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_start = page_to_phys(vmalloc_to_page(info->screen_buffer));
 117         info->fix.smem_len = screen_size;
 118
 119         /* deferred I/O */
 120         fb_helper->fbdefio.delay = HZ / 20;
 121         fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
 122
 123         info->fbdefio = &fb_helper->fbdefio;
 124         ret = fb_deferred_io_init(info);
 125         if (ret)
 126                 goto err_drm_fb_helper_release_info;
 127
 128         return 0;
 129
 130 err_drm_fb_helper_release_info:
 131         drm_fb_helper_release_info(fb_helper);
 132 err_vfree:
 133         vfree(screen_buffer);
 134 err_drm_client_framebuffer_delete:
 135         fb_helper->fb = NULL;
 136         fb_helper->buffer = NULL;
 137         drm_client_framebuffer_delete(buffer);
 138         return ret;
 139 }
 140
 141 static void drm_fbdev_generic_damage_blit_real(struct drm_fb_helper *fb_helper,
 142                                                struct drm_clip_rect *clip,
 143                                                struct iosys_map *dst)
 144 {
 145         struct drm_framebuffer *fb = fb_helper->fb;
 146         size_t offset = clip->y1 * fb->pitches[0];
 147         size_t len = clip->x2 - clip->x1;
 148         unsigned int y;
 149         void *src;
 150
 151         switch (drm_format_info_bpp(fb->format, 0)) {
 152         case 1:
 153                 offset += clip->x1 / 8;
 154                 len = DIV_ROUND_UP(len + clip->x1 % 8, 8);
 155                 break;
 156         case 2:
 157                 offset += clip->x1 / 4;
 158                 len = DIV_ROUND_UP(len + clip->x1 % 4, 4);
 159                 break;
 160         case 4:
 161                 offset += clip->x1 / 2;
 162                 len = DIV_ROUND_UP(len + clip->x1 % 2, 2);
 163                 break;
 164         default:
 165                 offset += clip->x1 * fb->format->cpp[0];
 166                 len *= fb->format->cpp[0];
 167                 break;
 168         }
 169
 170         src = fb_helper->info->screen_buffer + offset;
 171         iosys_map_incr(dst, offset); /* go to first pixel within clip rect */
 172
 173         for (y = clip->y1; y < clip->y2; y++) {
 174                 iosys_map_memcpy_to(dst, 0, src, len);
 175                 iosys_map_incr(dst, fb->pitches[0]);
 176                 src += fb->pitches[0];
 177         }
 178 }
 179
 180 static int drm_fbdev_generic_damage_blit(struct drm_fb_helper *fb_helper,
 181                                          struct drm_clip_rect *clip)
 182 {
 183         struct drm_client_buffer *buffer = fb_helper->buffer;
 184         struct iosys_map map, dst;
 185         int ret;
 186
 187         /*
 188          * We have to pin the client buffer to its current location while
 189          * flushing the shadow buffer. In the general case, concurrent
 190          * modesetting operations could try to move the buffer and would
 191          * fail. The modeset has to be serialized by acquiring the reservation
 192          * object of the underlying BO here.
 193          *
 194          * For fbdev emulation, we only have to protect against fbdev modeset
 195          * operations. Nothing else will involve the client buffer's BO. So it
 196          * is sufficient to acquire struct drm_fb_helper.lock here.
