// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * DRM driver for Sitronix ST7586 panels
 *
 * Copyright 2017 David Lechner <david@lechnology.com>
 */

#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_damage_helper.h>
#include <drm/drm_drv.h>
#include <drm/drm_fb_dma_helper.h>
#include <drm/drm_fbdev_dma.h>
#include <drm/drm_format_helper.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_dma_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_managed.h>
#include <drm/drm_mipi_dbi.h>
#include <drm/drm_print.h>
#include <drm/drm_rect.h>

/* controller-specific commands */
#define ST7586_DISP_MODE_GRAY   0x38
#define ST7586_DISP_MODE_MONO   0x39
#define ST7586_ENABLE_DDRAM     0x3a
#define ST7586_SET_DISP_DUTY    0xb0
#define ST7586_SET_PART_DISP    0xb4
#define ST7586_SET_NLINE_INV    0xb5
#define ST7586_SET_VOP          0xc0
#define ST7586_SET_BIAS_SYSTEM  0xc3
#define ST7586_SET_BOOST_LEVEL  0xc4
#define ST7586_SET_VOP_OFFSET   0xc7
#define ST7586_ENABLE_ANALOG    0xd0
#define ST7586_AUTO_READ_CTRL   0xd7
#define ST7586_OTP_RW_CTRL      0xe0
#define ST7586_OTP_CTRL_OUT     0xe1
#define ST7586_OTP_READ         0xe3

#define ST7586_DISP_CTRL_MX     BIT(6)
#define ST7586_DISP_CTRL_MY     BIT(7)

/*
 * The ST7586 controller has an unusual pixel format where 2bpp grayscale is
 * packed 3 pixels per byte with the first two pixels using 3 bits and the 3rd
 * pixel using only 2 bits.
 *
 * |  D7  |  D6  |  D5  ||      |      || 2bpp |
 * | (D4) | (D3) | (D2) ||  D1  |  D0  || GRAY |
 * +------+------+------++------+------++------+
 * |  1   |  1   |  1   ||  1   |  1   || 0  0 | black
 * |  1   |  0   |  0   ||  1   |  0   || 0  1 | dark gray
 * |  0   |  1   |  0   ||  0   |  1   || 1  0 | light gray
 * |  0   |  0   |  0   ||  0   |  0   || 1  1 | white
 */

static const u8 st7586_lookup[] = { 0x7, 0x4, 0x2, 0x0 };

static void st7586_xrgb8888_to_gray332(u8 *dst, void *vaddr,
                                       struct drm_framebuffer *fb,
                                       struct drm_rect *clip,
                                       struct drm_format_conv_state *fmtcnv_state)
{
        size_t len = (clip->x2 - clip->x1) * (clip->y2 - clip->y1);
        unsigned int x, y;
        u8 *src, *buf, val;
        struct iosys_map dst_map, vmap;

        buf = kmalloc(len, GFP_KERNEL);
        if (!buf)
                return;

        iosys_map_set_vaddr(&dst_map, buf);
        iosys_map_set_vaddr(&vmap, vaddr);
        drm_fb_xrgb8888_to_gray8(&dst_map, NULL, &vmap, fb, clip, fmtcnv_state);
        src = buf;

        for (y = clip->y1; y < clip->y2; y++) {
                for (x = clip->x1; x < clip->x2; x += 3) {
                        val = st7586_lookup[*src++ >> 6] << 5;
                        val |= st7586_lookup[*src++ >> 6] << 2;
                        val |= st7586_lookup[*src++ >> 6] >> 1;
                        *dst++ = val;
                }
        }

        kfree(buf);
}

static int st7586_buf_copy(void *dst, struct iosys_map *src, struct drm_framebuffer *fb,
                           struct drm_rect *clip, struct drm_format_conv_state *fmtcnv_state)
{
        int ret;

        ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
        if (ret)
                return ret;

        st7586_xrgb8888_to_gray332(dst, src->vaddr, fb, clip, fmtcnv_state);

        drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);

        return 0;
}

static void st7586_fb_dirty(struct iosys_map *src, struct drm_framebuffer *fb,
                            struct drm_rect *rect, struct drm_format_conv_state *fmtcnv_state)
{
        struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(fb->dev);
        struct mipi_dbi *dbi = &dbidev->dbi;
        int start, end, ret = 0;

        /* 3 pixels per byte, so grow clip to nearest multiple of 3 */
        rect->x1 = rounddown(rect->x1, 3);
        rect->x2 = roundup(rect->x2, 3);

        DRM_DEBUG_KMS("Flushing [FB:%d] " DRM_RECT_FMT "\n", fb->base.id, DRM_RECT_ARG(rect));

        ret = st7586_buf_copy(dbidev->tx_buf, src, fb, rect, fmtcnv_state);
        if (ret)
                goto err_msg;

