arch/sparc/kernel/led.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/kernel.h>
   3 #include <linux/module.h>
   4 #include <linux/init.h>
   5 #include <linux/proc_fs.h>
   6 #include <linux/seq_file.h>
   7 #include <linux/slab.h>
   8 #include <linux/string.h>
   9 #include <linux/jiffies.h>
  10 #include <linux/timer.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/sched/loadavg.h>
  13
  14 #include <asm/auxio.h>
  15
  16 #define LED_MAX_LENGTH 8 /* maximum chars written to proc file */
  17
  18 static inline void led_toggle(void)
  19 {
  20         unsigned char val = get_auxio();
  21         unsigned char on, off;
  22
  23         if (val & AUXIO_LED) {
  24                 on = 0;
  25                 off = AUXIO_LED;
  26         } else {
  27                 on = AUXIO_LED;
  28                 off = 0;
  29         }
  30
  31         set_auxio(on, off);
  32 }
  33
  34 static struct timer_list led_blink_timer;
  35 static unsigned long led_blink_timer_timeout;
  36
  37 static void led_blink(struct timer_list *unused)
  38 {
  39         unsigned long timeout = led_blink_timer_timeout;
  40
  41         led_toggle();
  42
  43         /* reschedule */
  44         if (!timeout) { /* blink according to load */
  45                 led_blink_timer.expires = jiffies +
  46                         ((1 + (avenrun[0] >> FSHIFT)) * HZ);
  47         } else { /* blink at user specified interval */
  48                 led_blink_timer.expires = jiffies + (timeout * HZ);
  49         }
  50         add_timer(&led_blink_timer);
  51 }
  52
  53 static int led_proc_show(struct seq_file *m, void *v)
  54 {
  55         if (get_auxio() & AUXIO_LED)
  56                 seq_puts(m, "on\n");
  57         else
  58                 seq_puts(m, "off\n");
  59         return 0;
  60 }
  61
  62 static int led_proc_open(struct inode *inode, struct file *file)
  63 {
  64         return single_open(file, led_proc_show, NULL);
  65 }
  66
  67 static ssize_t led_proc_write(struct file *file, const char __user *buffer,
  68                               size_t count, loff_t *ppos)
  69 {
  70         char *buf = NULL;
  71
  72         if (count > LED_MAX_LENGTH)
  73                 count = LED_MAX_LENGTH;
  74
  75         buf = memdup_user_nul(buffer, count);
  76         if (IS_ERR(buf))
  77                 return PTR_ERR(buf);
  78
  79         /* work around \n when echo'ing into proc */
  80         if (buf[count - 1] == '\n')
  81                 buf[count - 1] = '\0';
  82
  83         /* before we change anything we want to stop any running timers,
  84          * otherwise calls such as on will have no persistent effect
  85          */
  86         del_timer_sync(&led_blink_timer);
  87
  88         if (!strcmp(buf, "on")) {
  89                 auxio_set_led(AUXIO_LED_ON);
  90         } else if (!strcmp(buf, "toggle")) {
  91                 led_toggle();
  92         } else if ((*buf > '0') && (*buf <= '9')) {
  93                 led_blink_timer_timeout = simple_strtoul(buf, NULL, 10);
  94                 led_blink(&led_blink_timer);
  95         } else if (!strcmp(buf, "load")) {
  96                 led_blink_timer_timeout = 0;
  97                 led_blink(&led_blink_timer);
  98         } else {
  99                 auxio_set_led(AUXIO_LED_OFF);
 100         }
 101
 102         kfree(buf);
 103
 104         return count;
 105 }
 106
 107 static const struct proc_ops led_proc_ops = {
 108         .proc_open      = led_proc_open,
 109         .proc_read      = seq_read,
 110         .proc_lseek     = seq_lseek,
 111         .proc_release   = single_release,
 112         .proc_write     = led_proc_write,
 113 };
 114
 115 static struct proc_dir_entry *led;
 116
 117 #define LED_VERSION     "0.1"
 118
 119 static int __init led_init(void)
 120 {
 121         timer_setup(&led_blink_timer, led_blink, 0);
 122
 123         led = proc_create("led", 0, NULL, &led_proc_ops);
 124         if (!led)
 125                 return -ENOMEM;
 126
 127         printk(KERN_INFO
 128                "led: version %s, Lars Kotthoff <metalhead@metalhead.ws>\n",
 129                LED_VERSION);
 130
 131         return 0;
 132 }
 133
 134 static void __exit led_exit(void)
 135 {
 136         remove_proc_entry("led", NULL);
 137         del_timer_sync(&led_blink_timer);
 138 }
 139
 140 module_init(led_init);
 141 module_exit(led_exit);
 142
 143 MODULE_AUTHOR("Lars Kotthoff <metalhead@metalhead.ws>");
 144 MODULE_DESCRIPTION("Provides control of the front LED on SPARC systems.");
 145 MODULE_LICENSE("GPL");
 146 MODULE_VERSION(LED_VERSION);