linux-kernel - [PATCHv2 2/2] clocksource: fix clocksource_mmio_readX

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Message-ID: <1398219120-23029-2-git-send-email-Li.Xiubo@freescale.com>
Date:	Wed, 23 Apr 2014 10:12:00 +0800
From:	Xiubo Li <Li.Xiubo@...escale.com>
To:	<daniel.lezcano@...aro.org>, <tglx@...utronix.de>,
	<linux-kernel@...r.kernel.org>
CC:	Xiubo Li <Li.Xiubo@...escale.com>
Subject: [PATCHv2 2/2] clocksource: fix clocksource_mmio_readX_down

For some clocksource devices, for example, the registers are 32-bit, while
the lower 16-bit is used for timer counting(And reading the upper 16-bit
will return 0).

For example, when the counter value is 0x00001111, and then the
~readl_relaxed(to_mmio_clksrc(c)->reg) will return the value of 0xFFFFEEEE,
but it should be 0x0000EEEE.

So just using the c->mask to mask the unused bits.

Signed-off-by: Xiubo Li <Li.Xiubo@...escale.com>
---
 drivers/clocksource/mmio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clocksource/mmio.c b/drivers/clocksource/mmio.c
index 19a6b3f..1593ade 100644
--- a/drivers/clocksource/mmio.c
+++ b/drivers/clocksource/mmio.c
@@ -27,7 +27,7 @@ cycle_t clocksource_mmio_readl_up(struct clocksource *c)
 
 cycle_t clocksource_mmio_readl_down(struct clocksource *c)
 {
-	return ~(cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg);
+	return ~(cycle_t)readl_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
 }
 
 cycle_t clocksource_mmio_readw_up(struct clocksource *c)
@@ -37,7 +37,7 @@ cycle_t clocksource_mmio_readw_up(struct clocksource *c)
 
 cycle_t clocksource_mmio_readw_down(struct clocksource *c)
 {
-	return ~(cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg);
+	return ~(cycle_t)readw_relaxed(to_mmio_clksrc(c)->reg) & c->mask;
 }
 
 /**
-- 
1.8.4

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