慢慢学Linux驱动开发，第九篇，tiny6410_LED驱动
一直在看代码，今天准备真正去试试，就拿tiny6410的LED灯开刀，虽说是自己写，但实际上也是参考例程来的。不过还好基本的思路还是蛮清晰的。
定义本次驱动为misc device（杂项设备驱动），包含头文件miscdevice.h，其实所谓的杂项驱动程序就是主设备号为10的字符设备驱动，其实就是用主设备号10调用了函数register_chrdev()。且misc device会自动在/dev目录下建立设备节点，而不需用mkmod手动建立。
开发板IO定义：
S3C6410 GPK口：
#include <linux/miscdevice.h> #include <linux/fs.h> #include <linux/pci.h> #include <mach/map.h> #include <mach/regs-gpio.h> #include <mach/gpio-bank-k.h> #include "leds.h" #define DEVICE_NAME "tiny6410_leds" MODULE_LICENSE("GPL"); MODULE_AUTHOR("pang123hui"); static long sbc2440_leds_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { switch(cmd) { unsigned tmp; /* case 0: case 1: if(arg > 4) { //非法参数 return -EINVAL; } tmp = readl(S3C64XX_GPKDAT); tmp &= ~(1 << (3 + arg)); tmp |= ((cmd) << (3 + arg)); writel(tmp, S3C64XX_GPKDAT); return 0; */ case 1: case 2: case 3: case 4: tmp = readl(S3C64XX_GPKDAT); tmp = (tmp & ~(1<<(cmd - 1 + 4)))|(arg<<(cmd -1 + 4)); writel(tmp, S3C64XX_GPKDAT); return 0; default: return -EINVAL; } } static struct file_operations dev_fops = { .owner = THIS_MODULE, .unlocked_ioctl = sbc2440_leds_ioctl, }; //misc device：杂项设备，即主设备号为10的特殊字符设备 static struct miscdevice misc = { //次设备号，注意不要与/proc/misc中已有杂项设备次设备号冲突 //MISC_DYNAMIC_MINOR来动态获取次设备号 .minor = MISC_DYNAMIC_MINOR, //设备名称 .name = DEVICE_NAME, .fops = &dev_fops, }; static int __init dev_init(void) { int ret; { unsigned tmp; tmp = readl(S3C64XX_GPKCON); //GPKCON配置GPK4到GPK7配置为0001输出 tmp = (tmp & ~(0xffffU<<16))|(0x1111U<<16); writel(tmp, S3C64XX_GPKCON); //GPKDAT[7:4] = 1 //灯灭 tmp = readl(S3C64XX_GPKDAT); tmp |= (0xF << 4); writel(tmp, S3C64XX_GPKDAT); //禁止上拉下拉 tmp = readl(S3C64XX_GPKPUD); tmp &= (0x00 << 8); writel(tmp, S3C64XX_GPKPUD); } //该函数会自动创建设备节点，即设备文件 ret = misc_register(&misc); printk (DEVICE_NAME"/tinitialized/n"); return ret; } static void __exit dev_exit(void) { misc_deregister(&misc); } module_init(dev_init); module_exit(dev_exit);
makefile
ifneq ($(KERNELRELEASE),) obj-m := leds.o else KERNELDIR := /opt/FriendlyARM/mini6410/linux/linux-2.6.38 PWD:=$(shell pwd) all: make -C $(KERNELDIR) M=$(PWD) modules clean: rm -rf *.ko *.o *.mod.c *.mod.o *.symvers endif
leds_test
#include <stdio.h> //exit #include <stdlib.h> #include <sys/ioctl.h> int main(int argc, char **argv) { int num = 0; int led_state = 1; int fd = 0; //参数赋值 if(argc != 3 || sscanf(argv[1],"%d", &num) != 1 || sscanf(argv[2], "%d", &led_state) != 1 || num > 4 || led_state > 1) { fprintf(stderr, "error/n"); exit(1); } printf("num = %d, led_state = %d/n", num, led_state); fd = open("/dev/tiny6410_leds", 0); if (fd < 0) { fd = open("/dev/tiny6410_leds0", 0); } if (fd < 0) { perror("open device leds"); exit(1); } ioctl(fd, num, led_state); printf("led%d/n", num); close(fd); return 0; }