/*
 * drivers/gpu/drm/omapdrm/omap_fbdev.c
 *
 * Copyright (C) 2011 Texas Instruments
 * Author: Rob Clark <rob@ti.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "omap_drv.h"

#include "drm_crtc.h"
#include "drm_fb_helper.h"

MODULE_PARM_DESC(ywrap, "Enable ywrap scrolling (omap44xx and later, default 'y')");
static bool ywrap_enabled = true;
module_param_named(ywrap, ywrap_enabled, bool, 0644);

/*
 * fbdev funcs, to implement legacy fbdev interface on top of drm driver
 */

#define to_omap_fbdev(x) container_of(x, struct omap_fbdev, base)

struct omap_fbdev {
        struct drm_fb_helper base;
        struct drm_framebuffer *fb;
        struct drm_gem_object *bo;
        bool ywrap_enabled;

        /* for deferred dmm roll when getting called in atomic ctx */
        struct work_struct work;
};

static void omap_fbdev_flush(struct fb_info *fbi, int x, int y, int w, int h);
static struct drm_fb_helper *get_fb(struct fb_info *fbi);

static ssize_t omap_fbdev_write(struct fb_info *fbi, const char __user *buf,
                size_t count, loff_t *ppos)
{
        ssize_t res;

        res = fb_sys_write(fbi, buf, count, ppos);
        omap_fbdev_flush(fbi, 0, 0, fbi->var.xres, fbi->var.yres);

        return res;
}

static void omap_fbdev_fillrect(struct fb_info *fbi,
                const struct fb_fillrect *rect)
{
        sys_fillrect(fbi, rect);
        omap_fbdev_flush(fbi, rect->dx, rect->dy, rect->width, rect->height);
}

static void omap_fbdev_copyarea(struct fb_info *fbi,
                const struct fb_copyarea *area)
{
        sys_copyarea(fbi, area);
        omap_fbdev_flush(fbi, area->dx, area->dy, area->width, area->height);
}

static void omap_fbdev_imageblit(struct fb_info *fbi,
                const struct fb_image *image)
{
        sys_imageblit(fbi, image);
        omap_fbdev_flush(fbi, image->dx, image->dy,
                                image->width, image->height);
}

static void pan_worker(struct work_struct *work)
{
        struct omap_fbdev *fbdev = container_of(work, struct omap_fbdev, work);
        struct fb_info *fbi = fbdev->base.fbdev;
        int npages;

        /* DMM roll shifts in 4K pages: */
        npages = fbi->fix.line_length >> PAGE_SHIFT;
        omap_gem_roll(fbdev->bo, fbi->var.yoffset * npages);
}

static int omap_fbdev_pan_display(struct fb_var_screeninfo *var,
                struct fb_info *fbi)
{
        struct drm_fb_helper *helper = get_fb(fbi);
        struct omap_fbdev *fbdev = to_omap_fbdev(helper);

        if (!helper)
                goto fallback;

        if (!fbdev->ywrap_enabled)
                goto fallback;

        if (drm_can_sleep()) {
                pan_worker(&fbdev->work);
        } else {
                struct omap_drm_private *priv = helper->dev->dev_private;
                queue_work(priv->wq, &fbdev->work);
        }

        return 0;

fallback:
        return drm_fb_helper_pan_display(var, fbi);
}

static struct fb_ops omap_fb_ops = {
        .owner = THIS_MODULE,

        /* Note: to properly handle manual update displays, we wrap the
         * basic fbdev ops which write to the framebuffer
         */
        .fb_read = fb_sys_read,
        .fb_write = omap_fbdev_write,
        .fb_fillrect = omap_fbdev_fillrect,
        .fb_copyarea = omap_fbdev_copyarea,
        .fb_imageblit = omap_fbdev_imageblit,

