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![Luiz Sampaio](/assets/img/avatar_default.png)
Check if the pointer lcd->ops->init_display exists before dereferencing it. If a driver called charlcd_init() without defining the ops, this would return segmentation fault, as happened to me when implementing a charlcd driver. Checking the pointer before dereferencing protects from segmentation fault. Signed-off-by: Luiz Sampaio <sampaio.ime@gmail.com> Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
681 lines
15 KiB
C
681 lines
15 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Character LCD driver for Linux
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*
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* Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
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* Copyright (C) 2016-2017 Glider bvba
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*/
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#include <linux/atomic.h>
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#include <linux/ctype.h>
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#include <linux/fs.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/notifier.h>
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#include <linux/reboot.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/workqueue.h>
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#include <generated/utsrelease.h>
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#include "charlcd.h"
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/* Keep the backlight on this many seconds for each flash */
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#define LCD_BL_TEMPO_PERIOD 4
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#define LCD_ESCAPE_LEN 24 /* Max chars for LCD escape command */
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#define LCD_ESCAPE_CHAR 27 /* Use char 27 for escape command */
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struct charlcd_priv {
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struct charlcd lcd;
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struct delayed_work bl_work;
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struct mutex bl_tempo_lock; /* Protects access to bl_tempo */
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bool bl_tempo;
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bool must_clear;
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/* contains the LCD config state */
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unsigned long flags;
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/* Current escape sequence and it's length or -1 if outside */
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struct {
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char buf[LCD_ESCAPE_LEN + 1];
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int len;
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} esc_seq;
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unsigned long long drvdata[];
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};
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#define charlcd_to_priv(p) container_of(p, struct charlcd_priv, lcd)
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/* Device single-open policy control */
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static atomic_t charlcd_available = ATOMIC_INIT(1);
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/* turn the backlight on or off */
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void charlcd_backlight(struct charlcd *lcd, enum charlcd_onoff on)
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{
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struct charlcd_priv *priv = charlcd_to_priv(lcd);
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if (!lcd->ops->backlight)
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return;
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mutex_lock(&priv->bl_tempo_lock);
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if (!priv->bl_tempo)
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lcd->ops->backlight(lcd, on);
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mutex_unlock(&priv->bl_tempo_lock);
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}
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EXPORT_SYMBOL_GPL(charlcd_backlight);
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static void charlcd_bl_off(struct work_struct *work)
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{
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struct delayed_work *dwork = to_delayed_work(work);
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struct charlcd_priv *priv =
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container_of(dwork, struct charlcd_priv, bl_work);
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mutex_lock(&priv->bl_tempo_lock);
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if (priv->bl_tempo) {
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priv->bl_tempo = false;
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if (!(priv->flags & LCD_FLAG_L))
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priv->lcd.ops->backlight(&priv->lcd, CHARLCD_OFF);
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}
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mutex_unlock(&priv->bl_tempo_lock);
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}
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/* turn the backlight on for a little while */
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void charlcd_poke(struct charlcd *lcd)
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{
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struct charlcd_priv *priv = charlcd_to_priv(lcd);
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if (!lcd->ops->backlight)
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return;
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cancel_delayed_work_sync(&priv->bl_work);
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mutex_lock(&priv->bl_tempo_lock);
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if (!priv->bl_tempo && !(priv->flags & LCD_FLAG_L))
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lcd->ops->backlight(lcd, CHARLCD_ON);
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priv->bl_tempo = true;
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schedule_delayed_work(&priv->bl_work, LCD_BL_TEMPO_PERIOD * HZ);
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mutex_unlock(&priv->bl_tempo_lock);
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}
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EXPORT_SYMBOL_GPL(charlcd_poke);
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static void charlcd_home(struct charlcd *lcd)
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{
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lcd->addr.x = 0;
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lcd->addr.y = 0;
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lcd->ops->home(lcd);
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}
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static void charlcd_print(struct charlcd *lcd, char c)
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{
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if (lcd->addr.x >= lcd->width)
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return;
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if (lcd->char_conv)
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c = lcd->char_conv[(unsigned char)c];
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if (!lcd->ops->print(lcd, c))
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lcd->addr.x++;
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/* prevents the cursor from wrapping onto the next line */
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if (lcd->addr.x == lcd->width)
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lcd->ops->gotoxy(lcd, lcd->addr.x - 1, lcd->addr.y);
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}
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static void charlcd_clear_display(struct charlcd *lcd)
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{
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lcd->ops->clear_display(lcd);
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lcd->addr.x = 0;
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lcd->addr.y = 0;
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}
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/*
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* Parses a movement command of the form "(.*);", where the group can be
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* any number of subcommands of the form "(x|y)[0-9]+".
