/*
 * FB driver for the ST7789V LCD Controller
 *
 * Copyright (C) 2015 Dennis Menschel
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <video/mipi_display.h>

#include "fbtft.h"

#define DRVNAME "fb_st7789v"

#define DEFAULT_GAMMA \
        "70 2C 2E 15 10 09 48 33 53 0B 19 18 20 25\n" \
        "70 2C 2E 15 10 09 48 33 53 0B 19 18 20 25"

/**
 * enum st7789v_command - ST7789V display controller commands
 *
 * @PORCTRL: porch setting
 * @GCTRL: gate control
 * @VCOMS: VCOM setting
 * @VDVVRHEN: VDV and VRH command enable
 * @VRHS: VRH set
 * @VDVS: VDV set
 * @VCMOFSET: VCOM offset set
 * @PWCTRL1: power control 1
 * @PVGAMCTRL: positive voltage gamma control
 * @NVGAMCTRL: negative voltage gamma control
 *
 * The command names are the same as those found in the datasheet to ease
 * looking up their semantics and usage.
 *
 * Note that the ST7789V display controller offers quite a few more commands
 * which have been omitted from this list as they are not used at the moment.
 * Furthermore, commands that are compliant with the MIPI DCS have been left
 * out as well to avoid duplicate entries.
 */
enum st7789v_command {
        PORCTRL = 0xB2,
        GCTRL = 0xB7,
        VCOMS = 0xBB,
        VDVVRHEN = 0xC2,
        VRHS = 0xC3,
        VDVS = 0xC4,
        VCMOFSET = 0xC5,
        PWCTRL1 = 0xD0,
        PVGAMCTRL = 0xE0,
        NVGAMCTRL = 0xE1,
};

#define MADCTL_BGR BIT(3) /* bitmask for RGB/BGR order */
#define MADCTL_MV BIT(5) /* bitmask for page/column order */
#define MADCTL_MX BIT(6) /* bitmask for column address order */
#define MADCTL_MY BIT(7) /* bitmask for page address order */

/**
 * init_display() - initialize the display controller
 *
 * @par: FBTFT parameter object
 *
 * Most of the commands in this init function set their parameters to the
 * same default values which are already in place after the display has been
 * powered up. (The main exception to this rule is the pixel format which
 * would default to 18 instead of 16 bit per pixel.)
 * Nonetheless, this sequence can be used as a template for concrete
 * displays which usually need some adjustments.
 *
 * Return: 0 on success, < 0 if error occurred.
 */
static int init_display(struct fbtft_par *par)
{
        /* turn off sleep mode */
        write_reg(par, MIPI_DCS_EXIT_SLEEP_MODE);
        mdelay(120);

        /* set pixel format to RGB-565 */
        write_reg(par, MIPI_DCS_SET_PIXEL_FORMAT, MIPI_DCS_PIXEL_FMT_16BIT);

        write_reg(par, PORCTRL, 0x08, 0x08, 0x00, 0x22, 0x22);

        /*
         * VGH = 13.26V
         * VGL = -10.43V
         */
        write_reg(par, GCTRL, 0x35);

        /*
         * VDV and VRH register values come from command write
         * (instead of NVM)
         */
        write_reg(par, VDVVRHEN, 0x01, 0xFF);

        /*
         * VAP =  4.1V + (VCOM + VCOM offset + 0.5 * VDV)
         * VAN = -4.1V + (VCOM + VCOM offset + 0.5 * VDV)
         */
        write_reg(par, VRHS, 0x0B);

        /* VDV = 0V */
        write_reg(par, VDVS, 0x20);

        /* VCOM = 0.9V */
        write_reg(par, VCOMS, 0x20);

        /* VCOM offset = 0V */
        write_reg(par, VCMOFSET, 0x20);

