// SPDX-License-Identifier: MIT
/*
 * Copyright 2020 Noralf Trønnes
 */

#include <linux/lz4.h>
#include <linux/usb.h>
#include <linux/workqueue.h>

#include <drm/drm_atomic.h>
#include <drm/drm_connector.h>
#include <drm/drm_damage_helper.h>
#include <drm/drm_drv.h>
#include <drm/drm_format_helper.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_print.h>
#include <drm/drm_rect.h>
#include <drm/drm_simple_kms_helper.h>
#include <drm/gud.h>

#include "gud_internal.h"

/*
 * Some userspace rendering loops runs all displays in the same loop.
 * This means that a fast display will have to wait for a slow one.
 * For this reason gud does flushing asynchronous by default.
 * The down side is that in e.g. a single display setup userspace thinks
 * the display is insanely fast since the driver reports back immediately
 * that the flush/pageflip is done. This wastes CPU and power.
 * Such users might want to set this module parameter to false.
 */
static bool gud_async_flush = true;
module_param_named(async_flush, gud_async_flush, bool, 0644);
MODULE_PARM_DESC(async_flush, "Enable asynchronous flushing [default=true]");

/*
 * FIXME: The driver is probably broken on Big Endian machines.
 * See discussion:
 * https://lore.kernel.org/dri-devel/CAKb7UvihLX0hgBOP3VBG7O+atwZcUVCPVuBdfmDMpg0NjXe-cQ@mail.gmail.com/
 */

static bool gud_is_big_endian(void)
{
#if defined(__BIG_ENDIAN)
        return true;
#else
        return false;
#endif
}

static size_t gud_xrgb8888_to_r124(u8 *dst, const struct drm_format_info *format,
                                   void *src, struct drm_framebuffer *fb,
                                   struct drm_rect *rect)
{
        unsigned int block_width = drm_format_info_block_width(format, 0);
        unsigned int bits_per_pixel = 8 / block_width;
        unsigned int x, y, width, height;
        u8 pix, *pix8, *block = dst; /* Assign to silence compiler warning */
        size_t len;
        void *buf;

        WARN_ON_ONCE(format->char_per_block[0] != 1);

        /* Start on a byte boundary */
        rect->x1 = ALIGN_DOWN(rect->x1, block_width);
        width = drm_rect_width(rect);
        height = drm_rect_height(rect);
        len = drm_format_info_min_pitch(format, 0, width) * height;

        buf = kmalloc(width * height, GFP_KERNEL);
        if (!buf)
                return 0;

        drm_fb_xrgb8888_to_gray8(buf, src, fb, rect);
        pix8 = buf;

        for (y = 0; y < height; y++) {
                for (x = 0; x < width; x++) {
                        unsigned int pixpos = x % block_width; /* within byte from the left */
                        unsigned int pixshift = (block_width - pixpos - 1) * bits_per_pixel;

                        if (!pixpos) {
                                block = dst++;
                                *block = 0;
                        }

                        pix = (*pix8++) >> (8 - bits_per_pixel);
                        *block |= pix << pixshift;
                }
        }

        kfree(buf);

        return len;
}

static size_t gud_xrgb8888_to_color(u8 *dst, const struct drm_format_info *format,
                                    void *src, struct drm_framebuffer *fb,
                                    struct drm_rect *rect)
{
        unsigned int block_width = drm_format_info_block_width(format, 0);
        unsigned int bits_per_pixel = 8 / block_width;
        u8 r, g, b, pix, *block = dst; /* Assign to silence compiler warning */
        unsigned int x, y, width;
        u32 *pix32;
        size_t len;

        /* Start on a byte boundary */
        rect->x1 = ALIGN_DOWN(rect->x1, block_width);
        width = drm_rect_width(rect);
        len = drm_format_info_min_pitch(format, 0, width) * drm_rect_height(rect);

        for (y = rect->y1; y < rect->y2; y++) {
                pix32 = src + (y * fb->pitches[0]);
                pix32 += rect->x1;

                for (x = 0; x < width; x++) {
                        unsigned int pixpos = x % block_width; /* within byte from the left */
                        unsigned int pixshift = (block_width - pixpos - 1) * bits_per_pixel;

