/*
 * Copyright (C) 2012 Red Hat
 *
 * based in parts on udlfb.c:
 * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
 * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
 * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License v2. See the file COPYING in the main directory of this archive for
 * more details.
 */
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/dma-buf.h>

#include <drm/drmP.h>
#include <drm/drm_crtc.h>
#include <drm/drm_crtc_helper.h>
#include "udl_drv.h"

#include <drm/drm_fb_helper.h>

#define DL_DEFIO_WRITE_DELAY    (HZ/20) /* fb_deferred_io.delay in jiffies */

static int fb_defio = 0;  /* Optionally enable experimental fb_defio mmap support */
static int fb_bpp = 16;

module_param(fb_bpp, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);
module_param(fb_defio, int, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP);

struct udl_fbdev {
        struct drm_fb_helper helper;
        struct udl_framebuffer ufb;
        int fb_count;
};

#define DL_ALIGN_UP(x, a) ALIGN(x, a)
#define DL_ALIGN_DOWN(x, a) ALIGN(x-(a-1), a)

/** Read the red component (0..255) of a 32 bpp colour. */
#define DLO_RGB_GETRED(col) (uint8_t)((col) & 0xFF)

/** Read the green component (0..255) of a 32 bpp colour. */
#define DLO_RGB_GETGRN(col) (uint8_t)(((col) >> 8) & 0xFF)

/** Read the blue component (0..255) of a 32 bpp colour. */
#define DLO_RGB_GETBLU(col) (uint8_t)(((col) >> 16) & 0xFF)

/** Return red/green component of a 16 bpp colour number. */
#define DLO_RG16(red, grn) (uint8_t)((((red) & 0xF8) | ((grn) >> 5)) & 0xFF)

/** Return green/blue component of a 16 bpp colour number. */
#define DLO_GB16(grn, blu) (uint8_t)(((((grn) & 0x1C) << 3) | ((blu) >> 3)) & 0xFF)

/** Return 8 bpp colour number from red, green and blue components. */
#define DLO_RGB8(red, grn, blu) ((((red) << 5) | (((grn) & 3) << 3) | ((blu) & 7)) & 0xFF)

#if 0
static uint8_t rgb8(uint32_t col)
{
        uint8_t red = DLO_RGB_GETRED(col);
        uint8_t grn = DLO_RGB_GETGRN(col);
        uint8_t blu = DLO_RGB_GETBLU(col);

        return DLO_RGB8(red, grn, blu);
}

static uint16_t rgb16(uint32_t col)
{
        uint8_t red = DLO_RGB_GETRED(col);
        uint8_t grn = DLO_RGB_GETGRN(col);
        uint8_t blu = DLO_RGB_GETBLU(col);

        return (DLO_RG16(red, grn) << 8) + DLO_GB16(grn, blu);
}
#endif

/*
 * NOTE: fb_defio.c is holding info->fbdefio.mutex
 *   Touching ANY framebuffer memory that triggers a page fault
 *   in fb_defio will cause a deadlock, when it also tries to
 *   grab the same mutex.
 */
static void udlfb_dpy_deferred_io(struct fb_info *info,
                                  struct list_head *pagelist)
{
        struct page *cur;
        struct fb_deferred_io *fbdefio = info->fbdefio;
        struct udl_fbdev *ufbdev = info->par;
        struct drm_device *dev = ufbdev->ufb.base.dev;
        struct udl_device *udl = dev->dev_private;
        struct urb *urb;
        char *cmd;
        cycles_t start_cycles, end_cycles;
        int bytes_sent = 0;
        int bytes_identical = 0;
        int bytes_rendered = 0;

        if (!fb_defio)
                return;

        start_cycles = get_cycles();

        urb = udl_get_urb(dev);
        if (!urb)
                return;

        cmd = urb->transfer_buffer;

