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path: root/drivers/auxdisplay/charlcd.c
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-rw-r--r--drivers/auxdisplay/charlcd.c884
1 files changed, 884 insertions, 0 deletions
diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
new file mode 100644
index 000000000..60e0b7726
--- /dev/null
+++ b/drivers/auxdisplay/charlcd.c
@@ -0,0 +1,884 @@
+// 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/delay.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>
+
+#include <generated/utsrelease.h>
+
+#include <misc/charlcd.h>
+
+#define LCD_MINOR 156
+
+#define DEFAULT_LCD_BWIDTH 40
+#define DEFAULT_LCD_HWIDTH 64
+
+/* Keep the backlight on this many seconds for each flash */
+#define LCD_BL_TEMPO_PERIOD 4
+
+#define LCD_FLAG_B 0x0004 /* Blink on */
+#define LCD_FLAG_C 0x0008 /* Cursor on */
+#define LCD_FLAG_D 0x0010 /* Display on */
+#define LCD_FLAG_F 0x0020 /* Large font mode */
+#define LCD_FLAG_N 0x0040 /* 2-rows mode */
+#define LCD_FLAG_L 0x0080 /* Backlight enabled */
+
+/* LCD commands */
+#define LCD_CMD_DISPLAY_CLEAR 0x01 /* Clear entire display */
+
+#define LCD_CMD_ENTRY_MODE 0x04 /* Set entry mode */
+#define LCD_CMD_CURSOR_INC 0x02 /* Increment cursor */
+
+#define LCD_CMD_DISPLAY_CTRL 0x08 /* Display control */
+#define LCD_CMD_DISPLAY_ON 0x04 /* Set display on */
+#define LCD_CMD_CURSOR_ON 0x02 /* Set cursor on */
+#define LCD_CMD_BLINK_ON 0x01 /* Set blink on */
+
+#define LCD_CMD_SHIFT 0x10 /* Shift cursor/display */
+#define LCD_CMD_DISPLAY_SHIFT 0x08 /* Shift display instead of cursor */
+#define LCD_CMD_SHIFT_RIGHT 0x04 /* Shift display/cursor to the right */
+
+#define LCD_CMD_FUNCTION_SET 0x20 /* Set function */
+#define LCD_CMD_DATA_LEN_8BITS 0x10 /* Set data length to 8 bits */
+#define LCD_CMD_TWO_LINES 0x08 /* Set to two display lines */
+#define LCD_CMD_FONT_5X10_DOTS 0x04 /* Set char font to 5x10 dots */
+
+#define LCD_CMD_SET_CGRAM_ADDR 0x40 /* Set char generator RAM address */
+
+#define LCD_CMD_SET_DDRAM_ADDR 0x80 /* Set display data RAM address */
+
+#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 int flags;
+
+ /* Contains the LCD X and Y offset */
+ struct {
+ unsigned long int x;
+ unsigned long int y;
+ } addr;
+
+ /* 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[0];
+};
+
+#define to_priv(p) container_of(p, struct charlcd_priv, lcd)
+
+/* Device single-open policy control */
+static atomic_t charlcd_available = ATOMIC_INIT(1);
+
+/* sleeps that many milliseconds with a reschedule */
+static void long_sleep(int ms)
+{
+ schedule_timeout_interruptible(msecs_to_jiffies(ms));
+}
+
+/* turn the backlight on or off */
+static void charlcd_backlight(struct charlcd *lcd, int on)
+{
+ struct charlcd_priv *priv = 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);
+}
+
+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, 0);
+ }
+ mutex_unlock(&priv->bl_tempo_lock);
+}
+
+/* turn the backlight on for a little while */
+void charlcd_poke(struct charlcd *lcd)
+{
+ struct charlcd_priv *priv = 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, 1);
+ 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_gotoxy(struct charlcd *lcd)
+{
+ struct charlcd_priv *priv = to_priv(lcd);
+ unsigned int addr;
+
+ /*
+ * we force the cursor to stay at the end of the
+ * line if it wants to go farther
+ */
+ addr = priv->addr.x < lcd->bwidth ? priv->addr.x & (lcd->hwidth - 1)
