Re: IBM OCP GPIO driver for linux 2.6

In article <1154603751.17247.10.camel@jb-portable> you write:

I'm porting a custom PPC 405GP card based on a Walnut from Montavista
Linux 3.0 (kernel 2.4.18) to linux 2.6, and I was wondering if there is
a port of the IBM OCP GPIO driver (a char driver providing
device /dev/gpio, major 10 minor 185). The driver was written by Armin
Kuster, and it doesn't exist in the stock kernel 2.6.17.7.

Let me known if a port exists, or if there is a new way of accessing the
PPC 405GP GPIO under linux 2.6.

The recommended way of accessing GPIO registers is to mmap them
and manipulate them directly in user space.

Below, I've included a quick hack that blinks a LED on a Walnut-like
board.

-Dale

#include <stdint.h>
#include <stdio.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>

#define GPIO_PAGE_ADDR	0xef600000

#define OUTPUT_REG	0x0700
#define TRISTATE_REG	0x0704
#define OPENDRAIN_REG	0x0718
#define INPUT_REG	0x071c

#define MEDIA_LED_BIT	0x20000000

#define reg_addr(p, o)	((uint32_t *)((void *)p + o))

int main(int argc, char *argv[])
{
	int i;
	uint32_t *p;
	char *filename = "/dev/mem";
	void *addr	= 0;
	size_t length	= 4096;
	int prot	= PROT_READ | PROT_WRITE;
	int flags	= MAP_SHARED;
	int fd		= open(filename, O_RDWR);
	off_t offset	= (off_t)GPIO_PAGE_ADDR;

	if (fd < 0) {
		perror("open");
		return 1;
	}

	p = mmap(addr, length, prot, flags, fd, offset);
	if (p == MAP_FAILED) {
		perror("mmap");
		return 4;
	}

	/* drive led output */
	*reg_addr(p, TRISTATE_REG) |= MEDIA_LED_BIT;

	/* blink media led 10 times */
	for (i = 0; i < 10; i++) {
		/* turn media led on */
		*reg_addr(p, OUTPUT_REG) &= ~MEDIA_LED_BIT;
		sleep(1);
		/* turn media led off */
		*reg_addr(p, OUTPUT_REG) |= MEDIA_LED_BIT;
		sleep(1);
	}

	return 0;
}