led.c

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#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/uaccess.h>

#include <asm/auxio.h>

#define LED_MAX_LENGTH 8 /* maximum chars written to proc file */

static inline void led_toggle(void)
{
    unsigned char val = get_auxio();
    unsigned char on, off;

    if (val & AUXIO_LED) {
        on = 0;
        off = AUXIO_LED;
    } else {
        on = AUXIO_LED;
        off = 0;
    }

    set_auxio(on, off);
}

static struct timer_list led_blink_timer;

static void led_blink(unsigned long timeout)
{
    led_toggle();

    /* reschedule */
    if (!timeout) { /* blink according to load */
        led_blink_timer.expires = jiffies +
            ((1 + (avenrun[0] >> FSHIFT)) * HZ);
        led_blink_timer.data = 0;
    } else { /* blink at user specified interval */
        led_blink_timer.expires = jiffies + (timeout * HZ);
        led_blink_timer.data = timeout;
    }
    add_timer(&led_blink_timer);
}

static int led_proc_show(struct seq_file *m, void *v)
{
    if (get_auxio() & AUXIO_LED)
        seq_puts(m, "on\n");
    else
        seq_puts(m, "off\n");
    return 0;
}

static int led_proc_open(struct inode *inode, struct file *file)
{
    return single_open(file, led_proc_show, NULL);
}

static ssize_t led_proc_write(struct file *file, const char __user *buffer,
                  size_t count, loff_t *ppos)
{
    char *buf = NULL;

    if (count > LED_MAX_LENGTH)
        count = LED_MAX_LENGTH;

    buf = kmalloc(sizeof(char) * (count + 1), GFP_KERNEL);
    if (!buf)
        return -ENOMEM;

    if (copy_from_user(buf, buffer, count)) {
        kfree(buf);
        return -EFAULT;
    }

    buf[count] = '\0';

    /* work around \n when echo'ing into proc */
    if (buf[count - 1] == '\n')
        buf[count - 1] = '\0';

    /* before we change anything we want to stop any running timers,
     * otherwise calls such as on will have no persistent effect
     */
    del_timer_sync(&led_blink_timer);

    if (!strcmp(buf, "on")) {
        auxio_set_led(AUXIO_LED_ON);
    } else if (!strcmp(buf, "toggle")) {
        led_toggle();
    } else if ((*buf > '0') && (*buf <= '9')) {
        led_blink(simple_strtoul(buf, NULL, 10));
    } else if (!strcmp(buf, "load")) {
        led_blink(0);
    } else {
        auxio_set_led(AUXIO_LED_OFF);
    }

    kfree(buf);

    return count;
}

static const struct file_operations led_proc_fops = {
    .owner      = THIS_MODULE,
    .open       = led_proc_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = single_release,
    .write      = led_proc_write,
};

static struct proc_dir_entry *led;

#define LED_VERSION "0.1"

static int __init led_init(void)
{
    init_timer(&led_blink_timer);
    led_blink_timer.function = led_blink;

    led = proc_create("led", 0, NULL, &led_proc_fops);
    if (!led)
        return -ENOMEM;

    printk(KERN_INFO
           "led: version %s, Lars Kotthoff <[email protected]>\n",
           LED_VERSION);

    return 0;
}

static void __exit led_exit(void)
{
    remove_proc_entry("led", NULL);
    del_timer_sync(&led_blink_timer);
}

module_init(led_init);
module_exit(led_exit);

MODULE_AUTHOR("Lars Kotthoff <[email protected]>");
MODULE_DESCRIPTION("Provides control of the front LED on SPARC systems.");
MODULE_LICENSE("GPL");
MODULE_VERSION(LED_VERSION);