drivers/gpu/drm/drm_fbdev_generic.c

   1 // SPDX-License-Identifier: MIT
   2
   3 #include <linux/moduleparam.h>
   4 #include <linux/vmalloc.h>
   5
   6 #include <drm/drm_crtc_helper.h>
   7 #include <drm/drm_drv.h>
   8 #include <drm/drm_fb_helper.h>
   9 #include <drm/drm_framebuffer.h>
  10 #include <drm/drm_print.h>
  11
  12 #include <drm/drm_fbdev_generic.h>
  13
  14 static bool drm_fbdev_use_shadow_fb(struct drm_fb_helper *fb_helper)
  15 {
  16         struct drm_device *dev = fb_helper->dev;
  17         struct drm_framebuffer *fb = fb_helper->fb;
  18
  19         return dev->mode_config.prefer_shadow_fbdev ||
  20                dev->mode_config.prefer_shadow ||
  21                fb->funcs->dirty;
  22 }
  23
  24 /* @user: 1=userspace, 0=fbcon */
  25 static int drm_fbdev_fb_open(struct fb_info *info, int user)
  26 {
  27         struct drm_fb_helper *fb_helper = info->par;
  28
  29         /* No need to take a ref for fbcon because it unbinds on unregister */
  30         if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
  31                 return -ENODEV;
  32
  33         return 0;
  34 }
  35
  36 static int drm_fbdev_fb_release(struct fb_info *info, int user)
  37 {
  38         struct drm_fb_helper *fb_helper = info->par;
  39
  40         if (user)
  41                 module_put(fb_helper->dev->driver->fops->owner);
  42
  43         return 0;
  44 }
  45
  46 static void drm_fbdev_cleanup(struct drm_fb_helper *fb_helper)
  47 {
  48         struct fb_info *fbi = fb_helper->info;
  49         void *shadow = NULL;
  50
  51         if (!fb_helper->dev)
  52                 return;
  53
  54         if (fbi) {
  55                 if (fbi->fbdefio)
  56                         fb_deferred_io_cleanup(fbi);
  57                 if (drm_fbdev_use_shadow_fb(fb_helper))
  58                         shadow = fbi->screen_buffer;
  59         }
  60
  61         drm_fb_helper_fini(fb_helper);
  62
  63         if (shadow)
  64                 vfree(shadow);
  65         else if (fb_helper->buffer)
  66                 drm_client_buffer_vunmap(fb_helper->buffer);
  67
  68         drm_client_framebuffer_delete(fb_helper->buffer);
  69 }
  70
  71 static void drm_fbdev_release(struct drm_fb_helper *fb_helper)
  72 {
  73         drm_fbdev_cleanup(fb_helper);
  74         drm_client_release(&fb_helper->client);
  75         kfree(fb_helper);
  76 }
  77
  78 /*
  79  * fb_ops.fb_destroy is called by the last put_fb_info() call at the end of
  80  * unregister_framebuffer() or fb_release().
  81  */
  82 static void drm_fbdev_fb_destroy(struct fb_info *info)
  83 {
  84         drm_fbdev_release(info->par);
  85 }
  86
  87 static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
  88 {
  89         struct drm_fb_helper *fb_helper = info->par;
  90
  91         if (drm_fbdev_use_shadow_fb(fb_helper))
  92                 return fb_deferred_io_mmap(info, vma);
  93         else if (fb_helper->dev->driver->gem_prime_mmap)
  94                 return fb_helper->dev->driver->gem_prime_mmap(fb_helper->buffer->gem, vma);
  95         else
  96                 return -ENODEV;
  97 }
  98
  99 static bool drm_fbdev_use_iomem(struct fb_info *info)
 100 {
 101         struct drm_fb_helper *fb_helper = info->par;
 102         struct drm_client_buffer *buffer = fb_helper->buffer;
 103
 104         return !drm_fbdev_use_shadow_fb(fb_helper) && buffer->map.is_iomem;
 105 }
 106
 107 static ssize_t drm_fbdev_fb_read(struct fb_info *info, char __user *buf,
 108                                  size_t count, loff_t *ppos)
 109 {
 110         ssize_t ret;
 111
 112         if (drm_fbdev_use_iomem(info))
 113                 ret = drm_fb_helper_cfb_read(info, buf, count, ppos);
 114         else
 115                 ret = drm_fb_helper_sys_read(info, buf, count, ppos);
 116
 117         return ret;
 118 }
 119
 120 static ssize_t drm_fbdev_fb_write(struct fb_info *info, const char __user *buf,
 121                                   size_t count, loff_t *ppos)
 122 {
 123         ssize_t ret;
 124
 125         if (drm_fbdev_use_iomem(info))
 126                 ret = drm_fb_helper_cfb_write(info, buf, count, ppos);
 127         else
 128                 ret = drm_fb_helper_sys_write(info, buf, count, ppos);
 129
 130         return ret;
 131 }
 132
 133 static void drm_fbdev_fb_fillrect(struct fb_info *info,
 134                                   const struct fb_fillrect *rect)
