linux-kernel - [PATCH 4/7] gpio: omap: protect regs access in omap_gpio_irq

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Date:	Tue, 18 Aug 2015 14:10:55 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>, <ssantosh@...nel.org>,
	Kevin Hilman <khilman@...prootsystems.com>, <tony@...mide.com>
CC:	Javier Martinez Canillas <javier@...hile0.org>,
	<linux-omap@...r.kernel.org>, <linux-gpio@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	Grygorii Strashko <grygorii.strashko@...com>
Subject: [PATCH 4/7] gpio: omap: protect regs access in omap_gpio_irq_handler

The access to HW registers has to be be protected in
omap_gpio_irq_handler(), as it may race with code executed on
another CPUs.

Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
---
 drivers/gpio/gpio-omap.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index 9ed5a67..1f02acd 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -718,6 +718,7 @@ static void omap_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
 	int unmasked = 0;
 	struct irq_chip *irqchip = irq_desc_get_chip(desc);
 	struct gpio_chip *chip = irq_desc_get_handler_data(desc);
+	unsigned long lock_flags;
 
 	chained_irq_enter(irqchip, desc);
 
@@ -732,6 +733,8 @@ static void omap_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
 		u32 isr_saved, level_mask = 0;
 		u32 enabled;
 
+		raw_spin_lock_irqsave(&bank->lock, lock_flags);
+
 		enabled = omap_get_gpio_irqbank_mask(bank);
 		isr_saved = isr = readl_relaxed(isr_reg) & enabled;
 
@@ -745,6 +748,8 @@ static void omap_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
 		omap_clear_gpio_irqbank(bank, isr_saved & ~level_mask);
 		omap_enable_gpio_irqbank(bank, isr_saved & ~level_mask);
 
+		raw_spin_unlock_irqrestore(&bank->lock, lock_flags);
+
 		/* if there is only edge sensitive GPIO pin interrupts
 		configured, we could unmask GPIO bank interrupt immediately */
 		if (!level_mask && !unmasked) {
@@ -759,6 +764,7 @@ static void omap_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
 			bit = __ffs(isr);
 			isr &= ~(BIT(bit));
 
+			raw_spin_lock_irqsave(&bank->lock, lock_flags);
 			/*
 			 * Some chips can't respond to both rising and falling
 			 * at the same time.  If this irq was requested with
@@ -769,6 +775,8 @@ static void omap_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
 			if (bank->toggle_mask & (BIT(bit)))
 				omap_toggle_gpio_edge_triggering(bank, bit);
 
+			raw_spin_unlock_irqrestore(&bank->lock, lock_flags);
+
 			generic_handle_irq(irq_find_mapping(bank->chip.irqdomain,
 							    bit));
 		}
-- 
2.5.0

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