        .fb_check_var = drm_fb_helper_check_var,
        .fb_set_par = drm_fb_helper_set_par,
        .fb_pan_display = omap_fbdev_pan_display,
        .fb_blank = drm_fb_helper_blank,
        .fb_setcmap = drm_fb_helper_setcmap,
};

static int omap_fbdev_create(struct drm_fb_helper *helper,
                struct drm_fb_helper_surface_size *sizes)
{
        struct omap_fbdev *fbdev = to_omap_fbdev(helper);
        struct drm_device *dev = helper->dev;
        struct omap_drm_private *priv = dev->dev_private;
        struct drm_framebuffer *fb = NULL;
        union omap_gem_size gsize;
        struct fb_info *fbi = NULL;
        struct drm_mode_fb_cmd2 mode_cmd = {0};
        dma_addr_t paddr;
        int ret;

        /* only doing ARGB32 since this is what is needed to alpha-blend
         * with video overlays:
         */
        sizes->surface_bpp = 32;
        sizes->surface_depth = 32;

        DBG("create fbdev: %dx%d@%d (%dx%d)", sizes->surface_width,
                        sizes->surface_height, sizes->surface_bpp,
                        sizes->fb_width, sizes->fb_height);

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

        mode_cmd.width = sizes->surface_width;
        mode_cmd.height = sizes->surface_height;

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

        fbdev->ywrap_enabled = priv->has_dmm && ywrap_enabled;
        if (fbdev->ywrap_enabled) {
                /* need to align pitch to page size if using DMM scrolling */
                mode_cmd.pitches[0] = ALIGN(mode_cmd.pitches[0], PAGE_SIZE);
        }

        /* allocate backing bo */
        gsize = (union omap_gem_size){
                .bytes = PAGE_ALIGN(mode_cmd.pitches[0] * mode_cmd.height),
        };
        DBG("allocating %d bytes for fb %d", gsize.bytes, dev->primary->index);
        fbdev->bo = omap_gem_new(dev, gsize, OMAP_BO_SCANOUT | OMAP_BO_WC);
        if (!fbdev->bo) {
                dev_err(dev->dev, "failed to allocate buffer object\n");
                ret = -ENOMEM;
                goto fail;
        }

        fb = omap_framebuffer_init(dev, &mode_cmd, &fbdev->bo);
        if (IS_ERR(fb)) {
                dev_err(dev->dev, "failed to allocate fb\n");
                /* note: if fb creation failed, we can't rely on fb destroy
                 * to unref the bo:
                 */
                drm_gem_object_unreference(fbdev->bo);
                ret = PTR_ERR(fb);
                goto fail;
        }

        /* note: this keeps the bo pinned.. which is perhaps not ideal,
         * but is needed as long as we use fb_mmap() to mmap to userspace
         * (since this happens using fix.smem_start).  Possibly we could
         * implement our own mmap using GEM mmap support to avoid this
         * (non-tiled buffer doesn't need to be pinned for fbcon to write
         * to it).  Then we just need to be sure that we are able to re-
         * pin it in case of an opps.
         */
        ret = omap_gem_get_paddr(fbdev->bo, &paddr, true);
        if (ret) {
                dev_err(dev->dev,
                        "could not map (paddr)!  Skipping framebuffer alloc\n");
                ret = -ENOMEM;
                goto fail;
        }

        mutex_lock(&dev->struct_mutex);

        fbi = framebuffer_alloc(0, dev->dev);
        if (!fbi) {
                dev_err(dev->dev, "failed to allocate fb info\n");
                ret = -ENOMEM;
                goto fail_unlock;
        }

        DBG("fbi=%p, dev=%p", fbi, dev);

        fbdev->fb = fb;
        helper->fb = fb;
        helper->fbdev = fbi;

        fbi->par = helper;
        fbi->flags = FBINFO_DEFAULT;
        fbi->fbops = &omap_fb_ops;

        strcpy(fbi->fix.id, MODULE_NAME);

        ret = fb_alloc_cmap(&fbi->cmap, 256, 0);
        if (ret) {
                ret = -ENOMEM;
                goto fail_unlock;
        }

        drm_fb_helper_fill_fix(fbi, fb->pitches[0], fb->depth);
        drm_fb_helper_fill_var(fbi, helper, sizes->fb_width, sizes->fb_height);

        dev->mode_config.fb_base = paddr;

        fbi->screen_base = omap_gem_vaddr(fbdev->bo);
        fbi->screen_size = fbdev->bo->size;
        fbi->fix.smem_start = paddr;
        fbi->fix.smem_len = fbdev->bo->size;