                        if (!pixpos) {
                                block = dst++;
                                *block = 0;
                        }

                        r = *pix32 >> 16;
                        g = *pix32 >> 8;
                        b = *pix32++;

                        switch (format->format) {
                        case GUD_DRM_FORMAT_XRGB1111:
                                pix = ((r >> 7) << 2) | ((g >> 7) << 1) | (b >> 7);
                                break;
                        default:
                                WARN_ON_ONCE(1);
                                return len;
                        }

                        *block |= pix << pixshift;
                }
        }

        return len;
}

static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
                          const struct drm_format_info *format, struct drm_rect *rect,
                          struct gud_set_buffer_req *req)
{
        struct dma_buf_attachment *import_attach = fb->obj[0]->import_attach;
        u8 compression = gdrm->compression;
        struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
        struct dma_buf_map map_data[DRM_FORMAT_MAX_PLANES];
        void *vaddr, *buf;
        size_t pitch, len;
        int ret = 0;

        pitch = drm_format_info_min_pitch(format, 0, drm_rect_width(rect));
        len = pitch * drm_rect_height(rect);
        if (len > gdrm->bulk_len)
                return -E2BIG;

        ret = drm_gem_fb_vmap(fb, map, map_data);
        if (ret)
                return ret;

        vaddr = map_data[0].vaddr;

        ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
        if (ret)
                goto vunmap;
retry:
        if (compression)
                buf = gdrm->compress_buf;
        else
                buf = gdrm->bulk_buf;

        /*
         * Imported buffers are assumed to be write-combined and thus uncached
         * with slow reads (at least on ARM).
         */
        if (format != fb->format) {
                if (format->format == GUD_DRM_FORMAT_R1) {
                        len = gud_xrgb8888_to_r124(buf, format, vaddr, fb, rect);
                        if (!len) {
                                ret = -ENOMEM;
                                goto end_cpu_access;
                        }
                } else if (format->format == DRM_FORMAT_RGB565) {
                        drm_fb_xrgb8888_to_rgb565(buf, vaddr, fb, rect, gud_is_big_endian());
                } else {
                        len = gud_xrgb8888_to_color(buf, format, vaddr, fb, rect);
                }
        } else if (gud_is_big_endian() && format->cpp[0] > 1) {
                drm_fb_swab(buf, vaddr, fb, rect, !import_attach);
        } else if (compression && !import_attach && pitch == fb->pitches[0]) {
                /* can compress directly from the framebuffer */
                buf = vaddr + rect->y1 * pitch;
        } else {
                drm_fb_memcpy(buf, vaddr, fb, rect);
        }

        memset(req, 0, sizeof(*req));
        req->x = cpu_to_le32(rect->x1);
        req->y = cpu_to_le32(rect->y1);
        req->width = cpu_to_le32(drm_rect_width(rect));
        req->height = cpu_to_le32(drm_rect_height(rect));
        req->length = cpu_to_le32(len);

        if (compression & GUD_COMPRESSION_LZ4) {
                int complen;

                complen = LZ4_compress_default(buf, gdrm->bulk_buf, len, len, gdrm->lz4_comp_mem);
                if (complen <= 0) {
                        compression = 0;
                        goto retry;
                }

                req->compression = GUD_COMPRESSION_LZ4;
                req->compressed_length = cpu_to_le32(complen);
        }

end_cpu_access:
        drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
vunmap:
        drm_gem_fb_vunmap(fb, map);

        return ret;
}

struct gud_usb_bulk_context {
        struct timer_list timer;
        struct usb_sg_request sgr;
};

static void gud_usb_bulk_timeout(struct timer_list *t)
{
        struct gud_usb_bulk_context *ctx = from_timer(ctx, t, timer);

        usb_sg_cancel(&ctx->sgr);
}

static int gud_usb_bulk(struct gud_device *gdrm, size_t len)
{
        struct gud_usb_bulk_context ctx;
        int ret;

