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.
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.
19 With the event of the GPIOLIB in drivers/gpio, support for some
20 of the GPIO functions such as reading and writing a pin will
21 be removed in favour of this common access method.
23 Once all the extant drivers have been converted, the functions
24 listed below will be removed (they may be marked as __deprecated
27 The following functions now either have a s3c_ specific variant
28 or are merged into gpiolib. See the definitions in
29 arch/arm/plat-samsung/include/plat/gpio-cfg.h:
31 s3c2410_gpio_setpin() gpio_set_value() or gpio_direction_output()
32 s3c2410_gpio_getpin() gpio_get_value() or gpio_direction_input()
33 s3c2410_gpio_getirq() gpio_to_irq()
34 s3c2410_gpio_cfgpin() s3c_gpio_cfgpin()
35 s3c2410_gpio_getcfg() s3c_gpio_getcfg()
36 s3c2410_gpio_pullup() s3c_gpio_setpull()
42 See arch/arm/mach-s3c2410/include/mach/regs-gpio.h for the list
43 of GPIO pins, and the configuration values for them. This
44 is included by using #include <mach/regs-gpio.h>
46 The GPIO management functions are defined in the hardware
47 header arch/arm/mach-s3c2410/include/mach/hardware.h which can be
48 included by #include <mach/hardware.h>
50 A useful amount of documentation can be found in the hardware
51 header on how the GPIO functions (and others) work.
53 Whilst a number of these functions do make some checks on what
54 is passed to them, for speed of use, they may not always ensure
55 that the user supplied data to them is correct.
61 Each pin has an unique number associated with it in regs-gpio.h,
62 eg S3C2410_GPA(0) or S3C2410_GPF(1). These defines are used to tell
63 the GPIO functions which pin is to be used.
65 With the conversion to gpiolib, there is no longer a direct conversion
66 from gpio pin number to register base address as in earlier kernels. This
67 is due to the number space required for newer SoCs where the later
68 GPIOs are not contiguous.
74 The following function allows the configuration of a given pin to
77 void s3c2410_gpio_cfgpin(unsigned int pin, unsigned int function);
81 s3c2410_gpio_cfgpin(S3C2410_GPA(0), S3C2410_GPA0_ADDR0);
82 s3c2410_gpio_cfgpin(S3C2410_GPE(8), S3C2410_GPE8_SDDAT1);
84 which would turn GPA(0) into the lowest Address line A0, and set
85 GPE(8) to be connected to the SDIO/MMC controller's SDDAT1 line.
87 The s3c_gpio_cfgpin() call is a functional replacement for this call.
90 Reading the current configuration
91 ---------------------------------
93 The current configuration of a pin can be read by using:
95 s3c2410_gpio_getcfg(unsigned int pin);
97 The return value will be from the same set of values which can be
98 passed to s3c2410_gpio_cfgpin().
100 The s3c_gpio_getcfg() call should be a functional replacement for
104 Configuring a pull-up resistor
105 ------------------------------
107 A large proportion of the GPIO pins on the S3C2410 can have weak
108 pull-up resistors enabled. This can be configured by the following
111 void s3c2410_gpio_pullup(unsigned int pin, unsigned int to);
113 Where the to value is zero to set the pull-up off, and 1 to enable
114 the specified pull-up. Any other values are currently undefined.
116 The s3c_gpio_setpull() offers similar functionality, but with the
117 ability to encode whether the pull is up or down. Currently there
118 is no 'just on' state, so up or down must be selected.
121 Getting the state of a PIN
122 --------------------------
124 The state of a pin can be read by using the function:
126 unsigned int s3c2410_gpio_getpin(unsigned int pin);
128 This will return either zero or non-zero. Do not count on this
129 function returning 1 if the pin is set.
131 This call is now implemented by the relevant gpiolib calls, convert
132 your board or driver to use gpiolib.
135 Setting the state of a PIN
136 --------------------------
138 The value an pin is outputing can be modified by using the following:
140 void s3c2410_gpio_setpin(unsigned int pin, unsigned int to);
142 Which sets the given pin to the value. Use 0 to write 0, and 1 to
145 This call is now implemented by the relevant gpiolib calls, convert
146 your board or driver to use gpiolib.
149 Getting the IRQ number associated with a PIN
150 --------------------------------------------
152 The following function can map the given pin number to an IRQ
153 number to pass to the IRQ system.
155 int s3c2410_gpio_getirq(unsigned int pin);
157 Note, not all pins have an IRQ.
159 This call is now implemented by the relevant gpiolib calls, convert
160 your board or driver to use gpiolib.
167 Ben Dooks, 03 October 2004
168 Copyright 2004 Ben Dooks, Simtec Electronics