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gpio: timbgpio: use a copy of the IER register to avoid it being trashed

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Some versions of the hardware can trash the IER register if simultaneous
interrupts occur.  This patch works around it by using a local copy of the
register and restoring it after every interrupt.

Signed-off-by: Tomas Hallenberg <tomas.hallenberg@pelagicore.com>
Acked-by: Richard Röjfors <richard.rojfors@pelagicore.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tomas Hallenberg 2010-10-27 15:33:17 -07:00 committed by Linus Torvalds
parent 09cd9527d6
commit 76d800a5b6
1 changed files with 19 additions and 2 deletions
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21
drivers/gpio/timbgpio.c
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@ -47,6 +47,7 @@ struct timbgpio {
spinlock_t lock; /* mutual exclusion */
struct gpio_chip gpio;
int irq_base;
unsigned long last_ier;
};
static int timbgpio_update_bit(struct gpio_chip *gpio, unsigned index,
@ -112,16 +113,24 @@ static void timbgpio_irq_disable(unsigned irq)
{
struct timbgpio *tgpio = get_irq_chip_data(irq);
int offset = irq - tgpio->irq_base;
unsigned long flags;
timbgpio_update_bit(&tgpio->gpio, offset, TGPIO_IER, 0);
spin_lock_irqsave(&tgpio->lock, flags);
tgpio->last_ier &= ~(1 << offset);
iowrite32(tgpio->last_ier, tgpio->membase + TGPIO_IER);
spin_unlock_irqrestore(&tgpio->lock, flags);
}
static void timbgpio_irq_enable(unsigned irq)
{
struct timbgpio *tgpio = get_irq_chip_data(irq);
int offset = irq - tgpio->irq_base;
unsigned long flags;
timbgpio_update_bit(&tgpio->gpio, offset, TGPIO_IER, 1);
spin_lock_irqsave(&tgpio->lock, flags);
tgpio->last_ier |= 1 << offset;
iowrite32(tgpio->last_ier, tgpio->membase + TGPIO_IER);
spin_unlock_irqrestore(&tgpio->lock, flags);
}
static int timbgpio_irq_type(unsigned irq, unsigned trigger)
@ -194,8 +203,16 @@ static void timbgpio_irq(unsigned int irq, struct irq_desc *desc)
ipr = ioread32(tgpio->membase + TGPIO_IPR);
iowrite32(ipr, tgpio->membase + TGPIO_ICR);
/*
* Some versions of the hardware trash the IER register if more than
* one interrupt is received simultaneously.
*/
iowrite32(0, tgpio->membase + TGPIO_IER);
for_each_set_bit(offset, &ipr, tgpio->gpio.ngpio)
generic_handle_irq(timbgpio_to_irq(&tgpio->gpio, offset));
iowrite32(tgpio->last_ier, tgpio->membase + TGPIO_IER);
}
static struct irq_chip timbgpio_irqchip = {