1 S3C2410 GPIO Control 2 ==================== 3 4Introduction 5------------ 6 7 The s3c2410 kernel provides an interface to configure and 8 manipulate the state of the GPIO pins, and find out other 9 information about them. 10 11 There are a number of conditions attached to the configuration 12 of the s3c2410 GPIO system, please read the Samsung provided 13 data-sheet/users manual to find out the complete list. 14 15 16Headers 17------- 18 19 See include/asm-arm/arch-s3c2410/regs-gpio.h for the list 20 of GPIO pins, and the configuration values for them. This 21 is included by using #include <asm/arch/regs-gpio.h> 22 23 The GPIO management functions are defined in the hardware 24 header include/asm-arm/arch-s3c2410/hardware.h which can be 25 included by #include <asm/arch/hardware.h> 26 27 A useful amount of documentation can be found in the hardware 28 header on how the GPIO functions (and others) work. 29 30 Whilst a number of these functions do make some checks on what 31 is passed to them, for speed of use, they may not always ensure 32 that the user supplied data to them is correct. 33 34 35PIN Numbers 36----------- 37 38 Each pin has an unique number associated with it in regs-gpio.h, 39 eg S3C2410_GPA0 or S3C2410_GPF1. These defines are used to tell 40 the GPIO functions which pin is to be used. 41 42 43Configuring a pin 44----------------- 45 46 The following function allows the configuration of a given pin to 47 be changed. 48 49 void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function); 50 51 Eg: 52 53 s3c2410_gpio_cfgpin(S3C2410_GPA0, S3C2410_GPA0_ADDR0); 54 s3c2410_gpio_cfgpin(S3C2410_GPE8, S3C2410_GPE8_SDDAT1); 55 56 which would turn GPA0 into the lowest Address line A0, and set 57 GPE8 to be connected to the SDIO/MMC controller's SDDAT1 line. 58 59 60Reading the current configuration 61--------------------------------- 62 63 The current configuration of a pin can be read by using: 64 65 s3c2410_gpio_getcfg(unsigned int pin); 66 67 The return value will be from the same set of values which can be 68 passed to s3c2410_gpio_cfgpin(). 69 70 71Configuring a pull-up resistor 72------------------------------ 73 74 A large proportion of the GPIO pins on the S3C2410 can have weak 75 pull-up resistors enabled. This can be configured by the following 76 function: 77 78 void s3c2410_gpio_pullup(unsigned int pin, unsigned int to); 79 80 Where the to value is zero to set the pull-up off, and 1 to enable 81 the specified pull-up. Any other values are currently undefined. 82 83 84Getting the state of a PIN 85-------------------------- 86 87 The state of a pin can be read by using the function: 88 89 unsigned int s3c2410_gpio_getpin(unsigned int pin); 90 91 This will return either zero or non-zero. Do not count on this 92 function returning 1 if the pin is set. 93 94 95Setting the state of a PIN 96-------------------------- 97 98 The value an pin is outputing can be modified by using the following: 99 100 void s3c2410_gpio_setpin(unsigned int pin, unsigned int to); 101 102 Which sets the given pin to the value. Use 0 to write 0, and 1 to 103 set the output to 1. 104 105 106Getting the IRQ number associated with a PIN 107-------------------------------------------- 108 109 The following function can map the given pin number to an IRQ 110 number to pass to the IRQ system. 111 112 int s3c2410_gpio_getirq(unsigned int pin); 113 114 Note, not all pins have an IRQ. 115 116 117Authour 118------- 119 120 121Ben Dooks, 03 October 2004 122(c) 2004 Ben Dooks, Simtec Electronics 123