// SPDX-License-Identifier: GPL-2.0-or-later
#include <linux/hex.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>

#include "charlcd.h"
#include "hd44780_common.h"

/* 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 */

/* sleeps that many milliseconds with a reschedule */
static void long_sleep(int ms)
{
        schedule_timeout_interruptible(msecs_to_jiffies(ms));
}

int hd44780_common_print(struct charlcd *lcd, int c)
{
        struct hd44780_common *hdc = lcd->drvdata;

        if (lcd->addr.x < hdc->bwidth) {
                hdc->write_data(hdc, c);
                return 0;
        }

        return 1;
}
EXPORT_SYMBOL_GPL(hd44780_common_print);

int hd44780_common_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y)
{
        struct hd44780_common *hdc = lcd->drvdata;
        unsigned int addr;

        /*
         * we force the cursor to stay at the end of the
         * line if it wants to go farther
         */
        addr = x < hdc->bwidth ? x & (hdc->hwidth - 1) : hdc->bwidth - 1;
        if (y & 1)
                addr += hdc->hwidth;
        if (y & 2)
                addr += hdc->bwidth;
        hdc->write_cmd(hdc, LCD_CMD_SET_DDRAM_ADDR | addr);
        return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_gotoxy);

int hd44780_common_home(struct charlcd *lcd)
{
        return hd44780_common_gotoxy(lcd, 0, 0);
}
EXPORT_SYMBOL_GPL(hd44780_common_home);

/* clears the display and resets X/Y */
int hd44780_common_clear_display(struct charlcd *lcd)
{
        struct hd44780_common *hdc = lcd->drvdata;

        hdc->write_cmd(hdc, LCD_CMD_DISPLAY_CLEAR);
        /* datasheet says to wait 1,64 milliseconds */
        long_sleep(2);

        /*
         * The Hitachi HD44780 controller (and compatible ones) reset the DDRAM
         * address when executing the DISPLAY_CLEAR command, thus the
         * following call is not required. However, other controllers do not
         * (e.g. NewHaven NHD-0220DZW-AG5), thus move the cursor to home
         * unconditionally to support both.
         */
        return hd44780_common_home(lcd);
}
EXPORT_SYMBOL_GPL(hd44780_common_clear_display);

int hd44780_common_init_display(struct charlcd *lcd)
{
        struct hd44780_common *hdc = lcd->drvdata;

        void (*write_cmd_raw)(struct hd44780_common *hdc, int cmd);
        u8 init;

        if (hdc->ifwidth != 4 && hdc->ifwidth != 8)
                return -EINVAL;

        hdc->hd44780_common_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 (hdc->ifwidth == 4) {
                init >>= 4;
                write_cmd_raw = hdc->write_cmd_raw4;
        } else {
                write_cmd_raw = hdc->write_cmd;
        }
        write_cmd_raw(hdc, init);
        long_sleep(10);
        write_cmd_raw(hdc, init);
        long_sleep(10);
        write_cmd_raw(hdc, init);
        long_sleep(10);

        if (hdc->ifwidth == 4) {
                /* Switch to 4-bit mode, 1 line, small fonts */
                hdc->write_cmd_raw4(hdc, LCD_CMD_FUNCTION_SET >> 4);
                long_sleep(10);
        }

        /* set font height and lines number */
        hdc->write_cmd(hdc,
                LCD_CMD_FUNCTION_SET |
                ((hdc->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
                ((hdc->hd44780_common_flags & LCD_FLAG_F) ?
                        LCD_CMD_FONT_5X10_DOTS : 0) |
                ((hdc->hd44780_common_flags & LCD_FLAG_N) ?
                        LCD_CMD_TWO_LINES : 0));
        long_sleep(10);

        /* display off, cursor off, blink off */
        hdc->write_cmd(hdc, LCD_CMD_DISPLAY_CTRL);
        long_sleep(10);

        hdc->write_cmd(hdc,
                LCD_CMD_DISPLAY_CTRL |  /* set display mode */
                ((hdc->hd44780_common_flags & LCD_FLAG_D) ?
                        LCD_CMD_DISPLAY_ON : 0) |
                ((hdc->hd44780_common_flags & LCD_FLAG_C) ?
                        LCD_CMD_CURSOR_ON : 0) |
                ((hdc->hd44780_common_flags & LCD_FLAG_B) ?
                        LCD_CMD_BLINK_ON : 0));

        charlcd_backlight(lcd,
                        (hdc->hd44780_common_flags & LCD_FLAG_L) ? 1 : 0);

        long_sleep(10);

        /* entry mode set : increment, cursor shifting */
        hdc->write_cmd(hdc, LCD_CMD_ENTRY_MODE | LCD_CMD_CURSOR_INC);

        hd44780_common_clear_display(lcd);
        return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_init_display);

int hd44780_common_shift_cursor(struct charlcd *lcd, enum charlcd_shift_dir dir)
{
        struct hd44780_common *hdc = lcd->drvdata;

        if (dir == CHARLCD_SHIFT_LEFT) {
                /* back one char if not at end of line */
                if (lcd->addr.x < hdc->bwidth)
                        hdc->write_cmd(hdc, LCD_CMD_SHIFT);
        } else if (dir == CHARLCD_SHIFT_RIGHT) {
                /* allow the cursor to pass the end of the line */
                if (lcd->addr.x < (hdc->bwidth - 1))
                        hdc->write_cmd(hdc,
                                        LCD_CMD_SHIFT | LCD_CMD_SHIFT_RIGHT);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_shift_cursor);

int hd44780_common_shift_display(struct charlcd *lcd,
                enum charlcd_shift_dir dir)
{
        struct hd44780_common *hdc = lcd->drvdata;

