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