// SPDX-License-Identifier: GPL-2.0+
/*
 * FB driver for the TLS8204 LCD Controller
 *
 * The display is monochrome and the video memory is RGB565.
 * Any pixel value except 0 turns the pixel on.
 *
 * Copyright (C) 2013 Noralf Tronnes
 * Copyright (C) 2014 Michael Hope (adapted for the TLS8204)
 */

#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_tls8204"
#define WIDTH           84
#define HEIGHT          48
#define TXBUFLEN        WIDTH

/* gamma is used to control contrast in this driver */
#define DEFAULT_GAMMA   "40"

static unsigned int bs = 4;
module_param(bs, uint, 0000);
MODULE_PARM_DESC(bs, "BS[2:0] Bias voltage level: 0-7 (default: 4)");

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

        /* Enter extended command mode */
        write_reg(par, 0x21);   /* 5:1  1
                                 * 2:0  PD - Powerdown control: chip is active
                                 * 1:0  V  - Entry mode: horizontal addressing
                                 * 0:1  H  - Extended instruction set control:
                                 *           extended
                                 */

        /* H=1 Bias system */
        write_reg(par, 0x10 | (bs & 0x7));
                                /* 4:1  1
                                 * 3:0  0
                                 * 2:x  BS2 - Bias System
                                 * 1:x  BS1
                                 * 0:x  BS0
                                 */

        /* Set the address of the first display line. */
        write_reg(par, 0x04 | (64 >> 6));
        write_reg(par, 0x40 | (64 & 0x3F));

        /* Enter H=0 standard command mode */
        write_reg(par, 0x20);

        /* H=0 Display control */
        write_reg(par, 0x08 | 4);
                                /* 3:1  1
                                 * 2:1  D - DE: 10=normal mode
                                 * 1:0  0
                                 * 0:0  E
                                 */

        return 0;
}

static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
{
        /* H=0 Set X address of RAM */
        write_reg(par, 0x80);   /* 7:1  1
                                 * 6-0: X[6:0] - 0x00
                                 */

        /* H=0 Set Y address of RAM */
        write_reg(par, 0x40);   /* 7:0  0
                                 * 6:1  1
                                 * 2-0: Y[2:0] - 0x0
                                 */
}

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

        for (y = 0; y < HEIGHT / 8; y++) {
                u8 *buf = par->txbuf.buf;
                /* The display is 102x68 but the LCD is 84x48.
                 * Set the write pointer at the start of each row.
                 */
                gpiod_set_value(par->gpio.dc, 0);
                write_reg(par, 0x80 | 0);
                write_reg(par, 0x40 | y);

                for (x = 0; x < WIDTH; x++) {
                        u8 ch = 0;

                        for (i = 0; i < 8 * WIDTH; i += WIDTH) {
                                ch >>= 1;
                                if (vmem16[(y * 8 * WIDTH) + i + x])
                                        ch |= 0x80;
                        }
                        *buf++ = ch;
                }
                /* Write the row */
                gpiod_set_value(par->gpio.dc, 1);
                ret = par->fbtftops.write(par, par->txbuf.buf, WIDTH);
                if (ret < 0) {
                        dev_err(par->info->device,
                                "write failed and returned: %d\n", ret);
                        break;
                }
        }

        return ret;
}

static int set_gamma(struct fbtft_par *par, u32 *curves)
{
        /* apply mask */
        curves[0] &= 0x7F;

        write_reg(par, 0x21); /* turn on extended instruction set */
        write_reg(par, 0x80 | curves[0]);
        write_reg(par, 0x20); /* turn off extended instruction set */

        return 0;
}

static struct fbtft_display display = {
        .regwidth = 8,
        .width = WIDTH,
        .height = HEIGHT,
        .txbuflen = TXBUFLEN,
        .gamma_num = 1,
        .gamma_len = 1,
        .gamma = DEFAULT_GAMMA,
        .fbtftops = {
                .init_display = init_display,
                .set_addr_win = set_addr_win,
                .write_vmem = write_vmem,
                .set_gamma = set_gamma,
        },
        .backlight = 1,
};

FBTFT_REGISTER_DRIVER(DRVNAME, "teralane,tls8204", &display);

MODULE_ALIAS("spi:" DRVNAME);
MODULE_ALIAS("spi:tls8204");

MODULE_DESCRIPTION("FB driver for the TLS8204 LCD Controller");
MODULE_AUTHOR("Michael Hope");
MODULE_LICENSE("GPL");