linux-kernel - [06/36] arm/imx/gpio: add spinlock protection

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Date:	Fri, 06 Aug 2010 12:19:47 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Juergen Beisert <j.beisert@...gutronix.de>,
	Daniel Mack <daniel@...aq.de>,
	Baruch Siach <baruch@...s.co.il>,
	Sascha Hauer <s.hauer@...gutronix.de>
Subject: [06/36] arm/imx/gpio: add spinlock protection

2.6.34-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Baruch Siach <baruch@...s.co.il>

commit 14cb0deb66fcfca8fdbef75da8c84b5405a8c767 upstream.

The GPIO registers need protection from concurrent access for operations that
are not atomic.

Cc: Juergen Beisert <j.beisert@...gutronix.de>
Cc: Daniel Mack <daniel@...aq.de>
Reported-by: rpkamiak@...kwellcollins.com
Signed-off-by: Baruch Siach <baruch@...s.co.il>
Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 arch/arm/plat-mxc/gpio.c              |    8 ++++++++
 arch/arm/plat-mxc/include/mach/gpio.h |    1 +
 2 files changed, 9 insertions(+)

--- a/arch/arm/plat-mxc/gpio.c
+++ b/arch/arm/plat-mxc/gpio.c
@@ -215,13 +215,16 @@ static void _set_gpio_direction(struct g
 	struct mxc_gpio_port *port =
 		container_of(chip, struct mxc_gpio_port, chip);
 	u32 l;
+	unsigned long flags;
 
+	spin_lock_irqsave(&port->lock, flags);
 	l = __raw_readl(port->base + GPIO_GDIR);
 	if (dir)
 		l |= 1 << offset;
 	else
 		l &= ~(1 << offset);
 	__raw_writel(l, port->base + GPIO_GDIR);
+	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 static void mxc_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
@@ -230,9 +233,12 @@ static void mxc_gpio_set(struct gpio_chi
 		container_of(chip, struct mxc_gpio_port, chip);
 	void __iomem *reg = port->base + GPIO_DR;
 	u32 l;
+	unsigned long flags;
 
+	spin_lock_irqsave(&port->lock, flags);
 	l = (__raw_readl(reg) & (~(1 << offset))) | (value << offset);
 	__raw_writel(l, reg);
+	spin_unlock_irqrestore(&port->lock, flags);
 }
 
 static int mxc_gpio_get(struct gpio_chip *chip, unsigned offset)
@@ -286,6 +292,8 @@ int __init mxc_gpio_init(struct mxc_gpio
 		port[i].chip.base = i * 32;
 		port[i].chip.ngpio = 32;
 
+		spin_lock_init(&port[i].lock);
+
 		/* its a serious configuration bug when it fails */
 		BUG_ON( gpiochip_add(&port[i].chip) < 0 );
 
--- a/arch/arm/plat-mxc/include/mach/gpio.h
+++ b/arch/arm/plat-mxc/include/mach/gpio.h
@@ -36,6 +36,7 @@ struct mxc_gpio_port {
 	int virtual_irq_start;
 	struct gpio_chip chip;
 	u32 both_edges;
+	spinlock_t lock;
 };
 
 int mxc_gpio_init(struct mxc_gpio_port*, int);


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