gpio: timbgpio: use a copy of the IER register to avoid it being trashed
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>
diff --git a/drivers/gpio/timbgpio.c b/drivers/gpio/timbgpio.c
index ddd0531..4529366 100644
--- a/drivers/gpio/timbgpio.c
+++ b/drivers/gpio/timbgpio.c
@@ -47,6 +47,7 @@
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 @@
{
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 @@
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 = {