drivers/gpu/drm/drm_fbdev_shmem.c

   1 // SPDX-License-Identifier: MIT
   2
   3 #include <linux/fb.h>
   4
   5 #include <drm/drm_crtc_helper.h>
   6 #include <drm/drm_drv.h>
   7 #include <drm/drm_fb_helper.h>
   8 #include <drm/drm_framebuffer.h>
   9 #include <drm/drm_gem_framebuffer_helper.h>
  10 #include <drm/drm_gem_shmem_helper.h>
  11
  12 #include <drm/drm_fbdev_shmem.h>
  13
  14 /*
  15  * struct fb_ops
  16  */
  17
  18 static int drm_fbdev_shmem_fb_open(struct fb_info *info, int user)
  19 {
  20         struct drm_fb_helper *fb_helper = info->par;
  21
  22         /* No need to take a ref for fbcon because it unbinds on unregister */
  23         if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
  24                 return -ENODEV;
  25
  26         return 0;
  27 }
  28
  29 static int drm_fbdev_shmem_fb_release(struct fb_info *info, int user)
  30 {
  31         struct drm_fb_helper *fb_helper = info->par;
  32
  33         if (user)
  34                 module_put(fb_helper->dev->driver->fops->owner);
  35
  36         return 0;
  37 }
  38
  39 FB_GEN_DEFAULT_DEFERRED_SYSMEM_OPS(drm_fbdev_shmem,
  40                                    drm_fb_helper_damage_range,
  41                                    drm_fb_helper_damage_area);
  42
  43 static int drm_fbdev_shmem_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
  44 {
  45         struct drm_fb_helper *fb_helper = info->par;
  46         struct drm_framebuffer *fb = fb_helper->fb;
  47         struct drm_gem_object *obj = drm_gem_fb_get_obj(fb, 0);
  48         struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
  49
  50         if (shmem->map_wc)
  51                 vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
  52
  53         return fb_deferred_io_mmap(info, vma);
  54 }
  55
  56 static void drm_fbdev_shmem_fb_destroy(struct fb_info *info)
  57 {
  58         struct drm_fb_helper *fb_helper = info->par;
  59
  60         if (!fb_helper->dev)
  61                 return;
  62
  63         fb_deferred_io_cleanup(info);
  64         drm_fb_helper_fini(fb_helper);
  65
  66         drm_client_buffer_vunmap(fb_helper->buffer);
  67         drm_client_framebuffer_delete(fb_helper->buffer);
  68         drm_client_release(&fb_helper->client);
  69         drm_fb_helper_unprepare(fb_helper);
  70         kfree(fb_helper);
  71 }
  72
  73 static const struct fb_ops drm_fbdev_shmem_fb_ops = {
  74         .owner = THIS_MODULE,
  75         .fb_open = drm_fbdev_shmem_fb_open,
  76         .fb_release = drm_fbdev_shmem_fb_release,
  77         __FB_DEFAULT_DEFERRED_OPS_RDWR(drm_fbdev_shmem),
  78         DRM_FB_HELPER_DEFAULT_OPS,
  79         __FB_DEFAULT_DEFERRED_OPS_DRAW(drm_fbdev_shmem),
  80         .fb_mmap = drm_fbdev_shmem_fb_mmap,
  81         .fb_destroy = drm_fbdev_shmem_fb_destroy,
  82 };
  83
  84 static struct page *drm_fbdev_shmem_get_page(struct fb_info *info, unsigned long offset)
  85 {
  86         struct drm_fb_helper *fb_helper = info->par;
  87         struct drm_framebuffer *fb = fb_helper->fb;
  88         struct drm_gem_object *obj = drm_gem_fb_get_obj(fb, 0);
  89         struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
  90         unsigned int i = offset >> PAGE_SHIFT;
  91         struct page *page;
  92
  93         if (fb_WARN_ON_ONCE(info, offset > obj->size))
  94                 return NULL;
  95
  96         page = shmem->pages[i]; // protected by active vmap
  97         if (page)
  98                 get_page(page);
  99         fb_WARN_ON_ONCE(info, !page);
 100
 101         return page;
 102 }
 103
 104 /*
 105  * struct drm_fb_helper
 106  */
 107
 108 static int drm_fbdev_shmem_helper_fb_probe(struct drm_fb_helper *fb_helper,
 109                                            struct drm_fb_helper_surface_size *sizes)
 110 {
 111         struct drm_client_dev *client = &fb_helper->client;