        /* Pixels are packed 3 per byte */
        start = rect->x1 / 3;
        end = rect->x2 / 3;

        mipi_dbi_command(dbi, MIPI_DCS_SET_COLUMN_ADDRESS,
                         (start >> 8) & 0xFF, start & 0xFF,
                         (end >> 8) & 0xFF, (end - 1) & 0xFF);
        mipi_dbi_command(dbi, MIPI_DCS_SET_PAGE_ADDRESS,
                         (rect->y1 >> 8) & 0xFF, rect->y1 & 0xFF,
                         (rect->y2 >> 8) & 0xFF, (rect->y2 - 1) & 0xFF);

        ret = mipi_dbi_command_buf(dbi, MIPI_DCS_WRITE_MEMORY_START,
                                   (u8 *)dbidev->tx_buf,
                                   (end - start) * (rect->y2 - rect->y1));
err_msg:
        if (ret)
                dev_err_once(fb->dev->dev, "Failed to update display %d\n", ret);
}

static void st7586_pipe_update(struct drm_simple_display_pipe *pipe,
                               struct drm_plane_state *old_state)
{
        struct drm_plane_state *state = pipe->plane.state;
        struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(state);
        struct drm_framebuffer *fb = state->fb;
        struct drm_rect rect;
        int idx;

        if (!pipe->crtc.state->active)
                return;

        if (!drm_dev_enter(fb->dev, &idx))
                return;

        if (drm_atomic_helper_damage_merged(old_state, state, &rect))
                st7586_fb_dirty(&shadow_plane_state->data[0], fb, &rect,
                                &shadow_plane_state->fmtcnv_state);

        drm_dev_exit(idx);
}

static void st7586_pipe_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 drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
        struct drm_framebuffer *fb = plane_state->fb;
        struct mipi_dbi *dbi = &dbidev->dbi;
        struct drm_rect rect = {
                .x1 = 0,
                .x2 = fb->width,
                .y1 = 0,
                .y2 = fb->height,
        };
        int idx, ret;
        u8 addr_mode;

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

        DRM_DEBUG_KMS("\n");

        ret = mipi_dbi_poweron_reset(dbidev);
        if (ret)
                goto out_exit;

        mipi_dbi_command(dbi, ST7586_AUTO_READ_CTRL, 0x9f);
        mipi_dbi_command(dbi, ST7586_OTP_RW_CTRL, 0x00);

        msleep(10);

        mipi_dbi_command(dbi, ST7586_OTP_READ);

        msleep(20);

        mipi_dbi_command(dbi, ST7586_OTP_CTRL_OUT);
        mipi_dbi_command(dbi, MIPI_DCS_EXIT_SLEEP_MODE);
        mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_OFF);

        msleep(50);

        mipi_dbi_command(dbi, ST7586_SET_VOP_OFFSET, 0x00);
        mipi_dbi_command(dbi, ST7586_SET_VOP, 0xe3, 0x00);
        mipi_dbi_command(dbi, ST7586_SET_BIAS_SYSTEM, 0x02);
        mipi_dbi_command(dbi, ST7586_SET_BOOST_LEVEL, 0x04);
        mipi_dbi_command(dbi, ST7586_ENABLE_ANALOG, 0x1d);
        mipi_dbi_command(dbi, ST7586_SET_NLINE_INV, 0x00);
        mipi_dbi_command(dbi, ST7586_DISP_MODE_GRAY);
        mipi_dbi_command(dbi, ST7586_ENABLE_DDRAM, 0x02);

        switch (dbidev->rotation) {
        default:
                addr_mode = 0x00;
                break;
        case 90:
                addr_mode = ST7586_DISP_CTRL_MY;
                break;
        case 180:
                addr_mode = ST7586_DISP_CTRL_MX | ST7586_DISP_CTRL_MY;
                break;
        case 270:
                addr_mode = ST7586_DISP_CTRL_MX;
                break;
        }
        mipi_dbi_command(dbi, MIPI_DCS_SET_ADDRESS_MODE, addr_mode);

        mipi_dbi_command(dbi, ST7586_SET_DISP_DUTY, 0x7f);
        mipi_dbi_command(dbi, ST7586_SET_PART_DISP, 0xa0);
        mipi_dbi_command(dbi, MIPI_DCS_SET_PARTIAL_ROWS, 0x00, 0x00, 0x00, 0x77);
        mipi_dbi_command(dbi, MIPI_DCS_EXIT_INVERT_MODE);

        msleep(100);

        st7586_fb_dirty(&shadow_plane_state->data[0], fb, &rect,
                        &shadow_plane_state->fmtcnv_state);

        mipi_dbi_command(dbi, MIPI_DCS_SET_DISPLAY_ON);
out_exit:
        drm_dev_exit(idx);
}

static void st7586_pipe_disable(struct drm_simple_display_pipe *pipe)
{
        struct mipi_dbi_dev *dbidev = drm_to_mipi_dbi_dev(pipe->crtc.dev);

