// SPDX-License-Identifier: GPL-2.0+
/*
 * FB driver for the UC1701 LCD Controller
 *
 * The display is monochrome and the video memory is RGB565.
 * Any pixel value except 0 turns the pixel on.
 *
 * Copyright (C) 2014 Juergen Holzmann
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/gpio/consumer.h>
#include <linux/spi/spi.h>
#include <linux/delay.h>

#include "fbtft.h"

#define DRVNAME "fb_uc1701"
#define WIDTH     102
#define HEIGHT   64
#define PAGES     (HEIGHT / 8)

/* 1: Display on/off */
#define LCD_DISPLAY_ENABLE    0xAE
/* 2: display start line set */
#define LCD_START_LINE  0x40
/* 3: Page address set (lower 4 bits select one of the pages) */
#define LCD_PAGE_ADDRESS      0xB0
/* 4: column address */
#define LCD_COL_ADDRESS       0x10
/* 8: select orientation */
#define LCD_BOTTOMVIEW  0xA0
/* 9: inverted display */
#define LCD_DISPLAY_INVERT    0xA6
/* 10: show memory content or switch all pixels on */
#define LCD_ALL_PIXEL    0xA4
/* 11: lcd bias set */
#define LCD_BIAS              0xA2
/* 14: Reset Controller */
#define LCD_RESET_CMD    0xE2
/* 15: output mode select (turns display upside-down) */
#define LCD_SCAN_DIR      0xC0
/* 16: power control set */
#define LCD_POWER_CONTROL     0x28
/* 17: voltage regulator resistor ratio set */
#define LCD_VOLTAGE        0x20
/* 18: Volume mode set */
#define LCD_VOLUME_MODE       0x81
/* 22: NOP command */
#define LCD_NO_OP            0xE3
/* 25: advanced program control */
#define LCD_ADV_PROG_CTRL     0xFA
/* 25: advanced program control2 */
#define LCD_ADV_PROG_CTRL2    0x10
#define LCD_TEMPCOMP_HIGH     0x80
/* column offset for normal orientation */
#define SHIFT_ADDR_NORMAL     0
/* column offset for bottom view orientation */
#define SHIFT_ADDR_TOPVIEW    30

static int init_display(struct fbtft_par *par)
{
        par->fbtftops.reset(par);

        /* softreset of LCD */
        write_reg(par, LCD_RESET_CMD);
        mdelay(10);

        /* set startpoint */
        write_reg(par, LCD_START_LINE);

        /* select orientation BOTTOMVIEW */
        write_reg(par, LCD_BOTTOMVIEW | 1);

        /* output mode select (turns display upside-down) */
        write_reg(par, LCD_SCAN_DIR | 0x00);

        /* Normal Pixel mode */
        write_reg(par, LCD_ALL_PIXEL | 0);

        /* positive display */
        write_reg(par, LCD_DISPLAY_INVERT | 0);

        /* bias 1/9 */
        write_reg(par, LCD_BIAS | 0);

        /* power control mode: all features on */
        write_reg(par, LCD_POWER_CONTROL | 0x07);

        /* set voltage regulator R/R */
        write_reg(par, LCD_VOLTAGE | 0x07);

        /* volume mode set */
        write_reg(par, LCD_VOLUME_MODE);
        write_reg(par, 0x09);
        write_reg(par, LCD_NO_OP);

        /* advanced program control */
        write_reg(par, LCD_ADV_PROG_CTRL);
        write_reg(par, LCD_ADV_PROG_CTRL2 | LCD_TEMPCOMP_HIGH);

        /* enable display */
        write_reg(par, LCD_DISPLAY_ENABLE | 1);

        return 0;
}

static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
{
        /* goto address */
        write_reg(par, LCD_PAGE_ADDRESS);
        write_reg(par, 0x00);
        write_reg(par, LCD_COL_ADDRESS);
}

static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
{
        u16 *vmem16 = (u16 *)par->info->screen_buffer;
        u8 *buf;
        int x, y, i;
        int ret = 0;

        for (y = 0; y < PAGES; y++) {
                buf = par->txbuf.buf;
                for (x = 0; x < WIDTH; x++) {
                        *buf = 0x00;
                        for (i = 0; i < 8; i++)
                                *buf |= (vmem16[((y * 8 * WIDTH) +
                                                 (i * WIDTH)) + x] ?
                                         1 : 0) << i;
                        buf++;
                }

                write_reg(par, LCD_PAGE_ADDRESS | (u8)y);
                write_reg(par, 0x00);
                write_reg(par, LCD_COL_ADDRESS);
                gpiod_set_value(par->gpio.dc, 1);
                ret = par->fbtftops.write(par, par->txbuf.buf, WIDTH);
                gpiod_set_value(par->gpio.dc, 0);
        }

        if (ret < 0)
                dev_err(par->info->device, "write failed and returned: %d\n",
                        ret);

        return ret;
}

static struct fbtft_display display = {
        .regwidth = 8,
        .width = WIDTH,
        .height = HEIGHT,
        .fbtftops = {
                .init_display = init_display,
                .set_addr_win = set_addr_win,
                .write_vmem = write_vmem,
        },
        .backlight = 1,
};

FBTFT_REGISTER_DRIVER(DRVNAME, "UltraChip,uc1701", &display);

MODULE_ALIAS("spi:" DRVNAME);
MODULE_ALIAS("spi:uc1701");

MODULE_DESCRIPTION("FB driver for the UC1701 LCD Controller");
MODULE_AUTHOR("Juergen Holzmann");
MODULE_LICENSE("GPL");