arm/imx/gpio: add spinlock protection

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

Cc: stable@kernel.org
Cc: Juergen Beisert <j.beisert@pengutronix.de>
Cc: Daniel Mack <daniel@caiaq.de>
Reported-by: rpkamiak@rockwellcollins.com
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

2 files changed, 9 insertions, 0 deletions

diff --git a/arch/arm/plat-mxc/gpio.c b/arch/arm/plat-mxc/gpio.c
index 11dc06190b5d..57ec4a896a5d 100644
--- a/arch/arm/plat-mxc/gpio.c
+++ b/arch/arm/plat-mxc/gpio.c
@@ -214,13 +214,16 @@ static void _set_gpio_direction(struct gpio_chip *chip, unsigned offset,
         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)
@@ -229,9 +232,12 @@ static void mxc_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
                 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)
@@ -285,6 +291,8 @@ int __init mxc_gpio_init(struct mxc_gpio_port *port, int cnt)
                 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 );
 
diff --git a/arch/arm/plat-mxc/include/mach/gpio.h b/arch/arm/plat-mxc/include/mach/gpio.h
index 9541ecbfd22c..661fbc605759 100644
--- a/arch/arm/plat-mxc/include/mach/gpio.h
+++ b/arch/arm/plat-mxc/include/mach/gpio.h
@@ -37,6 +37,7 @@ 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);