        /* if we have DMM, then we can use it for scrolling by just
         * shuffling pages around in DMM rather than doing sw blit.
         */
        if (fbdev->ywrap_enabled) {
                DRM_INFO("Enabling DMM ywrap scrolling\n");
                fbi->flags |= FBINFO_HWACCEL_YWRAP | FBINFO_READS_FAST;
                fbi->fix.ywrapstep = 1;
        }


        DBG("par=%p, %dx%d", fbi->par, fbi->var.xres, fbi->var.yres);
        DBG("allocated %dx%d fb", fbdev->fb->width, fbdev->fb->height);

        mutex_unlock(&dev->struct_mutex);

        return 0;

fail_unlock:
        mutex_unlock(&dev->struct_mutex);
fail:

        if (ret) {
                if (fbi)
                        framebuffer_release(fbi);
                if (fb) {
                        drm_framebuffer_unregister_private(fb);
                        drm_framebuffer_remove(fb);
                }
        }

        return ret;
}

static struct drm_fb_helper_funcs omap_fb_helper_funcs = {
        .fb_probe = omap_fbdev_create,
};

static struct drm_fb_helper *get_fb(struct fb_info *fbi)
{
        if (!fbi || strcmp(fbi->fix.id, MODULE_NAME)) {
                /* these are not the fb's you're looking for */
                return NULL;
        }
        return fbi->par;
}

/* flush an area of the framebuffer (in case of manual update display that
 * is not automatically flushed)
 */
static void omap_fbdev_flush(struct fb_info *fbi, int x, int y, int w, int h)
{
        struct drm_fb_helper *helper = get_fb(fbi);

        if (!helper)
                return;

        VERB("flush fbdev: %d,%d %dx%d, fbi=%p", x, y, w, h, fbi);

        omap_framebuffer_flush(helper->fb, x, y, w, h);
}

/* initialize fbdev helper */
struct drm_fb_helper *omap_fbdev_init(struct drm_device *dev)
{
        struct omap_drm_private *priv = dev->dev_private;
        struct omap_fbdev *fbdev = NULL;
        struct drm_fb_helper *helper;
        int ret = 0;

        fbdev = kzalloc(sizeof(*fbdev), GFP_KERNEL);
        if (!fbdev)
                goto fail;

        INIT_WORK(&fbdev->work, pan_worker);

        helper = &fbdev->base;

        helper->funcs = &omap_fb_helper_funcs;

        ret = drm_fb_helper_init(dev, helper,
                        priv->num_crtcs, priv->num_connectors);
        if (ret) {
                dev_err(dev->dev, "could not init fbdev: ret=%d\n", ret);
                goto fail;
        }

        drm_fb_helper_single_add_all_connectors(helper);

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

        drm_fb_helper_initial_config(helper, 32);

        priv->fbdev = helper;

        return helper;

fail:
        kfree(fbdev);
        return NULL;
}

void omap_fbdev_free(struct drm_device *dev)
{
        struct omap_drm_private *priv = dev->dev_private;
        struct drm_fb_helper *helper = priv->fbdev;
        struct omap_fbdev *fbdev;
        struct fb_info *fbi;

        DBG();

        fbi = helper->fbdev;

        /* only cleanup framebuffer if it is present */
        if (fbi) {
                unregister_framebuffer(fbi);
                framebuffer_release(fbi);
        }

        drm_fb_helper_fini(helper);

        fbdev = to_omap_fbdev(priv->fbdev);

        /* this will free the backing object */
        if (fbdev->fb) {
                drm_framebuffer_unregister_private(fbdev->fb);
                drm_framebuffer_remove(fbdev->fb);
        }

        kfree(fbdev);

        priv->fbdev = NULL;
}