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led.c

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.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;
      led->owner = THIS_MODULE;

      printk(KERN_INFO
             "led: version %s, Lars Kotthoff <metalhead@metalhead.ws>\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 <metalhead@metalhead.ws>");
MODULE_DESCRIPTION("Provides control of the front LED on SPARC systems.");
MODULE_LICENSE("GPL");
MODULE_VERSION(LED_VERSION);

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