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gpio: Add fast access to GPIO level

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The current gpio_get_level() is pretty slow because it looks things up each
time. Add a new function to find out the register address and mask to use
to check the value for a particular GPIO.

Time-critical code can then use this to check a GPIO.

BUG=chrome-os-partner:10146
TEST=manual:
build and boot on snow;
Power on the board, hold power button for 10s and see that it powers off
Power control still works, thus GPIOs are functional

Change-Id: Ifc6c56f5cb811e0243e7712725a51948eabd42ab
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/26175
This commit is contained in:
Simon Glass
2012-06-24 12:00:07 -07:00
committed by Gerrit
parent 9a4eff992f
commit aa64550a3f
2 changed files with 19 additions and 0 deletions
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7
chip/stm32/gpio-stm32f100.c
View File

@@ -174,6 +174,13 @@ void gpio_set_alternate_function(int port, int mask, int func)
}
uint16_t *gpio_get_level_reg(enum gpio_signal signal, uint32_t *mask)
{
*mask = gpio_list[signal].mask;
return (uint16_t *)&STM32_GPIO_IDR_OFF(gpio_list[signal].port);
}
int gpio_get_level(enum gpio_signal signal)
{
return !!(STM32_GPIO_IDR_OFF(gpio_list[signal].port) &

12
include/gpio.h
View File

@@ -65,6 +65,18 @@ int gpio_pre_init(void);
/* Get the current value of a signal (0=low, 1=hi). */
int gpio_get_level(enum gpio_signal signal);
/**
* Get faster access to a GPIO level
*
* Use this function to find out the register address and mask for a GPIO
* value. Then you can just check that instead of calling gpio_get_level().
*
* @param signal Signal to return details for
* @param mask Mask value to use
* @return pointer to register to read to get GPIO value
*/
uint16_t *gpio_get_level_reg(enum gpio_signal signal, uint32_t *mask);
/**
* Returns the name of a given GPIO signal.
*