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Commit 21d01c9c authored by Julia Cartwright's avatar Julia Cartwright Committed by Linus Walleij
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gpio: altera: make use of raw_spinlock variants 



The altera 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: default avatarJulia Cartwright <julia@ni.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 660549e0

drivers/gpio/gpio-altera.c

+12 −12
Original line number Diff line number Diff line
@@ -38,7 +38,7 @@ 
*/

struct altera_gpio_chip {

	struct of_mm_gpio_chip mmchip;

	spinlock_t gpio_lock;

	raw_spinlock_t gpio_lock;

	int interrupt_trigger;

	int mapped_irq;

};
@@ -53,12 +53,12 @@ static void altera_gpio_irq_unmask(struct irq_data *d) 
	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));

	mm_gc = &altera_gc->mmchip;



	spin_lock_irqsave(&altera_gc->gpio_lock, flags);

	raw_spin_lock_irqsave(&altera_gc->gpio_lock, flags);

	intmask = readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);

	/* Set ALTERA_GPIO_IRQ_MASK bit to unmask */

	intmask |= BIT(irqd_to_hwirq(d));

	writel(intmask, mm_gc->regs + ALTERA_GPIO_IRQ_MASK);

	spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);

	raw_spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);

}



static void altera_gpio_irq_mask(struct irq_data *d)
@@ -71,12 +71,12 @@ static void altera_gpio_irq_mask(struct irq_data *d) 
	altera_gc = gpiochip_get_data(irq_data_get_irq_chip_data(d));

	mm_gc = &altera_gc->mmchip;



	spin_lock_irqsave(&altera_gc->gpio_lock, flags);

	raw_spin_lock_irqsave(&altera_gc->gpio_lock, flags);

	intmask = readl(mm_gc->regs + ALTERA_GPIO_IRQ_MASK);

	/* Clear ALTERA_GPIO_IRQ_MASK bit to mask */

	intmask &= ~BIT(irqd_to_hwirq(d));

	writel(intmask, mm_gc->regs + ALTERA_GPIO_IRQ_MASK);

	spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);

	raw_spin_unlock_irqrestore(&altera_gc->gpio_lock, flags);

}



/**
@@ -143,14 +143,14 @@ static void altera_gpio_set(struct gpio_chip *gc, unsigned offset, int value) 
	mm_gc = to_of_mm_gpio_chip(gc);

	chip = gpiochip_get_data(gc);



	spin_lock_irqsave(&chip->gpio_lock, flags);

	raw_spin_lock_irqsave(&chip->gpio_lock, flags);

	data_reg = readl(mm_gc->regs + ALTERA_GPIO_DATA);

	if (value)

		data_reg |= BIT(offset);

	else

		data_reg &= ~BIT(offset);

	writel(data_reg, mm_gc->regs + ALTERA_GPIO_DATA);

	spin_unlock_irqrestore(&chip->gpio_lock, flags);

	raw_spin_unlock_irqrestore(&chip->gpio_lock, flags);

}



static int altera_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
@@ -163,12 +163,12 @@ static int altera_gpio_direction_input(struct gpio_chip *gc, unsigned offset) 
	mm_gc = to_of_mm_gpio_chip(gc);

	chip = gpiochip_get_data(gc);



	spin_lock_irqsave(&chip->gpio_lock, flags);

	raw_spin_lock_irqsave(&chip->gpio_lock, flags);

	/* Set pin as input, assumes software controlled IP */

	gpio_ddr = readl(mm_gc->regs + ALTERA_GPIO_DIR);

	gpio_ddr &= ~BIT(offset);

	writel(gpio_ddr, mm_gc->regs + ALTERA_GPIO_DIR);

	spin_unlock_irqrestore(&chip->gpio_lock, flags);

	raw_spin_unlock_irqrestore(&chip->gpio_lock, flags);



	return 0;

}
@@ -184,7 +184,7 @@ static int altera_gpio_direction_output(struct gpio_chip *gc, 
	mm_gc = to_of_mm_gpio_chip(gc);

	chip = gpiochip_get_data(gc);



	spin_lock_irqsave(&chip->gpio_lock, flags);

	raw_spin_lock_irqsave(&chip->gpio_lock, flags);

	/* Sets the GPIO value */

	data_reg = readl(mm_gc->regs + ALTERA_GPIO_DATA);

	if (value)
@@ -197,7 +197,7 @@ static int altera_gpio_direction_output(struct gpio_chip *gc, 
	gpio_ddr = readl(mm_gc->regs + ALTERA_GPIO_DIR);

	gpio_ddr |= BIT(offset);

	writel(gpio_ddr, mm_gc->regs + ALTERA_GPIO_DIR);

	spin_unlock_irqrestore(&chip->gpio_lock, flags);

	raw_spin_unlock_irqrestore(&chip->gpio_lock, flags);



	return 0;

}
@@ -266,7 +266,7 @@ static int altera_gpio_probe(struct platform_device *pdev) 
	if (!altera_gc)

		return -ENOMEM;



	spin_lock_init(&altera_gc->gpio_lock);

	raw_spin_lock_init(&altera_gc->gpio_lock);



	if (of_property_read_u32(node, "altr,ngpio", &reg))

		/* By default assume maximum ngpio */