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_gem.h>
  11 #include <drm/drm_print.h>
  12
  13 #include <drm/drm_fbdev_generic.h>
  14
  15 /* @user: 1=userspace, 0=fbcon */
  16 static int drm_fbdev_generic_fb_open(struct fb_info *info, int user)
  17 {
  18         struct drm_fb_helper *fb_helper = info->par;
  19
  20         /* No need to take a ref for fbcon because it unbinds on unregister */
  21         if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
  22                 return -ENODEV;
  23
  24         return 0;
  25 }
  26
  27 static int drm_fbdev_generic_fb_release(struct fb_info *info, int user)
  28 {
  29         struct drm_fb_helper *fb_helper = info->par;
  30
  31         if (user)
  32                 module_put(fb_helper->dev->driver->fops->owner);
  33
  34         return 0;
  35 }
  36
  37 static void drm_fbdev_generic_fb_destroy(struct fb_info *info)
  38 {
  39         struct drm_fb_helper *fb_helper = info->par;
  40         void *shadow = info->screen_buffer;
  41
  42         if (!fb_helper->dev)
  43                 return;
  44
  45         fb_deferred_io_cleanup(info);
  46         drm_fb_helper_fini(fb_helper);
  47         vfree(shadow);
  48         drm_client_framebuffer_delete(fb_helper->buffer);
  49
  50         drm_client_release(&fb_helper->client);
  51         drm_fb_helper_unprepare(fb_helper);
  52         kfree(fb_helper);
  53 }
  54
  55 static const struct fb_ops drm_fbdev_generic_fb_ops = {
  56         .owner          = THIS_MODULE,
  57         .fb_open        = drm_fbdev_generic_fb_open,
  58         .fb_release     = drm_fbdev_generic_fb_release,
  59         .fb_read        = drm_fb_helper_sys_read,
  60         .fb_write       = drm_fb_helper_sys_write,
  61         DRM_FB_HELPER_DEFAULT_OPS,
  62         .fb_fillrect    = drm_fb_helper_sys_fillrect,
  63         .fb_copyarea    = drm_fb_helper_sys_copyarea,
  64         .fb_imageblit   = drm_fb_helper_sys_imageblit,
  65         .fb_mmap        = fb_deferred_io_mmap,
  66         .fb_destroy     = drm_fbdev_generic_fb_destroy,
  67 };
  68
  69 /*
  70  * This function uses the client API to create a framebuffer backed by a dumb buffer.
  71  */
  72 static int drm_fbdev_generic_helper_fb_probe(struct drm_fb_helper *fb_helper,
  73                                              struct drm_fb_helper_surface_size *sizes)
  74 {
  75         struct drm_client_dev *client = &fb_helper->client;
  76         struct drm_device *dev = fb_helper->dev;
  77         struct drm_client_buffer *buffer;
  78         struct fb_info *info;
  79         size_t screen_size;
  80         void *screen_buffer;
  81         u32 format;
  82         int ret;
  83
  84         drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n",
  85                     sizes->surface_width, sizes->surface_height,
  86                     sizes->surface_bpp);
  87
  88         format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
  89         buffer = drm_client_framebuffer_create(client, sizes->surface_width,
  90                                                sizes->surface_height, format);
  91         if (IS_ERR(buffer))
  92                 return PTR_ERR(buffer);
  93
  94         fb_helper->buffer = buffer;
  95         fb_helper->fb = buffer->fb;
  96
  97         screen_size = buffer->gem->size;
  98         screen_buffer = vzalloc(screen_size);
  99         if (!screen_buffer) {
 100                 ret = -ENOMEM;
 101                 goto err_drm_client_framebuffer_delete;
 102         }
 103
 104         info = drm_fb_helper_alloc_info(fb_helper);
 105         if (IS_ERR(info)) {
 106                 ret = PTR_ERR(info);
