Hi,

I have SAM9G45 Atmel kit and i am trying to write a simple utility for gpio control.
I came across the following function at91_set_gpio_output() in the kernel source for Atmel for gpio control. I see they have include few header files which are already part of kernel.
When i write my own application and try to include the following header in my application, it fails says not able to find the header files.

#include <linux/clk.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <mach/at91_pio.h>
#include <mach/gpio.h>

Below is content of my makefile


[root@localhost dbgene]# vi Makefile
CC = /usr/local/arm/arm-2007q1/bin/arm-none-linux-gnueabi-gcc
DIR = /home/workspace/Debug_box/Atmel_ARM_Board/dbgene_fw/source_code/linux-2.6.30_atmel_patch/arch/arm/mach-at91/
LDIR = /home/workspace/Debug_box_Atmel_ARM_Board/dbgene_fw/source_code/linux-2.6.30_atmel_patch/arch/arm/kernel

INCLUDES = -I$(DIR)

all:
$(CC) $(INCLUDES) -o led led.c

Here is my application
[root@localhost dbgene]# vi led.c
#include <linux/mm.h>
#include <linux/module.h>
#include <mach/gpio.h>
#include <mach/at91sam9g45.h>

void main()
{
printf("Glowing LED ");
at91_set_gpio_output(AT91_PIN_PB21, 1);

}



I have pointed it to pick up header files from Kernel source bu then too it fails. Can any one please help me out?

Thanks
Prashanth

If this is a user space application, you'll need to mmap() the ATMEL peripheral space to a pointer you can access, and write your own GPIO access routines.

If you are just wanting GPIO access, then enable CONFIG_GPIO_SYSFS in your kernel config.

Then something along these lines will work. This is just the first link I found on google.
http://squidge.sourceforge.net/gpio/

Thanks for the reply.

Currently i am using gnu tool chain provided by codesourcery using which mmap() call fails as the tool chain doesn't have page.h file.

Below is snippet of my file using mmap.
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <sys/mman.h>
#include <asm/page.h>

#define PIOBASEADDR 0xFFFFF000 //generic address which can be mapped to any port
#define PIOB_PER 0xFFFFF400 //offset 400 from base address
#define PIOB_OER 0xFFFFF410
#define PIOB_OWER 0xFFFFF4A0
#define PIOB_SODR 0xFFFFF430


#define PIO_PER_VAL 0x00F00000
#define PIO_OER_VAL 0x00F00000
#define PIO_OWER_VAL 0x00F00000


int main(int argc, char *argv[])
{
FILE * mem_fh;
unsigned long int* vid_addr;
unsigned long int baseAddr = 0;
unsigned long int value = 0;
unsigned int baseOffset;


if ((mem_fh = fopen("/dev/mem", "r+") ) < 0)
{
printf("can't open /dev/mem \n");
exit (-1);
}

// First enable PIO_PER

baseAddr = PIOB_PER;

// adjust the base address at the page boundary

baseOffset = baseAddr & ~PAGE_MASK;
baseAddr &= PAGE_MASK;

vid_addr = (unsigned char*)mmap(NULL, /* where to map to: don't mind */
PAGE_SIZE, /* how many bytes ? */
PROT_READ | PROT_WRITE, /* want to read and write */
MAP_SHARED, /* no copy on write */
fileno(mem_fh), /* handle to /dev/mem */
baseAddr); /* hopefully the Text-buffer :-)*/

// Now write the value to enable PIO_PER
vid_addr[baseAddr] = PIO_PER_VAL;

Even the above code was not compiling with codesourcery compiler. I used one more gcc compiler which we had and was based on arm-linux which can compile the above code.
Strangely when i flash the compiled code my board, and execute my file ./gpio, it says cannot find the file even thought is it present

Below is o/p from my debug console... i have never seen such thing....
[root@Mini6045:/dbgene]# ls -l
-rwxr--r-- 1 root root 371 Mar 4 2011 Makefile
-rwxr-xr-x 1 root root 9201 Jan 3 2011 gpio
-rwxr--r-- 1 root root 3438 Jan 3 2011 gpio.c
-rwxr-xr-x 1 root root 8216 Mar 4 2011 hello
-rw-r--r-- 1 root root 101 Jan 1 2011 hello.c
-rwxrwxr-x 1 root root 4908 Mar 1 2011 hello386
-rw-r--r-- 1 root root 37 Dec 29 2010 pk.txt
-rw-r--r-- 1 root root 28 Mar 1 2011 pkmk
[root@Mini6045:/dbgene]#
[root@Mini6045:/dbgene]# ./gpio
-/bin/sh: ./gpio: not found
[root@Mini6045:/dbgene]#


Later on i wrote the following file to use atmel kernel source


#include <linux/mm.h>
#include <linux/module.h>
#nclude <linux/clk.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/io.h>
#include <stdio.h>

void main()
{
printf("Glowing LED ");
//at91_set_gpio_output(AT91_PIN_PB21, 1);

}

When i compile this code with codesourcery compiler (GNU EABI), it givs tons and tons of error saying lot of header files are not present.

Below is how my makefile looks

[root@localhost dbgene]# pwd
/home/workspace/Debug_box/Atmel_ARM_Board/dbgene_fw/source_code/dbgene_fs/dbgene
[root@localhost dbgene]# vi Makefile
CC = /usr/local/arm/arm-2007q1/bin/arm-none-linux-gnueabi-gcc
#CC = /usr/local/arm/intcc/bin/arm-linux-gcc

IDIR = /home/workspace/Debug_box/Atmel_ARM_Board/dbgene_fw/source_code/linux-2.6.30_atmel_patch/include
IDIR1 = /home/workspace/Debug_box/Atmel_ARM_Board/dbgene_fw/source_code/linux-2.6.30_atmel_patch/arch/arm/include

INCLUDES = -I$(IDIR) -I$(IDIR1)

all:
$(CC) $(INCLUDES) -o atmelled atmelled.c
#(CC) -o atmelled atmelled.c


This is making me go crazy as i am not able to find any help from Google...


canat91,

Even if i enable GPIO capability, i still need to write a user level application to link to the module during which i still need to use Atmel kernel source and it fails :(

I found more about sysfs LED class in the below link ...

http://www.mjmwired.net/kernel/Document ... -class.txt

When i execute the following command, i am able to turn off or on a LED but their is not much details on how they have done it. I still need a user space application from which i meed to access GPIO, I2C, PWM drivers and there method might not be much helpful...

The mmap() is a bit broken, this should be better.

// adjust the base address at the page boundary

baseOffset = baseAddr & PAGE_MASK; // Byte Offset within the page
baseAddr &= ~PAGE_MASK; // Address on page boundary

vid_addr = (unsigned long int*)mmap(NULL, /* where to map to: don't mind */
PAGE_SIZE, /* how many bytes ? */
PROT_READ | PROT_WRITE, /* want to read and write */
MAP_SHARED, /* no copy on write */
fileno(mem_fh), /* handle to /dev/mem */
baseAddr); /* hopefully the Text-buffer :-)*/

// Now write the value to enable PIO_PER
vid_addr[baseOffset / sizeof(unsigned long int)] = PIO_PER_VAL;