+ : lcd->bwidth - 1;
+ if (priv->addr.y & 1)
+ addr += lcd->hwidth;
+ if (priv->addr.y & 2)
+ addr += lcd->bwidth;
+ lcd->ops->write_cmd(lcd, LCD_CMD_SET_DDRAM_ADDR | addr);
+}
+
+static void charlcd_home(struct charlcd *lcd)
+{
+ struct charlcd_priv *priv = to_priv(lcd);
+
+ priv->addr.x = 0;
+ priv->addr.y = 0;
+ charlcd_gotoxy(lcd);
+}
+
+static void charlcd_print(struct charlcd *lcd, char c)
+{
+ struct charlcd_priv *priv = to_priv(lcd);
+
+ if (priv->addr.x < lcd->bwidth) {
+ if (lcd->char_conv)
+ c = lcd->char_conv[(unsigned char)c];
+ lcd->ops->write_data(lcd, c);
+ priv->addr.x++;
+
+ /* prevents the cursor from wrapping onto the next line */
+ if (priv->addr.x == lcd->bwidth)
+ charlcd_gotoxy(lcd);
+ }
+}
+
+static void charlcd_clear_fast(struct charlcd *lcd)
+{
+ int pos;
+
+ charlcd_home(lcd);
+
+ if (lcd->ops->clear_fast)
+ lcd->ops->clear_fast(lcd);
+ else
+ for (pos = 0; pos < min(2, lcd->height) * lcd->hwidth; pos++)
+ lcd->ops->write_data(lcd, ' ');
+
+ charlcd_home(lcd);
+}
+
+/* clears the display and resets X/Y */
+static void charlcd_clear_display(struct charlcd *lcd)
+{
+ struct charlcd_priv *priv = to_priv(lcd);
+
+ lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CLEAR);
+ priv->addr.x = 0;
+ priv->addr.y = 0;
+ /* we must wait a few milliseconds (15) */
+ long_sleep(15);
+}
+
+static int charlcd_init_display(struct charlcd *lcd)
+{
+ void (*write_cmd_raw)(struct charlcd *lcd, int cmd);
+ struct charlcd_priv *priv = to_priv(lcd);
+ u8 init;
+
+ if (lcd->ifwidth != 4 && lcd->ifwidth != 8)
+ return -EINVAL;
+
+ priv->flags = ((lcd->height > 1) ? LCD_FLAG_N : 0) | LCD_FLAG_D |
+ LCD_FLAG_C | LCD_FLAG_B;
+
+ long_sleep(20); /* wait 20 ms after power-up for the paranoid */
+
+ /*
+ * 8-bit mode, 1 line, small fonts; let's do it 3 times, to make sure
+ * the LCD is in 8-bit mode afterwards
+ */
+ init = LCD_CMD_FUNCTION_SET | LCD_CMD_DATA_LEN_8BITS;
+ if (lcd->ifwidth == 4) {
+ init >>= 4;
+ write_cmd_raw = lcd->ops->write_cmd_raw4;
+ } else {
+ write_cmd_raw = lcd->ops->write_cmd;
+ }
+ write_cmd_raw(lcd, init);
+ long_sleep(10);
+ write_cmd_raw(lcd, init);
+ long_sleep(10);
+ write_cmd_raw(lcd, init);
+ long_sleep(10);
+
+ if (lcd->ifwidth == 4) {
+ /* Switch to 4-bit mode, 1 line, small fonts */
+ lcd->ops->write_cmd_raw4(lcd, LCD_CMD_FUNCTION_SET >> 4);
+ long_sleep(10);
+ }
+
+ /* set font height and lines number */
+ lcd->ops->write_cmd(lcd,
+ LCD_CMD_FUNCTION_SET |
+ ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
+ ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
+ ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
+ long_sleep(10);
+
+ /* display off, cursor off, blink off */
+ lcd->ops->write_cmd(lcd, LCD_CMD_DISPLAY_CTRL);
+ long_sleep(10);
+
+ lcd->ops->write_cmd(lcd,
+ LCD_CMD_DISPLAY_CTRL | /* set display mode */
+ ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
+ ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
+ ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
+
+ charlcd_backlight(lcd, (priv->flags & LCD_FLAG_L) ? 1 : 0);
+
+ long_sleep(10);
+
+ /* entry mode set : increment, cursor shifting */
+ lcd->ops->write_cmd(lcd, LCD_CMD_ENTRY_MODE | LCD_CMD_CURSOR_INC);
+
+ charlcd_clear_display(lcd);
+ return 0;
+}
+
+/*
+ * Parses an unsigned integer from a string, until a non-digit character
+ * is found. The empty string is not accepted. No overflow checks are done.
