dadrv.c

at91rm9200 AD/DA转换驱动 很好的驱动开发范例

/* DA convert driver for H9200M and H9200T board 
   Author: Wei An
   E-Mail: [e-mail]/[e-mail]
   Date:   2005/6/1
*/
#ifdef MODULE
#include <linux/module.h>
#include <linux/version.h>
#else
#endif

#define __KERNEL__
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <linux/fcntl.h>
#include <asm/arch/AT91RM9200_SYS.h>



#define DA_PHYSICAL_REG_SIZE   ((unsigned int)  0x00000004)
//PHY addressd def
#define AT91_nDACCS0_ADDR      ((unsigned int) 	0x80000000)
#define AT91_nDACCS1_ADDR      ((unsigned int) 	0x80000010)



//global variables def
volatile unsigned int * nDACCS0_ADDR;
volatile unsigned int * nDACCS1_ADDR;
volatile unsigned int * nDACCS_ADDR;


//local variables def
static int DA_write(struct file *,const char *,int,loff_t *);

static struct file_operations da_fops=
{
      write     :(void(*))DA_write,
};
char da_name[]="dadrv";
static unsigned int major =0;

static void Delay (int);
/* Configure pio */
void AT91_CfgPIO_DA(void)
{
     AT91PS_SYS sys = (AT91PS_SYS) AT91C_VA_BASE_SYS;
     // Enable PIOC
     sys->PIOC_PDR=(unsigned int)(1<<13);
     // Select Peripheral A         
     sys->PIOC_ASR=(unsigned int)(1<<13);
}

/* Select channel for anolog voltage input */
static int DA_write(struct file *DA_file, const char *buf,int len,loff_t *loff)
{
       int retv;
       unsigned char ch;
       unsigned int iopdata;
       /* obtain channel selection data from user space */
       if(len==0x1)
        {
          if(copy_from_user((char*)&ch,buf,len))
          return -EFAULT;
          switch(ch)
           {
        
             case '0':
              {
                nDACCS_ADDR=nDACCS0_ADDR;        
              }
              break;  
             case '1':
              {
                nDACCS_ADDR=nDACCS1_ADDR;        
              }
              break;
         default:
             break;        
                 
          }
        }
      else if(len==0x4)
       {
        if(copy_from_user((char*)&iopdata,buf,len))
               return -EFAULT;
               writel(iopdata,nDACCS_ADDR);
      
        Delay(100000);
       }
      else
       {}
return len;     
}
/*
 * Main initialization routine
 */

static int __init DA_at91_init(void)
{
       int retv;
       AT91PS_SYS sys = (AT91PS_SYS) AT91C_VA_BASE_SYS;
       
       sys->EBI_SMC2_CSR[7] =(AT91C_SMC2_NWS & 0xff) | AT91C_SMC2_WSEN \
       | (AT91C_SMC2_TDF & 0x300) | AT91C_SMC2_BAT | AT91C_SMC2_DBW_16;

       AT91_CfgPIO_DA();
       /* map hardware I/O address to virtual memory address */
       nDACCS0_ADDR=(unsigned int*)ioremap(AT91_nDACCS0_ADDR,DA_PHYSICAL_REG_SIZE);
       nDACCS1_ADDR=(unsigned int*)ioremap(AT91_nDACCS1_ADDR,DA_PHYSICAL_REG_SIZE);
       /* register module */
       retv=register_chrdev(major,da_name,&da_fops);
       if(retv<0)
       {
         printk("<1>Register Fail!\n");
         return retv;
       }
      if(major==0)
        major=retv;
      return 0;
}
/* unregister module */
static void __exit DA_at91_cleanup(void)
{     int retv;
      retv=unregister_chrdev(major,da_name);
      if(retv<0)
      {
        printk("<1>UnRegister Fail!\n");
        return;
      }
      printk("<1>ADDRV:GOOD-bye!\n");
       
}

void Delay(int i)
{	int j,k;
	for(j=0;j<i*800;j++)
	{
	k=0;
	}    
}

module_init(DA_at91_init);
module_exit(DA_at91_cleanup);