text: #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 <linux/sched/loadavg.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 <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);
  