        ret = usb_sg_init(&ctx.sgr, gud_to_usb_device(gdrm), gdrm->bulk_pipe, 0,
                          gdrm->bulk_sgt.sgl, gdrm->bulk_sgt.nents, len, GFP_KERNEL);
        if (ret)
                return ret;

        timer_setup_on_stack(&ctx.timer, gud_usb_bulk_timeout, 0);
        mod_timer(&ctx.timer, jiffies + msecs_to_jiffies(3000));

        usb_sg_wait(&ctx.sgr);

        if (!del_timer_sync(&ctx.timer))
                ret = -ETIMEDOUT;
        else if (ctx.sgr.status < 0)
                ret = ctx.sgr.status;
        else if (ctx.sgr.bytes != len)
                ret = -EIO;

        destroy_timer_on_stack(&ctx.timer);

        return ret;
}

static int gud_flush_rect(struct gud_device *gdrm, struct drm_framebuffer *fb,
                          const struct drm_format_info *format, struct drm_rect *rect)
{
        struct gud_set_buffer_req req;
        size_t len, trlen;
        int ret;

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

        ret = gud_prep_flush(gdrm, fb, format, rect, &req);
        if (ret)
                return ret;

        len = le32_to_cpu(req.length);

        if (req.compression)
                trlen = le32_to_cpu(req.compressed_length);
        else
                trlen = len;

        gdrm->stats_length += len;
        /* Did it wrap around? */
        if (gdrm->stats_length <= len && gdrm->stats_actual_length) {
                gdrm->stats_length = len;
                gdrm->stats_actual_length = 0;
        }
        gdrm->stats_actual_length += trlen;

        if (!(gdrm->flags & GUD_DISPLAY_FLAG_FULL_UPDATE) || gdrm->prev_flush_failed) {
                ret = gud_usb_set(gdrm, GUD_REQ_SET_BUFFER, 0, &req, sizeof(req));
                if (ret)
                        return ret;
        }

        ret = gud_usb_bulk(gdrm, trlen);
        if (ret)
                gdrm->stats_num_errors++;

        return ret;
}

void gud_clear_damage(struct gud_device *gdrm)
{
        gdrm->damage.x1 = INT_MAX;
        gdrm->damage.y1 = INT_MAX;
        gdrm->damage.x2 = 0;
        gdrm->damage.y2 = 0;
}

static void gud_add_damage(struct gud_device *gdrm, struct drm_rect *damage)
{
        gdrm->damage.x1 = min(gdrm->damage.x1, damage->x1);
        gdrm->damage.y1 = min(gdrm->damage.y1, damage->y1);
        gdrm->damage.x2 = max(gdrm->damage.x2, damage->x2);
        gdrm->damage.y2 = max(gdrm->damage.y2, damage->y2);
}

static void gud_retry_failed_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
                                   struct drm_rect *damage)
{
        /*
         * pipe_update waits for the worker when the display mode is going to change.
         * This ensures that the width and height is still the same making it safe to
         * add back the damage.
         */

        mutex_lock(&gdrm->damage_lock);
        if (!gdrm->fb) {
                drm_framebuffer_get(fb);
                gdrm->fb = fb;
        }
        gud_add_damage(gdrm, damage);
        mutex_unlock(&gdrm->damage_lock);

        /* Retry only once to avoid a possible storm in case of continues errors. */
        if (!gdrm->prev_flush_failed)
                queue_work(system_long_wq, &gdrm->work);
        gdrm->prev_flush_failed = true;
}

void gud_flush_work(struct work_struct *work)
{
        struct gud_device *gdrm = container_of(work, struct gud_device, work);
        const struct drm_format_info *format;
        struct drm_framebuffer *fb;
        struct drm_rect damage;
        unsigned int i, lines;
        int idx, ret = 0;
        size_t pitch;

        if (!drm_dev_enter(&gdrm->drm, &idx))
                return;

        mutex_lock(&gdrm->damage_lock);
        fb = gdrm->fb;
        gdrm->fb = NULL;
        damage = gdrm->damage;
        gud_clear_damage(gdrm);
        mutex_unlock(&gdrm->damage_lock);

        if (!fb)
                goto out;

        format = fb->format;
        if (format->format == DRM_FORMAT_XRGB8888 && gdrm->xrgb8888_emulation_format)
                format = gdrm->xrgb8888_emulation_format;

