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gpio: zynq: protect direction in/out with a spinlock

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Fix race condition when changing the direction (in/out) of the GPIO pin.
The read-modify-write sequence (as coded in the driver) isn't atomic and
requires synchronization (spinlock).

Signed-off-by: Glenn Langedock <Glenn.Langedock@barco.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
This commit is contained in:
Glenn Langedock 2020-06-17 17:07:21 +05:30 committed by Bartosz Golaszewski
parent 8346b92ecd
commit fdcfec11b2
1 changed files with 11 additions and 0 deletions
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11
drivers/gpio/gpio-zynq.c
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@ -10,6 +10,7 @@
#include <linux/gpio/driver.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
@ -116,6 +117,7 @@ struct gpio_regs {
* @irq: interrupt for the GPIO device
* @p_data: pointer to platform data
* @context: context registers
* @dirlock: lock used for direction in/out synchronization
*/
struct zynq_gpio {
struct gpio_chip chip;
@ -124,6 +126,7 @@ struct zynq_gpio {
int irq;
const struct zynq_platform_data *p_data;
struct gpio_regs context;
spinlock_t dirlock; /* lock */
};
/**
@ -297,6 +300,7 @@ static int zynq_gpio_dir_in(struct gpio_chip *chip, unsigned int pin)
{
u32 reg;
unsigned int bank_num, bank_pin_num;
unsigned long flags;
struct zynq_gpio *gpio = gpiochip_get_data(chip);
zynq_gpio_get_bank_pin(pin, &bank_num, &bank_pin_num, gpio);
@ -310,9 +314,11 @@ static int zynq_gpio_dir_in(struct gpio_chip *chip, unsigned int pin)
return -EINVAL;
/* clear the bit in direction mode reg to set the pin as input */
spin_lock_irqsave(&gpio->dirlock, flags);
reg = readl_relaxed(gpio->base_addr + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
reg &= ~BIT(bank_pin_num);
writel_relaxed(reg, gpio->base_addr + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
spin_unlock_irqrestore(&gpio->dirlock, flags);
return 0;
}
@ -334,11 +340,13 @@ static int zynq_gpio_dir_out(struct gpio_chip *chip, unsigned int pin,
{
u32 reg;
unsigned int bank_num, bank_pin_num;
unsigned long flags;
struct zynq_gpio *gpio = gpiochip_get_data(chip);
zynq_gpio_get_bank_pin(pin, &bank_num, &bank_pin_num, gpio);
/* set the GPIO pin as output */
spin_lock_irqsave(&gpio->dirlock, flags);
reg = readl_relaxed(gpio->base_addr + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
reg |= BIT(bank_pin_num);
writel_relaxed(reg, gpio->base_addr + ZYNQ_GPIO_DIRM_OFFSET(bank_num));
@ -347,6 +355,7 @@ static int zynq_gpio_dir_out(struct gpio_chip *chip, unsigned int pin,
reg = readl_relaxed(gpio->base_addr + ZYNQ_GPIO_OUTEN_OFFSET(bank_num));
reg |= BIT(bank_pin_num);
writel_relaxed(reg, gpio->base_addr + ZYNQ_GPIO_OUTEN_OFFSET(bank_num));
spin_unlock_irqrestore(&gpio->dirlock, flags);
/* set the state of the pin */
zynq_gpio_set_value(chip, pin, state);
@ -885,6 +894,8 @@ static int zynq_gpio_probe(struct platform_device *pdev)
return ret;
}
spin_lock_init(&gpio->dirlock);
pm_runtime_set_active(&pdev->dev);
pm_runtime_enable(&pdev->dev);
ret = pm_runtime_get_sync(&pdev->dev);