// SPDX-License-Identifier: GPL-2.0+
/*
 * DRM driver for Ilitek ILI9486 panels
 *
 * Copyright 2020 Kamlesh Gurudasani <kamlesh.gurudasani@gmail.com>
 */

#include <linux/backlight.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/spi/spi.h>

#include <video/mipi_display.h>

#include <drm/clients/drm_client_setup.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_drv.h>
#include <drm/drm_fbdev_dma.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_dma_helper.h>
#include <drm/drm_managed.h>
#include <drm/drm_mipi_dbi.h>
#include <drm/drm_modeset_helper.h>
#include <drm/drm_print.h>

#define ILI9486_ITFCTR1         0xb0
#define ILI9486_PWCTRL1         0xc2
#define ILI9486_VMCTRL1         0xc5
#define ILI9486_PGAMCTRL        0xe0
#define ILI9486_NGAMCTRL        0xe1
#define ILI9486_DGAMCTRL        0xe2
#define ILI9486_MADCTL_BGR      BIT(3)
#define ILI9486_MADCTL_MV       BIT(5)
#define ILI9486_MADCTL_MX       BIT(6)
#define ILI9486_MADCTL_MY       BIT(7)

/*
 * The PiScreen/waveshare rpi-lcd-35 has a SPI to 16-bit parallel bus converter
 * in front of the  display controller. This means that 8-bit values have to be
 * transferred as 16-bit.
 */
static int waveshare_command(struct mipi_dbi *mipi, u8 *cmd, u8 *par,
                             size_t num)
{
        struct spi_device *spi = mipi->spi;
        unsigned int bpw = 8;
        void *data = par;
        u32 speed_hz;
        int i, ret;
        __be16 *buf;

        buf = kmalloc(32 * sizeof(u16), GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        /*
         * The displays are Raspberry Pi HATs and connected to the 8-bit only
         * SPI controller, so 16-bit command and parameters need byte swapping
         * before being transferred as 8-bit on the big endian SPI bus.
         */
        buf[0] = cpu_to_be16(*cmd);
        spi_bus_lock(spi->controller);
        gpiod_set_value_cansleep(mipi->dc, 0);
        speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 2);
        ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, buf, 2);
        spi_bus_unlock(spi->controller);
        if (ret || !num)
                goto free;

        /* 8-bit configuration data, not 16-bit pixel data */
        if (num <= 32) {
                for (i = 0; i < num; i++)
                        buf[i] = cpu_to_be16(par[i]);
                num *= 2;
                data = buf;
        }

        /*
         * Check whether pixel data bytes needs to be swapped or not
         */
        if (*cmd == MIPI_DCS_WRITE_MEMORY_START && !mipi->swap_bytes)
                bpw = 16;

        spi_bus_lock(spi->controller);
        gpiod_set_value_cansleep(mipi->dc, 1);
        speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
        ret = mipi_dbi_spi_transfer(spi, speed_hz, bpw, data, num);
        spi_bus_unlock(spi->controller);
 free:
        kfree(buf);

        return ret;
}

static void waveshare_enable(struct drm_simple_display_pipe *pipe,
                             struct drm_crtc_state *crtc_state,
                             struct drm_plane_state *plane_state)
{
        struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(pipe->crtc.dev);
        struct mipi_dbi *dbi = &dbidev->dbi;
        u8 addr_mode;
        int ret, idx;

        if (!drm_dev_enter(pipe->crtc.dev, &idx))
                return;

        DRM_DEBUG_KMS("\n");

        ret = mipi_dbi_poweron_conditional_reset(dbidev);
        if (ret < 0)
                goto out_exit;
        if (ret == 1)
                goto out_enable;

        mipi_dbi_command(dbi, ILI9486_ITFCTR1);
        mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
        msleep(250);

        mipi_dbi_command(dbi, MIPI_DCS_SET_PIXEL_FORMAT, 0x55);

        mipi_dbi_command(dbi, ILI9486_PWCTRL1, 0x44);

        mipi_dbi_command(dbi, ILI9486_VMCTRL1, 0x00, 0x00, 0x00, 0x00);

        mipi_dbi_command(dbi, ILI9486_PGAMCTRL,
                         0x0F, 0x1F, 0x1C, 0x0C, 0x0F, 0x08, 0x48, 0x98,
                         0x37, 0x0A, 0x13, 0x04, 0x11, 0x0D, 0x0);
        mipi_dbi_command(dbi, ILI9486_NGAMCTRL,
                         0x0F, 0x32, 0x2E, 0x0B, 0x0D, 0x05, 0x47, 0x75,
                         0x37, 0x06, 0x10, 0x03, 0x24, 0x20, 0x00);
        mipi_dbi_command(dbi, ILI9486_DGAMCTRL,
                         0x0F, 0x32, 0x2E, 0x0B, 0x0D, 0x05, 0x47, 0x75,
                         0x37, 0x06, 0x10, 0x03, 0x24, 0x20, 0x00);

        mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
        msleep(100);

 out_enable:
        switch (dbidev->rotation) {
        case 90:
                addr_mode = ILI9486_MADCTL_MY;
                break;
        case 180:
                addr_mode = ILI9486_MADCTL_MV;
                break;
        case 270:
                addr_mode = ILI9486_MADCTL_MX;
                break;
        default:
                addr_mode = ILI9486_MADCTL_MV | ILI9486_MADCTL_MY |
                        ILI9486_MADCTL_MX;
                break;
        }
        addr_mode |= ILI9486_MADCTL_BGR;
        mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, addr_mode);
        mipi_dbi_enable_flush(dbidev, crtc_state, plane_state);
 out_exit:
        drm_dev_exit(idx);
}

static const struct drm_simple_display_pipe_funcs waveshare_pipe_funcs = {
        DRM_MIPI_DBI_SIMPLE_DISPLAY_PIPE_FUNCS(waveshare_enable),
};

static const struct drm_display_mode waveshare_mode = {
        DRM_SIMPLE_MODE(480, 320, 73, 49),
};

DEFINE_DRM_GEM_DMA_FOPS(ili9486_fops);

static const struct drm_driver ili9486_driver = {
        .driver_features        = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
        .fops                   = &ili9486_fops,
        DRM_GEM_DMA_DRIVER_OPS_VMAP,
        DRM_FBDEV_DMA_DRIVER_OPS,
        .debugfs_init           = mipi_dbi_debugfs_init,
        .name                   = "ili9486",
        .desc                   = "Ilitek ILI9486",
        .major                  = 1,
        .minor                  = 0,
};

static const struct of_device_id ili9486_of_match[] = {
        { .compatible = "waveshare,rpi-lcd-35" },
        { .compatible = "ozzmaker,piscreen" },
        {},
};
MODULE_DEVICE_TABLE(of, ili9486_of_match);

static const struct spi_device_id ili9486_id[] = {
        { "ili9486", 0 },
        { "rpi-lcd-35", 0 },
        { "piscreen", 0 },
        { }
};
MODULE_DEVICE_TABLE(spi, ili9486_id);

static int ili9486_probe(struct spi_device *spi)
{
        struct device *dev = &spi->dev;
        struct mipi_dbi_dev *dbidev;
        struct drm_device *drm;
        struct mipi_dbi *dbi;
        struct gpio_desc *dc;
        u32 rotation = 0;
        int ret;

        dbidev = devm_drm_dev_alloc(dev, &ili9486_driver,
                                    struct mipi_dbi_dev, drm);
        if (IS_ERR(dbidev))
                return PTR_ERR(dbidev);

        dbi = &dbidev->dbi;
        drm = &dbidev->drm;

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

        dc = devm_gpiod_get(dev, "dc", GPIOD_OUT_LOW);
        if (IS_ERR(dc))
                return dev_err_probe(dev, PTR_ERR(dc), "Failed to get GPIO 'dc'\n");

        dbidev->backlight = devm_of_find_backlight(dev);
        if (IS_ERR(dbidev->backlight))
                return PTR_ERR(dbidev->backlight);

        device_property_read_u32(dev, "rotation", &rotation);

        ret = mipi_dbi_spi_init(spi, dbi, dc);
        if (ret)
                return ret;

        dbi->command = waveshare_command;
        dbi->read_commands = NULL;

        ret = mipi_dbi_dev_init(dbidev, &waveshare_pipe_funcs,
                                &waveshare_mode, rotation);
        if (ret)
                return ret;

        drm_mode_config_reset(drm);

        ret = drm_dev_register(drm, 0);
        if (ret)
                return ret;

        spi_set_drvdata(spi, drm);

        drm_client_setup(drm, NULL);

        return 0;
}

static void ili9486_remove(struct spi_device *spi)
{
        struct drm_device *drm = spi_get_drvdata(spi);

        drm_dev_unplug(drm);
        drm_atomic_helper_shutdown(drm);
}

static void ili9486_shutdown(struct spi_device *spi)
{
        drm_atomic_helper_shutdown(spi_get_drvdata(spi));
}

static struct spi_driver ili9486_spi_driver = {
        .driver = {
                .name = "ili9486",
                .of_match_table = ili9486_of_match,
        },
        .id_table = ili9486_id,
        .probe = ili9486_probe,
        .remove = ili9486_remove,
        .shutdown = ili9486_shutdown,
};
module_spi_driver(ili9486_spi_driver);

MODULE_DESCRIPTION("Ilitek ILI9486 DRM driver");
MODULE_AUTHOR("Kamlesh Gurudasani <kamlesh.gurudasani@gmail.com>");
MODULE_LICENSE("GPL");