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

Julia Cartwright
2017-03-21T22:51:03Z

The pci-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-pci-idio-16.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/gpio/gpio-pci-idio-16.c b/drivers/gpio/gpio-pci-idio-16.c
index 269ab628634b..7de4f6a2cb49 100644
--- a/drivers/gpio/gpio-pci-idio-16.c
+++ b/drivers/gpio/gpio-pci-idio-16.c
@@ -59,7 +59,7 @@ struct idio_16_gpio_reg {
*/
struct idio_16_gpio {
struct gpio_chip chip;
- spinlock_t lock;
+ raw_spinlock_t lock;
struct idio_16_gpio_reg __iomem *reg;
unsigned long irq_mask;
};
@@ -121,7 +121,7 @@ static void idio_16_gpio_set(struct gpio_chip *chip, unsigned int offset,
} else
base = &idio16gpio->reg->out0_7;

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

if (value)
out_state = ioread8(base) | mask;
@@ -130,7 +130,7 @@ static void idio_16_gpio_set(struct gpio_chip *chip, unsigned int offset,

iowrite8(out_state, 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,
@@ -140,7 +140,7 @@ static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
unsigned long flags;
unsigned int out_state;

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

/* process output lines 0-7 */
if (*mask & 0xFF) {
@@ -160,7 +160,7 @@ static void idio_16_gpio_set_multiple(struct gpio_chip *chip,
iowrite8(out_state, &idio16gpio->reg->out8_15);
}

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

static void idio_16_irq_ack(struct irq_data *data)
@@ -177,11 +177,11 @@ 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);

iowrite8(0, &idio16gpio->reg->irq_ctl);

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

@@ -196,11 +196,11 @@ 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);

ioread8(&idio16gpio->reg->irq_ctl);

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

@@ -229,11 +229,11 @@ static irqreturn_t idio_16_irq_handler(int irq, void *dev_id)
struct gpio_chip *const chip = &idio16gpio->chip;
int gpio;

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

irq_status = ioread8(&idio16gpio->reg->irq_status);

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

/* Make sure our device generated IRQ */
if (!(irq_status & 0x3) || !(irq_status & 0x4))
@@ -242,12 +242,12 @@ 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);

/* Clear interrupt */
iowrite8(0, &idio16gpio->reg->in0_7);

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

return IRQ_HANDLED;
}
@@ -302,7 +302,7 @@ static int idio_16_probe(struct pci_dev *pdev, const struct pci_device_id *id)
idio16gpio->chip.set = idio_16_gpio_set;
idio16gpio->chip.set_multiple = idio_16_gpio_set_multiple;

- 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