root/drivers/gpu/drm/panel/panel-novatek-nt39016.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Novatek NT39016 TFT LCD panel driver
 *
 * Copyright (C) 2017, Maarten ter Huurne <maarten@treewalker.org>
 * Copyright (C) 2019, Paul Cercueil <paul@crapouillou.net>
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/media-bus-format.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>

#include <drm/drm_modes.h>
#include <drm/drm_panel.h>

enum nt39016_regs {
        NT39016_REG_SYSTEM,
        NT39016_REG_TIMING,
        NT39016_REG_OP,
        NT39016_REG_DATA_IN,
        NT39016_REG_SRC_TIMING_DELAY,
        NT39016_REG_GATE_TIMING_DELAY,
        NT39016_REG_RESERVED,
        NT39016_REG_INITIAL_FUNC,
        NT39016_REG_CONTRAST,
        NT39016_REG_BRIGHTNESS,
        NT39016_REG_HUE_SATURATION,
        NT39016_REG_RB_SUBCONTRAST,
        NT39016_REG_R_SUBBRIGHTNESS,
        NT39016_REG_B_SUBBRIGHTNESS,
        NT39016_REG_VCOMDC,
        NT39016_REG_VCOMAC,
        NT39016_REG_VGAM2,
        NT39016_REG_VGAM34,
        NT39016_REG_VGAM56,
        NT39016_REG_VCOMDC_TRIM = 0x1e,
        NT39016_REG_DISPLAY_MODE = 0x20,
};

#define NT39016_SYSTEM_RESET_N  BIT(0)
#define NT39016_SYSTEM_STANDBY  BIT(1)

struct nt39016_panel_info {
        const struct drm_display_mode *display_modes;
        unsigned int num_modes;
        u16 width_mm, height_mm;
        u32 bus_format, bus_flags;
};

struct nt39016 {
        struct drm_panel drm_panel;
        struct regmap *map;
        struct regulator *supply;
        const struct nt39016_panel_info *panel_info;

        struct gpio_desc *reset_gpio;
};

static inline struct nt39016 *to_nt39016(struct drm_panel *panel)
{
        return container_of(panel, struct nt39016, drm_panel);
}

#define RV(REG, VAL) { .reg = (REG), .def = (VAL), .delay_us = 2 }
static const struct reg_sequence nt39016_panel_regs[] = {
        RV(NT39016_REG_SYSTEM, 0x00),
        RV(NT39016_REG_TIMING, 0x00),
        RV(NT39016_REG_OP, 0x03),
        RV(NT39016_REG_DATA_IN, 0xCC),
        RV(NT39016_REG_SRC_TIMING_DELAY, 0x46),
        RV(NT39016_REG_GATE_TIMING_DELAY, 0x05),
        RV(NT39016_REG_RESERVED, 0x00),
        RV(NT39016_REG_INITIAL_FUNC, 0x00),
        RV(NT39016_REG_CONTRAST, 0x08),
        RV(NT39016_REG_BRIGHTNESS, 0x40),
        RV(NT39016_REG_HUE_SATURATION, 0x88),
        RV(NT39016_REG_RB_SUBCONTRAST, 0x88),
        RV(NT39016_REG_R_SUBBRIGHTNESS, 0x20),
        RV(NT39016_REG_B_SUBBRIGHTNESS, 0x20),
        RV(NT39016_REG_VCOMDC, 0x67),
        RV(NT39016_REG_VCOMAC, 0xA4),
        RV(NT39016_REG_VGAM2, 0x04),
        RV(NT39016_REG_VGAM34, 0x24),
        RV(NT39016_REG_VGAM56, 0x24),
        RV(NT39016_REG_DISPLAY_MODE, 0x00),
};

#undef RV

static const struct regmap_range nt39016_regmap_no_ranges[] = {
        regmap_reg_range(0x13, 0x1D),
        regmap_reg_range(0x1F, 0x1F),
};

static const struct regmap_access_table nt39016_regmap_access_table = {
        .no_ranges = nt39016_regmap_no_ranges,
        .n_no_ranges = ARRAY_SIZE(nt39016_regmap_no_ranges),
};

static const struct regmap_config nt39016_regmap_config = {
        .reg_bits = 6,
        .pad_bits = 2,
        .val_bits = 8,

