Linux菜鸟关于gpio驱动的问题
请问各位大侠：小弟我刚学Linux驱动开发，自己尝试着写了一个gpio驱动，功能就是简单控制GPIO的输出电平
随内核一起编译后下载到目标板运行，打印显示驱动加载成功，但在 /dev下没有生成相应的设备节点
不知道是什么原因，希望各位高人能指导一下，内核版本为2.6.20.1 驱动源码如下：
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <asm/arch/gpio.h>
#include <asm/arch/at91_pio.h>
#include <asm/arch/hardware.h>
#define GPIO_MAJOR 220
#undef DEBUG_GPIO
/* ......................................................................... */
/*
* GPIO read .
*/
static ssize_t gpio_rd (struct file *file, char *buf, size_t count, loff_t *offset)
{
return count;
}
/*
* GPIO Write .
*/
static ssize_t gpio_wr(struct file *file, char *buf, size_t count, loff_t *offset)
{
return count;
}
static int gpio_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
int io_status;
switch (cmd)
{
case 0:
*(long *)(AT91_PIOC+PIO_CODR) |= (1<<13);
break;
case 1:
*(long *)(AT91_PIOC+PIO_SODR) |= (1<<13);
break;
case 2:
io_status = *(long *)(AT91_PIOC+PIO_PDSR);
break;
default:
break;
}
return io_status;
}
/*
* Open the GPIO device
*/
static int gpio_open(struct inode *inode, struct file *file)
{
//AT91_PMC |= 1<<AT91RM9200_ID_PIOC;
*(long *)(AT91_PIOC+PIO_OER)|= (1<<13);
*(long *)(AT91_PIOC+PIO_PUDR) |= (1<<13);
return 0;
}
/*
* Close the GPIO device
*/
static int gpio_close(struct inode *inode, struct file *file)
{
return 0;
}
/* ......................................................................... */
static struct file_operations gpio_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.read = gpio_rd,
.write = gpio_wr,
.ioctl = gpio_ioctl,
.open = gpio_open,
.release = gpio_close,
};
/*
* Install the gpio /dev interface driver
*/
static int __init at91_gpio_init(void)
{
printk(KERN_INFO "gpio /dev entries driver\n");
if (register_chrdev(GPIO_MAJOR, "gpio", &gpio_fops)) {
printk(KERN_ERR "at91_spidev: Unable to get major %d for gpio\n", GPIO_MAJOR);
return -EIO;
}
printk(KERN_INFO "AT91 GPIO driver loaded\n");
return 0;
}
/*
* Remove the gpio /dev interface driver
*/
static void __exit at91_gpio_exit(void)
{
if (unregister_chrdev(GPIO_MAJOR, "gpio")) {
printk(KERN_ERR "at91_gpio: Unable to release major %d for gpio\n", GPIO_MAJOR);
return;
}
}
module_init(at91_gpio_init);
module_exit(at91_gpio_exit);
MODULE_LICENSE("GPL")
MODULE_AUTHOR("Guo Shuqiang")
MODULE_DESCRIPTION("GPIO /dev interface for Atmel AT91RM9200")
/*end of at91_gpioctl.c */
系统启动的打印消息：
io scheduler noop registered
io scheduler anticipatory registered (default)
AT91 GPIO driver loaded
at91_spi: Baud rate set to 5990400
AT91 SPI driver loaded
AT91 Watchdog Timer enabled (5 seconds, nowayout)
atmel_usart.0: ttyS0 at MMIO 0xfefff200 (irq = 1) is a ATMEL_SERIAL
atmel_usart.1: ttyS1 at MMIO 0xfffc4000 (irq = 7) is a ATMEL_SERIAL 节点要自己加的 比如 mknod /dev/gpio1 c 220 0
这样你在测试函数中就可以打开节点调用ioctl函数了
比如fd = open("/dev/gpio1" O_RDWR);
ioctl(;1;);
回复 #2 zhongfrank 的帖子
大家回复的很快啊，此地果然高人不少，谢谢！我是Linux菜鸟对驱动开发流程不熟，有没有专门的函数实现设备节点的添加？
[ 本帖最后由 guode0724 于 2009-3-10 10:49 编辑 ] 就是mknod
回复 #5 zhongfrank 的帖子
能不能在驱动里面添加代码然后加载后自动在/dev生成设备节点呢？回复 #6 guode0724 的帖子
写驱动和加节点是两码事，况且节点添加之后如果不是手动删除的话也会一直在。如果你觉得麻烦，可以写一个shell脚本，一次完成模块加载、节点添加，运行测试等等
回复 #7 zhongfrank 的帖子
Linux下如何实现设备节点的自动添加和删除呢？ 原帖由 guode0724 于 2009-3-10 11:34 发表 http://linux.chinaunix.net/bbs/images/common/back.gifLinux下如何实现设备节点的自动添加和删除呢？
自己写一个脚本实现啊。建议LZ看一下LDD3源码中关于scull模块的自动加载和卸载的脚本scull_load/unload 好的，谢谢指点！
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