dev_gpio.c.txt

gpio 驱动源码 也许有用！！与大家共享！

*   src/dev_gpio.c 
* 
*   This   file   provide   IO   reading   and   writing   from   user   space. 
*   Pls   create   some   device   file   in   diretory   /dev/gpiotest   whose   major   is   220. 
*   This   driver   support   0-255   devices.   In   user   space   user   can   read   and   write 
*   IO   through   open   and   ioctl   function   provided   by   glibc. 
* 
*/ 
#include   "dev_gpio.h " 

static   ioport_device_t   gpio_devices[256]; 

int   __init   gpio_init(void) 
{ 
int   i; 
register_chrdev(IOPORT_MAJOR,   "gpiotest ",   &gpio_ctl_fops); 
return   0; 
} 
__initcall(gpio_init); 
/* 
*   Open/close   code   for   raw   IO. 
*/ 
int   gpio_open(struct   inode   *inode,   struct   file   *filp) 
{ 
int   minor; 
minor   =   MINOR(inode-> i_rdev); 

/*   if   (ioport_devices[minor].io_lock)   { 
printk( "Device   is   busy\n "); 
return   -1; 
}*/ 
*(volatile   unsigned   short*)(0xfff00000+0x962)&=~0x0080; 
*(volatile   unsigned   short*)(0xfff00000+0x960)|=0x0080; 
gpio_devices[minor]++; 
return   0; 
} 
//__ioremap 
int   gpio_release(struct   inode   *inode,   struct   file   *filp) 
{ 
int   minor; 
minor   =   MINOR(inode-> i_rdev); 
if   (gpio_devices[minor]) 
gpio_devices[minor]--; 
*(volatile   unsigned   short*)(0xfff00000+0x960)&=~0x0080; 
*(volatile   unsigned   short*)(0xfff00000+0x962)|=0x0080; 
return   0; 
} 
/* 
*   Deal   with   ioctls   against   the   raw-device   control   interface,   to   bind 
*   and   unbind   other   raw   devices. 
*/ 
int   gpio_ctl_ioctl(struct   inode   *inode,struct   file   *flip,unsigned   int   command,unsigned   long   arg) 
{ 
int   err   =   0; 
int   minor   =   MINOR(inode-> i_rdev); 
switch   (command) 
{ 
case   IOWRITE: 
*(volatile   unsigned   short*)(0xfff00000+0x966)&=~0x0080; 
return   0; 
case   IOCLEAR: 
*(volatile   unsigned   short*)(0xfff00000+0x966)|=0x0080; 
return   0; 
default: 
err   =   -EINVAL; 
} 
return   err; 
}