        /* walk the written page list and render each to device */
        list_for_each_entry(cur, &fbdefio->pagelist, lru) {

                if (udl_render_hline(dev, (ufbdev->ufb.base.bits_per_pixel / 8),
                                     &urb, (char *) info->fix.smem_start,
                                     &cmd, cur->index << PAGE_SHIFT,
                                     cur->index << PAGE_SHIFT,
                                     PAGE_SIZE, &bytes_identical, &bytes_sent))
                        goto error;
                bytes_rendered += PAGE_SIZE;
        }

        if (cmd > (char *) urb->transfer_buffer) {
                /* Send partial buffer remaining before exiting */
                int len = cmd - (char *) urb->transfer_buffer;
                udl_submit_urb(dev, urb, len);
                bytes_sent += len;
        } else
                udl_urb_completion(urb);

error:
        atomic_add(bytes_sent, &udl->bytes_sent);
        atomic_add(bytes_identical, &udl->bytes_identical);
        atomic_add(bytes_rendered, &udl->bytes_rendered);
        end_cycles = get_cycles();
        atomic_add(((unsigned int) ((end_cycles - start_cycles)
                    >> 10)), /* Kcycles */
                   &udl->cpu_kcycles_used);
}

int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
                      int width, int height)
{
        struct drm_device *dev = fb->base.dev;
        struct udl_device *udl = dev->dev_private;
        int i, ret;
        char *cmd;
        cycles_t start_cycles, end_cycles;
        int bytes_sent = 0;
        int bytes_identical = 0;
        struct urb *urb;
        int aligned_x;
        int bpp = (fb->base.bits_per_pixel / 8);
        int x2, y2;
        bool store_for_later = false;
        unsigned long flags;

        if (!fb->active_16)
                return 0;

        if (!fb->obj->vmapping) {
                ret = udl_gem_vmap(fb->obj);
                if (ret == -ENOMEM) {
                        DRM_ERROR("failed to vmap fb\n");
                        return 0;
                }
                if (!fb->obj->vmapping) {
                        DRM_ERROR("failed to vmapping\n");
                        return 0;
                }
        }

        aligned_x = DL_ALIGN_DOWN(x, sizeof(unsigned long));
        width = DL_ALIGN_UP(width + (x-aligned_x), sizeof(unsigned long));
        x = aligned_x;

        if ((width <= 0) ||
            (x + width > fb->base.width) ||
            (y + height > fb->base.height))
                return -EINVAL;

        /* if we are in atomic just store the info
           can't test inside spin lock */
        if (in_atomic())
                store_for_later = true;

        x2 = x + width - 1;
        y2 = y + height - 1;

        spin_lock_irqsave(&fb->dirty_lock, flags);

        if (fb->y1 < y)
                y = fb->y1;
        if (fb->y2 > y2)
                y2 = fb->y2;
        if (fb->x1 < x)
                x = fb->x1;
        if (fb->x2 > x2)
                x2 = fb->x2;

        if (store_for_later) {
                fb->x1 = x;
                fb->x2 = x2;
                fb->y1 = y;
                fb->y2 = y2;
                spin_unlock_irqrestore(&fb->dirty_lock, flags);
                return 0;
        }

        fb->x1 = fb->y1 = INT_MAX;
        fb->x2 = fb->y2 = 0;

        spin_unlock_irqrestore(&fb->dirty_lock, flags);
        start_cycles = get_cycles();

        urb = udl_get_urb(dev);
        if (!urb)
                return 0;
        cmd = urb->transfer_buffer;

        for (i = y; i <= y2 ; i++) {
                const int line_offset = fb->base.pitches[0] * i;
                const int byte_offset = line_offset + (x * bpp);
                const int dev_byte_offset = (fb->base.width * bpp * i) + (x * bpp);
                if (udl_render_hline(dev, bpp, &urb,
                                     (char *) fb->obj->vmapping,
                                     &cmd, byte_offset, dev_byte_offset,
                                     (x2 - x + 1) * bpp,
                                     &bytes_identical, &bytes_sent))
                        goto error;
        }

        if (cmd > (char *) urb->transfer_buffer) {
                /* Send partial buffer remaining before exiting */
                int len = cmd - (char *) urb->transfer_buffer;
                ret = udl_submit_urb(dev, urb, len);
                bytes_sent += len;
        } else
                udl_urb_completion(urb);

error:
        atomic_add(bytes_sent, &udl->bytes_sent);
        atomic_add(bytes_identical, &udl->bytes_identical);
        atomic_add(width*height*bpp, &udl->bytes_rendered);
        end_cycles = get_cycles();
        atomic_add(((unsigned int) ((end_cycles - start_cycles)
                    >> 10)), /* Kcycles */
                   &udl->cpu_kcycles_used);

        return 0;
}

static int udl_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
{
        unsigned long start = vma->vm_start;
        unsigned long size = vma->vm_end - vma->vm_start;
        unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
        unsigned long page, pos;

        if (offset + size > info->fix.smem_len)
                return -EINVAL;

        pos = (unsigned long)info->fix.smem_start + offset;

        pr_notice("mmap() framebuffer addr:%lu size:%lu\n",
                  pos, size);

        while (size > 0) {
                page = vmalloc_to_pfn((void *)pos);
                if (remap_pfn_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
                        return -EAGAIN;

                start += PAGE_SIZE;
                pos += PAGE_SIZE;
                if (size > PAGE_SIZE)
                        size -= PAGE_SIZE;
                else
                        size = 0;
        }

