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Subject[PATCH] pch_gpio: transform mutex into spinlock
Date
gpio_chip.can_sleep is 0, but gpio_set_value & friends lock a mutex. Thus
those functions are not callable from interrupt context.
Changing mutex into spinlock.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
---
I just noticed that the patch introduced at
http://marc.info/?l=linux-kernel&m=130863151431202&w=2
also added a spinlock. I think those two spinlock can be merged into one.

drivers/gpio/pch_gpio.c | 19 +++++++++++--------
1 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/gpio/pch_gpio.c b/drivers/gpio/pch_gpio.c
index 36919e7..262c200 100644
--- a/drivers/gpio/pch_gpio.c
+++ b/drivers/gpio/pch_gpio.c
@@ -62,15 +62,16 @@ struct pch_gpio {
struct device *dev;
struct gpio_chip gpio;
struct pch_gpio_reg_data pch_gpio_reg;
- struct mutex lock;
+ struct spinlock lock;
};

static void pch_gpio_set(struct gpio_chip *gpio, unsigned nr, int val)
{
u32 reg_val;
+ unsigned long flags;
struct pch_gpio *chip = container_of(gpio, struct pch_gpio, gpio);

- mutex_lock(&chip->lock);
+ spin_lock_irqsave(&chip->lock, flags);
reg_val = ioread32(&chip->reg->po);
if (val)
reg_val |= (1 << nr);
@@ -78,7 +79,7 @@ static void pch_gpio_set(struct gpio_chip *gpio, unsigned nr, int val)
reg_val &= ~(1 << nr);

iowrite32(reg_val, &chip->reg->po);
- mutex_unlock(&chip->lock);
+ spin_unlock_irqrestore(&chip->lock, flags);
}

static int pch_gpio_get(struct gpio_chip *gpio, unsigned nr)
@@ -94,8 +95,9 @@ static int pch_gpio_direction_output(struct gpio_chip *gpio, unsigned nr,
struct pch_gpio *chip = container_of(gpio, struct pch_gpio, gpio);
u32 pm;
u32 reg_val;
+ unsigned long flags;

- mutex_lock(&chip->lock);
+ spin_lock_irqsave(&chip->lock, flags);
pm = ioread32(&chip->reg->pm) & PCH_GPIO_ALL_PINS;
pm |= (1 << nr);
iowrite32(pm, &chip->reg->pm);
@@ -107,7 +109,7 @@ static int pch_gpio_direction_output(struct gpio_chip *gpio, unsigned nr,
reg_val &= ~(1 << nr);
iowrite32(reg_val, &chip->reg->po);

- mutex_unlock(&chip->lock);
+ spin_unlock_irqrestore(&chip->lock, flags);

return 0;
}
@@ -116,12 +118,13 @@ static int pch_gpio_direction_input(struct gpio_chip *gpio, unsigned nr)
{
struct pch_gpio *chip = container_of(gpio, struct pch_gpio, gpio);
u32 pm;
+ unsigned long flags;

- mutex_lock(&chip->lock);
+ spin_lock_irqsave(&chip->lock, flags);
pm = ioread32(&chip->reg->pm) & PCH_GPIO_ALL_PINS; /*bits 0-11*/
pm &= ~(1 << nr);
iowrite32(pm, &chip->reg->pm);
- mutex_unlock(&chip->lock);
+ spin_unlock_irqrestore(&chip->lock, flags);

return 0;
}
@@ -194,7 +197,7 @@ static int __devinit pch_gpio_probe(struct pci_dev *pdev,

chip->reg = chip->base;
pci_set_drvdata(pdev, chip);
- mutex_init(&chip->lock);
+ spin_lock_init(&chip->lock);
pch_gpio_setup(chip);
ret = gpiochip_add(&chip->gpio);
if (ret) {
--
1.7.3.4


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