 135 {
 136         if (drm_fbdev_use_iomem(info))
 137                 drm_fb_helper_cfb_fillrect(info, rect);
 138         else
 139                 drm_fb_helper_sys_fillrect(info, rect);
 140 }
 141
 142 static void drm_fbdev_fb_copyarea(struct fb_info *info,
 143                                   const struct fb_copyarea *area)
 144 {
 145         if (drm_fbdev_use_iomem(info))
 146                 drm_fb_helper_cfb_copyarea(info, area);
 147         else
 148                 drm_fb_helper_sys_copyarea(info, area);
 149 }
 150
 151 static void drm_fbdev_fb_imageblit(struct fb_info *info,
 152                                    const struct fb_image *image)
 153 {
 154         if (drm_fbdev_use_iomem(info))
 155                 drm_fb_helper_cfb_imageblit(info, image);
 156         else
 157                 drm_fb_helper_sys_imageblit(info, image);
 158 }
 159
 160 static const struct fb_ops drm_fbdev_fb_ops = {
 161         .owner          = THIS_MODULE,
 162         DRM_FB_HELPER_DEFAULT_OPS,
 163         .fb_open        = drm_fbdev_fb_open,
 164         .fb_release     = drm_fbdev_fb_release,
 165         .fb_destroy     = drm_fbdev_fb_destroy,
 166         .fb_mmap        = drm_fbdev_fb_mmap,
 167         .fb_read        = drm_fbdev_fb_read,
 168         .fb_write       = drm_fbdev_fb_write,
 169         .fb_fillrect    = drm_fbdev_fb_fillrect,
 170         .fb_copyarea    = drm_fbdev_fb_copyarea,
 171         .fb_imageblit   = drm_fbdev_fb_imageblit,
 172 };
 173
 174 static struct fb_deferred_io drm_fbdev_defio = {
 175         .delay          = HZ / 20,
 176         .deferred_io    = drm_fb_helper_deferred_io,
 177 };
 178
 179 /*
 180  * This function uses the client API to create a framebuffer backed by a dumb buffer.
 181  */
 182 static int drm_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
 183                               struct drm_fb_helper_surface_size *sizes)
 184 {
 185         struct drm_client_dev *client = &fb_helper->client;
 186         struct drm_device *dev = fb_helper->dev;
 187         struct drm_client_buffer *buffer;
 188         struct drm_framebuffer *fb;
 189         struct fb_info *fbi;
 190         u32 format;
 191         struct iosys_map map;
 192         int ret;
 193
 194         drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n",
 195                     sizes->surface_width, sizes->surface_height,
 196                     sizes->surface_bpp);
 197
 198         format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
 199         buffer = drm_client_framebuffer_create(client, sizes->surface_width,
 200                                                sizes->surface_height, format);
 201         if (IS_ERR(buffer))
 202                 return PTR_ERR(buffer);
 203
 204         fb_helper->buffer = buffer;
 205         fb_helper->fb = buffer->fb;
 206         fb = buffer->fb;
 207
 208         fbi = drm_fb_helper_alloc_info(fb_helper);
 209         if (IS_ERR(fbi))
 210                 return PTR_ERR(fbi);
 211
 212         fbi->fbops = &drm_fbdev_fb_ops;
 213         fbi->screen_size = sizes->surface_height * fb->pitches[0];
 214         fbi->fix.smem_len = fbi->screen_size;
 215         fbi->flags = FBINFO_DEFAULT;
 216
 217         drm_fb_helper_fill_info(fbi, fb_helper, sizes);
 218
 219         if (drm_fbdev_use_shadow_fb(fb_helper)) {
 220                 fbi->screen_buffer = vzalloc(fbi->screen_size);
 221                 if (!fbi->screen_buffer)
 222                         return -ENOMEM;
 223                 fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
 224
 225                 fbi->fbdefio = &drm_fbdev_defio;
 226                 fb_deferred_io_init(fbi);
 227         } else {
 228                 /* buffer is mapped for HW framebuffer */
 229                 ret = drm_client_buffer_vmap(fb_helper->buffer, &map);
 230                 if (ret)
 231                         return ret;
 232                 if (map.is_iomem) {
 233                         fbi->screen_base = map.vaddr_iomem;
 234                 } else {
 235                         fbi->screen_buffer = map.vaddr;
 236                         fbi->flags |= FBINFO_VIRTFB;
 237                 }
 238
 239                 /*
 240                  * Shamelessly leak the physical address to user-space. As
 241                  * page_to_phys() is undefined for I/O memory, warn in this
 242                  * case.
