[linux-block.git] / drivers / auxdisplay / charlcd.c

// 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");
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0+
	2	/*
	3	* Character LCD driver for Linux
	4	*
	5	* Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
	6	* Copyright (C) 2016-2017 Glider bvba
	7	*/
	8
	9	#include <linux/atomic.h>
	10	#include <linux/ctype.h>
	11	#include <linux/fs.h>
	12	#include <linux/miscdevice.h>
	13	#include <linux/module.h>
	14	#include <linux/notifier.h>
	15	#include <linux/reboot.h>
	16	#include <linux/slab.h>
	17	#include <linux/uaccess.h>
	18	#include <linux/workqueue.h>
	19
	20	#ifndef CONFIG_PANEL_BOOT_MESSAGE
	21	#include <generated/utsrelease.h>
	22	#endif
	23
	24	#include "charlcd.h"
	25
	26	/* Keep the backlight on this many seconds for each flash */
	27	#define LCD_BL_TEMPO_PERIOD 4
	28
	29	#define LCD_ESCAPE_LEN 24 /* Max chars for LCD escape command */
	30	#define LCD_ESCAPE_CHAR 27 /* Use char 27 for escape command */
	31
	32	struct charlcd_priv {
	33	struct charlcd lcd;
	34
	35	struct delayed_work bl_work;
	36	struct mutex bl_tempo_lock; /* Protects access to bl_tempo */
	37	bool bl_tempo;
	38
	39	bool must_clear;
	40
	41	/* contains the LCD config state */
	42	unsigned long flags;
	43
	44	/* Current escape sequence and it's length or -1 if outside */
	45	struct {
	46	char buf[LCD_ESCAPE_LEN + 1];
	47	int len;
	48	} esc_seq;
	49
	50	unsigned long long drvdata[];
	51	};
	52
	53	#define charlcd_to_priv(p) container_of(p, struct charlcd_priv, lcd)
	54
	55	/* Device single-open policy control */
	56	static atomic_t charlcd_available = ATOMIC_INIT(1);
	57
	58	/* turn the backlight on or off */
	59	void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on)
	60	{
	61	struct charlcd_priv *priv = charlcd_to_priv(lcd);
	62
	63	if (!lcd->ops->backlight)
	64	return;
	65
	66	mutex_lock(&priv->bl_tempo_lock);
	67	if (!priv->bl_tempo)
	68	lcd->ops->backlight(lcd, on);
	69	mutex_unlock(&priv->bl_tempo_lock);
	70	}
	71	EXPORT_SYMBOL_GPL(charlcd_backlight);
	72
	73	static void charlcd_bl_off(struct work_struct *work)
	74	{
	75	struct delayed_work *dwork = to_delayed_work(work);
	76	struct charlcd_priv *priv =
	77	container_of(dwork, struct charlcd_priv, bl_work);
	78
	79	mutex_lock(&priv->bl_tempo_lock);
	80	if (priv->bl_tempo) {
	81	priv->bl_tempo = false;
	82	if (!(priv->flags & LCD_FLAG_L))
	83	priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF);
	84	}
	85	mutex_unlock(&priv->bl_tempo_lock);
	86	}
	87
	88	/* turn the backlight on for a little while */
	89	void charlcd_poke(struct charlcd *lcd)
	90	{
	91	struct charlcd_priv *priv = charlcd_to_priv(lcd);
	92
	93	if (!lcd->ops->backlight)
	94	return;
	95
	96	cancel_delayed_work_sync(&priv->bl_work);
	97
	98	mutex_lock(&priv->bl_tempo_lock);
	99	if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
	100	lcd->ops->backlight(lcd, CHARLCD_ON);
	101	priv->bl_tempo = true;
	102	schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
	103	mutex_unlock(&priv->bl_tempo_lock);
	104	}
	105	EXPORT_SYMBOL_GPL(charlcd_poke);
	106
	107	static void charlcd_home(struct charlcd *lcd)
	108	{
	109	lcd->addr.x = 0;
	110	lcd->addr.y = 0;
	111	lcd->ops->home(lcd);
	112	}
	113
	114	static void charlcd_print(struct charlcd *lcd, char c)
	115	{
	116	if (lcd->addr.x >= lcd->width)
	117	return;
	118
	119	if (lcd->char_conv)
	120	c = lcd->char_conv[(unsigned char)c];
	121
	122	if (!lcd->ops->print(lcd, c))
	123	lcd->addr.x++;
	124
	125	/* prevents the cursor from wrapping onto the next line */
	126	if (lcd->addr.x == lcd->width)
	127	lcd->ops->gotoxy(lcd, lcd->addr.x - 1, lcd->addr.y);
	128	}
	129
	130	static void charlcd_clear_display(struct charlcd *lcd)
	131	{
	132	lcd->ops->clear_display(lcd);
	133	lcd->addr.x = 0;
	134	lcd->addr.y = 0;
	135	}
	136
	137	/*
	138	* Parses a movement command of the form "(.*);", where the group can be
	139	* any number of subcommands of the form "(x\|y)[0-9]+".
