// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2011 Texas Instruments Incorporated - https://www.ti.com/
 * Author: Rob Clark <rob@ti.com>
 */

#include <linux/fb.h>

#include <drm/clients/drm_client_setup.h>
#include <drm/drm_drv.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_fb_helper.h>
#include <drm/drm_file.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_managed.h>
#include <drm/drm_print.h>
#include <drm/drm_util.h>

#include "omap_drv.h"
#include "omap_fbdev.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
 */

struct omap_fbdev {
        struct drm_device *dev;
        bool ywrap_enabled;

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

static struct drm_fb_helper *get_fb(struct fb_info *fbi);

static void pan_worker(struct work_struct *work)
{
        struct omap_fbdev *fbdev = container_of(work, struct omap_fbdev, work);
        struct drm_fb_helper *helper = fbdev->dev->fb_helper;
        struct fb_info *fbi = helper->info;
        struct drm_gem_object *bo = drm_gem_fb_get_obj(helper->fb, 0);
        int npages;

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

FB_GEN_DEFAULT_DEFERRED_DMAMEM_OPS(omap_fbdev,
                                   drm_fb_helper_damage_range,
                                   drm_fb_helper_damage_area)

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_drm_private *priv;
        struct omap_fbdev *fbdev;

        if (!helper)
                goto fallback;

        priv = helper->dev->dev_private;
        fbdev = priv->fbdev;

        if (!fbdev->ywrap_enabled)
                goto fallback;

        if (drm_can_sleep())
                pan_worker(&fbdev->work);
        else
                queue_work(priv->wq, &fbdev->work);

        return 0;

fallback:
        return drm_fb_helper_pan_display(var, fbi);
}

static int omap_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
{
        vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));

        return fb_deferred_io_mmap(info, vma);
}

static void omap_fbdev_fb_destroy(struct fb_info *info)
{
        struct drm_fb_helper *helper = info->par;
        struct drm_framebuffer *fb = helper->fb;
        struct drm_gem_object *bo = drm_gem_fb_get_obj(fb, 0);

        DBG();

        fb_deferred_io_cleanup(info);
        drm_fb_helper_fini(helper);

        omap_gem_unpin(bo);
        drm_framebuffer_remove(fb);

        drm_client_release(&helper->client);
}

/*
 * For now, we cannot use FB_DEFAULT_DEFERRED_OPS and fb_deferred_io_mmap()
 * because we use write-combine.
 */
static const struct fb_ops omap_fb_ops = {
        .owner = THIS_MODULE,
        __FB_DEFAULT_DEFERRED_OPS_RDWR(omap_fbdev),
        .fb_check_var   = drm_fb_helper_check_var,
        .fb_set_par     = drm_fb_helper_set_par,
        .fb_setcmap     = drm_fb_helper_setcmap,
        .fb_blank       = drm_fb_helper_blank,
        .fb_pan_display = omap_fbdev_pan_display,
        __FB_DEFAULT_DEFERRED_OPS_DRAW(omap_fbdev),
        .fb_ioctl       = drm_fb_helper_ioctl,
        .fb_mmap        = omap_fbdev_fb_mmap,
        .fb_destroy     = omap_fbdev_fb_destroy,
};

static int omap_fbdev_dirty(struct drm_fb_helper *helper, struct drm_clip_rect *clip)
{
        if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
                return 0;

        if (helper->fb->funcs->dirty)
                return helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);

        return 0;
}

static const struct drm_fb_helper_funcs omap_fbdev_helper_funcs = {
        .fb_dirty = omap_fbdev_dirty,
};

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;
}

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

        sizes->surface_bpp = 32;
        sizes->surface_depth = 24;

        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] =
                        DIV_ROUND_UP(mode_cmd.width * sizes->surface_bpp, 8);

        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] = PAGE_ALIGN(mode_cmd.pitches[0]);
        }

        /* 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);
        bo = omap_gem_new(dev, gsize, OMAP_BO_SCANOUT | OMAP_BO_WC);
        if (!bo) {
                dev_err(dev->dev, "failed to allocate buffer object\n");
                ret = -ENOMEM;
                goto fail;
        }

        fb = omap_framebuffer_init(dev,
                                   drm_get_format_info(dev, mode_cmd.pixel_format,
                                                       mode_cmd.modifier[0]),
                                   &mode_cmd, &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_put(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_pin(bo, &dma_addr);
        if (ret) {
                dev_err(dev->dev, "could not pin framebuffer\n");
                ret = -ENOMEM;
                goto fail;
        }

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

        helper->funcs = &omap_fbdev_helper_funcs;
        helper->fb = fb;

        fbi->fbops = &omap_fb_ops;

        drm_fb_helper_fill_info(fbi, helper, sizes);

        fbi->flags |= FBINFO_VIRTFB;
        fbi->screen_buffer = omap_gem_vaddr(bo);
        fbi->screen_size = bo->size;
        fbi->fix.smem_start = dma_addr;
        fbi->fix.smem_len = bo->size;

        /* deferred I/O */
        helper->fbdefio.delay = HZ / 20;
        helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;

        fbi->fbdefio = &helper->fbdefio;
        ret = fb_deferred_io_init(fbi);
        if (ret)
                goto fail;

        /* 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", fb->width, fb->height);

        return 0;

fail:

        if (ret) {
                if (fb)
                        drm_framebuffer_remove(fb);
        }

        return ret;
}

void omap_fbdev_setup(struct drm_device *dev)
{
        struct omap_drm_private *priv = dev->dev_private;
        struct omap_fbdev *fbdev;

        drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
        drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n");

        fbdev = drmm_kzalloc(dev, sizeof(*fbdev), GFP_KERNEL);
        if (!fbdev)
                return;
        fbdev->dev = dev;
        INIT_WORK(&fbdev->work, pan_worker);

        priv->fbdev = fbdev;

        drm_client_setup(dev, NULL);
}