FL2440 adc 实验

#include <linux/kernel.h>#include <linux/module.h>#include <linux/init.h>#include <linux/kdev_t.h>#include <linux/fs.h>#include <linux/cdev.h>#include <linux/wait.h>#include <linux/timer.h>#include <linux/sched.h>#include <linux/interrupt.h>#include <linux/uaccess.h>//copy_to_user#include <asm/io.h>#include <linux/clk.h>//ADC的一些地址的定义#define S3C2440_ADC_BASE 0x58000000#define IO_REMAP_SIZE0x20//IO映射地址大小#define S3C2440_ADCCON 0#define S3C2440_ADCDLY 0x8#define S3C2440_ADCDAT0 0xC/*预分频值39,AIN0通道,正常转换,禁止读启动,无操作*/#define ADCCON_CONFIG_VALUE ((1<<14)|(39<<6)|(0<<3)|(0<<2)|(0<<1)|(0))#define ADC_START(ADCCON_CONFIG_VALUE | 0x1)#define ADCDLY_VALUE 0xff/*保存从平台时钟队列中获取ADC的时钟*/static struct clk *adc_clk;#define DEV_NAME "fl2440_adc"#define DEV_COUNT1void *adc_base_addr=NULL;DECLARE_MUTEX(dev_sem_lock);struct DEV_STRUCT{int dev_major;//主设备号struct cdev cdev;}dev_struct;//初始化ADCvoid init_adc(void){writel(ADCCON_CONFIG_VALUE,adc_base_addr+S3C2440_ADCCON);writel(ADCDLY_VALUE,adc_base_addr+S3C2440_ADCDLY);}//启动ADCvoid start_adc(void){writel(ADC_START,adc_base_addr+S3C2440_ADCCON);}//等待转换开始并完成void wait_conv(void){unsigned long i;do{i=readl(adc_base_addr+S3C2440_ADCCON);}while(i & 0x1);do{i=readl(adc_base_addr+S3C2440_ADCCON);}while(!(i & 0x8000));}static int dev_open(struct inode* inode,struct file *filp){return 0;}static int dev_release(struct inode *inode,struct file *filp){return 0;}ssize_t dev_read(struct file *filp,char __user *userp,size_t count,loff_t *offp){int data=0;if(down_trylock(&dev_sem_lock)){if(filp->f_flags & O_NONBLOCK)return -EAGAIN;}start_adc();wait_conv();data=readl(adc_base_addr+S3C2440_ADCDAT0) & 0x3ff;copy_to_user(userp,(void*)&data,4);up(&dev_sem_lock);return count;}struct file_operations fops={.owner=THIS_MODULE,.open=dev_open,.release=dev_release,.read=dev_read,};static int __init dev_init(void){dev_t dev_id;int err;dev_struct.dev_major=0;err=alloc_chrdev_region(&dev_id,0,DEV_COUNT,DEV_NAME);if(err)goto error0;dev_struct.dev_major=MAJOR(dev_id);cdev_init(&dev_struct.cdev,&fops);dev_struct.cdev.owner=THIS_MODULE;err=cdev_add(&dev_struct.cdev,dev_id,DEV_COUNT);if(err)goto error2;adc_clk = clk_get(NULL, "adc"); if (!adc_clk) { /*错误处理*/ printk(KERN_ERR "failed to find adc clock source/n"); return -ENOENT; } /*时钟获取后要使能后才可以使用，clk_enable定义在arch/arm/plat-s3c/clock.c中*/ clk_enable(adc_clk);adc_base_addr=ioremap(S3C2440_ADC_BASE,IO_REMAP_SIZE);//映射IO到内存区if(IS_ERR(adc_base_addr))goto error2;init_adc();// 初始化ADCprintk("init module successful!/n");return 0;error2:cdev_del(&dev_struct.cdev);unregister_chrdev_region(dev_id,DEV_COUNT);error0:return err;}static void __exit dev_exit(void){cdev_del(&dev_struct.cdev);iounmap(adc_base_addr);unregister_chrdev_region(MKDEV(dev_struct.dev_major,0),DEV_COUNT);if (adc_clk) /*屏蔽和销毁时钟*/ { clk_disable(adc_clk); clk_put(adc_clk); adc_clk = NULL; }printk("exit module!/n");}module_init(dev_init);module_exit(dev_exit);MODULE_LICENSE("GPL");