 107                 goto err_vfree;
 108         }
 109
 110         drm_fb_helper_fill_info(info, fb_helper, sizes);
 111
 112         info->fbops = &drm_fbdev_generic_fb_ops;
 113         info->flags = FBINFO_DEFAULT;
 114
 115         /* screen */
 116         info->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
 117         info->screen_buffer = screen_buffer;
 118         info->fix.smem_start = page_to_phys(vmalloc_to_page(info->screen_buffer));
 119         info->fix.smem_len = screen_size;
 120
 121         /* deferred I/O */
 122         fb_helper->fbdefio.delay = HZ / 20;
 123         fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
 124
 125         info->fbdefio = &fb_helper->fbdefio;
 126         ret = fb_deferred_io_init(info);
 127         if (ret)
 128                 goto err_drm_fb_helper_release_info;
 129
 130         return 0;
 131
 132 err_drm_fb_helper_release_info:
 133         drm_fb_helper_release_info(fb_helper);
 134 err_vfree:
 135         vfree(screen_buffer);
 136 err_drm_client_framebuffer_delete:
 137         fb_helper->fb = NULL;
 138         fb_helper->buffer = NULL;
 139         drm_client_framebuffer_delete(buffer);
 140         return ret;
 141 }
 142
 143 static void drm_fbdev_generic_damage_blit_real(struct drm_fb_helper *fb_helper,
 144                                                struct drm_clip_rect *clip,
 145                                                struct iosys_map *dst)
 146 {
 147         struct drm_framebuffer *fb = fb_helper->fb;
 148         size_t offset = clip->y1 * fb->pitches[0];
 149         size_t len = clip->x2 - clip->x1;
 150         unsigned int y;
 151         void *src;
 152
 153         switch (drm_format_info_bpp(fb->format, 0)) {
 154         case 1:
 155                 offset += clip->x1 / 8;
 156                 len = DIV_ROUND_UP(len + clip->x1 % 8, 8);
 157                 break;
 158         case 2:
 159                 offset += clip->x1 / 4;
 160                 len = DIV_ROUND_UP(len + clip->x1 % 4, 4);
 161                 break;
 162         case 4:
 163                 offset += clip->x1 / 2;
 164                 len = DIV_ROUND_UP(len + clip->x1 % 2, 2);
 165                 break;
 166         default:
 167                 offset += clip->x1 * fb->format->cpp[0];
 168                 len *= fb->format->cpp[0];
 169                 break;
 170         }
 171
 172         src = fb_helper->info->screen_buffer + offset;
 173         iosys_map_incr(dst, offset); /* go to first pixel within clip rect */
 174
 175         for (y = clip->y1; y < clip->y2; y++) {
 176                 iosys_map_memcpy_to(dst, 0, src, len);
 177                 iosys_map_incr(dst, fb->pitches[0]);
 178                 src += fb->pitches[0];
 179         }
 180 }
 181
 182 static int drm_fbdev_generic_damage_blit(struct drm_fb_helper *fb_helper,
 183                                          struct drm_clip_rect *clip)
 184 {
 185         struct drm_client_buffer *buffer = fb_helper->buffer;
 186         struct iosys_map map, dst;
 187         int ret;
 188
 189         /*
 190          * We have to pin the client buffer to its current location while
 191          * flushing the shadow buffer. In the general case, concurrent
 192          * modesetting operations could try to move the buffer and would
 193          * fail. The modeset has to be serialized by acquiring the reservation
 194          * object of the underlying BO here.
 195          *
 196          * For fbdev emulation, we only have to protect against fbdev modeset
 197          * operations. Nothing else will involve the client buffer's BO. So it
 198          * is sufficient to acquire struct drm_fb_helper.lock here.
