// SPDX-License-Identifier: GPL-2.0
/*
 * Orisetech OTA5601A TFT LCD panel driver
 *
 * Copyright (C) 2021, Christophe Branchereau <cbranchereau@gmail.com>
 */

#include <linux/bits.h>
#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>

#define OTA5601A_CTL 0x01
#define OTA5601A_CTL_OFF 0x00
#define OTA5601A_CTL_ON BIT(0)

struct ota5601a_panel_info {
        const struct drm_display_mode *display_modes;
        unsigned int num_modes;
        u16 width_mm, height_mm;
        u32 bus_format, bus_flags;
};

struct ota5601a {
        struct drm_panel drm_panel;
        struct regmap *map;
        struct regulator *supply;
        const struct ota5601a_panel_info *panel_info;

        struct gpio_desc *reset_gpio;
};

static inline struct ota5601a *to_ota5601a(struct drm_panel *panel)
{
        return container_of(panel, struct ota5601a, drm_panel);
}

static const struct reg_sequence ota5601a_panel_regs[] = {
        { 0xfd, 0x00 }, /* Page Shift */
        { 0x02, 0x00 }, /* Reset */

        { 0x18, 0x00 }, /* Interface Sel: RGB 24 Bits */
        { 0x34, 0x20 }, /* Undocumented */

        { 0x0c, 0x01 }, /* Contrast set by CMD1 == within page 0x00 */
        { 0x0d, 0x48 }, /* R Brightness */
        { 0x0e, 0x48 }, /* G Brightness */
        { 0x0f, 0x48 }, /* B Brightness */
        { 0x07, 0x40 }, /* R Contrast */
        { 0x08, 0x33 }, /* G Contrast */
        { 0x09, 0x3a }, /* B Contrast */

        { 0x16, 0x01 }, /* NTSC Sel */
        { 0x19, 0x8d }, /* VBLK */
        { 0x1a, 0x28 }, /* HBLK */
        { 0x1c, 0x00 }, /* Scan Shift Dir. */

        { 0xfd, 0xc5 }, /* Page Shift */
        { 0x82, 0x0c }, /* PWR_CTRL Pump */
        { 0xa2, 0xb4 }, /* PWR_CTRL VGH/VGL */

        { 0xfd, 0xc4 }, /* Page Shift - What follows is listed as "RGB 24bit Timing Set" */
        { 0x82, 0x45 },

        { 0xfd, 0xc1 },
        { 0x91, 0x02 },

        { 0xfd, 0xc0 },
        { 0xa1, 0x01 },
        { 0xa2, 0x1f },
        { 0xa3, 0x0b },
        { 0xa4, 0x38 },
        { 0xa5, 0x00 },
        { 0xa6, 0x0a },
        { 0xa7, 0x38 },
        { 0xa8, 0x00 },
        { 0xa9, 0x0a },
        { 0xaa, 0x37 },

        { 0xfd, 0xce },
        { 0x81, 0x18 },
        { 0x82, 0x43 },
        { 0x83, 0x43 },
        { 0x91, 0x06 },
        { 0x93, 0x38 },
        { 0x94, 0x02 },
        { 0x95, 0x06 },
        { 0x97, 0x38 },
        { 0x98, 0x02 },
        { 0x99, 0x06 },
        { 0x9b, 0x38 },
        { 0x9c, 0x02 },

        { 0xfd, 0x00 }, /* Page Shift */
};

static const struct regmap_config ota5601a_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
};

static int ota5601a_prepare(struct drm_panel *drm_panel)
{
        struct ota5601a *panel = to_ota5601a(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 to be held low for 10us min according to the doc, 10ms before sending commands */
        gpiod_set_value_cansleep(panel->reset_gpio, 1);
        usleep_range(10, 30);
        gpiod_set_value_cansleep(panel->reset_gpio, 0);
        usleep_range(10000, 20000);

        /* Init all registers. */
        err = regmap_multi_reg_write(panel->map, ota5601a_panel_regs,
                                     ARRAY_SIZE(ota5601a_panel_regs));
        if (err) {
                dev_err(drm_panel->dev, "Failed to init registers: %d\n", err);
                goto err_disable_regulator;
        }

        msleep(120);

        return 0;