 112         struct drm_device *dev = fb_helper->dev;
 113         struct drm_client_buffer *buffer;
 114         struct drm_gem_shmem_object *shmem;
 115         struct drm_framebuffer *fb;
 116         struct fb_info *info;
 117         u32 format;
 118         struct iosys_map map;
 119         int ret;
 120
 121         drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n",
 122                     sizes->surface_width, sizes->surface_height,
 123                     sizes->surface_bpp);
 124
 125         format = drm_driver_legacy_fb_format(dev, sizes->surface_bpp, sizes->surface_depth);
 126         buffer = drm_client_framebuffer_create(client, sizes->surface_width,
 127                                                sizes->surface_height, format);
 128         if (IS_ERR(buffer))
 129                 return PTR_ERR(buffer);
 130         shmem = to_drm_gem_shmem_obj(buffer->gem);
 131
 132         fb = buffer->fb;
 133
 134         ret = drm_client_buffer_vmap(buffer, &map);
 135         if (ret) {
 136                 goto err_drm_client_buffer_delete;
 137         } else if (drm_WARN_ON(dev, map.is_iomem)) {
 138                 ret = -ENODEV; /* I/O memory not supported; use generic emulation */
 139                 goto err_drm_client_buffer_delete;
 140         }
 141
 142         fb_helper->buffer = buffer;
 143         fb_helper->fb = fb;
 144
 145         info = drm_fb_helper_alloc_info(fb_helper);
 146         if (IS_ERR(info)) {
 147                 ret = PTR_ERR(info);
 148                 goto err_drm_client_buffer_vunmap;
 149         }
 150
 151         drm_fb_helper_fill_info(info, fb_helper, sizes);
 152
 153         info->fbops = &drm_fbdev_shmem_fb_ops;
 154
 155         /* screen */
 156         info->flags |= FBINFO_VIRTFB; /* system memory */
 157         if (!shmem->map_wc)
 158                 info->flags |= FBINFO_READS_FAST; /* signal caching */
 159         info->screen_size = sizes->surface_height * fb->pitches[0];
 160         info->screen_buffer = map.vaddr;
 161         info->fix.smem_len = info->screen_size;
 162
 163         /* deferred I/O */
 164         fb_helper->fbdefio.delay = HZ / 20;
 165         fb_helper->fbdefio.get_page = drm_fbdev_shmem_get_page;
 166         fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
 167
 168         info->fbdefio = &fb_helper->fbdefio;
 169         ret = fb_deferred_io_init(info);
 170         if (ret)
 171                 goto err_drm_fb_helper_release_info;
 172
 173         return 0;
 174
 175 err_drm_fb_helper_release_info:
 176         drm_fb_helper_release_info(fb_helper);
 177 err_drm_client_buffer_vunmap:
 178         fb_helper->fb = NULL;
 179         fb_helper->buffer = NULL;
 180         drm_client_buffer_vunmap(buffer);
 181 err_drm_client_buffer_delete:
 182         drm_client_framebuffer_delete(buffer);
 183         return ret;
 184 }
 185
 186 static int drm_fbdev_shmem_helper_fb_dirty(struct drm_fb_helper *helper,
 187                                            struct drm_clip_rect *clip)
 188 {
 189         struct drm_device *dev = helper->dev;
 190         int ret;
 191
 192         /* Call damage handlers only if necessary */
 193         if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
 194                 return 0;
 195
 196         if (helper->fb->funcs->dirty) {
 197                 ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
 198                 if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
 199                         return ret;
 200         }
 201
 202         return 0;
 203 }
 204
 205 static const struct drm_fb_helper_funcs drm_fbdev_shmem_helper_funcs = {
 206         .fb_probe = drm_fbdev_shmem_helper_fb_probe,
 207         .fb_dirty = drm_fbdev_shmem_helper_fb_dirty,
 208 };
 209
 210 /*
 211  * struct drm_client_funcs
 212  */
 213