        .max_register = NT39016_REG_DISPLAY_MODE,
        .wr_table = &nt39016_regmap_access_table,
        .write_flag_mask = 0x02,

        .cache_type = REGCACHE_FLAT,
};

static int nt39016_prepare(struct drm_panel *drm_panel)
{
        struct nt39016 *panel = to_nt39016(drm_panel);
        int err;

        err = regulator_enable(panel->supply);
        if (err) {
                dev_err(drm_panel->dev, "Failed to enable power supply: %d\n", err);
                return err;
        }

        /*
         * Reset the NT39016.
         * The documentation says the reset pulse should be at least 40 us to
         * pass the glitch filter, but when testing I see some resets fail and
         * some succeed when using a 70 us delay, so we use 100 us instead.
         */
        gpiod_set_value_cansleep(panel->reset_gpio, 1);
        usleep_range(100, 1000);
        gpiod_set_value_cansleep(panel->reset_gpio, 0);
        udelay(2);

        /* Init all registers. */
        err = regmap_multi_reg_write(panel->map, nt39016_panel_regs,
                                     ARRAY_SIZE(nt39016_panel_regs));
        if (err) {
                dev_err(drm_panel->dev, "Failed to init registers: %d\n", err);
                goto err_disable_regulator;
        }

        return 0;

err_disable_regulator:
        regulator_disable(panel->supply);
        return err;
}

static int nt39016_unprepare(struct drm_panel *drm_panel)
{
        struct nt39016 *panel = to_nt39016(drm_panel);

        gpiod_set_value_cansleep(panel->reset_gpio, 1);

        regulator_disable(panel->supply);

        return 0;
}

static int nt39016_enable(struct drm_panel *drm_panel)
{
        struct nt39016 *panel = to_nt39016(drm_panel);
        int ret;

        ret = regmap_write(panel->map, NT39016_REG_SYSTEM,
                           NT39016_SYSTEM_RESET_N | NT39016_SYSTEM_STANDBY);
        if (ret) {
                dev_err(drm_panel->dev, "Unable to enable panel: %d\n", ret);
                return ret;
        }

        if (drm_panel->backlight) {
                /* Wait for the picture to be ready before enabling backlight */
                msleep(150);
        }

        return 0;
}

static int nt39016_disable(struct drm_panel *drm_panel)
{
        struct nt39016 *panel = to_nt39016(drm_panel);
        int err;

        err = regmap_write(panel->map, NT39016_REG_SYSTEM,
                           NT39016_SYSTEM_RESET_N);
        if (err) {
                dev_err(drm_panel->dev, "Unable to disable panel: %d\n", err);
                return err;
        }

        return 0;
}

static int nt39016_get_modes(struct drm_panel *drm_panel,
                             struct drm_connector *connector)
{
        struct nt39016 *panel = to_nt39016(drm_panel);
        const struct nt39016_panel_info *panel_info = panel->panel_info;
        struct drm_display_mode *mode;
        unsigned int i;

        for (i = 0; i < panel_info->num_modes; i++) {
                mode = drm_mode_duplicate(connector->dev,
                                          &panel_info->display_modes[i]);
                if (!mode)
                        return -ENOMEM;

                drm_mode_set_name(mode);

                mode->type = DRM_MODE_TYPE_DRIVER;
                if (panel_info->num_modes == 1)
                        mode->type |= DRM_MODE_TYPE_PREFERRED;

                drm_mode_probed_add(connector, mode);
        }

        connector->display_info.bpc = 8;
        connector->display_info.width_mm = panel_info->width_mm;
        connector->display_info.height_mm = panel_info->height_mm;

        drm_display_info_set_bus_formats(&connector->display_info,
                                         &panel_info->bus_format, 1);
        connector->display_info.bus_flags = panel_info->bus_flags;

