[PATCH v2 8/9] gpio: 104-idio-16: make use of raw_spinlock variants

Julia Cartwright
2017-03-21T23:48:55Z

The 104-idio-16 gpio driver currently implements an irq_chip for handling
interrupts; due to how irq_chip handling is done, it's necessary for the
irq_chip methods to be invoked from hardirq context, even on a a
real-time kernel. Because the spinlock_t type becomes a "sleeping"
spinlock w/ RT kernels, it is not suitable to be used with irq_chips.

A quick audit of the operations under the lock reveal that they do only
minimal, bounded work, and are therefore safe to do under a raw spinlock.

Signed-off-by: Julia Cartwright <julia@ni.com>
---
New patch as of v2 of series.

drivers/gpio/gpio-104-idio-16.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/gpio-104-idio-16.c b/drivers/gpio/gpio-104-idio-16.c
index 7053cf736648..5281e1cedb01 100644
--- a/drivers/gpio/gpio-104-idio-16.c
+++ b/drivers/gpio/gpio-104-idio-16.c
@@ -50,7 +50,7 @@ MODULE_PARM_DESC(irq, "ACCES 104-IDIO-16 interrupt line numbers");
*/
struct idio_16_gpio {
struct gpio_chip chip;
- spinlock_t lock;
+ raw_spinlock_t lock;
unsigned long irq_mask;
unsigned base;
unsigned out_state;
@@ -99,7 +99,7 @@ static void idio_16_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
if (offset > 15)
return;

- spin_lock_irqsave(&idio16gpio->lock, flags);
+ raw_spin_lock_irqsave(&idio16gpio->lock, flags);

if (value)
idio16gpio->out_state |= mask;
@@ -111,7 +111,7 @@ static void idio_16_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
else
outb(idio16gpio->out_state, idio16gpio->base);

- spin_unlock_irqrestore(&idio16gpio->lock, flags);
+ raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
}

static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
@@ -120,7 +120,7 @@ static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
unsigned long flags;

- spin_lock_irqsave(&idio16gpio->lock, flags);
+ raw_spin_lock_irqsave(&idio16gpio->lock, flags);

idio16gpio->out_state &= ~*mask;
idio16gpio->out_state |= *mask & *bits;
@@ -130,7 +130,7 @@ static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
if ((*mask >> 8) & 0xFF)
outb(idio16gpio->out_state >> 8, idio16gpio->base + 4);

- spin_unlock_irqrestore(&idio16gpio->lock, flags);
+ raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
}

static void idio_16_irq_ack(struct irq_data *data)
@@ -147,11 +147,11 @@ static void idio_16_irq_mask(struct irq_data *data)
idio16gpio->irq_mask &= ~mask;

if (!idio16gpio->irq_mask) {
- spin_lock_irqsave(&idio16gpio->lock, flags);
+ raw_spin_lock_irqsave(&idio16gpio->lock, flags);

outb(0, idio16gpio->base + 2);

- spin_unlock_irqrestore(&idio16gpio->lock, flags);
+ raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
}
}

@@ -166,11 +166,11 @@ static void idio_16_irq_unmask(struct irq_data *data)
idio16gpio->irq_mask |= mask;

if (!prev_irq_mask) {
- spin_lock_irqsave(&idio16gpio->lock, flags);
+ raw_spin_lock_irqsave(&idio16gpio->lock, flags);

inb(idio16gpio->base + 2);

- spin_unlock_irqrestore(&idio16gpio->lock, flags);
+ raw_spin_unlock_irqrestore(&idio16gpio->lock, flags);
}
}

@@ -201,11 +201,11 @@ static irqreturn_t idio_16_irq_handler(int irq, void *dev_id)
for_each_set_bit(gpio, &idio16gpio->irq_mask, chip->ngpio)
generic_handle_irq(irq_find_mapping(chip->irqdomain, gpio));

- spin_lock(&idio16gpio->lock);
+ raw_spin_lock(&idio16gpio->lock);

outb(0, idio16gpio->base + 1);

- spin_unlock(&idio16gpio->lock);
+ raw_spin_unlock(&idio16gpio->lock);

return IRQ_HANDLED;
}
@@ -249,7 +249,7 @@ static int idio_16_probe(struct device *dev, unsigned int id)
idio16gpio->base = base[id];
idio16gpio->out_state = 0xFFFF;

- spin_lock_init(&idio16gpio->lock);
+ raw_spin_lock_init(&idio16gpio->lock);

err = devm_gpiochip_add_data(dev, &idio16gpio->chip, idio16gpio);
if (err) {
--
2.12.0