xref: /openbmc/linux/arch/sparc/kernel/led.c (revision 4ce94eab)
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 #ifdef CONFIG_PROC_FS
54 static int led_proc_show(struct seq_file *m, void *v)
55 {
56 	if (get_auxio() & AUXIO_LED)
57 		seq_puts(m, "on\n");
58 	else
59 		seq_puts(m, "off\n");
60 	return 0;
61 }
62 
63 static int led_proc_open(struct inode *inode, struct file *file)
64 {
65 	return single_open(file, led_proc_show, NULL);
66 }
67 
68 static ssize_t led_proc_write(struct file *file, const char __user *buffer,
69 			      size_t count, loff_t *ppos)
70 {
71 	char *buf = NULL;
72 
73 	if (count > LED_MAX_LENGTH)
74 		count = LED_MAX_LENGTH;
75 
76 	buf = memdup_user_nul(buffer, count);
77 	if (IS_ERR(buf))
78 		return PTR_ERR(buf);
79 
80 	/* work around \n when echo'ing into proc */
81 	if (buf[count - 1] == '\n')
82 		buf[count - 1] = '\0';
83 
84 	/* before we change anything we want to stop any running timers,
85 	 * otherwise calls such as on will have no persistent effect
86 	 */
87 	del_timer_sync(&led_blink_timer);
88 
89 	if (!strcmp(buf, "on")) {
90 		auxio_set_led(AUXIO_LED_ON);
91 	} else if (!strcmp(buf, "toggle")) {
92 		led_toggle();
93 	} else if ((*buf > '0') && (*buf <= '9')) {
94 		led_blink_timer_timeout = simple_strtoul(buf, NULL, 10);
95 		led_blink(&led_blink_timer);
96 	} else if (!strcmp(buf, "load")) {
97 		led_blink_timer_timeout = 0;
98 		led_blink(&led_blink_timer);
99 	} else {
100 		auxio_set_led(AUXIO_LED_OFF);
101 	}
102 
103 	kfree(buf);
104 
105 	return count;
106 }
107 
108 static const struct proc_ops led_proc_ops = {
109 	.proc_open	= led_proc_open,
110 	.proc_read	= seq_read,
111 	.proc_lseek	= seq_lseek,
112 	.proc_release	= single_release,
113 	.proc_write	= led_proc_write,
114 };
115 #endif
116 
117 static struct proc_dir_entry *led;
118 
119 #define LED_VERSION	"0.1"
120 
121 static int __init led_init(void)
122 {
123 	timer_setup(&led_blink_timer, led_blink, 0);
124 
125 	led = proc_create("led", 0, NULL, &led_proc_ops);
126 	if (!led)
127 		return -ENOMEM;
128 
129 	printk(KERN_INFO
130 	       "led: version %s, Lars Kotthoff <metalhead@metalhead.ws>\n",
131 	       LED_VERSION);
132 
133 	return 0;
134 }
135 
136 static void __exit led_exit(void)
137 {
138 	remove_proc_entry("led", NULL);
139 	del_timer_sync(&led_blink_timer);
140 }
141 
142 module_init(led_init);
143 module_exit(led_exit);
144 
145 MODULE_AUTHOR("Lars Kotthoff <metalhead@metalhead.ws>");
146 MODULE_DESCRIPTION("Provides control of the front LED on SPARC systems.");
147 MODULE_LICENSE("GPL");
148 MODULE_VERSION(LED_VERSION);
149