From: Glenn Langedock <glenn.langed...@barco.com>
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.langed...@barco.com>
Signed-off-by: Michal Simek <michal.si...@xilinx.com>
Signed-off-by: Srinivas Neeli <srinivas.ne...@xilinx.com>
---
drivers/gpio/gpio-zynq.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/gpio/gpio-zynq.c b/drivers/gpio/gpio-zynq.c
index 05ba16fffdad..fb93b35ab19e 100644
--- a/drivers/gpio/gpio-zynq.c
+++ b/drivers/gpio/gpio-zynq.c
@@ -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);
--
2.7.4