 197          */
 198         mutex_lock(&fb_helper->lock);
 199
 200         ret = drm_client_buffer_vmap(buffer, &map);
 201         if (ret)
 202                 goto out;
 203
 204         dst = map;
 205         drm_fbdev_generic_damage_blit_real(fb_helper, clip, &dst);
 206
 207         drm_client_buffer_vunmap(buffer);
 208
 209 out:
 210         mutex_unlock(&fb_helper->lock);
 211
 212         return ret;
 213 }
 214
 215 static int drm_fbdev_generic_helper_fb_dirty(struct drm_fb_helper *helper,
 216                                              struct drm_clip_rect *clip)
 217 {
 218         struct drm_device *dev = helper->dev;
 219         int ret;
 220
 221         /* Call damage handlers only if necessary */
 222         if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2))
 223                 return 0;
 224
 225         ret = drm_fbdev_generic_damage_blit(helper, clip);
 226         if (drm_WARN_ONCE(dev, ret, "Damage blitter failed: ret=%d\n", ret))
 227                 return ret;
 228
 229         if (helper->fb->funcs->dirty) {
 230                 ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1);
 231                 if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret))
 232                         return ret;
 233         }
 234
 235         return 0;
 236 }
 237
 238 static const struct drm_fb_helper_funcs drm_fbdev_generic_helper_funcs = {
 239         .fb_probe = drm_fbdev_generic_helper_fb_probe,
 240         .fb_dirty = drm_fbdev_generic_helper_fb_dirty,
 241 };
 242
 243 static void drm_fbdev_generic_client_unregister(struct drm_client_dev *client)
 244 {
 245         struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 246
 247         if (fb_helper->info) {
 248                 drm_fb_helper_unregister_info(fb_helper);
 249         } else {
 250                 drm_client_release(&fb_helper->client);
 251                 drm_fb_helper_unprepare(fb_helper);
 252                 kfree(fb_helper);
 253         }
 254 }
 255
 256 static int drm_fbdev_generic_client_restore(struct drm_client_dev *client)
 257 {
 258         drm_fb_helper_lastclose(client->dev);
 259
 260         return 0;
 261 }
 262
 263 static int drm_fbdev_generic_client_hotplug(struct drm_client_dev *client)
 264 {
 265         struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
 266         struct drm_device *dev = client->dev;
 267         int ret;
 268
 269         if (dev->fb_helper)
 270                 return drm_fb_helper_hotplug_event(dev->fb_helper);
 271
 272         ret = drm_fb_helper_init(dev, fb_helper);
 273         if (ret)
 274                 goto err_drm_err;
 275
 276         if (!drm_drv_uses_atomic_modeset(dev))
 277                 drm_helper_disable_unused_functions(dev);
 278
 279         ret = drm_fb_helper_initial_config(fb_helper);
 280         if (ret)
 281                 goto err_drm_fb_helper_fini;
 282
 283         return 0;
 284
 285 err_drm_fb_helper_fini:
 286         drm_fb_helper_fini(fb_helper);
 287 err_drm_err:
 288         drm_err(dev, "fbdev: Failed to setup generic emulation (ret=%d)\n", ret);
 289         return ret;
 290 }
 291
 292 static const struct drm_client_funcs drm_fbdev_generic_client_funcs = {
 293         .owner          = THIS_MODULE,
 294         .unregister     = drm_fbdev_generic_client_unregister,
 295         .restore        = drm_fbdev_generic_client_restore,
 296         .hotplug        = drm_fbdev_generic_client_hotplug,
 297 };
 298
 299 /**
 300  * drm_fbdev_generic_setup() - Setup generic fbdev emulation
 301  * @dev: DRM device
 302  * @preferred_bpp: Preferred bits per pixel for the device.
 303  *
 304  * This function sets up generic fbdev emulation for drivers that supports
 305  * dumb buffers with a virtual address and that can be mmap'ed.
 306  * drm_fbdev_generic_setup() shall be called after the DRM driver registered
 307  * the new DRM device with drm_dev_register().
 308  *
 309  * Restore, hotplug events and teardown are all taken care of. Drivers that do
 310  * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
 311  * Simple drivers might use drm_mode_config_helper_suspend().
 312  *
 313  * In order to provide fixed mmap-able memory ranges, generic fbdev emulation
 314  * uses a shadow buffer in system memory. The implementation blits the shadow
 315  * fbdev buffer onto the real buffer in regular intervals.
 316  *
 317  * This function is safe to call even when there are no connectors present.
 318  * Setup will be retried on the next hotplug event.
 319  *
 320  * The fbdev is destroyed by drm_dev_unregister().
 321  */
 322 void drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp)
 323 {
 324         struct drm_fb_helper *fb_helper;
 325         int ret;
 326
 327         drm_WARN(dev, !dev->registered, "Device has not been registered.\n");
 328         drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n");
 329
 330         fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
 331         if (!fb_helper)
 332                 return;
 333         drm_fb_helper_prepare(dev, fb_helper, preferred_bpp, &drm_fbdev_generic_helper_funcs);
 334
 335         ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_generic_client_funcs);
 336         if (ret) {
 337                 drm_err(dev, "Failed to register client: %d\n", ret);
 338                 goto err_drm_client_init;
 339         }
 340
 341         drm_client_register(&fb_helper->client);
 342
 343         return;
 344
 345 err_drm_client_init:
 346         drm_fb_helper_unprepare(fb_helper);
 347         kfree(fb_helper);
 348         return;
 349 }
 350 EXPORT_SYMBOL(drm_fbdev_generic_setup);