        /* Split update if it's too big */
        pitch = drm_format_info_min_pitch(format, 0, drm_rect_width(&damage));
        lines = drm_rect_height(&damage);

        if (gdrm->bulk_len < lines * pitch)
                lines = gdrm->bulk_len / pitch;

        for (i = 0; i < DIV_ROUND_UP(drm_rect_height(&damage), lines); i++) {
                struct drm_rect rect = damage;

                rect.y1 += i * lines;
                rect.y2 = min_t(u32, rect.y1 + lines, damage.y2);

                ret = gud_flush_rect(gdrm, fb, format, &rect);
                if (ret) {
                        if (ret != -ENODEV && ret != -ECONNRESET &&
                            ret != -ESHUTDOWN && ret != -EPROTO) {
                                bool prev_flush_failed = gdrm->prev_flush_failed;

                                gud_retry_failed_flush(gdrm, fb, &damage);
                                if (!prev_flush_failed)
                                        dev_err_ratelimited(fb->dev->dev,
                                                            "Failed to flush framebuffer: error=%d\n", ret);
                        }
                        break;
                }

                gdrm->prev_flush_failed = false;
        }

        drm_framebuffer_put(fb);
out:
        drm_dev_exit(idx);
}

static void gud_fb_queue_damage(struct gud_device *gdrm, struct drm_framebuffer *fb,
                                struct drm_rect *damage)
{
        struct drm_framebuffer *old_fb = NULL;

        mutex_lock(&gdrm->damage_lock);

        if (fb != gdrm->fb) {
                old_fb = gdrm->fb;
                drm_framebuffer_get(fb);
                gdrm->fb = fb;
        }

        gud_add_damage(gdrm, damage);

        mutex_unlock(&gdrm->damage_lock);

        queue_work(system_long_wq, &gdrm->work);

        if (old_fb)
                drm_framebuffer_put(old_fb);
}

int gud_pipe_check(struct drm_simple_display_pipe *pipe,
                   struct drm_plane_state *new_plane_state,
                   struct drm_crtc_state *new_crtc_state)
{
        struct gud_device *gdrm = to_gud_device(pipe->crtc.dev);
        struct drm_plane_state *old_plane_state = pipe->plane.state;
        const struct drm_display_mode *mode = &new_crtc_state->mode;
        struct drm_atomic_state *state = new_plane_state->state;
        struct drm_framebuffer *old_fb = old_plane_state->fb;
        struct drm_connector_state *connector_state = NULL;
        struct drm_framebuffer *fb = new_plane_state->fb;
        const struct drm_format_info *format = fb->format;
        struct drm_connector *connector;
        unsigned int i, num_properties;
        struct gud_state_req *req;
        int idx, ret;
        size_t len;

        if (WARN_ON_ONCE(!fb))
                return -EINVAL;

        if (old_plane_state->rotation != new_plane_state->rotation)
                new_crtc_state->mode_changed = true;

        if (old_fb && old_fb->format != format)
                new_crtc_state->mode_changed = true;

        if (!new_crtc_state->mode_changed && !new_crtc_state->connectors_changed)
                return 0;

        /* Only one connector is supported */
        if (hweight32(new_crtc_state->connector_mask) != 1)
                return -EINVAL;

        if (format->format == DRM_FORMAT_XRGB8888 && gdrm->xrgb8888_emulation_format)
                format = gdrm->xrgb8888_emulation_format;

        for_each_new_connector_in_state(state, connector, connector_state, i) {
                if (connector_state->crtc)
                        break;
        }