 199          */
 200         mutex_lock(&fb_helper->lock);
 201
 202         ret = drm_client_buffer_vmap(buffer, &map);
 203         if (ret)
 204                 goto out;
 205
 206         dst = map;
 207         drm_fbdev_generic_damage_blit_real(fb_helper, clip, &dst);
 208
 209         drm_client_buffer_vunmap(buffer);
 210
 211 out:
 212         mutex_unlock(&fb_helper->lock);
 213
 214         return ret;
 215 }
 216
 217 static int drm_fbdev_generic_helper_fb_dirty(struct drm_fb_helper *helper,
 218                                              struct drm_clip_rect *clip)
 219 {
 220         struct drm_device *dev = helper->dev;
 221         int ret;
 222
 223         /* Call damage handlers only if necessary */
 224         if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
 225                 return 0;
 226
 227         ret = drm_fbdev_generic_damage_blit(helper, clip);
 228         if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
 229                 return ret;
 230
 231         if (helper->fb->funcs->dirty) {
 232                 ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
 233                 if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
 234                         return ret;
 235         }
 236
 237         return 0;
 238 }
 239
 240 static const struct drm_fb_helper_funcs drm_fbdev_generic_helper_funcs = {
 241         .fb_probe = drm_fbdev_generic_helper_fb_probe,
 242         .fb_dirty = drm_fbdev_generic_helper_fb_dirty,
 243 };
 244
 245 static void drm_fbdev_generic_client_unregister(struct drm_client_dev *client)
 246 {
 247         struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 248
 249         if (fb_helper->info) {
 250                 drm_fb_helper_unregister_info(fb_helper);
 251         } else {
 252                 drm_client_release(&fb_helper->client);
 253                 drm_fb_helper_unprepare(fb_helper);
 254                 kfree(fb_helper);
 255         }
 256 }
 257
 258 static int drm_fbdev_generic_client_restore(struct drm_client_dev *client)
 259 {
 260         drm_fb_helper_lastclose(client->dev);
 261
 262         return 0;
 263 }
 264
 265 static int drm_fbdev_generic_client_hotplug(struct drm_client_dev *client)
 266 {
 267         struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 268         struct drm_device *dev = client->dev;
 269         int ret;
 270
 271         if (dev->fb_helper)
 272                 return drm_fb_helper_hotplug_event(dev->fb_helper);
 273
 274         ret = drm_fb_helper_init(dev, fb_helper);
 275         if (ret)
 276                 goto err_drm_err;
 277
 278         if (!drm_drv_uses_atomic_modeset(dev))
 279                 drm_helper_disable_unused_functions(dev);
 280
 281         ret = drm_fb_helper_initial_config(fb_helper);
 282         if (ret)
 283                 goto err_drm_fb_helper_fini;
 284
 285         return 0;
 286
 287 err_drm_fb_helper_fini:
 288         drm_fb_helper_fini(fb_helper);
 289 err_drm_err:
 290         drm_err(dev, "fbdev: Failed to setup generic emulation (ret=%d)\n", ret);
 291         return ret;
 292 }
 293
 294 static const struct drm_client_funcs drm_fbdev_generic_client_funcs = {
 295         .owner          = THIS_MODULE,
 296         .unregister     = drm_fbdev_generic_client_unregister,
 297         .restore        = drm_fbdev_generic_client_restore,
 298         .hotplug        = drm_fbdev_generic_client_hotplug,
 299 };
 300
 301 /**
 302  * drm_fbdev_generic_setup() - Setup generic fbdev emulation
 303  * @dev: DRM device
 304  * @preferred_bpp: Preferred bits per pixel for the device.
 305  *
 306  * This function sets up generic fbdev emulation for drivers that supports
 307  * dumb buffers with a virtual address and that can be mmap'ed.
 308  * drm_fbdev_generic_setup() shall be called after the DRM driver registered
 309  * the new DRM device with drm_dev_register().
 310  *
 311  * Restore, hotplug events and teardown are all taken care of. Drivers that do
 312  * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
 313  * Simple drivers might use drm_mode_config_helper_suspend().
 314  *
 315  * In order to provide fixed mmap-able memory ranges, generic fbdev emulation
 316  * uses a shadow buffer in system memory. The implementation blits the shadow
 317  * fbdev buffer onto the real buffer in regular intervals.
 318  *
 319  * This function is safe to call even when there are no connectors present.
 320  * Setup will be retried on the next hotplug event.
 321  *
 322  * The fbdev is destroyed by drm_dev_unregister().
 323  */
 324 void drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
 325 {
 326         struct drm_fb_helper *fb_helper;
 327         int ret;
 328
 329         drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
 330         drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n");
 331
 332         fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
 333         if (!fb_helper)
 334                 return;
 335         drm_fb_helper_prepare(dev, fb_helper, preferred_bpp, &drm_fbdev_generic_helper_funcs);
 336
 337         ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_generic_client_funcs);
 338         if (ret) {
 339                 drm_err(dev, "Failed to register client: %d\n", ret);
 340                 goto err_drm_client_init;
 341         }
 342
 343         ret = drm_fbdev_generic_client_hotplug(&fb_helper->client);
 344         if (ret)
 345                 drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);
 346
 347         drm_client_register(&fb_helper->client);
 348
 349         return;
 350
 351 err_drm_client_init:
 352         drm_fb_helper_unprepare(fb_helper);
 353         kfree(fb_helper);
 354         return;
 355 }
 356 EXPORT_SYMBOL(drm_fbdev_generic_setup);