        /*
         * AVDD = 6.8V
         * AVCL = -4.8V
         * VDS = 2.3V
         */
        write_reg(par, PWCTRL1, 0xA4, 0xA1);

        write_reg(par, MIPI_DCS_SET_DISPLAY_ON);
        return 0;
}

/**
 * set_var() - apply LCD properties like rotation and BGR mode
 *
 * @par: FBTFT parameter object
 *
 * Return: 0 on success, < 0 if error occurred.
 */
static int set_var(struct fbtft_par *par)
{
        u8 madctl_par = 0;

        if (par->bgr)
                madctl_par |= MADCTL_BGR;
        switch (par->info->var.rotate) {
        case 0:
                break;
        case 90:
                madctl_par |= (MADCTL_MV | MADCTL_MY);
                break;
        case 180:
                madctl_par |= (MADCTL_MX | MADCTL_MY);
                break;
        case 270:
                madctl_par |= (MADCTL_MV | MADCTL_MX);
                break;
        default:
                return -EINVAL;
        }
        write_reg(par, MIPI_DCS_SET_ADDRESS_MODE, madctl_par);
        return 0;
}

/**
 * set_gamma() - set gamma curves
 *
 * @par: FBTFT parameter object
 * @curves: gamma curves
 *
 * Before the gamma curves are applied, they are preprocessed with a bitmask
 * to ensure syntactically correct input for the display controller.
 * This implies that the curves input parameter might be changed by this
 * function and that illegal gamma values are auto-corrected and not
 * reported as errors.
 *
 * Return: 0 on success, < 0 if error occurred.
 */
static int set_gamma(struct fbtft_par *par, unsigned long *curves)
{
        int i;
        int j;
        int c; /* curve index offset */

        /*
         * Bitmasks for gamma curve command parameters.
         * The masks are the same for both positive and negative voltage
         * gamma curves.
         */
        const u8 gamma_par_mask[] = {
                0xFF, /* V63[3:0], V0[3:0]*/
                0x3F, /* V1[5:0] */
                0x3F, /* V2[5:0] */
                0x1F, /* V4[4:0] */
                0x1F, /* V6[4:0] */
                0x3F, /* J0[1:0], V13[3:0] */
                0x7F, /* V20[6:0] */
                0x77, /* V36[2:0], V27[2:0] */
                0x7F, /* V43[6:0] */
                0x3F, /* J1[1:0], V50[3:0] */
                0x1F, /* V57[4:0] */
                0x1F, /* V59[4:0] */
                0x3F, /* V61[5:0] */
                0x3F, /* V62[5:0] */
        };

        for (i = 0; i < par->gamma.num_curves; i++) {
                c = i * par->gamma.num_values;
                for (j = 0; j < par->gamma.num_values; j++)
                        curves[c + j] &= gamma_par_mask[j];
                write_reg(
                        par, PVGAMCTRL + i,
                        curves[c + 0], curves[c + 1], curves[c + 2],
                        curves[c + 3], curves[c + 4], curves[c + 5],
                        curves[c + 6], curves[c + 7], curves[c + 8],
                        curves[c + 9], curves[c + 10], curves[c + 11],
                        curves[c + 12], curves[c + 13]);
        }
        return 0;
}

/**
 * blank() - blank the display
 *
 * @par: FBTFT parameter object
 * @on: whether to enable or disable blanking the display
 *
 * Return: 0 on success, < 0 if error occurred.
 */
static int blank(struct fbtft_par *par, bool on)
{
        if (on)
                write_reg(par, MIPI_DCS_SET_DISPLAY_OFF);
        else
                write_reg(par, MIPI_DCS_SET_DISPLAY_ON);
        return 0;
}

static struct fbtft_display display = {
        .regwidth = 8,
        .width = 240,
        .height = 320,
        .gamma_num = 2,
        .gamma_len = 14,
        .gamma = DEFAULT_GAMMA,
        .fbtftops = {
                .init_display = init_display,
                .set_var = set_var,
                .set_gamma = set_gamma,
                .blank = blank,
        },
};

FBTFT_REGISTER_DRIVER(DRVNAME, "sitronix,st7789v", &display);

MODULE_ALIAS("spi:" DRVNAME);
MODULE_ALIAS("platform:" DRVNAME);
MODULE_ALIAS("spi:st7789v");
MODULE_ALIAS("platform:st7789v");

MODULE_DESCRIPTION("FB driver for the ST7789V LCD Controller");
MODULE_AUTHOR("Dennis Menschel");
MODULE_LICENSE("GPL");