cyc_buttons.c

我修改sbc2410开发板的例子成功运行的s3c2410的字符驱动。

#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>

#include <linux/miscdevice.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/spinlock.h>
//#include <linux/irq.h>
#include <linux/delay.h>

#include <asm-arm/arch-s3c2410/S3C2410.h>
#include <asm-arm/arch-s3c2410/irqs.h>

#define DEVICE_NAME	 "cyc_buttons"
#define BUTTON_MAJOR 242

static struct key_info {
	int irq_no;
	unsigned int gpio_port;
	int key_no;
} key_info_tab[4] = {
	{ IRQ_EINT1, GPIO_F1, 1 },
	{ IRQ_EINT2, GPIO_F2, 2 },
	{ IRQ_EINT3, GPIO_F3, 3 },
	{ IRQ_EINT7, GPIO_F7, 4 },
};

static int ready = 0;
static int key_value = 0;

static DECLARE_WAIT_QUEUE_HEAD(buttons_wait);

static void buttons_irq(int irq, void *dev_id, struct pt_regs *reg)
{
	struct key_info *k;
	int i;
	int found = 0;
	int up;
	int flags;
	for (i = 0; i < sizeof key_info_tab / sizeof key_info_tab[1]; i++) {
		k = key_info_tab + i;
		if (k->irq_no == irq) {
			found = 1;
			break;
		}
	}
	if (!found) {
		printk("bad irq %d in button\n", irq);
		return;
	}

	save_flags(flags);
	cli();
	set_gpio_mode_user(k->gpio_port, GPIO_MODE_IN);
	up = read_gpio_bit(k->gpio_port);
	set_external_irq(k->irq_no, EXT_BOTH_EDGES, GPIO_PULLUP_DIS);
	restore_flags(flags);
        if (up) {
               key_value = k->key_no + 0x80;
        } else {
               key_value = k->key_no;
        }
       	ready = 1;
	wake_up_interruptible(&buttons_wait);
}

static int request_irqs(void)
{
	struct key_info *k;
	int i;
	for (i = 0; i < sizeof key_info_tab / sizeof key_info_tab[1]; i++) {
		k = key_info_tab + i;
		set_external_irq(k->irq_no, EXT_BOTH_EDGES, GPIO_PULLUP_DIS);
		if (request_irq(k->irq_no, &buttons_irq, SA_INTERRUPT, DEVICE_NAME, &buttons_irq)) {
			return -1;
		}
		
	}
	return 0;
}

static void free_irqs(void)
{
	struct key_info *k;
	int i;
	for (i = 0; i < sizeof key_info_tab / sizeof key_info_tab[1]; i++) {
		k = key_info_tab + i;
		free_irq(k->irq_no, buttons_irq);
	}
}

static int sbc2410_buttons_read(struct file * file, char * buffer, size_t count, loff_t *ppos)
{
	static int key;
	int flags;
	int repeat;
        if (!ready)
                return -EAGAIN;
        if (count != sizeof key_value)
                return -EINVAL;
	save_flags(flags);
	if (key != key_value) {
		key = key_value;
		repeat = 0;
	} else {
		repeat = 1;
	}
	restore_flags(flags);

	if (repeat) {
		return -EAGAIN;
	}
	
        copy_to_user(buffer, &key, sizeof key);
        ready = 0;
        return sizeof key_value;
}

static unsigned int sbc2410_buttons_select(
        struct file *file,
        struct poll_table_struct *wait)
{
        if (ready)
                return 1;
        poll_wait(file, &buttons_wait, wait);
        return 0;
}


static int sbc2410_buttons_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
	switch(cmd) {
	default:
		return -EINVAL;
	}
}
static struct file_operations sbc2410_buttons_fops = {
	owner:	THIS_MODULE,
	ioctl:  sbc2410_buttons_ioctl,
	poll: sbc2410_buttons_select,
	read: sbc2410_buttons_read,
};

static devfs_handle_t devfs_handle;
static int __init sbc2410_buttons_init(void)
{
	int ret;

	ready = 0;
	ret = register_chrdev(BUTTON_MAJOR, DEVICE_NAME, &sbc2410_buttons_fops);
	if (ret < 0) {
	  printk(DEVICE_NAME " can't register major number\n");
	  return ret;
	}
	
	ret = request_irqs();
	if (ret) {
		unregister_chrdev(BUTTON_MAJOR, DEVICE_NAME);
		printk(DEVICE_NAME " can't request irqs\n");
		return ret;
	}
	devfs_handle = devfs_register(NULL, DEVICE_NAME, DEVFS_FL_DEFAULT,
				BUTTON_MAJOR, 0, S_IFCHR | S_IRUSR | S_IWUSR, &sbc2410_buttons_fops, NULL);

	return 0;
}

static void __exit sbc2410_buttons_exit(void)
{
	devfs_unregister(devfs_handle);
	free_irqs();
	unregister_chrdev(BUTTON_MAJOR, DEVICE_NAME);
}

module_init(sbc2410_buttons_init);
module_exit(sbc2410_buttons_exit);
MODULE_LICENSE("GPL");