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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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