Linux ARM9260 ADC驱动编程
#include <linux/module.h> 
#include <linux/kernel.h> 
#include <linux/init.h> 
#include <linux/interrupt.h> 
#include <linux/clk.h> 
#include <linux/fs.h> 
#include <asm/uaccess.h> 
#include <asm/io.h> 
#include <asm/arch/gpio.h> 
#include <asm/arch/at91_tc.h> 
#include <linux/time.h>
#include <linux/suspend.h>
#define ADC_CR          0x00    //Control Register Offset
#define ADC_MR          0x04    //Mode Register Offset
#define ADC_CHER        0x10    //Channel Enable Register Offset
#define ADC_CHDR        0x14    //Channel Disable Register Offset
#define ADC_CHSR        0x18    //Channel Status Register Offset
#define ADC_SR          0x1C    //Status Register Offset
#define ADC_LCDR        0x20    //Last Converted Data Register Offset
#define ADC_IER         0x24    //Interrupt Enable Register Offset
#define ADC_IDR         0x28    //Interrupt Disable Register Offset
#define ADC_IMR         0x2C    //Interrupt Mask Register Offset
#define ADC_CDR0        0x30    //Channel Data Register 0 Offset
#define ADC_CDR1        0x34    //Channel Data Register 1 Offset
#define ADC_CDR2        0x38    //Channel Data Register 2 Offset
#define ADC_CDR3        0x3C    //Channel Data Register 3 Offset
#define CH_EN           0x03    //Channels to Enable
#define CH_DIS          0x0C    //Channels to Disable
#define TRGEN           0x00    //Trigger Enable
#define TRGSEL          0x00    //Trigger Select
#define LOWRES          0x01    //Resolution
#define SLEEP_MODE      0x00    //Sleep Mode
#define PRESCAL         0x9   //Prescaler Rate Selection
#define STARTUP         0x7    //Start Up Time
#define SHTIM           0x3    //Sample and Hold Time
#define ADC_MAJOR       33            //Major Number
#define ADC_NAME        "at91adc_output"      //Device Name
void __iomem *adc_base;
struct clk *adc_clk;
static int my_adc_read(struct file *file, char __iomem buf, ssize_t count, loff_t *f_ops)
struct file_operations adc_file = {
        .owner = THIS_MODULE,
        .read = my_adc_read,
};
static int my_adc_read(struct file *filp, char __iomem buf, ssize_t count, loff_t *f_ops)
{
    int data, tmp[2];
    memset(tmp, 0, sizeof(tmp));
    data = __raw_readl(adc_base + ADC_CDR0);
    data &= 0x3ff;
    data = (data * 660) / 1024;
    tmp[0] = data;
    printk("Channel0: %d\n", data);
    data = __raw_readl(adc_base + ADC_CDR1);
    data &= 0x3ff;
    data = (data * 660) / 1024;
    tmp[1] = data;
    printk("Channel1: %d\n", data);
    if (copy_to_user(buf, tmp, sizeof(tmp)))
    {
        printk("copy to user failed\n");
        return 0;
    }
    return sizeof(tmp);
}
static int __init my_adc_init(void)
{
    int result;
    adc_clk = clk_get(NULL, "adc_clk"); //open adc clock
    clk_enable(adc_clk);    //trun on adc clock
设置PC0为外设A，adc采样，'0':is'nt use pullup
设置PC1为外设A，adc采样
将物理地映射到虚拟内存地址
将控制寄存器清零
模式控制寄存器,包括adc采样的频率
    __raw_writel(0x03, adc_base + ADC_CHER);    //enable channel 0, 1
    __raw_writel(0x0c, adc_base + ADC_CHDR);    //disable channel 2, 3
注册设备
    if (result < 0)
    {
        printk("Register ADC failed\n");
        return 0;
    }
启动ADC采样
    return 0;
}
static void __exit my_adc_exit()
{
释放 ADC设备
    iounmap(adc_base);
    clk_disable(adc_clk);   //turne off ADC clock
    clk_put(adc_clk);   //close ADC clock
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("MIKE CHEN");
module_init(my_adc_init);
module_exit(my_adc_exit);
应用程序：
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
int main(int argc, char **argv)
{
    int fd, data[2], ret;
    memset((char *)data, 0, 8);
    fd = open("/dev/at91adc_output", O_RDWR);
    if (fd < 0)
    {
        printf("open adc failed\n");
        return 0;
    }
    while (1)
    {
     sleep(3);
  memset((char *)data, 0, 8);
     ret = read(fd, data, sizeof(data));
     if (ret < 0)
     {
         printf("read failed\n");
         return 0;
     }
     printf("Channel0: %d, channel1: %d\n", data[0], data[1]);
    }
    return ret;
}

测试结果：

Linux arm9260 ADC驱动程序_ADC