Commit 76d800a5 authored by Tomas Hallenberg's avatar Tomas Hallenberg Committed by Linus Torvalds
Browse files

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: default avatarTomas Hallenberg <tomas.hallenberg@pelagicore.com>
Acked-by: default avatarRichard Röjfors <richard.rojfors@pelagicore.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 09cd9527

drivers/gpio/timbgpio.c

+19 −2
Original line number Diff line number Diff line
@@ -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 = {

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