        /* VM_IO | VM_DONTEXPAND | VM_DONTDUMP are set by remap_pfn_range() */
        return 0;
}

static void udl_fb_fillrect(struct fb_info *info, const struct fb_fillrect *rect)
{
        struct udl_fbdev *ufbdev = info->par;

        drm_fb_helper_sys_fillrect(info, rect);

        udl_handle_damage(&ufbdev->ufb, rect->dx, rect->dy, rect->width,
                          rect->height);
}

static void udl_fb_copyarea(struct fb_info *info, const struct fb_copyarea *region)
{
        struct udl_fbdev *ufbdev = info->par;

        drm_fb_helper_sys_copyarea(info, region);

        udl_handle_damage(&ufbdev->ufb, region->dx, region->dy, region->width,
                          region->height);
}

static void udl_fb_imageblit(struct fb_info *info, const struct fb_image *image)
{
        struct udl_fbdev *ufbdev = info->par;

        drm_fb_helper_sys_imageblit(info, image);

        udl_handle_damage(&ufbdev->ufb, image->dx, image->dy, image->width,
                          image->height);
}

/*
 * It's common for several clients to have framebuffer open simultaneously.
 * e.g. both fbcon and X. Makes things interesting.
 * Assumes caller is holding info->lock (for open and release at least)
 */
static int udl_fb_open(struct fb_info *info, int user)
{
        struct udl_fbdev *ufbdev = info->par;
        struct drm_device *dev = ufbdev->ufb.base.dev;
        struct udl_device *udl = dev->dev_private;

        /* If the USB device is gone, we don't accept new opens */
        if (drm_device_is_unplugged(udl->ddev))
                return -ENODEV;

        ufbdev->fb_count++;

        if (fb_defio && (info->fbdefio == NULL)) {
                /* enable defio at last moment if not disabled by client */

                struct fb_deferred_io *fbdefio;

                fbdefio = kmalloc(sizeof(struct fb_deferred_io), GFP_KERNEL);

                if (fbdefio) {
                        fbdefio->delay = DL_DEFIO_WRITE_DELAY;
                        fbdefio->deferred_io = udlfb_dpy_deferred_io;
                }

                info->fbdefio = fbdefio;
                fb_deferred_io_init(info);
        }

        pr_notice("open /dev/fb%d user=%d fb_info=%p count=%d\n",
                  info->node, user, info, ufbdev->fb_count);

        return 0;
}


/*
 * Assumes caller is holding info->lock mutex (for open and release at least)
 */
static int udl_fb_release(struct fb_info *info, int user)
{
        struct udl_fbdev *ufbdev = info->par;

        ufbdev->fb_count--;

        if ((ufbdev->fb_count == 0) && (info->fbdefio)) {
                fb_deferred_io_cleanup(info);
                kfree(info->fbdefio);
                info->fbdefio = NULL;
                info->fbops->fb_mmap = udl_fb_mmap;
        }

        pr_warn("released /dev/fb%d user=%d count=%d\n",
                info->node, user, ufbdev->fb_count);

        return 0;
}

static struct fb_ops udlfb_ops = {
        .owner = THIS_MODULE,
        .fb_check_var = drm_fb_helper_check_var,
        .fb_set_par = drm_fb_helper_set_par,
        .fb_fillrect = udl_fb_fillrect,
        .fb_copyarea = udl_fb_copyarea,
        .fb_imageblit = udl_fb_imageblit,
        .fb_pan_display = drm_fb_helper_pan_display,
        .fb_blank = drm_fb_helper_blank,
        .fb_setcmap = drm_fb_helper_setcmap,
        .fb_debug_enter = drm_fb_helper_debug_enter,
        .fb_debug_leave = drm_fb_helper_debug_leave,
        .fb_mmap = udl_fb_mmap,
        .fb_open = udl_fb_open,
        .fb_release = udl_fb_release,
};