	140	*
	141	* Returns whether the command is valid. The position arguments are
	142	* only written if the parsing was successful.
	143	*
	144	* For instance:
	145	* - ";" returns (<original x>, <original y>).
	146	* - "x1;" returns (1, <original y>).
	147	* - "y2x1;" returns (1, 2).
	148	* - "x12y34x56;" returns (56, 34).
	149	* - "" fails.
	150	* - "x" fails.
	151	* - "x;" fails.
	152	* - "x1" fails.
	153	* - "xy12;" fails.
	154	* - "x12yy12;" fails.
	155	* - "xx" fails.
	156	*/
	157	static bool parse_xy(const char s, unsigned long x, unsigned long *y)
	158	{
	159	unsigned long new_x = *x;
	160	unsigned long new_y = *y;
	161	char *p;
	162
	163	for (;;) {
	164	if (!*s)
	165	return false;
	166
	167	if (*s == ';')
	168	break;
	169
	170	if (*s == 'x') {
	171	new_x = simple_strtoul(s + 1, &p, 10);
	172	if (p == s + 1)
	173	return false;
	174	s = p;
	175	} else if (*s == 'y') {
	176	new_y = simple_strtoul(s + 1, &p, 10);
	177	if (p == s + 1)
	178	return false;
	179	s = p;
	180	} else {
	181	return false;
	182	}
	183	}
	184
	185	*x = new_x;
	186	*y = new_y;
	187	return true;
	188	}
	189
	190	/*
	191	* These are the file operation function for user access to /dev/lcd
	192	* This function can also be called from inside the kernel, by
	193	* setting file and ppos to NULL.
	194	*
	195	*/
	196
	197	static inline int handle_lcd_special_code(struct charlcd *lcd)
	198	{
	199	struct charlcd_priv *priv = charlcd_to_priv(lcd);
	200
	201	/* LCD special codes */
	202
	203	int processed = 0;
	204
	205	char *esc = priv->esc_seq.buf + 2;
	206	int oldflags = priv->flags;
	207
	208	/* check for display mode flags */
	209	switch (*esc) {
	210	case 'D': /* Display ON */
	211	priv->flags \|= LCD_FLAG_D;
	212	if (priv->flags != oldflags)
	213	lcd->ops->display(lcd, CHARLCD_ON);
	214
	215	processed = 1;
	216	break;
	217	case 'd': /* Display OFF */
	218	priv->flags &= ~LCD_FLAG_D;
	219	if (priv->flags != oldflags)
	220	lcd->ops->display(lcd, CHARLCD_OFF);
	221
	222	processed = 1;
	223	break;
	224	case 'C': /* Cursor ON */
	225	priv->flags \|= LCD_FLAG_C;
	226	if (priv->flags != oldflags)
	227	lcd->ops->cursor(lcd, CHARLCD_ON);
	228
	229	processed = 1;
	230	break;
	231	case 'c': /* Cursor OFF */
	232	priv->flags &= ~LCD_FLAG_C;
	233	if (priv->flags != oldflags)
	234	lcd->ops->cursor(lcd, CHARLCD_OFF);
	235
	236	processed = 1;
	237	break;
	238	case 'B': /* Blink ON */
	239	priv->flags \|= LCD_FLAG_B;
	240	if (priv->flags != oldflags)
	241	lcd->ops->blink(lcd, CHARLCD_ON);
	242
	243	processed = 1;
	244	break;
	245	case 'b': /* Blink OFF */
	246	priv->flags &= ~LCD_FLAG_B;
	247	if (priv->flags != oldflags)
	248	lcd->ops->blink(lcd, CHARLCD_OFF);
	249
	250	processed = 1;
	251	break;
	252	case '+': /* Back light ON */
	253	priv->flags \|= LCD_FLAG_L;
	254	if (priv->flags != oldflags)
	255	charlcd_backlight(lcd, CHARLCD_ON);
