字元裝置驅動之Buttons-輪詢

buttons.c

#include <linux/fs.h> #include <linux/module.h> #include <linux/errno.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/cdev.h> #include <linux/ioport.h> #include <linux/pci.h> #include <asm/uaccess.h> #include <asm/io.h> static int major = 0; static struct class *cls; /* gpecon 0x56000040 */ /* gpfcon 0x56000050 */ /* gpgcon 0x56000060 */ static volatile unsigned long *gpecon; static volatile unsigned long *gpedat; static volatile unsigned long *gpfcon; static volatile unsigned long *gpfdat; static volatile unsigned long *gpgcon; static volatile unsigned long *gpgdat; int buttons_open(struct inode *inode, struct file *file) {  /* 設定KSCAN0(GPE11)為輸出引腳,輸出0 */  *gpecon &= ~(0x3 << 22);  *gpecon |= (1 << 22);  *gpedat &= ~(1<<11);  /* 設定EINT0,2,11,19為輸入引腳   *     GPF0,2,GPG3,GPG11   */  *gpfcon &= ~((0x3<<0) | (0x3<<4));  *gpgcon &= ~((0x3<<6) | (0x3<<22));    return 0; } /* buf[0] => K1(GPG11), 0-按下, 1-鬆開  * buf[1] => K4(GPG3),  0-按下, 1-鬆開  * buf[2] => K7(GPF2),  0-按下, 1-鬆開  * buf[3] => K10(GPF0), 0-按下, 1-鬆開  */ ssize_t buttons_read(struct file *inode, char __user *buf, size_t size, loff_t *offset) {  char ker_buf[4];  unsigned long val;    if (size != 4)   return -EINVAL;  val = *gpgdat;  ker_buf[0] = (val & (1<<11)) ? 1 : 0;  ker_buf[1] = (val & (1<<3)) ? 1 : 0;  val = *gpfdat;  ker_buf[2] = (val & (1<<2)) ? 1 : 0;  ker_buf[3] = (val & (1<<0)) ? 1 : 0;  return copy_to_user(buf, ker_buf, 4);  } static const struct file_operations buttons_fops = {  .owner = THIS_MODULE,  .read = buttons_read,  .open = buttons_open  /* 設定引腳,申請資源 */ }; int buttons_init(void) {  major = register_chrdev(0, "buttons", &buttons_fops);  /* sysfs */  cls = class_create(THIS_MODULE, "buttons_class");  class_device_create(cls, NULL, MKDEV(major, 0), NULL, "buttons");  gpecon = ioremap(0x56000040, 4096);  gpedat = gpecon + 1;  gpfcon = gpecon + 4;  gpfdat = gpfcon + 1;  gpgcon = gpecon + 8;  gpgdat = gpgcon + 1;    return 0; } void buttons_exit(void) {  unregister_chrdev(major, "buttons");  class_device_destroy(cls, MKDEV(major, 0));  class_destroy(cls);  iounmap(gpecon); } module_init(buttons_init); module_exit(buttons_exit); MODULE_LICENSE("GPL");

buttons_test.c （測試程式）

#include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h>   int main(int argc, char **argv) {  char buf[4];  char pre_buf[4];  char key_num[] = {1,4,7,10};  int fd;  int i;  fd = open("/dev/buttons", O_RDONLY);  if (fd < 0)  {   printf("can't open /dev/buttons\n");   return -1;  } /*不斷的讀，這樣完全佔據CPU*/  while (1)  {   read(fd, buf, 4);   for (i = 0; i < 4; i++)   {    if (pre_buf[i] != buf[i])    {     printf("K%d %s\n", key_num[i], buf[i] ? "released" : "pressed");    }   }   memcpy(pre_buf, buf, 4);  }    return 0; }

Makefile

all:     make -C /home/kernel/linux-2.6.22.6 M=`pwd` modules clean:     make -C /home/kernel/linux-2.6.22.6 M=`pwd` clean obj-m += buttons.o