        /*
         * This callback is not protected by drm_dev_enter/exit since we want to
         * turn off the display on regular driver unload. It's highly unlikely
         * that the underlying SPI controller is gone should this be called after
         * unplug.
         */

        DRM_DEBUG_KMS("\n");

        mipi_dbi_command(&dbidev->dbi, MIPI_DCS_SET_DISPLAY_OFF);
}

static const u32 st7586_formats[] = {
        DRM_FORMAT_XRGB8888,
};

static const struct drm_simple_display_pipe_funcs st7586_pipe_funcs = {
        .mode_valid     = mipi_dbi_pipe_mode_valid,
        .enable         = st7586_pipe_enable,
        .disable        = st7586_pipe_disable,
        .update         = st7586_pipe_update,
        .begin_fb_access = mipi_dbi_pipe_begin_fb_access,
        .end_fb_access  = mipi_dbi_pipe_end_fb_access,
        .reset_plane    = mipi_dbi_pipe_reset_plane,
        .duplicate_plane_state = mipi_dbi_pipe_duplicate_plane_state,
        .destroy_plane_state = mipi_dbi_pipe_destroy_plane_state,
};

static const struct drm_display_mode st7586_mode = {
        DRM_SIMPLE_MODE(178, 128, 37, 27),
};

DEFINE_DRM_GEM_DMA_FOPS(st7586_fops);

static const struct drm_driver st7586_driver = {
        .driver_features        = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
        .fops                   = &st7586_fops,
        DRM_GEM_DMA_DRIVER_OPS_VMAP,
        DRM_FBDEV_DMA_DRIVER_OPS,
        .debugfs_init           = mipi_dbi_debugfs_init,
        .name                   = "st7586",
        .desc                   = "Sitronix ST7586",
        .major                  = 1,
        .minor                  = 0,
};

static const struct of_device_id st7586_of_match[] = {
        { .compatible = "lego,ev3-lcd" },
        {},
};
MODULE_DEVICE_TABLE(of, st7586_of_match);

static const struct spi_device_id st7586_id[] = {
        { "ev3-lcd", 0 },
        { },
};
MODULE_DEVICE_TABLE(spi, st7586_id);

static int st7586_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 *a0;
        u32 rotation = 0;
        size_t bufsize;
        int ret;

        dbidev = devm_drm_dev_alloc(dev, &st7586_driver,
                                    struct mipi_dbi_dev, drm);
        if (IS_ERR(dbidev))
                return PTR_ERR(dbidev);

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

        bufsize = (st7586_mode.vdisplay + 2) / 3 * st7586_mode.hdisplay;

        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");

        a0 = devm_gpiod_get(dev, "a0", GPIOD_OUT_LOW);
        if (IS_ERR(a0))
                return dev_err_probe(dev, PTR_ERR(a0), "Failed to get GPIO 'a0'\n");

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

        ret = mipi_dbi_spi_init(spi, dbi, a0);
        if (ret)
                return ret;

        /*
         * Override value set by mipi_dbi_spi_init(). This driver is a bit
         * non-standard, so best to set it explicitly here.
         */
        dbi->write_memory_bpw = 8;

        /* Cannot read from this controller via SPI */
        dbi->read_commands = NULL;

        ret = mipi_dbi_dev_init_with_formats(dbidev, &st7586_pipe_funcs,
                                             st7586_formats, ARRAY_SIZE(st7586_formats),
                                             &st7586_mode, rotation, bufsize);
        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 st7586_remove(struct spi_device *spi)
{
        struct drm_device *drm = spi_get_drvdata(spi);

        drm_dev_unplug(drm);
        drm_atomic_helper_shutdown(drm);
}

static void st7586_shutdown(struct spi_device *spi)
{
        drm_atomic_helper_shutdown(spi_get_drvdata(spi));
}

static struct spi_driver st7586_spi_driver = {
        .driver = {
                .name = "st7586",
                .of_match_table = st7586_of_match,
        },
        .id_table = st7586_id,
        .probe = st7586_probe,
        .remove = st7586_remove,
        .shutdown = st7586_shutdown,
};
module_spi_driver(st7586_spi_driver);

MODULE_DESCRIPTION("Sitronix ST7586 DRM driver");
MODULE_AUTHOR("David Lechner <david@lechnology.com>");
MODULE_LICENSE("GPL");