	256
	257	processed = 1;
	258	break;
	259	case '-': /* Back light OFF */
	260	priv->flags &= ~LCD_FLAG_L;
	261	if (priv->flags != oldflags)
	262	charlcd_backlight(lcd, CHARLCD_OFF);
	263
	264	processed = 1;
	265	break;
	266	case '': / Flash back light */
	267	charlcd_poke(lcd);
	268	processed = 1;
	269	break;
	270	case 'f': /* Small Font */
	271	priv->flags &= ~LCD_FLAG_F;
	272	if (priv->flags != oldflags)
	273	lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_SMALL);
	274
	275	processed = 1;
	276	break;
	277	case 'F': /* Large Font */
	278	priv->flags \|= LCD_FLAG_F;
	279	if (priv->flags != oldflags)
	280	lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_LARGE);
	281
	282	processed = 1;
	283	break;
	284	case 'n': /* One Line */
	285	priv->flags &= ~LCD_FLAG_N;
	286	if (priv->flags != oldflags)
	287	lcd->ops->lines(lcd, CHARLCD_LINES_1);
	288
	289	processed = 1;
	290	break;
	291	case 'N': /* Two Lines */
	292	priv->flags \|= LCD_FLAG_N;
	293	if (priv->flags != oldflags)
	294	lcd->ops->lines(lcd, CHARLCD_LINES_2);
	295
	296	processed = 1;
	297	break;
	298	case 'l': /* Shift Cursor Left */
	299	if (lcd->addr.x > 0) {
	300	if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
	301	lcd->addr.x--;
	302	}
	303
	304	processed = 1;
	305	break;
	306	case 'r': /* shift cursor right */
	307	if (lcd->addr.x < lcd->width) {
	308	if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_RIGHT))
	309	lcd->addr.x++;
	310	}
	311
	312	processed = 1;
	313	break;
	314	case 'L': /* shift display left */
	315	lcd->ops->shift_display(lcd, CHARLCD_SHIFT_LEFT);
	316	processed = 1;
	317	break;
	318	case 'R': /* shift display right */
	319	lcd->ops->shift_display(lcd, CHARLCD_SHIFT_RIGHT);
	320	processed = 1;
	321	break;
	322	case 'k': { /* kill end of line */
	323	int x, xs, ys;
	324
	325	xs = lcd->addr.x;
	326	ys = lcd->addr.y;
	327	for (x = lcd->addr.x; x < lcd->width; x++)
	328	lcd->ops->print(lcd, ' ');
	329
	330	/* restore cursor position */
	331	lcd->addr.x = xs;
	332	lcd->addr.y = ys;
	333	lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
	334	processed = 1;
	335	break;
	336	}
	337	case 'I': /* reinitialize display */
	338	lcd->ops->init_display(lcd);
	339	priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) \| LCD_FLAG_D \|
	340	LCD_FLAG_C \| LCD_FLAG_B;
	341	processed = 1;
	342	break;
	343	case 'G':
	344	if (lcd->ops->redefine_char)
	345	processed = lcd->ops->redefine_char(lcd, esc);
	346	else
	347	processed = 1;
	348	break;
	349
	350	case 'x': /* gotoxy : LxXXX[yYYY]; */
	351	case 'y': /* gotoxy : LyYYY[xXXX]; */
	352	if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
	353	break;
	354
	355	/* If the command is valid, move to the new address */
	356	if (parse_xy(esc, &lcd->addr.x, &lcd->addr.y))
	357	lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
