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