 243                  */
 244 #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
 245                 if (fb_helper->hint_leak_smem_start && fbi->fix.smem_start == 0 &&
 246                     !drm_WARN_ON_ONCE(dev, map.is_iomem))
 247                         fbi->fix.smem_start =
 248                                 page_to_phys(virt_to_page(fbi->screen_buffer));
 249 #endif
 250         }
 251
 252         return 0;
 253 }
 254
 255 static void drm_fbdev_damage_blit_real(struct drm_fb_helper *fb_helper,
 256                                        struct drm_clip_rect *clip,
 257                                        struct iosys_map *dst)
 258 {
 259         struct drm_framebuffer *fb = fb_helper->fb;
 260         size_t offset = clip->y1 * fb->pitches[0];
 261         size_t len = clip->x2 - clip->x1;
 262         unsigned int y;
 263         void *src;
 264
 265         switch (drm_format_info_bpp(fb->format, 0)) {
 266         case 1:
 267                 offset += clip->x1 / 8;
 268                 len = DIV_ROUND_UP(len + clip->x1 % 8, 8);
 269                 break;
 270         case 2:
 271                 offset += clip->x1 / 4;
 272                 len = DIV_ROUND_UP(len + clip->x1 % 4, 4);
 273                 break;
 274         case 4:
 275                 offset += clip->x1 / 2;
 276                 len = DIV_ROUND_UP(len + clip->x1 % 2, 2);
 277                 break;
 278         default:
 279                 offset += clip->x1 * fb->format->cpp[0];
 280                 len *= fb->format->cpp[0];
 281                 break;
 282         }
 283
 284         src = fb_helper->info->screen_buffer + offset;
 285         iosys_map_incr(dst, offset); /* go to first pixel within clip rect */
 286
 287         for (y = clip->y1; y < clip->y2; y++) {
 288                 iosys_map_memcpy_to(dst, 0, src, len);
 289                 iosys_map_incr(dst, fb->pitches[0]);
 290                 src += fb->pitches[0];
 291         }
 292 }
 293
 294 static int drm_fbdev_damage_blit(struct drm_fb_helper *fb_helper,
 295                                  struct drm_clip_rect *clip)
 296 {
 297         struct drm_client_buffer *buffer = fb_helper->buffer;
 298         struct iosys_map map, dst;
 299         int ret;
 300
 301         /*
 302          * We have to pin the client buffer to its current location while
 303          * flushing the shadow buffer. In the general case, concurrent
 304          * modesetting operations could try to move the buffer and would
 305          * fail. The modeset has to be serialized by acquiring the reservation
 306          * object of the underlying BO here.
 307          *
 308          * For fbdev emulation, we only have to protect against fbdev modeset
 309          * operations. Nothing else will involve the client buffer's BO. So it
 310          * is sufficient to acquire struct drm_fb_helper.lock here.
 311          */
 312         mutex_lock(&fb_helper->lock);
 313
 314         ret = drm_client_buffer_vmap(buffer, &map);
 315         if (ret)
 316                 goto out;
 317
 318         dst = map;
 319         drm_fbdev_damage_blit_real(fb_helper, clip, &dst);
 320
 321         drm_client_buffer_vunmap(buffer);
 322
 323 out:
 324         mutex_unlock(&fb_helper->lock);
 325
 326         return ret;
 327 }
 328
 329 static int drm_fbdev_fb_dirty(struct drm_fb_helper *helper, struct drm_clip_rect *clip)
 330 {
 331         struct drm_device *dev = helper->dev;
 332         int ret;
 333
 334         if (!drm_fbdev_use_shadow_fb(helper))
 335                 return 0;
 336
 337         /* Call damage handlers only if necessary */
 338         if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
 339                 return 0;
 340
 341         if (helper->buffer) {
 342                 ret = drm_fbdev_damage_blit(helper, clip);
 343                 if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
 344                         return ret;
 345         }
 346
 347         if (helper->fb->funcs->dirty) {
 348                 ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
 349                 if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
 350                         return ret;
 351         }
 352
 353         return 0;
 354 }
 355
 356 static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {
 357         .fb_probe = drm_fbdev_fb_probe,
 358         .fb_dirty = drm_fbdev_fb_dirty,
 359 };
 360
 361 static void drm_fbdev_client_unregister(struct drm_client_dev *client)
 362 {
 363         struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 364
 365         if (fb_helper->info)
 366                 /* drm_fbdev_fb_destroy() takes care of cleanup */
 367                 drm_fb_helper_unregister_info(fb_helper);
 368         else
 369                 drm_fbdev_release(fb_helper);
 370 }
 371
