1 files changed, 87 insertions, 0 deletions
diff --git a/kernel/drivers/clocksource/clksrc-dbx500-prcmu.c b/kernel/drivers/clocksource/clksrc-dbx500-prcmu.c
new file mode 100644
index 000000000..b37510684
--- /dev/null
+++ b/kernel/drivers/clocksource/clksrc-dbx500-prcmu.c
@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * License Terms: GNU General Public License v2
+ * Author: Mattias Wallin <mattias.wallin@stericsson.com> for ST-Ericsson
+ * Author: Sundar Iyer for ST-Ericsson
+ * sched_clock implementation is based on:
+ * plat-nomadik/timer.c Linus Walleij <linus.walleij@stericsson.com>
+ *
+ * DBx500-PRCMU Timer
+ * The PRCMU has 5 timers which are available in a always-on
+ * power domain.  We use the Timer 4 for our always-on clock
+ * source on DB8500.
+ */
+#include <linux/clockchips.h>
+#include <linux/clksrc-dbx500-prcmu.h>
+#include <linux/sched_clock.h>
+
+#define RATE_32K		32768
+
+#define TIMER_MODE_CONTINOUS	0x1
+#define TIMER_DOWNCOUNT_VAL	0xffffffff
+
+#define PRCMU_TIMER_REF		0
+#define PRCMU_TIMER_DOWNCOUNT	0x4
+#define PRCMU_TIMER_MODE	0x8
+
+#define SCHED_CLOCK_MIN_WRAP 131072 /* 2^32 / 32768 */
+
+static void __iomem *clksrc_dbx500_timer_base;
+
+static cycle_t notrace clksrc_dbx500_prcmu_read(struct clocksource *cs)
+{
+	void __iomem *base = clksrc_dbx500_timer_base;
+	u32 count, count2;
+
+	do {
+		count = readl_relaxed(base + PRCMU_TIMER_DOWNCOUNT);
+		count2 = readl_relaxed(base + PRCMU_TIMER_DOWNCOUNT);
+	} while (count2 != count);
+
+	/* Negate because the timer is a decrementing counter */
+	return ~count;
+}
+
+static struct clocksource clocksource_dbx500_prcmu = {
+	.name		= "dbx500-prcmu-timer",
+	.rating		= 300,
+	.read		= clksrc_dbx500_prcmu_read,
+	.mask		= CLOCKSOURCE_MASK(32),
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+#ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK
+
+static u64 notrace dbx500_prcmu_sched_clock_read(void)
+{
+	if (unlikely(!clksrc_dbx500_timer_base))
+		return 0;
+
+	return clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu);
+}
+
+#endif
+
+void __init clksrc_dbx500_prcmu_init(void __iomem *base)
+{
+	clksrc_dbx500_timer_base = base;
+
+	/*
+	 * The A9 sub system expects the timer to be configured as
+	 * a continous looping timer.
+	 * The PRCMU should configure it but if it for some reason
+	 * don't we do it here.
+	 */
+	if (readl(clksrc_dbx500_timer_base + PRCMU_TIMER_MODE) !=
+	    TIMER_MODE_CONTINOUS) {
+		writel(TIMER_MODE_CONTINOUS,
+		       clksrc_dbx500_timer_base + PRCMU_TIMER_MODE);
+		writel(TIMER_DOWNCOUNT_VAL,
+		       clksrc_dbx500_timer_base + PRCMU_TIMER_REF);
+	}
+#ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK
+	sched_clock_register(dbx500_prcmu_sched_clock_read, 32, RATE_32K);
+#endif
+	clocksource_register_hz(&clocksource_dbx500_prcmu, RATE_32K);
+}