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| -rw-r--r-- | Documentation/arm/Samsung-S3C24XX/GPIO.txt | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/Documentation/arm/Samsung-S3C24XX/GPIO.txt b/Documentation/arm/Samsung-S3C24XX/GPIO.txt index 9fe5feac212..228ecb61d2f 100644 --- a/Documentation/arm/Samsung-S3C24XX/GPIO.txt +++ b/Documentation/arm/Samsung-S3C24XX/GPIO.txt @@ -36,6 +36,50 @@ GPIOLIB s3c2410_gpio_pullup() s3c_gpio_setpull() +GPIOLIB conversion +------------------ + +If you need to convert your board or driver to use gpiolib from the exiting +s3c2410 api, then here are some notes on the process. + +1) If your board is exclusively using an GPIO, say to control peripheral + power, then it will require to claim the gpio with gpio_request() before + it can use it. + + It is recommended to check the return value, with at least WARN_ON() + during initialisation. + +2) The s3c2410_gpio_cfgpin() can be directly replaced with s3c_gpio_cfgpin() + as they have the same arguments, and can either take the pin specific + values, or the more generic special-function-number arguments. + +3) s3c2410_gpio_pullup() changs have the problem that whilst the + s3c2410_gpio_pullup(x, 1) can be easily translated to the + s3c_gpio_setpull(x, S3C_GPIO_PULL_NONE), the s3c2410_gpio_pullup(x, 0) + are not so easy. + + The s3c2410_gpio_pullup(x, 0) case enables the pull-up (or in the case + of some of the devices, a pull-down) and as such the new API distinguishes + between the UP and DOWN case. There is currently no 'just turn on' setting + which may be required if this becomes a problem. + +4) s3c2410_gpio_setpin() can be replaced by gpio_set_value(), the old call + does not implicitly configure the relevant gpio to output. The gpio + direction should be changed before using gpio_set_value(). + +5) s3c2410_gpio_getpin() is replaceable by gpio_get_value() if the pin + has been set to input. It is currently unknown what the behaviour is + when using gpio_get_value() on an output pin (s3c2410_gpio_getpin + would return the value the pin is supposed to be outputting). + +6) s3c2410_gpio_getirq() should be directly replacable with the + gpio_to_irq() call. + +The s3c2410_gpio and gpio_ calls have always operated on the same gpio +numberspace, so there is no problem with converting the gpio numbering +between the calls. + + Headers ------- |