	358
	359	/* Regardless of its validity, mark as processed */
	360	processed = 1;
	361	break;
	362	}
	363
	364	return processed;
	365	}
	366
	367	static void charlcd_write_char(struct charlcd *lcd, char c)
	368	{
	369	struct charlcd_priv *priv = charlcd_to_priv(lcd);
	370
	371	/* first, we'll test if we're in escape mode */
	372	if ((c != '\n') && priv->esc_seq.len >= 0) {
	373	/* yes, let's add this char to the buffer */
	374	priv->esc_seq.buf[priv->esc_seq.len++] = c;
	375	priv->esc_seq.buf[priv->esc_seq.len] = '\0';
	376	} else {
	377	/* aborts any previous escape sequence */
	378	priv->esc_seq.len = -1;
	379
	380	switch (c) {
	381	case LCD_ESCAPE_CHAR:
	382	/* start of an escape sequence */
	383	priv->esc_seq.len = 0;
	384	priv->esc_seq.buf[priv->esc_seq.len] = '\0';
	385	break;
	386	case '\b':
	387	/* go back one char and clear it */
	388	if (lcd->addr.x > 0) {
	389	/* back one char */
	390	if (!lcd->ops->shift_cursor(lcd,
	391	CHARLCD_SHIFT_LEFT))
	392	lcd->addr.x--;
	393	}
	394	/* replace with a space */
	395	charlcd_print(lcd, ' ');
	396	/* back one char again */
	397	if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
	398	lcd->addr.x--;
	399
	400	break;
	401	case '\f':
	402	/* quickly clear the display */
	403	charlcd_clear_display(lcd);
	404	break;
	405	case '\n':
	406	/*
	407	* flush the remainder of the current line and
	408	* go to the beginning of the next line
	409	*/
	410	for (; lcd->addr.x < lcd->width; lcd->addr.x++)
	411	lcd->ops->print(lcd, ' ');
	412
	413	lcd->addr.x = 0;
	414	lcd->addr.y = (lcd->addr.y + 1) % lcd->height;
	415	lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
	416	break;
	417	case '\r':
	418	/* go to the beginning of the same line */
	419	lcd->addr.x = 0;
	420	lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
	421	break;
	422	case '\t':
	423	/* print a space instead of the tab */
	424	charlcd_print(lcd, ' ');
	425	break;
	426	default:
	427	/* simply print this char */
	428	charlcd_print(lcd, c);
	429	break;
	430	}
	431	}
	432
	433	/*
	434	* now we'll see if we're in an escape mode and if the current
	435	* escape sequence can be understood.
	436	*/
	437	if (priv->esc_seq.len >= 2) {
	438	int processed = 0;
	439
	440	if (!strcmp(priv->esc_seq.buf, "[2J")) {
	441	/* clear the display */
	442	charlcd_clear_display(lcd);
	443	processed = 1;
	444	} else if (!strcmp(priv->esc_seq.buf, "[H")) {
	445	/* cursor to home */
	446	charlcd_home(lcd);
	447	processed = 1;
	448	}
	449	/* codes starting with ^[[L */
	450	else if ((priv->esc_seq.len >= 3) &&
	451	(priv->esc_seq.buf[0] == '[') &&
	452	(priv->esc_seq.buf[1] == 'L')) {
	453	processed = handle_lcd_special_code(lcd);
	454	}
	455
	456	/* LCD special escape codes */
	457	/*
	458	* flush the escape sequence if it's been processed
	459	* or if it is getting too long.