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*
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* Returns whether the command is valid. The position arguments are
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* only written if the parsing was successful.
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*
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* For instance:
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* - ";" returns (<original x>, <original y>).
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* - "x1;" returns (1, <original y>).
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* - "y2x1;" returns (1, 2).
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* - "x12y34x56;" returns (56, 34).
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* - "" fails.
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* - "x" fails.
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* - "x;" fails.
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* - "x1" fails.
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* - "xy12;" fails.
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* - "x12yy12;" fails.
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* - "xx" fails.
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*/
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static bool parse_xy(const char *s, unsigned long *x, unsigned long *y)
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{
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unsigned long new_x = *x;
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unsigned long new_y = *y;
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char *p;
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for (;;) {
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if (!*s)
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return false;
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if (*s == ';')
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break;
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if (*s == 'x') {
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new_x = simple_strtoul(s + 1, &p, 10);
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if (p == s + 1)
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return false;
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s = p;
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} else if (*s == 'y') {
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new_y = simple_strtoul(s + 1, &p, 10);
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if (p == s + 1)
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return false;
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s = p;
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} else {
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return false;
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}
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}
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*x = new_x;
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*y = new_y;
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return true;
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}
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/*
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* These are the file operation function for user access to /dev/lcd
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* This function can also be called from inside the kernel, by
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* setting file and ppos to NULL.
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*
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*/
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static inline int handle_lcd_special_code(struct charlcd *lcd)
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{
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struct charlcd_priv *priv = charlcd_to_priv(lcd);
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/* LCD special codes */
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int processed = 0;
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char *esc = priv->esc_seq.buf + 2;
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int oldflags = priv->flags;
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/* check for display mode flags */
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switch (*esc) {
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case 'D': /* Display ON */
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priv->flags |= LCD_FLAG_D;
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if (priv->flags != oldflags)
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lcd->ops->display(lcd, CHARLCD_ON);
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processed = 1;
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break;
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case 'd': /* Display OFF */
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priv->flags &= ~LCD_FLAG_D;
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if (priv->flags != oldflags)
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lcd->ops->display(lcd, CHARLCD_OFF);
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processed = 1;
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break;
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case 'C': /* Cursor ON */
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priv->flags |= LCD_FLAG_C;
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if (priv->flags != oldflags)
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lcd->ops->cursor(lcd, CHARLCD_ON);
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processed = 1;
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break;
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case 'c': /* Cursor OFF */
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priv->flags &= ~LCD_FLAG_C;
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if (priv->flags != oldflags)
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lcd->ops->cursor(lcd, CHARLCD_OFF);
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processed = 1;
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break;
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case 'B': /* Blink ON */
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priv->flags |= LCD_FLAG_B;
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if (priv->flags != oldflags)
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lcd->ops->blink(lcd, CHARLCD_ON);
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processed = 1;
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break;
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case 'b': /* Blink OFF */
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priv->flags &= ~LCD_FLAG_B;
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if (priv->flags != oldflags)
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lcd->ops->blink(lcd, CHARLCD_OFF);
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processed = 1;
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break;
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case '+': /* Back light ON */
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priv->flags |= LCD_FLAG_L;
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if (priv->flags != oldflags)
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charlcd_backlight(lcd, CHARLCD_ON);
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processed = 1;
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break;
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case '-': /* Back light OFF */
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priv->flags &= ~LCD_FLAG_L;
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if (priv->flags != oldflags)
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charlcd_backlight(lcd, CHARLCD_OFF);
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processed = 1;
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break;
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case '*': /* Flash back light */
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charlcd_poke(lcd);
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processed = 1;
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break;
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case 'f': /* Small Font */
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priv->flags &= ~LCD_FLAG_F;
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if (priv->flags != oldflags)
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lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_SMALL);
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processed = 1;
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break;
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case 'F': /* Large Font */
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priv->flags |= LCD_FLAG_F;
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if (priv->flags != oldflags)
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lcd->ops->fontsize(lcd, CHARLCD_FONTSIZE_LARGE);
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processed = 1;
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break;
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case 'n': /* One Line */
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priv->flags &= ~LCD_FLAG_N;
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if (priv->flags != oldflags)
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lcd->ops->lines(lcd, CHARLCD_LINES_1);
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processed = 1;
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break;
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case 'N': /* Two Lines */
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priv->flags |= LCD_FLAG_N;
