// SPDX-License-Identifier: GPL-2.0+
/*
 * Character LCD driver for Linux
 *
 * Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
 * Copyright (C) 2016-2017 Glider bvba
 */

#include <linux/atomic.h>
#include <linux/ctype.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/workqueue.h>

#ifndef CONFIG_PANEL_BOOT_MESSAGE
#include <generated/utsrelease.h>
#endif

#include "charlcd.h"

/* Keep the backlight on this many seconds for each flash */
#define LCD_BL_TEMPO_PERIOD     4

#define LCD_ESCAPE_LEN          24      /* Max chars for LCD escape command */
#define LCD_ESCAPE_CHAR         27      /* Use char 27 for escape command */

struct charlcd_priv {
        struct charlcd lcd;

        struct delayed_work bl_work;
        struct mutex bl_tempo_lock;     /* Protects access to bl_tempo */
        bool bl_tempo;

        bool must_clear;

        /* contains the LCD config state */
        unsigned long flags;

        /* Current escape sequence and it's length or -1 if outside */
        struct {
                char buf[LCD_ESCAPE_LEN + 1];
                int len;
        } esc_seq;

        unsigned long long drvdata[];
};

#define charlcd_to_priv(p)      container_of(p, struct charlcd_priv, lcd)

/* Device single-open policy control */
static atomic_t charlcd_available = ATOMIC_INIT(1);

/* turn the backlight on or off */
void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on)
{
        struct charlcd_priv *priv = charlcd_to_priv(lcd);

        if (!lcd->ops->backlight)
                return;

        mutex_lock(&priv->bl_tempo_lock);
        if (!priv->bl_tempo)
                lcd->ops->backlight(lcd, on);
        mutex_unlock(&priv->bl_tempo_lock);
}
EXPORT_SYMBOL_GPL(charlcd_backlight);

static void charlcd_bl_off(struct work_struct *work)
{
        struct delayed_work *dwork = to_delayed_work(work);
        struct charlcd_priv *priv =
                container_of(dwork, struct charlcd_priv, bl_work);

        mutex_lock(&priv->bl_tempo_lock);
        if (priv->bl_tempo) {
                priv->bl_tempo = false;
                if (!(priv->flags & LCD_FLAG_L))
                        priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF);
        }
        mutex_unlock(&priv->bl_tempo_lock);
}

/* turn the backlight on for a little while */
void charlcd_poke(struct charlcd *lcd)
{
        struct charlcd_priv *priv = charlcd_to_priv(lcd);

        if (!lcd->ops->backlight)
                return;

        cancel_delayed_work_sync(&priv->bl_work);

        mutex_lock(&priv->bl_tempo_lock);
        if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
                lcd->ops->backlight(lcd, CHARLCD_ON);
        priv->bl_tempo = true;
        schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
        mutex_unlock(&priv->bl_tempo_lock);
}
EXPORT_SYMBOL_GPL(charlcd_poke);

static void charlcd_home(struct charlcd *lcd)
{
        lcd->addr.x = 0;
        lcd->addr.y = 0;
        lcd->ops->home(lcd);
}

static void charlcd_print(struct charlcd *lcd, char c)
{
        if (lcd->addr.x >= lcd->width)
                return;

        if (lcd->char_conv)
                c = lcd->char_conv[(unsigned char)c];

        if (!lcd->ops->print(lcd, c))
                lcd->addr.x++;

        /* prevents the cursor from wrapping onto the next line */
        if (lcd->addr.x == lcd->width)
                lcd->ops->gotoxy(lcd, lcd->addr.x - 1, lcd->addr.y);
}

static void charlcd_clear_display(struct charlcd *lcd)
{
        lcd->ops->clear_display(lcd);
        lcd->addr.x = 0;
        lcd->addr.y = 0;
}

/*
 * Parses a movement command of the form "(.*);", where the group can be
 * any number of subcommands of the form "(x|y)[0-9]+".
 *
 * Returns whether the command is valid. The position arguments are
 * only written if the parsing was successful.
 *
 * For instance:
 *   - ";"          returns (<original x>, <original y>).
 *   - "x1;"        returns (1, <original y>).
 *   - "y2x1;"      returns (1, 2).
 *   - "x12y34x56;" returns (56, 34).
 *   - ""           fails.
 *   - "x"          fails.
 *   - "x;"         fails.
 *   - "x1"         fails.
 *   - "xy12;"      fails.
 *   - "x12yy12;"   fails.
 *   - "xx"         fails.
 */
static bool parse_xy(const char *s, unsigned long *x, unsigned long *y)
{
        unsigned long new_x = *x;
        unsigned long new_y = *y;
        char *p;

        for (;;) {
                if (!*s)
                        return false;

                if (*s == ';')
                        break;

                if (*s == 'x') {
                        new_x = simple_strtoul(s + 1, &p, 10);
                        if (p == s + 1)
                                return false;
                        s = p;
                } else if (*s == 'y') {
                        new_y = simple_strtoul(s + 1, &p, 10);
                        if (p == s + 1)
                                return false;
                        s = p;
                } else {
                        return false;
                }
        }

