From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- Documentation/arm/Samsung-S3C24XX/GPIO.txt | 122 +++++++++++++++++++++++++++++ 1 file changed, 122 insertions(+) create mode 100644 Documentation/arm/Samsung-S3C24XX/GPIO.txt (limited to 'Documentation/arm/Samsung-S3C24XX/GPIO.txt') diff --git a/Documentation/arm/Samsung-S3C24XX/GPIO.txt b/Documentation/arm/Samsung-S3C24XX/GPIO.txt new file mode 100644 index 00000000000..0822764ec27 --- /dev/null +++ b/Documentation/arm/Samsung-S3C24XX/GPIO.txt @@ -0,0 +1,122 @@ + S3C2410 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. + + +Headers +------- + + See include/asm-arm/arch-s3c2410/regs-gpio.h for the list + of GPIO pins, and the configuration values for them. This + is included by using #include + + The GPIO management functions are defined in the hardware + header include/asm-arm/arch-s3c2410/hardware.h which can be + included by #include + + A useful ammount 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 + the GPIO functions which pin is to be used. + + +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); + + Eg: + + s3c2410_gpio_cfgpin(S3C2410_GPA0, S3C2410_GPA0_ADDR0); + s3c2410_gpio_cfgpin(S3C2410_GPE8, S3C2410_GPE8_SDDAT1); + + which would turn GPA0 into the lowest Address line A0, and set + GPE8 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: + + s3c2410_gpio_getcfg(unsigned int pin); + + The return value will be from the same set of values which can be + passed to s3c2410_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 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. + + +Getting the state of a PIN +-------------------------- + + The state of a pin can be read by using the function: + + unsigned int s3c2410_gpio_getpin(unsigned int 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. + + +Getting the IRQ number associated with a PIN +-------------------------------------------- + + The following function can map the given pin number to an IRQ + number to pass to the IRQ system. + + int s3c2410_gpio_getirq(unsigned int pin); + + Note, not all pins have an IRQ. + + +Authour +------- + + +Ben Dooks, 03 October 2004 +(c) 2004 Ben Dooks, Simtec Electronics -- cgit v1.2.3