diff options
Diffstat (limited to 'Documentation/arm/Samsung-S3C24XX/GPIO.txt')
| -rw-r--r-- | Documentation/arm/Samsung-S3C24XX/GPIO.txt | 81 |
1 files changed, 79 insertions, 2 deletions
diff --git a/Documentation/arm/Samsung-S3C24XX/GPIO.txt b/Documentation/arm/Samsung-S3C24XX/GPIO.txt index 2af2cf39915f..816d6071669e 100644 --- a/Documentation/arm/Samsung-S3C24XX/GPIO.txt +++ b/Documentation/arm/Samsung-S3C24XX/GPIO.txt @@ -12,6 +12,8 @@ Introduction of the s3c2410 GPIO system, please read the Samsung provided data-sheet/users manual to find out the complete list. + See Documentation/arm/Samsung/GPIO.txt for the core implemetation. + GPIOLIB ------- @@ -24,8 +26,60 @@ GPIOLIB listed below will be removed (they may be marked as __deprecated in the near future). - - s3c2410_gpio_getpin - - s3c2410_gpio_setpin + The following functions now either have a s3c_ specific variant + or are merged into gpiolib. See the definitions in + arch/arm/plat-samsung/include/plat/gpio-cfg.h: + + s3c2410_gpio_setpin() gpio_set_value() or gpio_direction_output() + s3c2410_gpio_getpin() gpio_get_value() or gpio_direction_input() + s3c2410_gpio_getirq() gpio_to_irq() + s3c2410_gpio_cfgpin() s3c_gpio_cfgpin() + s3c2410_gpio_getcfg() s3c_gpio_getcfg() + 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 @@ -54,6 +108,11 @@ PIN Numbers eg S3C2410_GPA(0) or S3C2410_GPF(1). These defines are used to tell the GPIO functions which pin is to be used. + With the conversion to gpiolib, there is no longer a direct conversion + from gpio pin number to register base address as in earlier kernels. This + is due to the number space required for newer SoCs where the later + GPIOs are not contiguous. + Configuring a pin ----------------- @@ -71,6 +130,8 @@ Configuring a pin which would turn GPA(0) into the lowest Address line A0, and set GPE(8) to be connected to the SDIO/MMC controller's SDDAT1 line. + The s3c_gpio_cfgpin() call is a functional replacement for this call. + Reading the current configuration --------------------------------- @@ -82,6 +143,9 @@ Reading the current configuration The return value will be from the same set of values which can be passed to s3c2410_gpio_cfgpin(). + The s3c_gpio_getcfg() call should be a functional replacement for + this call. + Configuring a pull-up resistor ------------------------------ @@ -95,6 +159,10 @@ Configuring a pull-up resistor Where the to value is zero to set the pull-up off, and 1 to enable the specified pull-up. Any other values are currently undefined. + The s3c_gpio_setpull() offers similar functionality, but with the + ability to encode whether the pull is up or down. Currently there + is no 'just on' state, so up or down must be selected. + Getting the state of a PIN -------------------------- @@ -106,6 +174,9 @@ Getting the state of a PIN This will return either zero or non-zero. Do not count on this function returning 1 if the pin is set. + This call is now implemented by the relevant gpiolib calls, convert + your board or driver to use gpiolib. + Setting the state of a PIN -------------------------- @@ -117,6 +188,9 @@ Setting the state of a PIN Which sets the given pin to the value. Use 0 to write 0, and 1 to set the output to 1. + This call is now implemented by the relevant gpiolib calls, convert + your board or driver to use gpiolib. + Getting the IRQ number associated with a PIN -------------------------------------------- @@ -128,6 +202,9 @@ Getting the IRQ number associated with a PIN Note, not all pins have an IRQ. + This call is now implemented by the relevant gpiolib calls, convert + your board or driver to use gpiolib. + Authour ------- |