        *x = new_x;
        *y = new_y;
        return true;
}

/*
 * These are the file operation function for user access to /dev/lcd
 * This function can also be called from inside the kernel, by
 * setting file and ppos to NULL.
 *
 */

static inline int handle_lcd_special_code(struct charlcd *lcd)
{
        struct charlcd_priv *priv = charlcd_to_priv(lcd);

        /* LCD special codes */

        int processed = 0;

        char *esc = priv->esc_seq.buf + 2;
        int oldflags = priv->flags;

        /* check for display mode flags */
        switch (*esc) {
        case 'D':       /* Display ON */
                priv->flags |= LCD_FLAG_D;
                if (priv->flags != oldflags)
                        lcd->ops->display(lcd, CHARLCD_ON);

                processed = 1;
                break;
        case 'd':       /* Display OFF */
                priv->flags &= ~LCD_FLAG_D;
                if (priv->flags != oldflags)
                        lcd->ops->display(lcd, CHARLCD_OFF);

                processed = 1;
                break;
        case 'C':       /* Cursor ON */
                priv->flags |= LCD_FLAG_C;
                if (priv->flags != oldflags)
                        lcd->ops->cursor(lcd, CHARLCD_ON);

                processed = 1;
                break;
        case 'c':       /* Cursor OFF */
                priv->flags &= ~LCD_FLAG_C;
                if (priv->flags != oldflags)
                        lcd->ops->cursor(lcd, CHARLCD_OFF);

                processed = 1;
                break;
        case 'B':       /* Blink ON */
                priv->flags |= LCD_FLAG_B;
                if (priv->flags != oldflags)
                        lcd->ops->blink(lcd, CHARLCD_ON);

                processed = 1;
                break;
        case 'b':       /* Blink OFF */
                priv->flags &= ~LCD_FLAG_B;
                if (priv->flags != oldflags)
                        lcd->ops->blink(lcd, CHARLCD_OFF);

                processed = 1;
                break;
        case '+':       /* Back light ON */
                priv->flags |= LCD_FLAG_L;
                if (priv->flags != oldflags)
                        charlcd_backlight(lcd, CHARLCD_ON);

                processed = 1;
                break;
        case '-':       /* Back light OFF */
                priv->flags &= ~LCD_FLAG_L;
                if (priv->flags != oldflags)
                        charlcd_backlight(lcd, CHARLCD_OFF);

                processed = 1;
                break;
        case '*':       /* Flash back light */
                charlcd_poke(lcd);
                processed = 1;
                break;
        case 'f':       /* Small Font */
                priv->flags &= ~LCD_FLAG_F;
                if (priv->flags != oldflags)
                        lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_SMALL);

                processed = 1;
                break;
        case 'F':       /* Large Font */
                priv->flags |= LCD_FLAG_F;
                if (priv->flags != oldflags)
                        lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_LARGE);

                processed = 1;
                break;
        case 'n':       /* One Line */
                priv->flags &= ~LCD_FLAG_N;
                if (priv->flags != oldflags)
                        lcd->ops->lines(lcd, CHARLCD_LINES_1);

                processed = 1;
                break;
        case 'N':       /* Two Lines */
                priv->flags |= LCD_FLAG_N;
                if (priv->flags != oldflags)
                        lcd->ops->lines(lcd, CHARLCD_LINES_2);

                processed = 1;
                break;
        case 'l':       /* Shift Cursor Left */
                if (lcd->addr.x > 0) {
                        if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
                                lcd->addr.x--;
                }

                processed = 1;
                break;
        case 'r':       /* shift cursor right */
                if (lcd->addr.x < lcd->width) {
                        if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_RIGHT))
                                lcd->addr.x++;
                }

                processed = 1;
                break;
        case 'L':       /* shift display left */
                lcd->ops->shift_display(lcd, CHARLCD_SHIFT_LEFT);
                processed = 1;
                break;
        case 'R':       /* shift display right */
                lcd->ops->shift_display(lcd, CHARLCD_SHIFT_RIGHT);
                processed = 1;
                break;
        case 'k': {     /* kill end of line */
                int x, xs, ys;

                xs = lcd->addr.x;
                ys = lcd->addr.y;
                for (x = lcd->addr.x; x < lcd->width; x++)
                        lcd->ops->print(lcd, ' ');

