
+	/* We need elapsed ticks since last match */
+	elapsed = LATCH - ticks_to_match;
+
+	/* Now convert them to usec */
+	/* Insure no overflow when calculating the usec below */
+	for (i = 1, tick_usec = tick_nsec / 1000;; i *= 2) {
+		tick_usec /= i;
+		if ((0xFFFFFFFF / tick_usec) > elapsed)
+			break;
+	}
+	usec = (unsigned long)(elapsed * tick_usec) / (LATCH / i);
+
+	return usec;
+}
+
+/*!
+ * The OS tick timer interrupt structure.
+ */
+static struct irqaction timer_irq = {
+	.name = "MXC Timer Tick",
+	.flags = IRQF_DISABLED | IRQF_TIMER,
+	.handler = mxc_timer_interrupt
+};
+
+/*!
+ * This function is used to initialize the GPT to produce an interrupt
+ * based on HZ.  It is called by start_kernel() during system startup.
+ */
+void __init mxc_init_time(void)
+{
+	u32 reg, v;
+	reg = __raw_readl(MXC_GPT_GPTCR);
+	reg &= ~GPTCR_ENABLE;
+	__raw_writel(reg, MXC_GPT_GPTCR);
+	reg |= GPTCR_SWR;
+	__raw_writel(reg, MXC_GPT_GPTCR);
+
+	while ((__raw_readl(MXC_GPT_GPTCR) & GPTCR_SWR) != 0)
+		cpu_relax();
+
+	reg = GPTCR_FRR | GPTCR_CLKSRC_HIGHFREQ;
+	__raw_writel(reg, MXC_GPT_GPTCR);
+
+	/* TODO: get timer rate from clk driver */
+	v = 66500000;
+
+	__raw_writel((v / CLOCK_TICK_RATE) - 1, MXC_GPT_GPTPR);
+
+	if ((v % CLOCK_TICK_RATE) != 0) {
+		pr_info("\nWARNING: Can't generate CLOCK_TICK_RATE at %d Hz\n",
+			CLOCK_TICK_RATE);
+	}
+	pr_info("Actual CLOCK_TICK_RATE is %d Hz\n",
+		v / ((__raw_readl(MXC_GPT_GPTPR) & 0xFFF) + 1));
+
+	reg = __raw_readl(MXC_GPT_GPTCNT);
+	reg += LATCH;
+	__raw_writel(reg, MXC_GPT_GPTOCR1);
+
+	setup_irq(MXC_INT_GPT, &timer_irq);
+
+	reg = __raw_readl(MXC_GPT_GPTCR);
+	reg =
+	    GPTCR_FRR | GPTCR_CLKSRC_HIGHFREQ | GPTCR_STOPEN | GPTCR_DOZEN |
+	    GPTCR_WAITEN | GPTCR_ENMOD | GPTCR_ENABLE;
+	__raw_writel(reg, MXC_GPT_GPTCR);
+
+	__raw_writel(GPTIR_OF1IE, MXC_GPT_GPTIR);
+}
+
+struct sys_timer mxc_timer = {
+	.init = mxc_init_time,
+	.offset = mxc_gettimeoffset,
+};