        return panel_info->num_modes;
}

static const struct drm_panel_funcs nt39016_funcs = {
        .prepare        = nt39016_prepare,
        .unprepare      = nt39016_unprepare,
        .enable         = nt39016_enable,
        .disable        = nt39016_disable,
        .get_modes      = nt39016_get_modes,
};

static int nt39016_probe(struct spi_device *spi)
{
        struct device *dev = &spi->dev;
        struct nt39016 *panel;
        int err;

        panel = devm_drm_panel_alloc(dev, struct nt39016, drm_panel, &nt39016_funcs,
                                     DRM_MODE_CONNECTOR_DPI);
        if (IS_ERR(panel))
                return PTR_ERR(panel);

        spi_set_drvdata(spi, panel);

        panel->panel_info = of_device_get_match_data(dev);
        if (!panel->panel_info)
                return -EINVAL;

        panel->supply = devm_regulator_get(dev, "power");
        if (IS_ERR(panel->supply))
                return dev_err_probe(dev, PTR_ERR(panel->supply),
                                     "Failed to get power supply\n");

        panel->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
        if (IS_ERR(panel->reset_gpio))
                return dev_err_probe(dev, PTR_ERR(panel->reset_gpio), "Failed to get reset GPIO\n");

        spi->bits_per_word = 8;
        spi->mode = SPI_MODE_3 | SPI_3WIRE;
        err = spi_setup(spi);
        if (err) {
                dev_err(dev, "Failed to setup SPI\n");
                return err;
        }

        panel->map = devm_regmap_init_spi(spi, &nt39016_regmap_config);
        if (IS_ERR(panel->map)) {
                dev_err(dev, "Failed to init regmap\n");
                return PTR_ERR(panel->map);
        }

        err = drm_panel_of_backlight(&panel->drm_panel);
        if (err)
                return dev_err_probe(dev, err, "Failed to get backlight handle\n");

        drm_panel_add(&panel->drm_panel);

        return 0;
}

static void nt39016_remove(struct spi_device *spi)
{
        struct nt39016 *panel = spi_get_drvdata(spi);

        drm_panel_remove(&panel->drm_panel);

        nt39016_disable(&panel->drm_panel);
        nt39016_unprepare(&panel->drm_panel);
}

static const struct drm_display_mode kd035g6_display_modes[] = {
        {       /* 60 Hz */
                .clock = 6000,
                .hdisplay = 320,
                .hsync_start = 320 + 10,
                .hsync_end = 320 + 10 + 50,
                .htotal = 320 + 10 + 50 + 20,
                .vdisplay = 240,
                .vsync_start = 240 + 5,
                .vsync_end = 240 + 5 + 1,
                .vtotal = 240 + 5 + 1 + 4,
                .flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
        },
        {       /* 50 Hz */
                .clock = 5400,
                .hdisplay = 320,
                .hsync_start = 320 + 42,
                .hsync_end = 320 + 42 + 50,
                .htotal = 320 + 42 + 50 + 20,
                .vdisplay = 240,
                .vsync_start = 240 + 5,
                .vsync_end = 240 + 5 + 1,
                .vtotal = 240 + 5 + 1 + 4,
                .flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
        },
};

static const struct nt39016_panel_info kd035g6_info = {
        .display_modes = kd035g6_display_modes,
        .num_modes = ARRAY_SIZE(kd035g6_display_modes),
        .width_mm = 71,
        .height_mm = 53,
        .bus_format = MEDIA_BUS_FMT_RGB888_1X24,
        .bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
};

static const struct of_device_id nt39016_of_match[] = {
        { .compatible = "kingdisplay,kd035g6-54nt", .data = &kd035g6_info },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, nt39016_of_match);

static struct spi_driver nt39016_driver = {
        .driver = {
                .name = "nt39016",
                .of_match_table = nt39016_of_match,
        },
        .probe = nt39016_probe,
        .remove = nt39016_remove,
};

module_spi_driver(nt39016_driver);

MODULE_AUTHOR("Maarten ter Huurne <maarten@treewalker.org>");
MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
MODULE_DESCRIPTION("Novatek NT39016 TFT LCD panel driver");
MODULE_LICENSE("GPL v2");