 214 static void drm_fbdev_shmem_client_unregister(struct drm_client_dev *client)
 215 {
 216         struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 217
 218         if (fb_helper->info) {
 219                 drm_fb_helper_unregister_info(fb_helper);
 220         } else {
 221                 drm_client_release(&fb_helper->client);
 222                 drm_fb_helper_unprepare(fb_helper);
 223                 kfree(fb_helper);
 224         }
 225 }
 226
 227 static int drm_fbdev_shmem_client_restore(struct drm_client_dev *client)
 228 {
 229         drm_fb_helper_lastclose(client->dev);
 230
 231         return 0;
 232 }
 233
 234 static int drm_fbdev_shmem_client_hotplug(struct drm_client_dev *client)
 235 {
 236         struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 237         struct drm_device *dev = client->dev;
 238         int ret;
 239
 240         if (dev->fb_helper)
 241                 return drm_fb_helper_hotplug_event(dev->fb_helper);
 242
 243         ret = drm_fb_helper_init(dev, fb_helper);
 244         if (ret)
 245                 goto err_drm_err;
 246
 247         if (!drm_drv_uses_atomic_modeset(dev))
 248                 drm_helper_disable_unused_functions(dev);
 249
 250         ret = drm_fb_helper_initial_config(fb_helper);
 251         if (ret)
 252                 goto err_drm_fb_helper_fini;
 253
 254         return 0;
 255
 256 err_drm_fb_helper_fini:
 257         drm_fb_helper_fini(fb_helper);
 258 err_drm_err:
 259         drm_err(dev, "fbdev-shmem: Failed to setup emulation (ret=%d)\n", ret);
 260         return ret;
 261 }
 262
 263 static const struct drm_client_funcs drm_fbdev_shmem_client_funcs = {
 264         .owner          = THIS_MODULE,
 265         .unregister     = drm_fbdev_shmem_client_unregister,
 266         .restore        = drm_fbdev_shmem_client_restore,
 267         .hotplug        = drm_fbdev_shmem_client_hotplug,
 268 };
 269
 270 /**
 271  * drm_fbdev_shmem_setup() - Setup fbdev emulation for GEM SHMEM helpers
 272  * @dev: DRM device
 273  * @preferred_bpp: Preferred bits per pixel for the device.
 274  *                 32 is used if this is zero.
 275  *
 276  * This function sets up fbdev emulation for GEM DMA drivers that support
 277  * dumb buffers with a virtual address and that can be mmap'ed.
 278  * drm_fbdev_shmem_setup() shall be called after the DRM driver registered
 279  * the new DRM device with drm_dev_register().
 280  *
 281  * Restore, hotplug events and teardown are all taken care of. Drivers that do
 282  * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
 283  * Simple drivers might use drm_mode_config_helper_suspend().
 284  *
 285  * This function is safe to call even when there are no connectors present.
 286  * Setup will be retried on the next hotplug event.
 287  *
 288  * The fbdev is destroyed by drm_dev_unregister().
 289  */
 290 void drm_fbdev_shmem_setup(struct drm_device *dev, unsigned int preferred_bpp)
 291 {
 292         struct drm_fb_helper *fb_helper;
 293         int ret;
 294
 295         drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
 296         drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n");
 297
 298         fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
 299         if (!fb_helper)
 300                 return;
 301         drm_fb_helper_prepare(dev, fb_helper, preferred_bpp, &drm_fbdev_shmem_helper_funcs);
 302
 303         ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_shmem_client_funcs);
 304         if (ret) {
 305                 drm_err(dev, "Failed to register client: %d\n", ret);
 306                 goto err_drm_client_init;
 307         }
 308
 309         drm_client_register(&fb_helper->client);
 310
 311         return;
 312
 313 err_drm_client_init:
 314         drm_fb_helper_unprepare(fb_helper);
 315         kfree(fb_helper);
 316 }
 317 EXPORT_SYMBOL(drm_fbdev_shmem_setup);