mini2440之背光驱动

背光是由LCD上LCD_PWR(GPG4)控制的。

#include <linux/errno.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/input.h>#include <linux/init.h>#include <linux/serio.h>#include <linux/delay.h>#include <linux/clk.h>#include <linux/miscdevice.h>#include <linux/gpio.h>#include <asm/io.h>#include <asm/irq.h>#include <asm/uaccess.h>#include <mach/regs-clock.h>#include <plat/regs-timer.h> #include <mach/regs-gpio.h>#include <linux/cdev.h>#undef DEBUG//#define DEBUG#ifdef DEBUG#define DPRINTK(x...) {printk(__FUNCTION__"(%d): ",__LINE__);printk(##x);}#else#define DPRINTK(x...) (void)(0)#endif//定义设备名为backlight#define DEVICE_NAME"backlight"//定义背光变量bl_state,以记录背光的开关状态static unsigned int bl_state;//设置背光开关的函数主要是翻转背光变量bl_statestatic inline void set_bl(int state){bl_state = !!state;//翻转背光变量bl_state//把结果写入背光所用的寄存器GPG(4),s3c2410_gpio_setpin(S3C2410_GPG(4), bl_state);}//获取背光开关的函数static inline unsigned int get_bl(void){return bl_state;}//从应用程序读取参数并传递到内核中static ssize_t dev_write(struct file *file, const char *buffer, size_t count, loff_t * ppos){unsigned char ch;int ret;if (count == 0) {return count;//字节数} //从用户层读取参数ret = copy_from_user(&ch, buffer, sizeof ch) ? -EFAULT : 0;if (ret) {return ret;}    //判断是奇数还是偶数ch &= 0x01;//设置背光状态set_bl(ch);return count;}//把内核参数传递到用户层static ssize_t dev_read(struct file *filp, char *buffer, size_t count, loff_t *ppos){int ret;unsigned char str[] = {'0', '1' };if (count == 0) {return 0;}//从内核中读数据ret = copy_to_user(buffer, str + get_bl(), sizeof(unsigned char) ) ? -EFAULT : 0;if (ret) {return ret;}return sizeof(unsigned char);}static struct file_operations dev_fops = {owner:THIS_MODULE,read:dev_read,write:dev_write,};static struct miscdevice misc = {.minor = MISC_DYNAMIC_MINOR,.name = DEVICE_NAME,.fops = &dev_fops,};static int __init dev_init(void){int ret;ret = misc_register(&misc);printk (DEVICE_NAME"\tinitialized\n");//配置LCD背光引脚状态s3c2410_gpio_cfgpin(S3C2410_GPG(4), S3C2410_GPIO_OUTPUT);set_bl(1);return ret;}static void __exit dev_exit(void){misc_deregister(&misc);}module_init(dev_init);module_exit(dev_exit);MODULE_LICENSE("GPL");MODULE_AUTHOR("FriendlyARM Inc.");