1 files changed, 82 insertions, 0 deletions
diff --git a/arch/m68k/coldfire/dma_timer.c b/arch/m68k/coldfire/dma_timer.c
new file mode 100644
index 000000000..cbb289439
--- /dev/null
+++ b/arch/m68k/coldfire/dma_timer.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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 u64 cf_dt_get_cycles(struct clocksource *cs)
+{
+	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),
+	.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);
+	return clocksource_register_hz(&clocksource_cf_dt, DMA_FREQ);
+}
+
+arch_initcall(init_cf_dt_clocksource);
+
+#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
+#define CYC2NS_SCALE	((1000000 << CYC2NS_SCALE_FACTOR) / (DMA_FREQ / 1000))
+
+static unsigned long long cycles2ns(unsigned long cycl)
+{
+	return (unsigned long long) ((unsigned long long)cycl *
+			CYC2NS_SCALE) >> CYC2NS_SCALE_FACTOR;
+}
+
+unsigned long long sched_clock(void)
+{
+	unsigned long cycl = __raw_readl(DTCN0);
+
+	return cycles2ns(cycl);
+}