// SPDX-License-Identifier: GPL-2.0-only
#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 unsigned long led_blink_timer_timeout;

static void led_blink(struct timer_list *unused)
{
        unsigned long timeout = led_blink_timer_timeout;

        led_toggle();

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

#ifdef CONFIG_PROC_FS
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 = memdup_user_nul(buffer, count);
        if (IS_ERR(buf))
                return PTR_ERR(buf);

        /* 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
         */
        timer_delete_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_timer_timeout = simple_strtoul(buf, NULL, 10);
                led_blink(&led_blink_timer);
        } else if (!strcmp(buf, "load")) {
                led_blink_timer_timeout = 0;
                led_blink(&led_blink_timer);
        } else {
                auxio_set_led(AUXIO_LED_OFF);
        }

        kfree(buf);

        return count;
}

static const struct proc_ops led_proc_ops = {
        .proc_open      = led_proc_open,
        .proc_read      = seq_read,
        .proc_lseek     = seq_lseek,
        .proc_release   = single_release,
        .proc_write     = led_proc_write,
};
#endif

#define LED_VERSION     "0.1"

static int __init led_init(void)
{
        timer_setup(&led_blink_timer, led_blink, 0);

#ifdef CONFIG_PROC_FS
        if (!proc_create("led", 0, NULL, &led_proc_ops))
                return -ENOMEM;
#endif
        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);
        timer_delete_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);