[PATCH 2/2] clocksource: sprd: Add one persistent timer for Spreadtrum SC9860 platform

[Baolin Wang]

On Spreadtrum SC9860 platform, we need one persistent timer to calculate
the suspend time to compensate the OS time.

This patch registers one Spreadtrum AON timer as persistent timer, which
runs at 32bit and periodic mode.

Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
---
 drivers/clocksource/Kconfig      |    1 +
 drivers/clocksource/timer-sprd.c |   35 +++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 9cf3d41..322c02d 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -448,6 +448,7 @@ config SPRD_TIMER
 	bool "Spreadtrum timer driver" if COMPILE_TEST
 	depends on HAS_IOMEM
 	select TIMER_OF
+	select PERSISTENT_TIMER
 	help
 	  Enables the support for the Spreadtrum timer driver.
 
diff --git a/drivers/clocksource/timer-sprd.c b/drivers/clocksource/timer-sprd.c
index ef9ebea..2304a7c 100644
--- a/drivers/clocksource/timer-sprd.c
+++ b/drivers/clocksource/timer-sprd.c
@@ -7,6 +7,7 @@
 #include <linux/interrupt.h>
 
 #include "timer-of.h"
+#include "persistent-timer.h"
 
 #define TIMER_NAME		"sprd_timer"
 
@@ -157,3 +158,37 @@ static int __init sprd_timer_init(struct device_node *np)
 }
 
 TIMER_OF_DECLARE(sc9860_timer, "sprd,sc9860-timer", sprd_timer_init);
+
+static u64 sprd_persistent_timer_read(struct persistent_timer *p)
+{
+	return ~(u64)readl_relaxed(p->base + TIMER_VALUE_SHDW_LO) & p->mask;
+}
+
+static void sprd_persistent_timer_enable(struct persistent_timer *p)
+{
+	sprd_timer_disable(p->base);
+	sprd_timer_update_counter(p->base, TIMER_VALUE_LO_MASK);
+	sprd_timer_enable(p->base, TIMER_CTL_PERIOD_MODE);
+}
+
+static struct persistent_timer p = {
+	.read = sprd_persistent_timer_read,
+	.mask = CLOCKSOURCE_MASK(32),
+	.flags = PERSISTENT_TIMER_BASE | PERSISTENT_TIMER_CLOCK |
+		PERSISTENT_TIMER_MULT_SHIFT,
+};
+
+static int __init sprd_persistent_timer_init(struct device_node *np)
+{
+	int ret;
+
+	ret = persistent_timer_init_and_register(np, &p);
+	if (ret)
+		return ret;
+
+	sprd_persistent_timer_enable(&p);
+	return 0;
+}
+
+TIMER_OF_DECLARE(sc9860_persistent_timer, "sprd,sc9860-persistent-timer",
+		 sprd_persistent_timer_init);
-- 
1.7.9.5