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Diffstat (limited to 'Documentation/arm/Samsung-S3C24XX/GPIO.txt')
| -rw-r--r-- | Documentation/arm/Samsung-S3C24XX/GPIO.txt | 138 |
1 files changed, 86 insertions, 52 deletions
diff --git a/Documentation/arm/Samsung-S3C24XX/GPIO.txt b/Documentation/arm/Samsung-S3C24XX/GPIO.txt index ea7ccfc4b27..0ebd7e2244d 100644 --- a/Documentation/arm/Samsung-S3C24XX/GPIO.txt +++ b/Documentation/arm/Samsung-S3C24XX/GPIO.txt @@ -1,4 +1,4 @@ - S3C2410 GPIO Control + S3C24XX GPIO Control ==================== Introduction @@ -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 implementation. + GPIOLIB ------- @@ -24,36 +26,82 @@ 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 phased +out 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() changes 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 replaceable 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 ------- - See arch/arm/mach-s3c2410/include/mach/regs-gpio.h for the list + See arch/arm/mach-s3c24xx/include/mach/regs-gpio.h for the list of GPIO pins, and the configuration values for them. This is included by using #include <mach/regs-gpio.h> - The GPIO management functions are defined in the hardware - header arch/arm/mach-s3c2410/include/mach/hardware.h which can be - included by #include <mach/hardware.h> - - A useful amount of documentation can be found in the hardware - header on how the GPIO functions (and others) work. - - Whilst a number of these functions do make some checks on what - is passed to them, for speed of use, they may not always ensure - that the user supplied data to them is correct. - PIN Numbers ----------- Each pin has an unique number associated with it in regs-gpio.h, - eg S3C2410_GPA0 or S3C2410_GPF1. These defines are used to tell + e.g. 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 ----------------- @@ -61,26 +109,27 @@ Configuring a pin The following function allows the configuration of a given pin to be changed. - void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function); + void s3c_gpio_cfgpin(unsigned int pin, unsigned int function); - Eg: + e.g.: - s3c2410_gpio_cfgpin(S3C2410_GPA0, S3C2410_GPA0_ADDR0); - s3c2410_gpio_cfgpin(S3C2410_GPE8, S3C2410_GPE8_SDDAT1); + s3c_gpio_cfgpin(S3C2410_GPA(0), S3C_GPIO_SFN(1)); + s3c_gpio_cfgpin(S3C2410_GPE(8), S3C_GPIO_SFN(2)); - which would turn GPA0 into the lowest Address line A0, and set - GPE8 to be connected to the SDIO/MMC controller's SDDAT1 line. + 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. Reading the current configuration --------------------------------- - The current configuration of a pin can be read by using: + The current configuration of a pin can be read by using standard + gpiolib function: - s3c2410_gpio_getcfg(unsigned int pin); + s3c_gpio_getcfg(unsigned int pin); The return value will be from the same set of values which can be - passed to s3c2410_gpio_cfgpin(). + passed to s3c_gpio_cfgpin(). Configuring a pull-up resistor @@ -90,48 +139,33 @@ Configuring a pull-up resistor pull-up resistors enabled. This can be configured by the following function: - void s3c2410_gpio_pullup(unsigned int pin, unsigned int to); - - 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. - + void s3c_gpio_setpull(unsigned int pin, unsigned int to); -Getting the state of a PIN --------------------------- + Where the to value is S3C_GPIO_PULL_NONE to set the pull-up off, + and S3C_GPIO_PULL_UP to enable the specified pull-up. Any other + values are currently undefined. - The state of a pin can be read by using the function: - unsigned int s3c2410_gpio_getpin(unsigned int pin); +Getting and setting 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. - - -Setting the state of a PIN --------------------------- - - The value an pin is outputing can be modified by using the following: - - void s3c2410_gpio_setpin(unsigned int pin, unsigned int to); - - Which sets the given pin to the value. Use 0 to write 0, and 1 to - set the output to 1. + These calls are now implemented by the relevant gpiolib calls, convert + your board or driver to use gpiolib. Getting the IRQ number associated with a PIN -------------------------------------------- - The following function can map the given pin number to an IRQ + A standard gpiolib function can map the given pin number to an IRQ number to pass to the IRQ system. - int s3c2410_gpio_getirq(unsigned int pin); + int gpio_to_irq(unsigned int pin); Note, not all pins have an IRQ. -Authour +Author ------- - Ben Dooks, 03 October 2004 -(c) 2004 Ben Dooks, Simtec Electronics +Copyright 2004 Ben Dooks, Simtec Electronics |