1 files changed, 72 insertions, 0 deletions
diff --git a/drivers/clocksource/clksrc-dbx500-prcmu.c b/drivers/clocksource/clksrc-dbx500-prcmu.c
new file mode 100644
index 0000000000..2fc93e46ce
--- /dev/null
+++ b/drivers/clocksource/clksrc-dbx500-prcmu.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) ST-Ericsson SA 2011
+ *
+ * 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/of.h>
+#include <linux/of_address.h>
+#include <linux/clockchips.h>
+
+#define RATE_32K		32768
+
+#define TIMER_MODE_CONTINUOUS	0x1
+#define TIMER_DOWNCOUNT_VAL	0xffffffff
+
+#define PRCMU_TIMER_REF		0
+#define PRCMU_TIMER_DOWNCOUNT	0x4
+#define PRCMU_TIMER_MODE	0x8
+
+static void __iomem *clksrc_dbx500_timer_base;
+
+static u64 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		= 100,
+	.read		= clksrc_dbx500_prcmu_read,
+	.mask		= CLOCKSOURCE_MASK(32),
+	.flags		= CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP,
+};
+
+static int __init clksrc_dbx500_prcmu_init(struct device_node *node)
+{
+	clksrc_dbx500_timer_base = of_iomap(node, 0);
+
+	/*
+	 * The A9 sub system expects the timer to be configured as
+	 * a continuous 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_CONTINUOUS) {
+		writel(TIMER_MODE_CONTINUOUS,
+		       clksrc_dbx500_timer_base + PRCMU_TIMER_MODE);
+		writel(TIMER_DOWNCOUNT_VAL,
+		       clksrc_dbx500_timer_base + PRCMU_TIMER_REF);
+	}
+	return clocksource_register_hz(&clocksource_dbx500_prcmu, RATE_32K);
+}
+TIMER_OF_DECLARE(dbx500_prcmu, "stericsson,db8500-prcmu-timer-4",
+		       clksrc_dbx500_prcmu_init);