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diff --git a/Documentation/arm/samsung-s3c24xx/gpio.rst b/Documentation/arm/samsung-s3c24xx/gpio.rst deleted file mode 100644 index f4a8c800a457..000000000000 --- a/Documentation/arm/samsung-s3c24xx/gpio.rst +++ /dev/null @@ -1,172 +0,0 @@ -==================== -S3C24XX GPIO Control -==================== - -Introduction ------------- - - The s3c2410 kernel provides an interface to configure and - manipulate the state of the GPIO pins, and find out other - information about them. - - There are a number of conditions attached to the configuration - 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.rst for the core implementation. - - -GPIOLIB -------- - - With the event of the GPIOLIB in drivers/gpio, support for some - of the GPIO functions such as reading and writing a pin will - be removed in favour of this common access method. - - Once all the extant drivers have been converted, the functions - listed below will be removed (they may be marked as __deprecated - in the near future). - - The following functions now either have a `s3c_` specific variant - or are merged into gpiolib. See the definitions in - arch/arm/mach-s3c/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 while 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-s3c/regs-gpio-s3c24xx.h for the list - of GPIO pins, and the configuration values for them. This - is included by using #include <mach/regs-gpio.h> - - -PIN Numbers ------------ - - Each pin has an unique number associated with it in regs-gpio.h, - 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 ------------------ - - The following function allows the configuration of a given pin to - be changed. - - void s3c_gpio_cfgpin(unsigned int pin, unsigned int function); - - e.g.: - - s3c_gpio_cfgpin(S3C2410_GPA(0), S3C_GPIO_SFN(1)); - s3c_gpio_cfgpin(S3C2410_GPE(8), S3C_GPIO_SFN(2)); - - 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 standard - gpiolib function: - - s3c_gpio_getcfg(unsigned int pin); - - The return value will be from the same set of values which can be - passed to s3c_gpio_cfgpin(). - - -Configuring a pull-up resistor ------------------------------- - - A large proportion of the GPIO pins on the S3C2410 can have weak - pull-up resistors enabled. This can be configured by the following - function: - - void s3c_gpio_setpull(unsigned int pin, unsigned int to); - - 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. - - -Getting and setting the state of a PIN --------------------------------------- - - 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 --------------------------------------------- - - A standard gpiolib function can map the given pin number to an IRQ - number to pass to the IRQ system. - - int gpio_to_irq(unsigned int pin); - - Note, not all pins have an IRQ. - - -Author -------- - -Ben Dooks, 03 October 2004 -Copyright 2004 Ben Dooks, Simtec Electronics |