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if (priv->flags != oldflags)
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lcd->ops->lines(lcd, CHARLCD_LINES_2);
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processed = 1;
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break;
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case 'l': /* Shift Cursor Left */
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if (lcd->addr.x > 0) {
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if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
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lcd->addr.x--;
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}
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processed = 1;
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break;
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case 'r': /* shift cursor right */
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if (lcd->addr.x < lcd->width) {
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if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_RIGHT))
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lcd->addr.x++;
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}
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processed = 1;
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break;
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case 'L': /* shift display left */
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lcd->ops->shift_display(lcd, CHARLCD_SHIFT_LEFT);
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processed = 1;
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break;
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case 'R': /* shift display right */
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lcd->ops->shift_display(lcd, CHARLCD_SHIFT_RIGHT);
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processed = 1;
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break;
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case 'k': { /* kill end of line */
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int x, xs, ys;
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xs = lcd->addr.x;
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ys = lcd->addr.y;
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for (x = lcd->addr.x; x < lcd->width; x++)
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lcd->ops->print(lcd, ' ');
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/* restore cursor position */
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lcd->addr.x = xs;
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lcd->addr.y = ys;
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lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
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processed = 1;
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break;
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}
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case 'I': /* reinitialize display */
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lcd->ops->init_display(lcd);
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priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
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LCD_FLAG_C | LCD_FLAG_B;
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processed = 1;
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break;
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case 'G':
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if (lcd->ops->redefine_char)
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processed = lcd->ops->redefine_char(lcd, esc);
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else
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processed = 1;
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break;
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case 'x': /* gotoxy : LxXXX[yYYY]; */
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case 'y': /* gotoxy : LyYYY[xXXX]; */
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if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
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break;
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/* If the command is valid, move to the new address */
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if (parse_xy(esc, &lcd->addr.x, &lcd->addr.y))
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lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
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/* Regardless of its validity, mark as processed */
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processed = 1;
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break;
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}
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return processed;
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}
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static void charlcd_write_char(struct charlcd *lcd, char c)
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{
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struct charlcd_priv *priv = charlcd_to_priv(lcd);
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/* first, we'll test if we're in escape mode */
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if ((c != '\n') && priv->esc_seq.len >= 0) {
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/* yes, let's add this char to the buffer */
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priv->esc_seq.buf[priv->esc_seq.len++] = c;
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priv->esc_seq.buf[priv->esc_seq.len] = '\0';
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} else {
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/* aborts any previous escape sequence */
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priv->esc_seq.len = -1;
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switch (c) {
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case LCD_ESCAPE_CHAR:
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/* start of an escape sequence */
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priv->esc_seq.len = 0;
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priv->esc_seq.buf[priv->esc_seq.len] = '\0';
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break;
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case '\b':
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/* go back one char and clear it */
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if (lcd->addr.x > 0) {
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/* back one char */
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if (!lcd->ops->shift_cursor(lcd,
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CHARLCD_SHIFT_LEFT))
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lcd->addr.x--;
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}
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/* replace with a space */
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charlcd_print(lcd, ' ');
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/* back one char again */
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if (!lcd->ops->shift_cursor(lcd, CHARLCD_SHIFT_LEFT))
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lcd->addr.x--;
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break;
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case '\f':
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/* quickly clear the display */
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charlcd_clear_display(lcd);
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break;
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case '\n':
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/*
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* flush the remainder of the current line and
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* go to the beginning of the next line
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*/
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for (; lcd->addr.x < lcd->width; lcd->addr.x++)
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lcd->ops->print(lcd, ' ');
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lcd->addr.x = 0;
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lcd->addr.y = (lcd->addr.y + 1) % lcd->height;
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lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
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break;
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case '\r':
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/* go to the beginning of the same line */
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lcd->addr.x = 0;
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lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
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break;
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case '\t':
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/* print a space instead of the tab */
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charlcd_print(lcd, ' ');
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break;
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default:
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/* simply print this char */
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charlcd_print(lcd, c);
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break;
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}
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}
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/*
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* now we'll see if we're in an escape mode and if the current
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* escape sequence can be understood.