                /* restore cursor position */
                lcd->addr.x = xs;
                lcd->addr.y = ys;
                lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
                processed = 1;
                break;
        }
        case 'I':       /* reinitialize display */
                lcd->ops->init_display(lcd);
                priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
                        LCD_FLAG_C | LCD_FLAG_B;
                processed = 1;
                break;
        case 'G':
                if (lcd->ops->redefine_char)
                        processed = lcd->ops->redefine_char(lcd, esc);
                else
                        processed = 1;
                break;

        case 'x':       /* gotoxy : LxXXX[yYYY]; */
        case 'y':       /* gotoxy : LyYYY[xXXX]; */
                if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
                        break;

                /* If the command is valid, move to the new address */
                if (parse_xy(esc, &lcd->addr.x, &lcd->addr.y))
                        lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);

                /* Regardless of its validity, mark as processed */
                processed = 1;
                break;
        }

        return processed;
}

static void charlcd_write_char(struct charlcd *lcd, char c)
{
        struct charlcd_priv *priv = charlcd_to_priv(lcd);

        /* first, we'll test if we're in escape mode */
        if ((c != '\n') && priv->esc_seq.len >= 0) {
                /* yes, let's add this char to the buffer */
                priv->esc_seq.buf[priv->esc_seq.len++] = c;
                priv->esc_seq.buf[priv->esc_seq.len] = '\0';
        } else {
                /* aborts any previous escape sequence */
                priv->esc_seq.len = -1;

                switch (c) {
                case LCD_ESCAPE_CHAR:
                        /* start of an escape sequence */
                        priv->esc_seq.len = 0;
                        priv->esc_seq.buf[priv->esc_seq.len] = '\0';
                        break;
                case '\b':
                        /* go back one char and clear it */
                        if (lcd->addr.x > 0) {
                                /* back one char */
                                if (!lcd->ops->shift_cursor(lcd,
                                                        CHARLCD_SHIFT_LEFT))
                                        lcd->addr.x--;
                        }
                        /* replace with a space */
                        charlcd_print(lcd, ' ');
                        /* back one char again */
                        if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
                                lcd->addr.x--;

                        break;
                case '\f':
                        /* quickly clear the display */
                        charlcd_clear_display(lcd);
                        break;
                case '\n':
                        /*
                         * flush the remainder of the current line and
                         * go to the beginning of the next line
                         */
                        for (; lcd->addr.x < lcd->width; lcd->addr.x++)
                                lcd->ops->print(lcd, ' ');

                        lcd->addr.x = 0;
                        lcd->addr.y = (lcd->addr.y + 1) % lcd->height;
                        lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
                        break;
                case '\r':
                        /* go to the beginning of the same line */
                        lcd->addr.x = 0;
                        lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
                        break;
                case '\t':
                        /* print a space instead of the tab */
                        charlcd_print(lcd, ' ');
                        break;
                default:
                        /* simply print this char */
                        charlcd_print(lcd, c);
                        break;
                }
        }

        /*
         * now we'll see if we're in an escape mode and if the current
         * escape sequence can be understood.
         */
        if (priv->esc_seq.len >= 2) {
                int processed = 0;

                if (!strcmp(priv->esc_seq.buf, "[2J")) {
                        /* clear the display */
                        charlcd_clear_display(lcd);
                        processed = 1;
                } else if (!strcmp(priv->esc_seq.buf, "[H")) {
                        /* cursor to home */
                        charlcd_home(lcd);
                        processed = 1;
                }
                /* codes starting with ^[[L */
                else if ((priv->esc_seq.len >= 3) &&
                         (priv->esc_seq.buf[0] == '[') &&
                         (priv->esc_seq.buf[1] == 'L')) {
                        processed = handle_lcd_special_code(lcd);
                }

                /* LCD special escape codes */
                /*
                 * flush the escape sequence if it's been processed
                 * or if it is getting too long.
                 */
                if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN))
                        priv->esc_seq.len = -1;
        } /* escape codes */
}

static struct charlcd *the_charlcd;

static ssize_t charlcd_write(struct file *file, const char __user *buf,
                             size_t count, loff_t *ppos)
{
        const char __user *tmp = buf;
        char c;

        for (; count-- > 0; (*ppos)++, tmp++) {
                if (((count + 1) & 0x1f) == 0) {
                        /*
                         * charlcd_write() is invoked as a VFS->write() callback
                         * and as such it is always invoked from preemptible
                         * context and may sleep.
                         */
                        cond_resched();
                }

                if (get_user(c, tmp))
                        return -EFAULT;

                charlcd_write_char(the_charlcd, c);
        }

        return tmp - buf;
}

static int charlcd_open(struct inode *inode, struct file *file)
{
        struct charlcd_priv *priv = charlcd_to_priv(the_charlcd);
        int ret;

