linux-kernel - [PATCH 02/25] clocksource: sh_cmt: Replace global spinlock with a per-device spinlock

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Date:	Wed, 23 Jul 2014 12:53:44 +0200
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH 02/25] clocksource: sh_cmt: Replace global spinlock with a per-device spinlock

From: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>

The global spinlock is used to protect the shared start/stop register.
Now that all CMT channels are handled by a single device instance, use a
per-device spinlock.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>
Tested-by: Simon Horman <horms+renesas@...ge.net.au>
---
 drivers/clocksource/sh_cmt.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c
index fcd38db..190c655 100644
--- a/drivers/clocksource/sh_cmt.c
+++ b/drivers/clocksource/sh_cmt.c
@@ -118,6 +118,8 @@ struct sh_cmt_device {
 	void __iomem *mapbase;
 	struct clk *clk;
 
+	raw_spinlock_t lock; /* Protect the shared start/stop register */
+
 	struct sh_cmt_channel *channels;
 	unsigned int num_channels;
 
@@ -299,14 +301,12 @@ static unsigned long sh_cmt_get_counter(struct sh_cmt_channel *ch,
 	return v2;
 }
 
-static DEFINE_RAW_SPINLOCK(sh_cmt_lock);
-
 static void sh_cmt_start_stop_ch(struct sh_cmt_channel *ch, int start)
 {
 	unsigned long flags, value;
 
 	/* start stop register shared by multiple timer channels */
-	raw_spin_lock_irqsave(&sh_cmt_lock, flags);
+	raw_spin_lock_irqsave(&ch->cmt->lock, flags);
 	value = sh_cmt_read_cmstr(ch);
 
 	if (start)
@@ -315,7 +315,7 @@ static void sh_cmt_start_stop_ch(struct sh_cmt_channel *ch, int start)
 		value &= ~(1 << ch->timer_bit);
 
 	sh_cmt_write_cmstr(ch, value);
-	raw_spin_unlock_irqrestore(&sh_cmt_lock, flags);
+	raw_spin_unlock_irqrestore(&ch->cmt->lock, flags);
 }
 
 static int sh_cmt_enable(struct sh_cmt_channel *ch, unsigned long *rate)
@@ -934,6 +934,7 @@ static int sh_cmt_setup(struct sh_cmt_device *cmt, struct platform_device *pdev)
 
 	memset(cmt, 0, sizeof(*cmt));
 	cmt->pdev = pdev;
+	raw_spin_lock_init(&cmt->lock);
 
 	if (!cfg) {
 		dev_err(&cmt->pdev->dev, "missing platform data\n");
-- 
1.7.9.5

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