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内核7789源码：

// SPDX-License-Identifier: GPL-2.0+
/*
* FB driver for the ST7789V LCD Controller
*
* Copyright (C) 2015 Dennis Menschel
*/

#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, u32 *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.
     */
    static 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");