m68knommu: Add Coldfire DMA Timer support

This one could be used as a hrtimer.
Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>

arch/m68knommu/platform/coldfire/Makefile

@@ -18,7 +18,7 @@ obj-$(CONFIG_COLDFIRE)	+= dma.o entry.o vectors.o
 obj-$(CONFIG_M5206)	+= timers.o
 obj-$(CONFIG_M5206e)	+= timers.o
 obj-$(CONFIG_M520x)	+= pit.o
-obj-$(CONFIG_M523x)	+= pit.o
+obj-$(CONFIG_M523x)	+= pit.o dma_timer.o
 obj-$(CONFIG_M5249)	+= timers.o
 obj-$(CONFIG_M527x)	+= pit.o
 obj-$(CONFIG_M5272)	+= timers.o

arch/m68knommu/platform/coldfire/dma_timer.c

+/*
+ * dma_timer.c -- Freescale ColdFire DMA Timer.
+ *
+ * Copyright (C) 2007, Benedikt Spranger <b.spranger@linutronix.de>
+ * Copyright (C) 2008. Sebastian Siewior, Linutronix
+ *
+ */
+
+#include <linux/clocksource.h>
+#include <linux/io.h>
+
+#include <asm/machdep.h>
+#include <asm/coldfire.h>
+#include <asm/mcfpit.h>
+#include <asm/mcfsim.h>
+
+#define DMA_TIMER_0	(0x00)
+#define DMA_TIMER_1	(0x40)
+#define DMA_TIMER_2	(0x80)
+#define DMA_TIMER_3	(0xc0)
+
+#define DTMR0	(MCF_IPSBAR + DMA_TIMER_0 + 0x400)
+#define DTXMR0	(MCF_IPSBAR + DMA_TIMER_0 + 0x402)
+#define DTER0	(MCF_IPSBAR + DMA_TIMER_0 + 0x403)
+#define DTRR0	(MCF_IPSBAR + DMA_TIMER_0 + 0x404)
+#define DTCR0	(MCF_IPSBAR + DMA_TIMER_0 + 0x408)
+#define DTCN0	(MCF_IPSBAR + DMA_TIMER_0 + 0x40c)
+
+#define DMA_FREQ    ((MCF_CLK / 2) / 16)
+
+/* DTMR */
+#define DMA_DTMR_RESTART	(1 << 3)
+#define DMA_DTMR_CLK_DIV_1	(1 << 1)
+#define DMA_DTMR_CLK_DIV_16	(2 << 1)
+#define DMA_DTMR_ENABLE		(1 << 0)
+
+static cycle_t cf_dt_get_cycles(void)
+{
+	return __raw_readl(DTCN0);
+}
+
+static struct clocksource clocksource_cf_dt = {
+	.name		= "coldfire_dma_timer",
+	.rating		= 200,
+	.read		= cf_dt_get_cycles,
+	.mask		= CLOCKSOURCE_MASK(32),
+	.shift		= 20,
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init  init_cf_dt_clocksource(void)
+{
+	/*
+	 * We setup DMA timer 0 in free run mode. This incrementing counter is
+	 * used as a highly precious clock source. With MCF_CLOCK = 150 MHz we
+	 * get a ~213 ns resolution and the 32bit register will overflow almost
+	 * every 15 minutes.
+	 */
+	__raw_writeb(0x00, DTXMR0);
+	__raw_writeb(0x00, DTER0);
+	__raw_writel(0x00000000, DTRR0);
+	__raw_writew(DMA_DTMR_CLK_DIV_16 | DMA_DTMR_ENABLE, DTMR0);
+	clocksource_cf_dt.mult = clocksource_hz2mult(DMA_FREQ,
+						     clocksource_cf_dt.shift);
+	return clocksource_register(&clocksource_cf_dt);
+}
+
+arch_initcall(init_cf_dt_clocksource);