        ret = -EBUSY;
        if (!atomic_dec_and_test(&charlcd_available))
                goto fail;      /* open only once at a time */

        ret = -EPERM;
        if (file->f_mode & FMODE_READ)  /* device is write-only */
                goto fail;

        if (priv->must_clear) {
                priv->lcd.ops->clear_display(&priv->lcd);
                priv->must_clear = false;
                priv->lcd.addr.x = 0;
                priv->lcd.addr.y = 0;
        }
        return nonseekable_open(inode, file);

 fail:
        atomic_inc(&charlcd_available);
        return ret;
}

static int charlcd_release(struct inode *inode, struct file *file)
{
        atomic_inc(&charlcd_available);
        return 0;
}

static const struct file_operations charlcd_fops = {
        .write   = charlcd_write,
        .open    = charlcd_open,
        .release = charlcd_release,
};

static struct miscdevice charlcd_dev = {
        .minor  = LCD_MINOR,
        .name   = "lcd",
        .fops   = &charlcd_fops,
};

static void charlcd_puts(struct charlcd *lcd, const char *s)
{
        const char *tmp = s;
        int count = strlen(s);

        for (; count-- > 0; tmp++) {
                if (((count + 1) & 0x1f) == 0)
                        cond_resched();

                charlcd_write_char(lcd, *tmp);
        }
}

#ifdef CONFIG_PANEL_BOOT_MESSAGE
#define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE
#else
#define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n"
#endif

#ifdef CONFIG_CHARLCD_BL_ON
#define LCD_INIT_BL "\x1b[L+"
#elif defined(CONFIG_CHARLCD_BL_FLASH)
#define LCD_INIT_BL "\x1b[L*"
#else
#define LCD_INIT_BL "\x1b[L-"
#endif

/* initialize the LCD driver */
static int charlcd_init(struct charlcd *lcd)
{
        struct charlcd_priv *priv = charlcd_to_priv(lcd);
        int ret;

        priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
                      LCD_FLAG_C | LCD_FLAG_B;
        if (lcd->ops->backlight) {
                mutex_init(&priv->bl_tempo_lock);
                INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off);
        }

        /*
         * before this line, we must NOT send anything to the display.
         * Since charlcd_init_display() needs to write data, we have to
         * enable mark the LCD initialized just before.
         */
        if (WARN_ON(!lcd->ops->init_display))
                return -EINVAL;

        ret = lcd->ops->init_display(lcd);
        if (ret)
                return ret;

        /* display a short message */
        charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT);

        /* clear the display on the next device opening */
        priv->must_clear = true;
        charlcd_home(lcd);
        return 0;
}

struct charlcd *charlcd_alloc(unsigned int drvdata_size)
{
        struct charlcd_priv *priv;
        struct charlcd *lcd;

        priv = kzalloc(sizeof(*priv) + drvdata_size, GFP_KERNEL);
        if (!priv)
                return NULL;

        priv->esc_seq.len = -1;

        lcd = &priv->lcd;
        lcd->drvdata = priv->drvdata;

        return lcd;
}
EXPORT_SYMBOL_GPL(charlcd_alloc);

void charlcd_free(struct charlcd *lcd)
{
        kfree(charlcd_to_priv(lcd));
}
EXPORT_SYMBOL_GPL(charlcd_free);

static int panel_notify_sys(struct notifier_block *this, unsigned long code,
                            void *unused)
{
        struct charlcd *lcd = the_charlcd;

        switch (code) {
        case SYS_DOWN:
                charlcd_puts(lcd,
                             "\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+");
                break;
        case SYS_HALT:
                charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+");
                break;
        case SYS_POWER_OFF:
                charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+");
                break;
        default:
                break;
        }
        return NOTIFY_DONE;
}

static struct notifier_block panel_notifier = {
        .notifier_call = panel_notify_sys,
};

int charlcd_register(struct charlcd *lcd)
{
        int ret;

        ret = charlcd_init(lcd);
        if (ret)
                return ret;

        ret = misc_register(&charlcd_dev);
        if (ret)
                return ret;

        the_charlcd = lcd;
        register_reboot_notifier(&panel_notifier);
        return 0;
}
EXPORT_SYMBOL_GPL(charlcd_register);

int charlcd_unregister(struct charlcd *lcd)
{
        struct charlcd_priv *priv = charlcd_to_priv(lcd);

        unregister_reboot_notifier(&panel_notifier);
        charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-");
        misc_deregister(&charlcd_dev);
        the_charlcd = NULL;
        if (lcd->ops->backlight) {
                cancel_delayed_work_sync(&priv->bl_work);
                priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(charlcd_unregister);

MODULE_DESCRIPTION("Character LCD core support");
MODULE_LICENSE("GPL");