static int udl_user_framebuffer_dirty(struct drm_framebuffer *fb,
                                      struct drm_file *file,
                                      unsigned flags, unsigned color,
                                      struct drm_clip_rect *clips,
                                      unsigned num_clips)
{
        struct udl_framebuffer *ufb = to_udl_fb(fb);
        int i;
        int ret = 0;

        drm_modeset_lock_all(fb->dev);

        if (!ufb->active_16)
                goto unlock;

        if (ufb->obj->base.import_attach) {
                ret = dma_buf_begin_cpu_access(ufb->obj->base.import_attach->dmabuf,
                                               DMA_FROM_DEVICE);
                if (ret)
                        goto unlock;
        }

        for (i = 0; i < num_clips; i++) {
                ret = udl_handle_damage(ufb, clips[i].x1, clips[i].y1,
                                  clips[i].x2 - clips[i].x1,
                                  clips[i].y2 - clips[i].y1);
                if (ret)
                        break;
        }

        if (ufb->obj->base.import_attach) {
                ret = dma_buf_end_cpu_access(ufb->obj->base.import_attach->dmabuf,
                                             DMA_FROM_DEVICE);
        }

 unlock:
        drm_modeset_unlock_all(fb->dev);

        return ret;
}

static void udl_user_framebuffer_destroy(struct drm_framebuffer *fb)
{
        struct udl_framebuffer *ufb = to_udl_fb(fb);

        if (ufb->obj)
                drm_gem_object_unreference_unlocked(&ufb->obj->base);

        drm_framebuffer_cleanup(fb);
        kfree(ufb);
}

static const struct drm_framebuffer_funcs udlfb_funcs = {
        .destroy = udl_user_framebuffer_destroy,
        .dirty = udl_user_framebuffer_dirty,
};


static int
udl_framebuffer_init(struct drm_device *dev,
                     struct udl_framebuffer *ufb,
                     const struct drm_mode_fb_cmd2 *mode_cmd,
                     struct udl_gem_object *obj)
{
        int ret;

        spin_lock_init(&ufb->dirty_lock);
        ufb->obj = obj;
        drm_helper_mode_fill_fb_struct(&ufb->base, mode_cmd);
        ret = drm_framebuffer_init(dev, &ufb->base, &udlfb_funcs);
        return ret;
}


static int udlfb_create(struct drm_fb_helper *helper,
                        struct drm_fb_helper_surface_size *sizes)
{
        struct udl_fbdev *ufbdev =
                container_of(helper, struct udl_fbdev, helper);
        struct drm_device *dev = ufbdev->helper.dev;
        struct fb_info *info;
        struct drm_framebuffer *fb;
        struct drm_mode_fb_cmd2 mode_cmd;
        struct udl_gem_object *obj;
        uint32_t size;
        int ret = 0;

        if (sizes->surface_bpp == 24)
                sizes->surface_bpp = 32;

        mode_cmd.width = sizes->surface_width;
        mode_cmd.height = sizes->surface_height;
        mode_cmd.pitches[0] = mode_cmd.width * ((sizes->surface_bpp + 7) / 8);

        mode_cmd.pixel_format = drm_mode_legacy_fb_format(sizes->surface_bpp,
                                                          sizes->surface_depth);

        size = mode_cmd.pitches[0] * mode_cmd.height;
        size = ALIGN(size, PAGE_SIZE);

        obj = udl_gem_alloc_object(dev, size);
        if (!obj)
                goto out;

        ret = udl_gem_vmap(obj);
        if (ret) {
                DRM_ERROR("failed to vmap fb\n");
                goto out_gfree;
        }

        info = drm_fb_helper_alloc_fbi(helper);
        if (IS_ERR(info)) {
                ret = PTR_ERR(info);
                goto out_gfree;
        }
        info->par = ufbdev;

        ret = udl_framebuffer_init(dev, &ufbdev->ufb, &mode_cmd, obj);
        if (ret)
                goto out_destroy_fbi;

        fb = &ufbdev->ufb.base;

        ufbdev->helper.fb = fb;

        strcpy(info->fix.id, "udldrmfb");

        info->screen_base = ufbdev->ufb.obj->vmapping;
        info->fix.smem_len = size;
        info->fix.smem_start = (unsigned long)ufbdev->ufb.obj->vmapping;

        info->flags = FBINFO_DEFAULT | FBINFO_CAN_FORCE_OUTPUT;
        info->fbops = &udlfb_ops;
        drm_fb_helper_fill_fix(info, fb->pitches[0], fb->depth);
        drm_fb_helper_fill_var(info, &ufbdev->helper, sizes->fb_width, sizes->fb_height);