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*/
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if (priv->esc_seq.len >= 2) {
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int processed = 0;
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if (!strcmp(priv->esc_seq.buf, "[2J")) {
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/* clear the display */
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charlcd_clear_display(lcd);
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processed = 1;
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} else if (!strcmp(priv->esc_seq.buf, "[H")) {
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/* cursor to home */
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charlcd_home(lcd);
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processed = 1;
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}
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/* codes starting with ^[[L */
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else if ((priv->esc_seq.len >= 3) &&
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(priv->esc_seq.buf[0] == '[') &&
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(priv->esc_seq.buf[1] == 'L')) {
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processed = handle_lcd_special_code(lcd);
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}
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/* LCD special escape codes */
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/*
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* flush the escape sequence if it's been processed
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* or if it is getting too long.
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*/
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if (processed || (priv->esc_seq.len >= LCD_ESCAPE_LEN))
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priv->esc_seq.len = -1;
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} /* escape codes */
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}
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static struct charlcd *the_charlcd;
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static ssize_t charlcd_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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const char __user *tmp = buf;
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char c;
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for (; count-- > 0; (*ppos)++, tmp++) {
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if (((count + 1) & 0x1f) == 0) {
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/*
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* charlcd_write() is invoked as a VFS->write() callback
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* and as such it is always invoked from preemptible
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* context and may sleep.
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*/
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cond_resched();
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}
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if (get_user(c, tmp))
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return -EFAULT;
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charlcd_write_char(the_charlcd, c);
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}
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return tmp - buf;
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}
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static int charlcd_open(struct inode *inode, struct file *file)
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{
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struct charlcd_priv *priv = charlcd_to_priv(the_charlcd);
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int ret;
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ret = -EBUSY;
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if (!atomic_dec_and_test(&charlcd_available))
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goto fail; /* open only once at a time */
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ret = -EPERM;
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if (file->f_mode & FMODE_READ) /* device is write-only */
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goto fail;
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if (priv->must_clear) {
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priv->lcd.ops->clear_display(&priv->lcd);
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priv->must_clear = false;
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priv->lcd.addr.x = 0;
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priv->lcd.addr.y = 0;
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}
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return nonseekable_open(inode, file);
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fail:
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atomic_inc(&charlcd_available);
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return ret;
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}
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static int charlcd_release(struct inode *inode, struct file *file)
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{
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atomic_inc(&charlcd_available);
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return 0;
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}
|
|
|
|
static const struct file_operations charlcd_fops = {
|
|
.write = charlcd_write,
|
|
.open = charlcd_open,
|
|
.release = charlcd_release,
|
|
.llseek = no_llseek,
|
|
};
|
|
|
|
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(void)
|
|
{
|
|
struct charlcd_priv *priv;
|
|
struct charlcd *lcd;
|
|
|
|
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
|
|
if (!priv)
|
|
return NULL;
|
|
|
|
priv->esc_seq.len = -1;
|
|
|
|
lcd = &priv->lcd;
|
|
|
|
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_LICENSE("GPL");
|