Where is the GPIO header file ("linux/gpio.h")?

Question

I've been reading about the linux GPIO functions and tried to make a small example using the function gpio_is_valid, but the compile fails because it can't find linux/gpio.h.

#include <iostream>

#include <linux/gpio.h>

int main()
{
    const bool is17Valid = !!gpio_is_valid(17);
    if (is17Valid)
    {
        std::cout << "17 is valid!" << std::endl;
    }
    else
    {
        std::cout << "17 is *not* valid!" << std::endl;
    }

    return 0;
}

Is linux/gpio.h available on the Raspberry Pi? If not, are none of the functions described in the linux documentation available?

I'm using the original Debian "Squeeze" image.

Did you setup up the linker?What are the error messages? Would "return 0;" be pointless since it isn't C? — ArchHaskeller, Jul 18 '12 at 21:31
I'm using the original Debian "Squeeze" image and the error message was, can't find "linux/gpio.h". — Mark Ingram, Jul 18 '12 at 21:34
You have to interact with the GPIO as `root`. Are you `root`? — Jivings, Jul 18 '12 at 22:54
@Haskeller: C++ is backwards compatible with C, so you still need `return 0;` because you're in a function that returns an `int`. Omitting this results in a compiler error. — Malvineous, Jul 18 '12 at 23:07
None of the driving examples I can find use `linux/gpio.h`; have you got an example of one that does? — Alex Chamberlain, Jul 19 '12 at 06:23
@AlexChamberlain: I was guessing that `linux/gpio.h` is inaccessible without root access. I don't see how that is irrelevant. — Jivings, Jul 19 '12 at 09:20
@Jivings That would be an awful plan! Root permissions should be needed to access GPIO (they are memory mapped), but you don't want to be running `gcc` as root! — Alex Chamberlain, Jul 19 '12 at 09:23

score 1 · Answer 1 · answered Jul 18 '12 at 23:05

1

Assuming you're compiling on the Pi itself, you'll probably need to install some development packages, as precompiled binaries don't need header files present to run (so they're not installed by default.)

I think in this case the name of the package you want is probably linux-headers, which will put gpio.h into /usr/include/linux/gpio.h. Because the file sits in /usr/include it means you don't need to specify this part of the path either in your code or to the compiler, so #include <linux/gpio.h> as you have there is enough, once you've installed the correct package.

answered Jul 18 '12 at 23:05

Malvineous

1,694
11
20

Has anyone tested this? – Alex Chamberlain Jul 19 '12 at 06:06
Through a series of links I managed to find the following - https://github.com/raspberrypi/linux/blob/rpi-patches/include/linux/gpio.h - it looks like the functions aren't implemented anyway! – Mark Ingram Jul 19 '12 at 08:19

score 1 · Accepted Answer · edited Apr 13 '17 at 12:56

1

I don't think you need linux/gpio.h - as you stated in a comment, the RPi repo has a pretty redundant version of it.

The GPIO's are memory-mapped, which you can read about it in How does memory-mapped I/O addressing work?.

edited Apr 13 '17 at 12:56

Community

1

answered Jul 19 '12 at 09:28

Alex Chamberlain

15,120
13
63
112

Where is the GPIO header file ("linux/gpio.h")?

2 Answers2