        /*
         * DRM_IOCTL_MODE_OBJ_SETPROPERTY on the rotation property will not have
         * the connector included in the state.
         */
        if (!connector_state) {
                struct drm_connector_list_iter conn_iter;

                drm_connector_list_iter_begin(pipe->crtc.dev, &conn_iter);
                drm_for_each_connector_iter(connector, &conn_iter) {
                        if (connector->state->crtc) {
                                connector_state = connector->state;
                                break;
                        }
                }
                drm_connector_list_iter_end(&conn_iter);
        }

        if (WARN_ON_ONCE(!connector_state))
                return -ENOENT;

        len = struct_size(req, properties,
                          GUD_PROPERTIES_MAX_NUM + GUD_CONNECTOR_PROPERTIES_MAX_NUM);
        req = kzalloc(len, GFP_KERNEL);
        if (!req)
                return -ENOMEM;

        gud_from_display_mode(&req->mode, mode);

        req->format = gud_from_fourcc(format->format);
        if (WARN_ON_ONCE(!req->format)) {
                ret = -EINVAL;
                goto out;
        }

        req->connector = drm_connector_index(connector_state->connector);

        ret = gud_connector_fill_properties(connector_state, req->properties);
        if (ret < 0)
                goto out;

        num_properties = ret;
        for (i = 0; i < gdrm->num_properties; i++) {
                u16 prop = gdrm->properties[i];
                u64 val;

                switch (prop) {
                case GUD_PROPERTY_ROTATION:
                        /* DRM UAPI matches the protocol so use value directly */
                        val = new_plane_state->rotation;
                        break;
                default:
                        WARN_ON_ONCE(1);
                        ret = -EINVAL;
                        goto out;
                }

                req->properties[num_properties + i].prop = cpu_to_le16(prop);
                req->properties[num_properties + i].val = cpu_to_le64(val);
                num_properties++;
        }

        if (drm_dev_enter(fb->dev, &idx)) {
                len = struct_size(req, properties, num_properties);
                ret = gud_usb_set(gdrm, GUD_REQ_SET_STATE_CHECK, 0, req, len);
                drm_dev_exit(idx);
        }  else {
                ret = -ENODEV;
        }
out:
        kfree(req);

        return ret;
}

void gud_pipe_update(struct drm_simple_display_pipe *pipe,
                     struct drm_plane_state *old_state)
{
        struct drm_device *drm = pipe->crtc.dev;
        struct gud_device *gdrm = to_gud_device(drm);
        struct drm_plane_state *state = pipe->plane.state;
        struct drm_framebuffer *fb = state->fb;
        struct drm_crtc *crtc = &pipe->crtc;
        struct drm_rect damage;
        int idx;

        if (crtc->state->mode_changed || !crtc->state->enable) {
                cancel_work_sync(&gdrm->work);
                mutex_lock(&gdrm->damage_lock);
                if (gdrm->fb) {
                        drm_framebuffer_put(gdrm->fb);
                        gdrm->fb = NULL;
                }
                gud_clear_damage(gdrm);
                mutex_unlock(&gdrm->damage_lock);
        }

        if (!drm_dev_enter(drm, &idx))
                return;

        if (!old_state->fb)
                gud_usb_set_u8(gdrm, GUD_REQ_SET_CONTROLLER_ENABLE, 1);

        if (fb && (crtc->state->mode_changed || crtc->state->connectors_changed))
                gud_usb_set(gdrm, GUD_REQ_SET_STATE_COMMIT, 0, NULL, 0);

        if (crtc->state->active_changed)
                gud_usb_set_u8(gdrm, GUD_REQ_SET_DISPLAY_ENABLE, crtc->state->active);

        if (drm_atomic_helper_damage_merged(old_state, state, &damage)) {
                if (gdrm->flags & GUD_DISPLAY_FLAG_FULL_UPDATE)
                        drm_rect_init(&damage, 0, 0, fb->width, fb->height);
                gud_fb_queue_damage(gdrm, fb, &damage);
                if (!gud_async_flush)
                        flush_work(&gdrm->work);
        }

        if (!crtc->state->enable)
                gud_usb_set_u8(gdrm, GUD_REQ_SET_CONTROLLER_ENABLE, 0);

        drm_dev_exit(idx);
}