+ *
+ * Returns whether the parsing was successful. Only in that case
+ * the output parameters are written to.
+ *
+ * TODO: If the kernel adds an inplace version of kstrtoul(), this function
+ * could be easily replaced by that.
+ */
+static bool parse_n(const char *s, unsigned long *res, const char **next_s)
+{
+ if (!isdigit(*s))
+ return false;
+
+ *res = 0;
+ while (isdigit(*s)) {
+ *res = *res * 10 + (*s - '0');
+ ++s;
+ }
+
+ *next_s = s;
+ return true;
+}
+
+/*
+ * 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;
+
+ for (;;) {
+ if (!*s)
+ return false;
+
+ if (*s == ';')
+ break;
+
+ if (*s == 'x') {
+ if (!parse_n(s + 1, &new_x, &s))
+ return false;
+ } else if (*s == 'y') {
+ if (!parse_n(s + 1, &new_y, &s))
+ return false;
+ } 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 = 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;
+ processed = 1;
+ break;
+ case 'd': /* Display OFF */
+ priv->flags &= ~LCD_FLAG_D;
+ processed = 1;
+ break;
+ case 'C': /* Cursor ON */
+ priv->flags |= LCD_FLAG_C;
+ processed = 1;
+ break;
+ case 'c': /* Cursor OFF */
+ priv->flags &= ~LCD_FLAG_C;
+ processed = 1;
+ break;
+ case 'B': /* Blink ON */
+ priv->flags |= LCD_FLAG_B;
+ processed = 1;
+ break;
+ case 'b': /* Blink OFF */
+ priv->flags &= ~LCD_FLAG_B;
+ processed = 1;
+ break;
+ case '+': /* Back light ON */
+ priv->flags |= LCD_FLAG_L;
+ processed = 1;
+ break;
+ case '-': /* Back light OFF */
+ priv->flags &= ~LCD_FLAG_L;
+ processed = 1;
+ break;
+ case '*': /* Flash back light */
+ charlcd_poke(lcd);
+ processed = 1;
+ break;
+ case 'f': /* Small Font */
+ priv->flags &= ~LCD_FLAG_F;
+ processed = 1;
+ break;
+ case 'F': /* Large Font */
+ priv->flags |= LCD_FLAG_F;
+ processed = 1;
+ break;
+ case 'n': /* One Line */
+ priv->flags &= ~LCD_FLAG_N;
+ processed = 1;
+ break;
+ case 'N': /* Two Lines */
+ priv->flags |= LCD_FLAG_N;
+ processed = 1;
+ break;
+ case 'l': /* Shift Cursor Left */
+ if (priv->addr.x > 0) {
+ /* back one char if not at end of line */
+ if (priv->addr.x < lcd->bwidth)
+ lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
+ priv->addr.x--;
+ }
+ processed = 1;
+ break;
+ case 'r': /* shift cursor right */
+ if (priv->addr.x < lcd->width) {
+ /* allow the cursor to pass the end of the line */
+ if (priv->addr.x < (lcd->bwidth - 1))
+ lcd->ops->write_cmd(lcd,
+ LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT);
+ priv->addr.x++;
+ }
+ processed = 1;
+ break;
+ case 'L': /* shift display left */
+ lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT);
+ processed = 1;
+ break;
+ case 'R': /* shift display right */
+ lcd->ops->write_cmd(lcd,
+ LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT |
+ LCD_CMD_SHIFT_RIGHT);
+ processed = 1;
+ break;
+ case 'k': { /* kill end of line */
+ int x;
+