	460	*/
	461	if (processed \|\| (priv->esc_seq.len >= LCD_ESCAPE_LEN))
	462	priv->esc_seq.len = -1;
	463	} /* escape codes */
	464	}
	465
	466	static struct charlcd *the_charlcd;
	467
	468	static ssize_t charlcd_write(struct file file, const char __user buf,
	469	size_t count, loff_t *ppos)
	470	{
	471	const char __user *tmp = buf;
	472	char c;
	473
	474	for (; count-- > 0; (*ppos)++, tmp++) {
	475	if (((count + 1) & 0x1f) == 0) {
	476	/*
	477	* charlcd_write() is invoked as a VFS->write() callback
	478	* and as such it is always invoked from preemptible
	479	* context and may sleep.
	480	*/
	481	cond_resched();
	482	}
	483
	484	if (get_user(c, tmp))
	485	return -EFAULT;
	486
	487	charlcd_write_char(the_charlcd, c);
	488	}
	489
	490	return tmp - buf;
	491	}
	492
	493	static int charlcd_open(struct inode inode, struct file file)
	494	{
	495	struct charlcd_priv *priv = charlcd_to_priv(the_charlcd);
	496	int ret;
	497
	498	ret = -EBUSY;
	499	if (!atomic_dec_and_test(&charlcd_available))
	500	goto fail; /* open only once at a time */
	501
	502	ret = -EPERM;
	503	if (file->f_mode & FMODE_READ) /* device is write-only */
	504	goto fail;
	505
	506	if (priv->must_clear) {
	507	priv->lcd.ops->clear_display(&priv->lcd);
	508	priv->must_clear = false;
	509	priv->lcd.addr.x = 0;
	510	priv->lcd.addr.y = 0;
	511	}
	512	return nonseekable_open(inode, file);
	513
	514	fail:
	515	atomic_inc(&charlcd_available);
	516	return ret;
	517	}
	518
	519	static int charlcd_release(struct inode inode, struct file file)
	520	{
	521	atomic_inc(&charlcd_available);
	522	return 0;
	523	}
	524
	525	static const struct file_operations charlcd_fops = {
	526	.write = charlcd_write,
	527	.open = charlcd_open,
	528	.release = charlcd_release,
	529	};
	530
	531	static struct miscdevice charlcd_dev = {
	532	.minor = LCD_MINOR,
	533	.name = "lcd",
	534	.fops = &charlcd_fops,
	535	};
	536
	537	static void charlcd_puts(struct charlcd lcd, const char s)
	538	{
	539	const char *tmp = s;
	540	int count = strlen(s);
	541
	542	for (; count-- > 0; tmp++) {
	543	if (((count + 1) & 0x1f) == 0)
	544	cond_resched();
	545
	546	charlcd_write_char(lcd, *tmp);
	547	}
	548	}
	549
	550	#ifdef CONFIG_PANEL_BOOT_MESSAGE
	551	#define LCD_INIT_TEXT CONFIG_PANEL_BOOT_MESSAGE
	552	#else
	553	#define LCD_INIT_TEXT "Linux-" UTS_RELEASE "\n"
	554	#endif
	555
	556	#ifdef CONFIG_CHARLCD_BL_ON
	557	#define LCD_INIT_BL "\x1b[L+"
	558	#elif defined(CONFIG_CHARLCD_BL_FLASH)
	559	#define LCD_INIT_BL "\x1b[L*"
	560	#else
	561	#define LCD_INIT_BL "\x1b[L-"
	562	#endif
	563
	564	/* initialize the LCD driver */
	565	static int charlcd_init(struct charlcd *lcd)
	566	{
	567	struct charlcd_priv *priv = charlcd_to_priv(lcd);
	568	int ret;
	569
	570	priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) \| LCD_FLAG_D \|
	571	LCD_FLAG_C \| LCD_FLAG_B;
	572	if (lcd->ops->backlight) {
	573	mutex_init(&priv->bl_tempo_lock);
	574	INIT_DELAYED_WORK(&priv->bl_work, charlcd_bl_off);
	575	}
	576
	577	/*
	578	* before this line, we must NOT send anything to the display.