        DRM_DEBUG_KMS("allocated %dx%d vmal %p\n",
                      fb->width, fb->height,
                      ufbdev->ufb.obj->vmapping);

        return ret;
out_destroy_fbi:
        drm_fb_helper_release_fbi(helper);
out_gfree:
        drm_gem_object_unreference_unlocked(&ufbdev->ufb.obj->base);
out:
        return ret;
}

static const struct drm_fb_helper_funcs udl_fb_helper_funcs = {
        .fb_probe = udlfb_create,
};

static void udl_fbdev_destroy(struct drm_device *dev,
                              struct udl_fbdev *ufbdev)
{
        drm_fb_helper_unregister_fbi(&ufbdev->helper);
        drm_fb_helper_release_fbi(&ufbdev->helper);
        drm_fb_helper_fini(&ufbdev->helper);
        drm_framebuffer_unregister_private(&ufbdev->ufb.base);
        drm_framebuffer_cleanup(&ufbdev->ufb.base);
        drm_gem_object_unreference_unlocked(&ufbdev->ufb.obj->base);
}

int udl_fbdev_init(struct drm_device *dev)
{
        struct udl_device *udl = dev->dev_private;
        int bpp_sel = fb_bpp;
        struct udl_fbdev *ufbdev;
        int ret;

        ufbdev = kzalloc(sizeof(struct udl_fbdev), GFP_KERNEL);
        if (!ufbdev)
                return -ENOMEM;

        udl->fbdev = ufbdev;

        drm_fb_helper_prepare(dev, &ufbdev->helper, &udl_fb_helper_funcs);

        ret = drm_fb_helper_init(dev, &ufbdev->helper,
                                 1, 1);
        if (ret)
                goto free;

        ret = drm_fb_helper_single_add_all_connectors(&ufbdev->helper);
        if (ret)
                goto fini;

        /* disable all the possible outputs/crtcs before entering KMS mode */
        drm_helper_disable_unused_functions(dev);

        ret = drm_fb_helper_initial_config(&ufbdev->helper, bpp_sel);
        if (ret)
                goto fini;

        return 0;

fini:
        drm_fb_helper_fini(&ufbdev->helper);
free:
        kfree(ufbdev);
        return ret;
}

void udl_fbdev_cleanup(struct drm_device *dev)
{
        struct udl_device *udl = dev->dev_private;
        if (!udl->fbdev)
                return;

        udl_fbdev_destroy(dev, udl->fbdev);
        kfree(udl->fbdev);
        udl->fbdev = NULL;
}

void udl_fbdev_unplug(struct drm_device *dev)
{
        struct udl_device *udl = dev->dev_private;
        struct udl_fbdev *ufbdev;
        if (!udl->fbdev)
                return;

        ufbdev = udl->fbdev;
        drm_fb_helper_unlink_fbi(&ufbdev->helper);
}

struct drm_framebuffer *
udl_fb_user_fb_create(struct drm_device *dev,
                   struct drm_file *file,
                   const struct drm_mode_fb_cmd2 *mode_cmd)
{
        struct drm_gem_object *obj;
        struct udl_framebuffer *ufb;
        int ret;
        uint32_t size;

        obj = drm_gem_object_lookup(dev, file, mode_cmd->handles[0]);
        if (obj == NULL)
                return ERR_PTR(-ENOENT);

        size = mode_cmd->pitches[0] * mode_cmd->height;
        size = ALIGN(size, PAGE_SIZE);

        if (size > obj->size) {
                DRM_ERROR("object size not sufficient for fb %d %zu %d %d\n", size, obj->size, mode_cmd->pitches[0], mode_cmd->height);
                return ERR_PTR(-ENOMEM);
        }

        ufb = kzalloc(sizeof(*ufb), GFP_KERNEL);
        if (ufb == NULL)
                return ERR_PTR(-ENOMEM);

        ret = udl_framebuffer_init(dev, ufb, mode_cmd, to_udl_bo(obj));
        if (ret) {
                kfree(ufb);
                return ERR_PTR(-EINVAL);
        }
        return &ufb->base;
}