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Diffstat (limited to 'drivers/auxdisplay/charlcd.c')
-rw-r--r--drivers/auxdisplay/charlcd.c119
1 files changed, 89 insertions, 30 deletions
diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
index 642afd88870b..8673fc2b9eb8 100644
--- a/drivers/auxdisplay/charlcd.c
+++ b/drivers/auxdisplay/charlcd.c
@@ -1,16 +1,13 @@
+// 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
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
*/
#include <linux/atomic.h>
+#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
@@ -192,10 +189,11 @@ static void charlcd_print(struct charlcd *lcd, char c)
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);
}
- /* 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)
@@ -293,6 +291,79 @@ static int charlcd_init_display(struct charlcd *lcd)
}
/*
+ * 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.
@@ -362,6 +433,7 @@ static inline int handle_lcd_special_code(struct charlcd *lcd)
break;
case 'N': /* Two Lines */
priv->flags |= LCD_FLAG_N;
+ processed = 1;
break;
case 'l': /* Shift Cursor Left */
if (priv->addr.x > 0) {
@@ -441,9 +513,9 @@ static inline int handle_lcd_special_code(struct charlcd *lcd)
shift ^= 4;
if (*esc >= '0' && *esc <= '9') {
value |= (*esc - '0') << shift;
- } else if (*esc >= 'A' && *esc <= 'Z') {
+ } else if (*esc >= 'A' && *esc <= 'F') {
value |= (*esc - 'A' + 10) << shift;
- } else if (*esc >= 'a' && *esc <= 'z') {
+ } else if (*esc >= 'a' && *esc <= 'f') {
value |= (*esc - 'a' + 10) << shift;
} else {
esc++;
@@ -469,24 +541,11 @@ static inline int handle_lcd_special_code(struct charlcd *lcd)
}
case 'x': /* gotoxy : LxXXX[yYYY]; */
case 'y': /* gotoxy : LyYYY[xXXX]; */
- if (!strchr(esc, ';'))
- break;
-
- while (*esc) {
- if (*esc == 'x') {
- esc++;
- if (kstrtoul(esc, 10, &priv->addr.x) < 0)
- break;
- } else if (*esc == 'y') {
- esc++;
- if (kstrtoul(esc, 10, &priv->addr.y) < 0)
- break;
- } else {
- break;
- }
- }
+ /* If the command is valid, move to the new address */
+ if (parse_xy(esc, &priv->addr.x, &priv->addr.y))
+ charlcd_gotoxy(lcd);
- charlcd_gotoxy(lcd);
+ /* Regardless of its validity, mark as processed */
processed = 1;
break;
}
@@ -527,7 +586,7 @@ static void charlcd_write_char(struct charlcd *lcd, char c)
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;
+ priv->esc_seq.buf[priv->esc_seq.len] = '\0';
} else {
/* aborts any previous escape sequence */
priv->esc_seq.len = -1;
@@ -536,7 +595,7 @@ static void charlcd_write_char(struct charlcd *lcd, char c)
case LCD_ESCAPE_CHAR:
/* start of an escape sequence */
priv->esc_seq.len = 0;
- priv->esc_seq.buf[priv->esc_seq.len] = 0;
+ priv->esc_seq.buf[priv->esc_seq.len] = '\0';
break;
case '\b':
/* go back one char and clear it */
@@ -555,7 +614,7 @@ static void charlcd_write_char(struct charlcd *lcd, char c)
/* back one char again */
lcd->ops->write_cmd(lcd, LCD_CMD_SHIFT);
break;
- case '\014':
+ case '\f':
/* quickly clear the display */
charlcd_clear_fast(lcd);
break;