linux 2.6.30内核，9g45开发板，gpio驱动

[gaoqiaoming]

求一个atmel sam9g45开发板的gpio驱动程序，应用程序通过写入1/0控制led灯的亮暗，管脚用AT91_PIN_PB20,用insmod加载，小弟对驱动一无所知，也不知道问题讲清楚没，刚开始了解一天，求大牛帮忙

[awsqsh]

去找本书 抄抄得了 要别人帮你写个驱动，估计大家都不愿意。

[pengchy]

给你提供一个代码,你在自己的内核交叉编译环境上编译,有可能头文件引用的不怎么正确,编译的时候修改一下就OK了.
头文件: geo_ds_gpio.h

#ifndef __GEO_DS_GPIO_H__
#define __GEO_DS_GPIO_H__

#include <linux/sched.h>
#include <linux/init.h>

/* PIN definitions */

#define GEO_DS_GPIO_MAGIC       's'

#define SWITCH_LED_ON           _IOW( GEO_DS_GPIO_MAGIC, 0, int ))

#define GEO_DS_GPIO_MAXNR       1

/* PIN definitions */
#define PIN_LED_STAT            AT91_PIN_PB30

#endif  // __GEO_DS_GPIO_H__

代码: geo_ds_gpio.c

#include <linux/init.h>
#include <linux/module.h>           /* get MOD_DEC_USE_COUNT, not the version string */
#include <linux/moduleparam.h>
#include <linux/version.h>          /* need it for conditionals in geoad.h */
#include <linux/kernel.h>
#include <linux/proc_fs.h>
#include <linux/errno.h>            /* error codes */
#include <linux/types.h>            /* size_t */
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/string.h>
#include <asm/arch/gpio.h>
#include <linux/cdev.h>
#include <linux/delay.h>

#include <asm/system.h>             /* rmb(), wmb() */
#include <asm/io.h>                 /* inb(), outb() */
#include <asm/uaccess.h>

#include <mach/board.h>
#include <mach/gpio.h>
#include <mach/at91sam9_smc.h>
#include <mach/at91_ssc.h>

#include "geo_ds_gpio.h"            /* local definitions */

#define GPIO_NR_DEVS        1       /* device number */

int gpio_major = 105;               /* major device number */
int gpio_nr_devs = GPIO_NR_DEVS;    /* number of gpio control devices */
char gpio_name[16];                 /* device name */

MODULE_AUTHOR( "Pengchy" );
MODULE_LICENSE( "GPL" );

int gpio_ioctl( struct inode *inode, struct file *filp, unsigned int cmd,
                unsigned long arg )
{
    if( _IOC_TYPE(cmd) != GEO_DS_GPIO_MAGIC )
        return -EINVAL;
    if( _IOC_NR(cmd) >= GEO_DS_GPIO_MAXNR )
        return -EINVAL;
    
    switch( cmd )
    {
    case SWITCH_LED_ON:
        at91_set_gpio_value( PIN_LED_STAT, arg ); break;
    default:
        return -ENOTTY;
    }

    return 0;
}

/*
 * Open and close.
 */
int gpio_open( struct inode *inode, struct file *filp )
{    
    return 0;
}

int gpio_release( struct inode *inode, struct file *filp )
{
    return 0;
}

/* for device gpio control */
static struct file_operations gpio_fops = 
{
    .owner   =  THIS_MODULE,
    .open    =  gpio_open,
    .release =  gpio_release,
    .ioctl   =  gpio_ioctl,
};

struct GPIO_DEVS
{
    struct cdev cdev;                   /* Char device structure */
};

static struct GPIO_DEVS gpio_device;

static struct gpio_dev_info
{
    char *name;
    struct GPIO_DEVS *dev;
    struct file_operations *fops;
} gpio_devs[] = {
    { "gpio_ctl", &gpio_device, &gpio_fops }
};

/*
 * Set up the char_dev structure for this device.
 */
void gpio_setup_cdev( struct gpio_dev_info *devinfo, int index )
{
    int err, devno = MKDEV( gpio_major, index );
    struct GPIO_DEVS *dev = devinfo->dev;
    
    /* Do the cdev stuff. */
    cdev_init( &dev->cdev, devinfo->fops );
    kobject_set_name( &dev->cdev.kobj, devinfo->name );
    dev->cdev.owner = THIS_MODULE;
    dev->cdev.ops = devinfo->fops;
    err = cdev_add( &dev->cdev, devno, 1 );
    
    /* Fail gracefully if need be */
    if( err )
    {
        printk( KERN_NOTICE "Error %d adding %s\n", err, devinfo->name );
        kobject_put( &dev->cdev.kobj );
    }
    else
        printk( KERN_NOTICE "%s registered at %x\n", devinfo->name, devno );
}

static void init_hardware_pin()
{
    at91_set_gpio_output( PIN_LED_STAT, 1 );
}

static int __init gpio_init( void )
{
    int err = -1, i = 0;
    dev_t devno = MKDEV( gpio_major, 0 );
    
    memset( gpio_name, '\0', sizeof(gpio_name) );
    sprintf( gpio_name, "%s", "gpio_ctl" );
    
    /*
     * Get a range of minor numbers to work with, asking for a dynamic
     * major unless directed otherwise at load time.
     */
    if( gpio_major )
        err = register_chrdev_region( devno, gpio_nr_devs, gpio_name );
    else
    {
        err = alloc_chrdev_region( &devno, 0, gpio_nr_devs, gpio_name );
        gpio_major = MAJOR( devno );
    }
    
    if( err < 0 )
    {
        printk( KERN_WARNING "gpio: can't get major %d\n", gpio_major );
        goto err001;
    }
    
    // Setup the geo devices.
    for( i = 0; i < gpio_nr_devs; i++ )
        gpio_setup_cdev( &gpio_devs[i], i );
    
    init_hardware_pin();
    
    printk( KERN_INFO "***************** gpio control driver started **************\n" );
    
    return 0;

err001:
    return err;
}

static void __exit gpio_exit( void )
{
    int i = 0;
    dev_t devno = MKDEV( gpio_major, 0 );
        
    init_hardware_pin();

    /* Clean up the static devs */
    for( i = 0; i < gpio_nr_devs; i++ )
    {
        struct GPIO_DEVS *dev = gpio_devs[i].dev;
        cdev_del( &dev->cdev );
    }
    
    unregister_chrdev_region( devno, gpio_nr_devs );
}

module_init( gpio_init );
module_exit( gpio_exit );

[nadleeh]

说下步骤吧，首先你得有电路图，知道LED和芯片怎么连的，连到那跟脚上去了（一般是GPXX），然后去查芯片文档关于GPXX的描述，然后建立指针，赋值。。。。

[nadleeh]

内核里面写的话 要用到ioremap，具体百度下

[gaoqiaoming]

驱动已经好了，成功加载实现控制led的亮跟灭了，结贴给分了