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

static int ota5601a_unprepare(struct drm_panel *drm_panel)
{
        struct ota5601a *panel = to_ota5601a(drm_panel);

        gpiod_set_value_cansleep(panel->reset_gpio, 1);

        regulator_disable(panel->supply);

        return 0;
}

static int ota5601a_enable(struct drm_panel *drm_panel)
{
        struct ota5601a *panel = to_ota5601a(drm_panel);
        int err;

        err = regmap_write(panel->map, OTA5601A_CTL, OTA5601A_CTL_ON);

        if (err) {
                dev_err(drm_panel->dev, "Unable to enable panel: %d\n", err);
                return err;
        }

        if (drm_panel->backlight) {
                /* Wait for the picture to be ready before enabling backlight */
                msleep(120);
        }

        return 0;
}

static int ota5601a_disable(struct drm_panel *drm_panel)
{
        struct ota5601a *panel = to_ota5601a(drm_panel);
        int err;

        err = regmap_write(panel->map, OTA5601A_CTL, OTA5601A_CTL_OFF);

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

        return 0;
}

static int ota5601a_get_modes(struct drm_panel *drm_panel,
                              struct drm_connector *connector)
{
        struct ota5601a *panel = to_ota5601a(drm_panel);
        const struct ota5601a_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 ota5601a_funcs = {
        .prepare        = ota5601a_prepare,
        .unprepare      = ota5601a_unprepare,
        .enable         = ota5601a_enable,
        .disable        = ota5601a_disable,
        .get_modes      = ota5601a_get_modes,
};

static int ota5601a_probe(struct spi_device *spi)
{
        const struct spi_device_id *id = spi_get_device_id(spi);
        struct device *dev = &spi->dev;
        struct ota5601a *panel;
        int err;

        panel = devm_drm_panel_alloc(dev, struct ota5601a, drm_panel,
                                     &ota5601a_funcs,
                                     DRM_MODE_CONNECTOR_DPI);
        if (IS_ERR(panel))
                return PTR_ERR(panel);

        spi_set_drvdata(spi, panel);

        panel->panel_info = (const struct ota5601a_panel_info *)id->driver_data;
        if (!panel->panel_info)
                return -EINVAL;

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

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

        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, &ota5601a_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 ota5601a_remove(struct spi_device *spi)
{
        struct ota5601a *panel = spi_get_drvdata(spi);

        drm_panel_remove(&panel->drm_panel);

        ota5601a_disable(&panel->drm_panel);
        ota5601a_unprepare(&panel->drm_panel);
}

static const struct drm_display_mode gpt3_display_modes[] = {
        { /* 60 Hz */
                .clock = 27000,
                .hdisplay = 640,
                .hsync_start = 640 + 220,
                .hsync_end = 640 + 220 + 20,
                .htotal = 640 + 220 + 20 + 20,
                .vdisplay = 480,
                .vsync_start = 480 + 7,
                .vsync_end = 480 + 7 + 6,
                .vtotal = 480 + 7 + 6 + 7,
                .flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
        },

        { /* 50 Hz */
                .clock = 24000,
                .hdisplay = 640,
                .hsync_start = 640 + 280,
                .hsync_end = 640 + 280 + 20,
                .htotal = 640 + 280 + 20 + 20,
                .vdisplay = 480,
                .vsync_start = 480 + 7,
                .vsync_end = 480 + 7 + 6,
                .vtotal = 480 + 7 + 6 + 7,
                .flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_NVSYNC,
        },
};

static const struct ota5601a_panel_info gpt3_info = {
        .display_modes = gpt3_display_modes,
        .num_modes = ARRAY_SIZE(gpt3_display_modes),
        .width_mm = 71,
        .height_mm = 51,
        .bus_format = MEDIA_BUS_FMT_RGB888_1X24,
        .bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
};

static const struct spi_device_id gpt3_id[] = {
        { "gpt3", (kernel_ulong_t)&gpt3_info },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(spi, gpt3_id);

static const struct of_device_id ota5601a_of_match[] = {
        { .compatible = "focaltech,gpt3" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, ota5601a_of_match);

static struct spi_driver ota5601a_driver = {
        .driver = {
                .name = "ota5601a",
                .of_match_table = ota5601a_of_match,
        },
        .id_table = gpt3_id,
        .probe = ota5601a_probe,
        .remove = ota5601a_remove,
};

module_spi_driver(ota5601a_driver);

MODULE_AUTHOR("Christophe Branchereau <cbranchereau@gmail.com>");
MODULE_DESCRIPTION("Orisetech OTA5601A TFT LCD panel driver");
MODULE_LICENSE("GPL");