gpio: ws16c48: make use of raw_spinlock variants

The ws16c48 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>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpio-ws16c48.c b/drivers/gpio/gpio-ws16c48.c
index 901b5ccb032ddd53eb7e20b04044a68eb721ce9d..87d63695dfcf796d73c04c795ab2eaf17d2acb74 100644 (file)
--- a/drivers/gpio/gpio-ws16c48.c
+++ b/drivers/gpio/gpio-ws16c48.c
@@ -51,7 +51,7 @@ struct ws16c48_gpio {
        struct gpio_chip chip;
        unsigned char io_state[6];
        unsigned char out_state[6];
-       spinlock_t lock;
+       raw_spinlock_t lock;
        unsigned long irq_mask;
        unsigned long flow_mask;
        unsigned base;
@@ -73,13 +73,13 @@ static int ws16c48_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
        const unsigned mask = BIT(offset % 8);
        unsigned long flags;
 
-       spin_lock_irqsave(&ws16c48gpio->lock, flags);
+       raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
        ws16c48gpio->io_state[port] |= mask;
        ws16c48gpio->out_state[port] &= ~mask;
        outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
 
-       spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+       raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 
        return 0;
 }
@@ -92,7 +92,7 @@ static int ws16c48_gpio_direction_output(struct gpio_chip *chip,
        const unsigned mask = BIT(offset % 8);
        unsigned long flags;
 
-       spin_lock_irqsave(&ws16c48gpio->lock, flags);
+       raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
        ws16c48gpio->io_state[port] &= ~mask;
        if (value)
@@ -101,7 +101,7 @@ static int ws16c48_gpio_direction_output(struct gpio_chip *chip,
                ws16c48gpio->out_state[port] &= ~mask;
        outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
 
-       spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+       raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 
        return 0;
 }
@@ -114,17 +114,17 @@ static int ws16c48_gpio_get(struct gpio_chip *chip, unsigned offset)
        unsigned long flags;
        unsigned port_state;
 
-       spin_lock_irqsave(&ws16c48gpio->lock, flags);
+       raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
        /* ensure that GPIO is set for input */
        if (!(ws16c48gpio->io_state[port] & mask)) {
-               spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+               raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
                return -EINVAL;
        }
 
        port_state = inb(ws16c48gpio->base + port);
 
-       spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+       raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 
        return !!(port_state & mask);
 }
@@ -136,11 +136,11 @@ static void ws16c48_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
        const unsigned mask = BIT(offset % 8);
        unsigned long flags;
 
-       spin_lock_irqsave(&ws16c48gpio->lock, flags);
+       raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
        /* ensure that GPIO is set for output */
        if (ws16c48gpio->io_state[port] & mask) {
-               spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+               raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
                return;
        }
 
@@ -150,7 +150,7 @@ static void ws16c48_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
                ws16c48gpio->out_state[port] &= ~mask;
        outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
 
-       spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+       raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 }
 
 static void ws16c48_gpio_set_multiple(struct gpio_chip *chip,
@@ -178,14 +178,14 @@ static void ws16c48_gpio_set_multiple(struct gpio_chip *chip,
                iomask = mask[BIT_WORD(i)] & ~ws16c48gpio->io_state[port];
                bitmask = iomask & bits[BIT_WORD(i)];
 
-               spin_lock_irqsave(&ws16c48gpio->lock, flags);
+               raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
                /* update output state data and set device gpio register */
                ws16c48gpio->out_state[port] &= ~iomask;
                ws16c48gpio->out_state[port] |= bitmask;
                outb(ws16c48gpio->out_state[port], ws16c48gpio->base + port);
 
-               spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+               raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 
                /* prepare for next gpio register set */
                mask[BIT_WORD(i)] >>= gpio_reg_size;
@@ -207,7 +207,7 @@ static void ws16c48_irq_ack(struct irq_data *data)
        if (port > 2)
                return;
 
-       spin_lock_irqsave(&ws16c48gpio->lock, flags);
+       raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
        port_state = ws16c48gpio->irq_mask >> (8*port);
 
@@ -216,7 +216,7 @@ static void ws16c48_irq_ack(struct irq_data *data)
        outb(port_state | mask, ws16c48gpio->base + 8 + port);
        outb(0xC0, ws16c48gpio->base + 7);
 
-       spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+       raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 }
 
 static void ws16c48_irq_mask(struct irq_data *data)
@@ -232,7 +232,7 @@ static void ws16c48_irq_mask(struct irq_data *data)
        if (port > 2)
                return;
 
-       spin_lock_irqsave(&ws16c48gpio->lock, flags);
+       raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
        ws16c48gpio->irq_mask &= ~mask;
 
@@ -240,7 +240,7 @@ static void ws16c48_irq_mask(struct irq_data *data)
        outb(ws16c48gpio->irq_mask >> (8*port), ws16c48gpio->base + 8 + port);
        outb(0xC0, ws16c48gpio->base + 7);
 
-       spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+       raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 }
 
 static void ws16c48_irq_unmask(struct irq_data *data)
@@ -256,7 +256,7 @@ static void ws16c48_irq_unmask(struct irq_data *data)
        if (port > 2)
                return;
 
-       spin_lock_irqsave(&ws16c48gpio->lock, flags);
+       raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
        ws16c48gpio->irq_mask |= mask;
 
@@ -264,7 +264,7 @@ static void ws16c48_irq_unmask(struct irq_data *data)
        outb(ws16c48gpio->irq_mask >> (8*port), ws16c48gpio->base + 8 + port);
        outb(0xC0, ws16c48gpio->base + 7);
 
-       spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+       raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 }
 
 static int ws16c48_irq_set_type(struct irq_data *data, unsigned flow_type)
@@ -280,7 +280,7 @@ static int ws16c48_irq_set_type(struct irq_data *data, unsigned flow_type)
        if (port > 2)
                return -EINVAL;
 
-       spin_lock_irqsave(&ws16c48gpio->lock, flags);
+       raw_spin_lock_irqsave(&ws16c48gpio->lock, flags);
 
        switch (flow_type) {
        case IRQ_TYPE_NONE:
@@ -292,7 +292,7 @@ static int ws16c48_irq_set_type(struct irq_data *data, unsigned flow_type)
                ws16c48gpio->flow_mask &= ~mask;
                break;
        default:
-               spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+               raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
                return -EINVAL;
        }
 
@@ -300,7 +300,7 @@ static int ws16c48_irq_set_type(struct irq_data *data, unsigned flow_type)
        outb(ws16c48gpio->flow_mask >> (8*port), ws16c48gpio->base + 8 + port);
        outb(0xC0, ws16c48gpio->base + 7);
 
-       spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
+       raw_spin_unlock_irqrestore(&ws16c48gpio->lock, flags);
 
        return 0;
 }
@@ -387,7 +387,7 @@ static int ws16c48_probe(struct device *dev, unsigned int id)
        ws16c48gpio->chip.set_multiple = ws16c48_gpio_set_multiple;
        ws16c48gpio->base = base[id];
 
-       spin_lock_init(&ws16c48gpio->lock);
+       raw_spin_lock_init(&ws16c48gpio->lock);
 
        err = devm_gpiochip_add_data(dev, &ws16c48gpio->chip, ws16c48gpio);
        if (err) {