        if (dir == CHARLCD_SHIFT_LEFT)
                hdc->write_cmd(hdc, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT);
        else if (dir == CHARLCD_SHIFT_RIGHT)
                hdc->write_cmd(hdc, LCD_CMD_SHIFT | LCD_CMD_DISPLAY_SHIFT |
                        LCD_CMD_SHIFT_RIGHT);

        return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_shift_display);

static void hd44780_common_set_mode(struct hd44780_common *hdc)
{
        hdc->write_cmd(hdc,
                LCD_CMD_DISPLAY_CTRL |
                ((hdc->hd44780_common_flags & LCD_FLAG_D) ?
                        LCD_CMD_DISPLAY_ON : 0) |
                ((hdc->hd44780_common_flags & LCD_FLAG_C) ?
                        LCD_CMD_CURSOR_ON : 0) |
                ((hdc->hd44780_common_flags & LCD_FLAG_B) ?
                        LCD_CMD_BLINK_ON : 0));
}

int hd44780_common_display(struct charlcd *lcd, enum charlcd_onoff on)
{
        struct hd44780_common *hdc = lcd->drvdata;

        if (on == CHARLCD_ON)
                hdc->hd44780_common_flags |= LCD_FLAG_D;
        else
                hdc->hd44780_common_flags &= ~LCD_FLAG_D;

        hd44780_common_set_mode(hdc);
        return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_display);

int hd44780_common_cursor(struct charlcd *lcd, enum charlcd_onoff on)
{
        struct hd44780_common *hdc = lcd->drvdata;

        if (on == CHARLCD_ON)
                hdc->hd44780_common_flags |= LCD_FLAG_C;
        else
                hdc->hd44780_common_flags &= ~LCD_FLAG_C;

        hd44780_common_set_mode(hdc);
        return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_cursor);

int hd44780_common_blink(struct charlcd *lcd, enum charlcd_onoff on)
{
        struct hd44780_common *hdc = lcd->drvdata;

        if (on == CHARLCD_ON)
                hdc->hd44780_common_flags |= LCD_FLAG_B;
        else
                hdc->hd44780_common_flags &= ~LCD_FLAG_B;

        hd44780_common_set_mode(hdc);
        return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_blink);

static void hd44780_common_set_function(struct hd44780_common *hdc)
{
        hdc->write_cmd(hdc,
                LCD_CMD_FUNCTION_SET |
                ((hdc->ifwidth == 8) ? LCD_CMD_DATA_LEN_8BITS : 0) |
                ((hdc->hd44780_common_flags & LCD_FLAG_F) ?
                        LCD_CMD_FONT_5X10_DOTS : 0) |
                ((hdc->hd44780_common_flags & LCD_FLAG_N) ?
                        LCD_CMD_TWO_LINES : 0));
}

int hd44780_common_fontsize(struct charlcd *lcd, enum charlcd_fontsize size)
{
        struct hd44780_common *hdc = lcd->drvdata;

        if (size == CHARLCD_FONTSIZE_LARGE)
                hdc->hd44780_common_flags |= LCD_FLAG_F;
        else
                hdc->hd44780_common_flags &= ~LCD_FLAG_F;

        hd44780_common_set_function(hdc);
        return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_fontsize);

int hd44780_common_lines(struct charlcd *lcd, enum charlcd_lines lines)
{
        struct hd44780_common *hdc = lcd->drvdata;

        if (lines == CHARLCD_LINES_2)
                hdc->hd44780_common_flags |= LCD_FLAG_N;
        else
                hdc->hd44780_common_flags &= ~LCD_FLAG_N;

        hd44780_common_set_function(hdc);
        return 0;
}
EXPORT_SYMBOL_GPL(hd44780_common_lines);

int hd44780_common_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 hd44780_common *hdc = lcd->drvdata;
        unsigned char cgbytes[8];
        unsigned char cgaddr;
        int cgoffset;
        int shift;
        char value;
        int addr;

        if (!strchr(esc, ';'))
                return 0;

        esc++;

        cgaddr = *(esc++) - '0';
        if (cgaddr > 7)
                return 1;

        cgoffset = 0;
        shift = 0;
        value = 0;
        while (*esc && cgoffset < 8) {
                int half;

                shift ^= 4;
                half = hex_to_bin(*esc++);
                if (half < 0)
                        continue;

                value |= half << shift;
                if (shift == 0) {
                        cgbytes[cgoffset++] = value;
                        value = 0;
                }
        }

        hdc->write_cmd(hdc, LCD_CMD_SET_CGRAM_ADDR | (cgaddr * 8));
        for (addr = 0; addr < cgoffset; addr++)
                hdc->write_data(hdc, cgbytes[addr]);

        /* ensures that we stop writing to CGRAM */
        lcd->ops->gotoxy(lcd, lcd->addr.x, lcd->addr.y);
        return 1;
}
EXPORT_SYMBOL_GPL(hd44780_common_redefine_char);

struct charlcd *hd44780_common_alloc(void)
{
        struct hd44780_common *hdc;
        struct charlcd *lcd;

        lcd = charlcd_alloc(sizeof(*hdc));
        if (!lcd)
                return NULL;

        hdc = lcd->drvdata;
        hdc->ifwidth = 8;
        hdc->bwidth = DEFAULT_LCD_BWIDTH;
        hdc->hwidth = DEFAULT_LCD_HWIDTH;
        return lcd;
}
EXPORT_SYMBOL_GPL(hd44780_common_alloc);

void hd44780_common_free(struct charlcd *lcd)
{
        charlcd_free(lcd);
}
EXPORT_SYMBOL_GPL(hd44780_common_free);

MODULE_DESCRIPTION("Common functions for HD44780 (and compatibles) LCD displays");
MODULE_LICENSE("GPL");