	579	* Since charlcd_init_display() needs to write data, we have to
	580	* enable mark the LCD initialized just before.
	581	*/
	582	if (WARN_ON(!lcd->ops->init_display))
	583	return -EINVAL;
	584
	585	ret = lcd->ops->init_display(lcd);
	586	if (ret)
	587	return ret;
	588
	589	/* display a short message */
	590	charlcd_puts(lcd, "\x1b[Lc\x1b[Lb" LCD_INIT_BL LCD_INIT_TEXT);
	591
	592	/* clear the display on the next device opening */
	593	priv->must_clear = true;
	594	charlcd_home(lcd);
	595	return 0;
	596	}
	597
	598	struct charlcd *charlcd_alloc(unsigned int drvdata_size)
	599	{
	600	struct charlcd_priv *priv;
	601	struct charlcd *lcd;
	602
	603	priv = kzalloc(sizeof(*priv) + drvdata_size, GFP_KERNEL);
	604	if (!priv)
	605	return NULL;
	606
	607	priv->esc_seq.len = -1;
	608
	609	lcd = &priv->lcd;
	610	lcd->drvdata = priv->drvdata;
	611
	612	return lcd;
	613	}
	614	EXPORT_SYMBOL_GPL(charlcd_alloc);
	615
	616	void charlcd_free(struct charlcd *lcd)
	617	{
	618	kfree(charlcd_to_priv(lcd));
	619	}
	620	EXPORT_SYMBOL_GPL(charlcd_free);
	621
	622	static int panel_notify_sys(struct notifier_block *this, unsigned long code,
	623	void *unused)
	624	{
	625	struct charlcd *lcd = the_charlcd;
	626
	627	switch (code) {
	628	case SYS_DOWN:
	629	charlcd_puts(lcd,
	630	"\x0cReloading\nSystem...\x1b[Lc\x1b[Lb\x1b[L+");
	631	break;
	632	case SYS_HALT:
	633	charlcd_puts(lcd, "\x0cSystem Halted.\x1b[Lc\x1b[Lb\x1b[L+");
	634	break;
	635	case SYS_POWER_OFF:
	636	charlcd_puts(lcd, "\x0cPower off.\x1b[Lc\x1b[Lb\x1b[L+");
	637	break;
	638	default:
	639	break;
	640	}
	641	return NOTIFY_DONE;
	642	}
	643
	644	static struct notifier_block panel_notifier = {
	645	.notifier_call = panel_notify_sys,
	646	};
	647
	648	int charlcd_register(struct charlcd *lcd)
	649	{
	650	int ret;
	651
	652	ret = charlcd_init(lcd);
	653	if (ret)
	654	return ret;
	655
	656	ret = misc_register(&charlcd_dev);
	657	if (ret)
	658	return ret;
	659
	660	the_charlcd = lcd;
	661	register_reboot_notifier(&panel_notifier);
	662	return 0;
	663	}
	664	EXPORT_SYMBOL_GPL(charlcd_register);
	665
	666	int charlcd_unregister(struct charlcd *lcd)
	667	{
	668	struct charlcd_priv *priv = charlcd_to_priv(lcd);
	669
	670	unregister_reboot_notifier(&panel_notifier);
	671	charlcd_puts(lcd, "\x0cLCD driver unloaded.\x1b[Lc\x1b[Lb\x1b[L-");
	672	misc_deregister(&charlcd_dev);
	673	the_charlcd = NULL;
	674	if (lcd->ops->backlight) {
	675	cancel_delayed_work_sync(&priv->bl_work);
	676	priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF);
	677	}
	678
	679	return 0;
	680	}
	681	EXPORT_SYMBOL_GPL(charlcd_unregister);
	682
	683	MODULE_DESCRIPTION("Character LCD core support");
	684	MODULE_LICENSE("GPL");