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linux-stable/drivers/auxdisplay/lcd2s.c
Andy Shevchenko 9ed331f8a0 auxdisplay: lcd2s: Use proper API to free the instance of charlcd object 
While it might work, the current approach is fragile in a few ways:
- whenever members in the structure are shuffled, the pointer will be wrong
- the resource freeing may include more than covered by kfree()

Fix this by using charlcd_free() call instead of kfree().

Fixes: 8c9108d014 ("auxdisplay: add a driver for lcd2s character display")
Cc: Lars Poeschel <poeschel@lemonage.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2022-03-03 00:30:31 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* console driver for LCD2S 4x20 character displays connected through i2c.
* The display also has a spi interface, but the driver does not support
* this yet.
*
* This is a driver allowing you to use a LCD2S 4x20 from modtronix
* engineering as auxdisplay character device.
*
* (C) 2019 by Lemonage Software GmbH
* Author: Lars Pöschel <poeschel@lemonage.de>
* All rights reserved.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include "charlcd.h"
#define LCD2S_CMD_CUR_MOVES_FWD 0x09
#define LCD2S_CMD_CUR_BLINK_OFF 0x10
#define LCD2S_CMD_CUR_UL_OFF 0x11
#define LCD2S_CMD_DISPLAY_OFF 0x12
#define LCD2S_CMD_CUR_BLINK_ON 0x18
#define LCD2S_CMD_CUR_UL_ON 0x19
#define LCD2S_CMD_DISPLAY_ON 0x1a
#define LCD2S_CMD_BACKLIGHT_OFF 0x20
#define LCD2S_CMD_BACKLIGHT_ON 0x28
#define LCD2S_CMD_WRITE 0x80
#define LCD2S_CMD_MOV_CUR_RIGHT 0x83
#define LCD2S_CMD_MOV_CUR_LEFT 0x84
#define LCD2S_CMD_SHIFT_RIGHT 0x85
#define LCD2S_CMD_SHIFT_LEFT 0x86
#define LCD2S_CMD_SHIFT_UP 0x87
#define LCD2S_CMD_SHIFT_DOWN 0x88
#define LCD2S_CMD_CUR_ADDR 0x89
#define LCD2S_CMD_CUR_POS 0x8a
#define LCD2S_CMD_CUR_RESET 0x8b
#define LCD2S_CMD_CLEAR 0x8c
#define LCD2S_CMD_DEF_CUSTOM_CHAR 0x92
#define LCD2S_CMD_READ_STATUS 0xd0
#define LCD2S_CHARACTER_SIZE 8
#define LCD2S_STATUS_BUF_MASK 0x7f
struct lcd2s_data {
struct i2c_client *i2c;
struct charlcd *charlcd;
};
static s32 lcd2s_wait_buf_free(const struct i2c_client *client, int count)
{
s32 status;
status = i2c_smbus_read_byte_data(client, LCD2S_CMD_READ_STATUS);
if (status < 0)
return status;
while ((status & LCD2S_STATUS_BUF_MASK) < count) {
mdelay(1);
status = i2c_smbus_read_byte_data(client,
LCD2S_CMD_READ_STATUS);
if (status < 0)
return status;
}
return 0;
}
static int lcd2s_i2c_master_send(const struct i2c_client *client,
const char *buf, int count)
{
s32 status;
status = lcd2s_wait_buf_free(client, count);
if (status < 0)
return status;
return i2c_master_send(client, buf, count);
}
static int lcd2s_i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
{
s32 status;
status = lcd2s_wait_buf_free(client, 1);
if (status < 0)
return status;
return i2c_smbus_write_byte(client, value);
}
static int lcd2s_print(struct charlcd *lcd, int c)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
u8 buf[2] = { LCD2S_CMD_WRITE, c };
lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf));
return 0;
}
static int lcd2s_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
u8 buf[] = { LCD2S_CMD_CUR_POS, y + 1, x + 1};
lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf));
return 0;
}
static int lcd2s_home(struct charlcd *lcd)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_RESET);
return 0;
}
static int lcd2s_init_display(struct charlcd *lcd)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
/* turn everything off, but display on */
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON);
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF);
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_MOVES_FWD);
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF);
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF);
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR);
return 0;
}
static int lcd2s_shift_cursor(struct charlcd *lcd, enum charlcd_shift_dir dir)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
if (dir == CHARLCD_SHIFT_LEFT)
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_LEFT);
else
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_RIGHT);
return 0;
}
static int lcd2s_shift_display(struct charlcd *lcd, enum charlcd_shift_dir dir)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
if (dir == CHARLCD_SHIFT_LEFT)
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_LEFT);
else
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_RIGHT);
return 0;
}
static void lcd2s_backlight(struct charlcd *lcd, enum charlcd_onoff on)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
if (on)
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_ON);
else
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF);
}
static int lcd2s_display(struct charlcd *lcd, enum charlcd_onoff on)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
if (on)
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON);
else
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_OFF);
return 0;
}
static int lcd2s_cursor(struct charlcd *lcd, enum charlcd_onoff on)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
if (on)
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_ON);
else
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF);
return 0;
}
static int lcd2s_blink(struct charlcd *lcd, enum charlcd_onoff on)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
if (on)
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_ON);
else
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF);
return 0;
}
static int lcd2s_fontsize(struct charlcd *lcd, enum charlcd_fontsize size)
{
return 0;
}
static int lcd2s_lines(struct charlcd *lcd, enum charlcd_lines lines)
{
return 0;
}
static int lcd2s_redefine_char(struct charlcd *lcd, char *esc)
{
/* 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.
