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硬件平台: 基于讯为开发板itop4412 scp 1G
驱动说明：
本驱动基于三星提供的通用api函数来实现的,具体adc寄存器操作有三星公司实 现，我们要做的是调用三星公司提供的api来实现我们自己的功能。下面对相关的结构体和api函数进行解析
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struct s3c_adc_client {
struct platform_device *pdev;
struct list_head pend;
wait_queue_head_t *wait;
unsigned int nr_samples;
int result;
unsigned char is_ts;
unsigned char channel;
void (*select_cb)(struct s3c_adc_client *c, unsigned selected);
void (*convert_cb)(struct s3c_adc_client *c,
unsigned val1, unsigned val2,
unsigned *samples_left);
};
一个具体s3c_adc_client结构体来描述一个具体的客户(一个具体的驱动)
2.我们需要在驱动中构建这个驱动，并且注册到linux的内核
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struct s3c_adc_client *s3c_adc_register(struct platform_device *pdev,
void (*select)(struct s3c_adc_client *client,
unsigned int selected),
void (*conv)(struct s3c_adc_client *client,
unsigned d0, unsigned d1,
unsigned *samples_left),
unsigned int is_ts)
例子:
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adcdev.client = s3c_adc_register(dev, NULL, NULL, 0);
3.adc开始和停止转换函数
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int s3c_adc_start(struct s3c_adc_client *client,
unsigned int channel, unsigned int nr_samples)
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static void s3c_adc_stop(struct s3c_adc_client *client)
4.读取adc转换数据
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int s3c_adc_read(struct s3c_adc_client *client, unsigned int ch)
5.adc配置相关的函数
具体的讲解可以读取博客http://blog.csdn.net/liuhaoyutz/article/details/7461268
平台文件adc设备注册
方法一:在配置文件/home/topeet/Android4.0/iTop4412_Kernel_3.0/arch/arm/mach-exynos中的mach-iTop4412.添加
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struct platform_device s3c_device_adc_ctl = {
.name = "adc_ll",
.id = -1,
};
方法二:以模块的方式注册到内核
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#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
static struct platform_device adc_dev = {
.name = "adc_ll",
.id = -1,
};
static int __init adc_dev_init(void)
{
platform_device_register(&adc_dev);
return 0;
}
static void __exit adc_dev_exit(void)
{
platform_device_unregister(&adc_dev);
}
module_init(adc_dev_init);
module_exit(adc_dev_exit);
MODULE_LICENSE("GPL");
第二部分:基于杂项设备方式的设备驱动
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/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define DEVICE_NAME "adc"
#define DRIVER_NAME "adc_ll"
typedef struct {
struct mutex lock;
struct s3c_adc_client *client;
int channel;
} ADC_DEV;
static ADC_DEV adcdev;
static inline int exynos_adc_read_ch(void) {
int ret;
ret = mutex_lock_interruptible(&adcdev.lock);
if (ret < 0)
return ret;
ret = s3c_adc_read(adcdev.client, adcdev.channel);
mutex_unlock(&adcdev.lock);
return ret;
}
static inline void exynos_adc_set_channel(int channel) {
if (channel < 0 || channel > 3)
return;
adcdev.channel = channel;
}
static ssize_t exynos_adc_read(struct file *filp, char *buffer,
size_t count, loff_t *ppos)
{
char str[20];
int value;
size_t len;
value = exynos_adc_read_ch();
printk("value = 0x%x ", value);
len = sprintf(str, "%d ", value);
if (count >= len) {
int r = copy_to_user(buffer, str, len);
return r ? r : len;
} else {
return -EINVAL;
}
}
static long exynos_adc_ioctl(struct file *file,
unsigned int cmd, unsigned long arg)
{
#define ADC_SET_CHANNEL 0xc000fa01
#define ADC_SET_ADCTSC 0xc000fa02
switch (cmd) {
case ADC_SET_CHANNEL:
exynos_adc_set_channel(arg);
break;
case ADC_SET_ADCTSC:
/* do nothing */
break;
default:
return -EINVAL;
}
return 0;
}
static int exynos_adc_open(struct inode *inode, struct file *filp)
{
exynos_adc_set_channel(0);
printk("adc opened ");
return 0;
}
static int exynos_adc_release(struct inode *inode, struct file *filp)
{
printk("adc closed ");
return 0;
}
static struct file_operations adc_dev_fops = {
owner: THIS_MODULE,
open: exynos_adc_open,
read: exynos_adc_read,
unlocked_ioctl: exynos_adc_ioctl,
release: exynos_adc_release,
};
static struct miscdevice misc = {
.minor = MISC_DYNAMIC_MINOR,
.name = DEVICE_NAME,
.fops = &adc_dev_fops,
};
static int __devinit exynos_adc_probe(struct platform_device *dev)
{
int ret;
mutex_init(&adcdev.lock);
printk("%s, %d ", __FUNCTION__, __LINE__);
/* Register with the core ADC driver. */
#if 1
adcdev.client = s3c_adc_register(dev, NULL, NULL, 0);
if (IS_ERR(adcdev.client)) {
printk("itop4412_adc: cannot register adc ");
ret = PTR_ERR(adcdev.client);
goto err_mem;
}
#endif
printk("%s, %d ", __FUNCTION__, __LINE__);
ret = misc_register(&misc);
printk("%s, %d ", __FUNCTION__, __LINE__);
printk(DEVICE_NAME" initialized ");
err_mem:
return ret;
}
static int __devexit exynos_adc_remove(struct platform_device *dev)
{
misc_deregister(&misc);
s3c_adc_release(adcdev.client);
return 0;
}
static int itop4412_adc_ctl_suspend (struct platform_device *pdev, pm_message_t state)
{
printk("itop4412_led_ctl suspend:power off! ");
return 0;
}
static int itop4412_adc_ctl_resume (struct platform_device *pdev)
{
printk("itop4412_led_ctl resume:power on! ");
return 0;
}
static struct platform_driver exynos_adc_driver = {
.probe = exynos_adc_probe,
.remove = exynos_adc_remove,
.suspend = itop4412_adc_ctl_suspend,
.resume = itop4412_adc_ctl_resume,
.driver = {
.name = DRIVER_NAME,
.owner = THIS_MODULE,
},
};
static int __init exynos_adc_init(void)
{
return platform_driver_register(&exynos_adc_driver);
}
static void __exit exynos_adc_exit(void)
{
platform_driver_unregister(&exynos_adc_driver);
}
module_init(exynos_adc_init);
module_exit(exynos_adc_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("TOPEET Inc.");
测试代码
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#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
//#include
//#include
int main(void){
int fd;
char *adc = "/dev/adc";
char buffer[512];
int len=0, r=0;
memset(buffer,0,sizeof(buffer));
printf("adc ready! ");
if((fd = open(adc, O_RDWR|O_NOCTTY|O_NDELAY))<0)
printf("open adc err! ");
else{
printf("open adc success! ");
len=read(fd,buffer,10);
if(len == 0)
printf("return null ");
else{
r = atoi(buffer);
r = (int)(r*10000/4095); //Datas transition to Res
printf("res value is %d ",r);
}
}
}
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