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1da177e4 LT |
1 | S3C2410 GPIO Control |
2 | ==================== | |
3 | ||
4 | Introduction | |
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 | ||
16 | Headers | |
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 | ||
3f6dee9b | 27 | A useful amount of documentation can be found in the hardware |
1da177e4 LT |
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 | ||
35 | PIN 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 | ||
43 | Configuring 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 | ||
60 | Reading 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 | ||
71 | Configuring 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 | ||
84 | Getting 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 | ||
95 | Setting 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 | ||
106 | Getting 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 | ||
117 | Authour | |
118 | ------- | |
119 | ||
120 | ||
121 | Ben Dooks, 03 October 2004 | |
122 | (c) 2004 Ben Dooks, Simtec Electronics |