+ for (x = priv->addr.x; x < lcd->bwidth; x++)
+ lcd->ops->write_data(lcd, ' ');
+
+ /* restore cursor position */
+ charlcd_gotoxy(lcd);
+ processed = 1;
+ break;
+ }
+ case 'I': /* reinitialize display */
+ charlcd_init_display(lcd);
+ processed = 1;
+ break;
+ case 'G': {
+ /* Generator : LGcxxxxx...xx; must have <c> between '0'
+ * and '7', representing the numerical ASCII code of the
+ * redefined character, and <xx...xx> a sequence of 16
+ * hex digits representing 8 bytes for each character.
+ * Most LCDs will only use 5 lower bits of the 7 first
+ * bytes.
+ */
+
+ unsigned char cgbytes[8];
+ unsigned char cgaddr;
+ int cgoffset;
+ int shift;
+ char value;
+ int addr;
+
+ if (!strchr(esc, ';'))
+ break;
+
+ esc++;
+
+ cgaddr = *(esc++) - '0';
+ if (cgaddr > 7) {
+ processed = 1;
+ break;
+ }
+
+ cgoffset = 0;
+ shift = 0;
+ value = 0;
+ while (*esc && cgoffset < 8) {
+ shift ^= 4;
+ if (*esc >= '0' && *esc <= '9') {
+ value |= (*esc - '0') << shift;
+ } else if (*esc >= 'A' && *esc <= 'F') {
+ value |= (*esc - 'A' + 10) << shift;
+ } else if (*esc >= 'a' && *esc <= 'f') {
+ value |= (*esc - 'a' + 10) << shift;
+ } else {
+ esc++;
+ continue;
+ }
+
+ if (shift == 0) {
+ cgbytes[cgoffset++] = value;
+ value = 0;
+ }
+
+ esc++;
+ }
+
+ lcd->ops->write_cmd(lcd, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8));
+ for (addr = 0; addr < cgoffset; addr++)
+ lcd->ops->write_data(lcd, cgbytes[addr]);
+
+ /* ensures that we stop writing to CGRAM */
+ charlcd_gotoxy(lcd);
+ 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, &priv->addr.x, &priv->addr.y))
+ charlcd_gotoxy(lcd);
+
+ /* Regardless of its validity, mark as processed */
+ processed = 1;
+ break;
+ }
+
+ /* TODO: This indent party here got ugly, clean it! */
+ /* Check whether one flag was changed */
+ if (oldflags == priv->flags)
+ return processed;
+
+ /* check whether one of B,C,D flags were changed */
+ if ((oldflags ^ priv->flags) &
+ (LCD_FLAG_B | LCD_FLAG_C | LCD_FLAG_D))
+ /* set display mode */
+ lcd->ops->write_cmd(lcd,
+ LCD_CMD_DISPLAY_CTRL |
+ ((priv->flags & LCD_FLAG_D) ? LCD_CMD_DISPLAY_ON : 0) |
+ ((priv->flags & LCD_FLAG_C) ? LCD_CMD_CURSOR_ON : 0) |
+ ((priv->flags & LCD_FLAG_B) ? LCD_CMD_BLINK_ON : 0));
+ /* check whether one of F,N flags was changed */
+ else if ((oldflags ^ priv->flags) & (LCD_FLAG_F | LCD_FLAG_N))
+ lcd->ops->write_cmd(lcd,
+ LCD_CMD_FUNCTION_SET |
+ ((lcd->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
+ ((priv->flags & LCD_FLAG_F) ? LCD_CMD_FONT_5X10_DOTS : 0) |
+ ((priv->flags & LCD_FLAG_N) ? LCD_CMD_TWO_LINES : 0));
+ /* check whether L flag was changed */
+ else if ((oldflags ^ priv->flags) & LCD_FLAG_L)
+ charlcd_backlight(lcd, !!(priv->flags & LCD_FLAG_L));
+
+ return processed;
+}
+
+static void charlcd_write_char(struct charlcd *lcd, char c)
+{
