Previously, samsung_gpio_drection_in/output function were not covered
with a spinlock.
For example, samsung_gpio_direction_output function consists of
two functions.
1. samsung_gpio_set
2. samsung_gpio_set_direction
When 2 CPUs try to control the same gpio pin heavily,
(situation like i2c control with gpio emulation)
This situation can cause below problem.
CPU 0 | CPU1
|
samsung_gpio_direction_output |
samsung_gpio_set(pin A as 1) | samsung_gpio_direction_output
| samsung_gpio_set(pin A as 0)
samsung_gpio_set_direction |
| samsung_gpio_set_direction
The initial value of pin A will be set as 0 while we wanted to set pin A as 1.
This patch modifies samsung_gpio_direction_in/output function
to be done in one spinlock to fix race condition.
Additionally, the new samsung_gpio_set_value was added to implement
gpio set callback(samsung_gpio_set) with spinlock using this function.
Cc: stable@vger.kernel.org
Signed-off-by: Youngmin Nam <ym0914@gmail.com>
Acked-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
d9ff0eb9ca