 372 static int drm_fbdev_client_restore(struct drm_client_dev *client)
 373 {
 374         drm_fb_helper_lastclose(client->dev);
 375
 376         return 0;
 377 }
 378
 379 static int drm_fbdev_client_hotplug(struct drm_client_dev *client)
 380 {
 381         struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 382         struct drm_device *dev = client->dev;
 383         int ret;
 384
 385         /* Setup is not retried if it has failed */
 386         if (!fb_helper->dev && fb_helper->funcs)
 387                 return 0;
 388
 389         if (dev->fb_helper)
 390                 return drm_fb_helper_hotplug_event(dev->fb_helper);
 391
 392         if (!dev->mode_config.num_connector) {
 393                 drm_dbg_kms(dev, "No connectors found, will not create framebuffer!\n");
 394                 return 0;
 395         }
 396
 397         drm_fb_helper_prepare(dev, fb_helper, &drm_fb_helper_generic_funcs);
 398
 399         ret = drm_fb_helper_init(dev, fb_helper);
 400         if (ret)
 401                 goto err;
 402
 403         if (!drm_drv_uses_atomic_modeset(dev))
 404                 drm_helper_disable_unused_functions(dev);
 405
 406         ret = drm_fb_helper_initial_config(fb_helper, fb_helper->preferred_bpp);
 407         if (ret)
 408                 goto err_cleanup;
 409
 410         return 0;
 411
 412 err_cleanup:
 413         drm_fbdev_cleanup(fb_helper);
 414 err:
 415         fb_helper->dev = NULL;
 416         fb_helper->info = NULL;
 417
 418         drm_err(dev, "fbdev: Failed to setup generic emulation (ret=%d)\n", ret);
 419
 420         return ret;
 421 }
 422
 423 static const struct drm_client_funcs drm_fbdev_client_funcs = {
 424         .owner          = THIS_MODULE,
 425         .unregister     = drm_fbdev_client_unregister,
 426         .restore        = drm_fbdev_client_restore,
 427         .hotplug        = drm_fbdev_client_hotplug,
 428 };
 429
 430 /**
 431  * drm_fbdev_generic_setup() - Setup generic fbdev emulation
 432  * @dev: DRM device
 433  * @preferred_bpp: Preferred bits per pixel for the device.
 434  *                 @dev->mode_config.preferred_depth is used if this is zero.
 435  *
 436  * This function sets up generic fbdev emulation for drivers that supports
 437  * dumb buffers with a virtual address and that can be mmap'ed.
 438  * drm_fbdev_generic_setup() shall be called after the DRM driver registered
 439  * the new DRM device with drm_dev_register().
 440  *
 441  * Restore, hotplug events and teardown are all taken care of. Drivers that do
 442  * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
 443  * Simple drivers might use drm_mode_config_helper_suspend().
 444  *
 445  * Drivers that set the dirty callback on their framebuffer will get a shadow
 446  * fbdev buffer that is blitted onto the real buffer. This is done in order to
 447  * make deferred I/O work with all kinds of buffers. A shadow buffer can be
 448  * requested explicitly by setting struct drm_mode_config.prefer_shadow or
 449  * struct drm_mode_config.prefer_shadow_fbdev to true beforehand. This is
 450  * required to use generic fbdev emulation with SHMEM helpers.
 451  *
 452  * This function is safe to call even when there are no connectors present.
 453  * Setup will be retried on the next hotplug event.
 454  *
 455  * The fbdev is destroyed by drm_dev_unregister().
 456  */
 457 void drm_fbdev_generic_setup(struct drm_device *dev,
 458                              unsigned int preferred_bpp)
 459 {
 460         struct drm_fb_helper *fb_helper;
 461         int ret;
 462
 463         drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
 464         drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n");
 465
 466         fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
 467         if (!fb_helper)
 468                 return;
 469
 470         ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs);
 471         if (ret) {
 472                 kfree(fb_helper);
 473                 drm_err(dev, "Failed to register client: %d\n", ret);
 474                 return;
 475         }
 476
 477         /*
 478          * FIXME: This mixes up depth with bpp, which results in a glorious
 479          * mess, resulting in some drivers picking wrong fbdev defaults and
 480          * others wrong preferred_depth defaults.
 481          */
 482         if (!preferred_bpp)
 483                 preferred_bpp = dev->mode_config.preferred_depth;
 484         if (!preferred_bpp)
 485                 preferred_bpp = 32;
 486         fb_helper->preferred_bpp = preferred_bpp;
 487
 488         ret = drm_fbdev_client_hotplug(&fb_helper->client);
 489         if (ret)
 490                 drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);
 491
 492         drm_client_register(&fb_helper->client);
 493 }
 494 EXPORT_SYMBOL(drm_fbdev_generic_setup);