*/
struct lcd2s_data *lcd2s = lcd->drvdata;
u8 buf[LCD2S_CHARACTER_SIZE + 2] = { LCD2S_CMD_DEF_CUSTOM_CHAR };
u8 value;
int shift, i;
if (!strchr(esc, ';'))
return 0;
esc++;
buf[1] = *(esc++) - '0';
if (buf[1] > 7)
return 1;
i = 2;
shift = 0;
value = 0;
while (*esc && i < LCD2S_CHARACTER_SIZE + 2) {
int half;
shift ^= 4;
half = hex_to_bin(*esc++);
if (half < 0)
continue;
value |= half << shift;
if (shift == 0) {
buf[i++] = value;
value = 0;
}
}
lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf));
return 1;
}
static int lcd2s_clear_display(struct charlcd *lcd)
{
struct lcd2s_data *lcd2s = lcd->drvdata;
/* This implicitly sets cursor to first row and column */
lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR);
return 0;
}
static const struct charlcd_ops lcd2s_ops = {
.print = lcd2s_print,
.backlight = lcd2s_backlight,
.gotoxy = lcd2s_gotoxy,
.home = lcd2s_home,
.clear_display = lcd2s_clear_display,
.init_display = lcd2s_init_display,
.shift_cursor = lcd2s_shift_cursor,
.shift_display = lcd2s_shift_display,
.display = lcd2s_display,
.cursor = lcd2s_cursor,
.blink = lcd2s_blink,
.fontsize = lcd2s_fontsize,
.lines = lcd2s_lines,
.redefine_char = lcd2s_redefine_char,
};
static int lcd2s_i2c_probe(struct i2c_client *i2c,
const struct i2c_device_id *id)
{
struct charlcd *lcd;
struct lcd2s_data *lcd2s;
int err;
if (!i2c_check_functionality(i2c->adapter,
I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
I2C_FUNC_SMBUS_WRITE_BLOCK_DATA))
return -EIO;
lcd2s = devm_kzalloc(&i2c->dev, sizeof(*lcd2s), GFP_KERNEL);
if (!lcd2s)
return -ENOMEM;
/* Test, if the display is responding */
err = lcd2s_i2c_smbus_write_byte(i2c, LCD2S_CMD_DISPLAY_OFF);
if (err < 0)
return err;
lcd = charlcd_alloc();
if (!lcd)
return -ENOMEM;
lcd->drvdata = lcd2s;
lcd2s->i2c = i2c;
lcd2s->charlcd = lcd;
/* Required properties */
err = device_property_read_u32(&i2c->dev, "display-height-chars",
&lcd->height);
if (err)
goto fail1;
err = device_property_read_u32(&i2c->dev, "display-width-chars",
&lcd->width);
if (err)
goto fail1;
lcd->ops = &lcd2s_ops;
err = charlcd_register(lcd2s->charlcd);
if (err)
goto fail1;
i2c_set_clientdata(i2c, lcd2s);
return 0;
fail1:
charlcd_free(lcd2s->charlcd);
return err;
}
static int lcd2s_i2c_remove(struct i2c_client *i2c)
{
struct lcd2s_data *lcd2s = i2c_get_clientdata(i2c);
charlcd_unregister(lcd2s->charlcd);
charlcd_free(lcd2s->charlcd);
return 0;
}
static const struct i2c_device_id lcd2s_i2c_id[] = {
{ "lcd2s", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, lcd2s_i2c_id);
#ifdef CONFIG_OF
static const struct of_device_id lcd2s_of_table[] = {
{ .compatible = "modtronix,lcd2s" },
{ }
};
MODULE_DEVICE_TABLE(of, lcd2s_of_table);
#endif
static struct i2c_driver lcd2s_i2c_driver = {
.driver = {
.name = "lcd2s",
#ifdef CONFIG_OF
.of_match_table = of_match_ptr(lcd2s_of_table),
#endif
},
.probe = lcd2s_i2c_probe,
.remove = lcd2s_i2c_remove,
.id_table = lcd2s_i2c_id,
};
static int __init lcd2s_modinit(void)
{
int ret = 0;
ret = i2c_add_driver(&lcd2s_i2c_driver);
if (ret != 0)
pr_err("Failed to register lcd2s driver\n");
return ret;
}
module_init(lcd2s_modinit)
static void __exit lcd2s_exit(void)
{
i2c_del_driver(&lcd2s_i2c_driver);
}
module_exit(lcd2s_exit)
MODULE_DESCRIPTION("LCD2S character display driver");
MODULE_AUTHOR("Lars Poeschel");
MODULE_LICENSE("GPL");
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