[PATCH V2] clocksource/drivers/sprd: Enable register for timer counter from 32 bit to 64 bit

[Enlin Mu <enlin.mu@linux.dev>]

From: Enlin Mu <enlin.mu@unisoc.com>

Using 32 bit for suspend compensation, the max compensation time is 36
hours(working clock is 32k).In some IOT devices, the suspend time may
be long, even exceeding 36 hours. Therefore, a 64 bit timer counter
is needed for counting.

Signed-off-by: Enlin Mu <enlin.mu@unisoc.com>
---
 drivers/clocksource/timer-sprd.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/clocksource/timer-sprd.c b/drivers/clocksource/timer-sprd.c
index 430cb99d8d79..2c07dd2af760 100644
--- a/drivers/clocksource/timer-sprd.c
+++ b/drivers/clocksource/timer-sprd.c
@@ -30,6 +30,7 @@
 #define TIMER_VALUE_SHDW_HI	0x1c
 
 #define TIMER_VALUE_LO_MASK	GENMASK(31, 0)
+#define TIMER_VALUE_HI_MASK	GENMASK(31, 0)
 
 static void sprd_timer_enable(void __iomem *base, u32 flag)
 {
@@ -162,15 +163,26 @@ static struct timer_of suspend_to = {
 
 static u64 sprd_suspend_timer_read(struct clocksource *cs)
 {
-	return ~(u64)readl_relaxed(timer_of_base(&suspend_to) +
-				   TIMER_VALUE_SHDW_LO) & cs->mask;
+	u32 lo, hi;
+
+	do {
+		hi = readl_relaxed(timer_of_base(&suspend_to) +
+				   TIMER_VALUE_SHDW_HI);
+		lo = readl_relaxed(timer_of_base(&suspend_to) +
+				   TIMER_VALUE_SHDW_LO);
+	} while (hi != readl_relaxed(timer_of_base(&suspend_to) + TIMER_VALUE_SHDW_HI));
+
+	return ~(((u64)hi << 32) | lo);
 }
 
 static int sprd_suspend_timer_enable(struct clocksource *cs)
 {
-	sprd_timer_update_counter(timer_of_base(&suspend_to),
-				  TIMER_VALUE_LO_MASK);
-	sprd_timer_enable(timer_of_base(&suspend_to), TIMER_CTL_PERIOD_MODE);
+	writel_relaxed(TIMER_VALUE_LO_MASK,
+		       timer_of_base(&suspend_to) + TIMER_LOAD_LO);
+	writel_relaxed(TIMER_VALUE_HI_MASK,
+		       timer_of_base(&suspend_to) + TIMER_LOAD_HI);
+	sprd_timer_enable(timer_of_base(&suspend_to),
+			  TIMER_CTL_PERIOD_MODE|TIMER_CTL_64BIT_WIDTH);
 
 	return 0;
 }
@@ -186,7 +198,7 @@ static struct clocksource suspend_clocksource = {
 	.read	= sprd_suspend_timer_read,
 	.enable = sprd_suspend_timer_enable,
 	.disable = sprd_suspend_timer_disable,
-	.mask	= CLOCKSOURCE_MASK(32),
+	.mask	= CLOCKSOURCE_MASK(64),
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP,
 };
 
-- 
2.39.5