IOREMAP的使用

#include 
#include 
#include 
#include 
#include 
#include 
#define GPFCON_DANCY 0x56000050
#define GPFCON_SIZE 0x20
static void __iomem *io_base;
static struct resource  *io_mem;
MODULE_LICENSE("GPL");
static int hello_init(void)
{
 int dancy;
 static unsigned long io_cntl;
 printk("Hello world\n");
 io_mem = request_region(GPFCON_DANCY, GPFCON_SIZE, "io");
 if (io_mem == NULL) 
 {
  printk("failed to get memory region\n");
 }
 io_base = ioremap(GPFCON_DANCY, GPFCON_SIZE);
 if (io_base == 0) 
 {
  printk("failed to ioremap() region\n");
 }
 printk("io_base = %p\n",io_base);
 io_cntl = 0x00007dee;
 writel(io_cntl, io_base);
 dancy = 50;
 while(dancy--)
 {
  io_cntl = ~0x10;
  writel(io_cntl, io_base + 0x4);
  msleep(0x10);
  io_cntl = ~0x80;
  writel(io_cntl, io_base + 0x4);
  msleep(0x10);
 }
 printk("Hello world\n");
    return 0;
}
static void hello_exit(void)
{
 release_resource(io_mem);
 kfree(io_mem);
 iounmap(io_base);
 printk("Goodbye world\n");
}
module_init(hello_init);
module_exit(hello_exit);