+ struct charlcd_priv *priv = 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 (priv->addr.x > 0) {
+ /*
+ * check if we're not at the
+ * end of the line
+ */
+ if (priv->addr.x < lcd->bwidth)
+ /* back one char */
+ lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
+ priv->addr.x--;
+ }
+ /* replace with a space */
+ lcd->ops->write_data(lcd, ' ');
+ /* back one char again */
+ lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
+ break;
+ case '\f':
+ /* quickly clear the display */
+ charlcd_clear_fast(lcd);
+ break;
+ case '\n':
+ /*
+ * flush the remainder of the current line and
+ * go to the beginning of the next line
+ */
+ for (; priv->addr.x < lcd->bwidth; priv->addr.x++)
+ lcd->ops->write_data(lcd, ' ');
+ priv->addr.x = 0;
+ priv->addr.y = (priv->addr.y + 1) % lcd->height;
+ charlcd_gotoxy(lcd);
+ break;
+ case '\r':
+ /* go to the beginning of the same line */
+ priv->addr.x = 0;
+ charlcd_gotoxy(lcd);
+ 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_fast(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 (!in_interrupt() && (((count + 1) & 0x1f) == 0))
+ /*
+ * let's be a little nice with other processes
+ * that need some CPU
+ */
+ schedule();
+
+ 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 = 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) {
+ charlcd_clear_display(&priv->lcd);
+ priv->must_clear = false;
+ }
+ 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,
+ .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 (!in_interrupt() && (((count + 1) & 0x1f) == 0))
+ /*
+ * let's be a little nice with other processes
+ * that need some CPU
+ */
+ schedule();
+
+ charlcd_write_char(lcd, *tmp);
+ }
+}
+
+/* initialize the LCD driver */
+static int charlcd_init(struct charlcd *lcd)
+{
+ struct charlcd_priv *priv = to_priv(lcd);
+ int ret;
+
+ 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.
+ */
+ ret = charlcd_init_display(lcd);
+ if (ret)
+ return ret;
+
+ /* display a short message */
+#ifdef CONFIG_PANEL_CHANGE_MESSAGE
+#ifdef CONFIG_PANEL_BOOT_MESSAGE
+ charlcd_puts(lcd, "\x1b[Lc\x1b[Lb\x1b[L*" CONFIG_PANEL_BOOT_MESSAGE);
+#endif
+#else
+ charlcd_puts(lcd, "\x1b[Lc\x1b[Lb\x1b[L*Linux-" UTS_RELEASE "\n");
+#endif
+ /* 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->ifwidth = 8;
+ lcd->bwidth = DEFAULT_LCD_BWIDTH;
+ lcd->hwidth = DEFAULT_LCD_HWIDTH;
+ lcd->drvdata = priv->drvdata;
+
+ return lcd;
+}
+EXPORT_SYMBOL_GPL(charlcd_alloc);
+
+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 = {
+ panel_notify_sys,
+ NULL,
+ 0
+};
+
+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 = 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, 0);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(charlcd_unregister);
+
+MODULE_LICENSE("GPL");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-24 16:59:17 +0000