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>

2 files changed, 69 insertions, 1 deletions

diff --git a/arch/m68knommu/platform/coldfire/Makefile b/arch/m68knommu/platform/coldfire/Makefile
index 40cf20be1b90..4f416a91a829 100644
--- a/arch/m68knommu/platform/coldfire/Makefile
+++ b/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
diff --git a/arch/m68knommu/platform/coldfire/dma_timer.c b/arch/m68knommu/platform/coldfire/dma_timer.c
new file mode 100644
index 000000000000..b623c993219e
--- /dev/null
+++ b/arch/m68knommu/platform/coldfire/dma_timer.c
@@ -0,0 +1,68 @@
+/*
+ * 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);