vkms_drv.c

  1// SPDX-License-Identifier: GPL-2.0+
  2
  3/**
  4 * DOC: vkms (Virtual Kernel Modesetting)
  5 *
  6 * VKMS is a software-only model of a KMS driver that is useful for testing
  7 * and for running X (or similar) on headless machines. VKMS aims to enable
  8 * a virtual display with no need of a hardware display capability, releasing
  9 * the GPU in DRM API tests.
 10 */
 11
 12#include <linux/module.h>
 13#include <linux/device/faux.h>
 14#include <linux/dma-mapping.h>
 15
 16#include <drm/clients/drm_client_setup.h>
 17#include <drm/drm_gem.h>
 18#include <drm/drm_atomic.h>
 19#include <drm/drm_atomic_helper.h>
 20#include <drm/drm_colorop.h>
 21#include <drm/drm_drv.h>
 22#include <drm/drm_fbdev_shmem.h>
 23#include <drm/drm_file.h>
 24#include <drm/drm_gem_framebuffer_helper.h>
 25#include <drm/drm_ioctl.h>
 26#include <drm/drm_managed.h>
 27#include <drm/drm_print.h>
 28#include <drm/drm_probe_helper.h>
 29#include <drm/drm_gem_shmem_helper.h>
 30#include <drm/drm_vblank.h>
 31
 32#include "vkms_config.h"
 33#include "vkms_configfs.h"
 34#include "vkms_drv.h"
 35
 36#define DRIVER_NAME	"vkms"
 37#define DRIVER_DESC	"Virtual Kernel Mode Setting"
 38#define DRIVER_MAJOR	1
 39#define DRIVER_MINOR	0
 40
 41static struct vkms_config *default_config;
 42
 43static bool enable_cursor = true;
 44module_param_named(enable_cursor, enable_cursor, bool, 0444);
 45MODULE_PARM_DESC(enable_cursor, "Enable/Disable cursor support");
 46
 47static bool enable_writeback = true;
 48module_param_named(enable_writeback, enable_writeback, bool, 0444);
 49MODULE_PARM_DESC(enable_writeback, "Enable/Disable writeback connector support");
 50
 51static bool enable_overlay;
 52module_param_named(enable_overlay, enable_overlay, bool, 0444);
 53MODULE_PARM_DESC(enable_overlay, "Enable/Disable overlay support");
 54
 55static bool enable_plane_pipeline;
 56module_param_named(enable_plane_pipeline, enable_plane_pipeline, bool, 0444);
 57MODULE_PARM_DESC(enable_plane_pipeline, "Enable/Disable plane pipeline support");
 58
 59static bool create_default_dev = true;
 60module_param_named(create_default_dev, create_default_dev, bool, 0444);
 61MODULE_PARM_DESC(create_default_dev, "Create or not the default VKMS device");
 62
 63DEFINE_DRM_GEM_FOPS(vkms_driver_fops);
 64
 65static void vkms_atomic_commit_tail(struct drm_atomic_state *old_state)
 66{
 67	struct drm_device *dev = old_state->dev;
 68	struct drm_crtc *crtc;
 69	struct drm_crtc_state *old_crtc_state;
 70	int i;
 71
 72	drm_atomic_helper_commit_modeset_disables(dev, old_state);
 73
 74	drm_atomic_helper_commit_planes(dev, old_state, 0);
 75
 76	drm_atomic_helper_commit_modeset_enables(dev, old_state);
 77
 78	drm_atomic_helper_fake_vblank(old_state);
 79
 80	drm_atomic_helper_commit_hw_done(old_state);
 81
 82	drm_atomic_helper_wait_for_flip_done(dev, old_state);
 83
 84	for_each_old_crtc_in_state(old_state, crtc, old_crtc_state, i) {
 85		struct vkms_crtc_state *vkms_state = to_vkms_crtc_state(old_crtc_state);
 86
 87		flush_work(&vkms_state->composer_work);
 88	}
 89
 90	drm_atomic_helper_cleanup_planes(dev, old_state);
 91}
 92
 93static const struct drm_driver vkms_driver = {
 94	.driver_features	= DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_GEM,
 95	.fops			= &vkms_driver_fops,
 96	DRM_GEM_SHMEM_DRIVER_OPS,
 97	DRM_FBDEV_SHMEM_DRIVER_OPS,
 98
 99	.name			= DRIVER_NAME,
100	.desc			= DRIVER_DESC,
101	.major			= DRIVER_MAJOR,
102	.minor			= DRIVER_MINOR,
103};
104
105static int vkms_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
106{
107	struct drm_crtc *crtc;
108	struct drm_crtc_state *new_crtc_state;
109	int i;
110
111	for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
112		if (!new_crtc_state->gamma_lut || !new_crtc_state->color_mgmt_changed)
113			continue;
114
115		if (new_crtc_state->gamma_lut->length / sizeof(struct drm_color_lut *)
116		    > VKMS_LUT_SIZE)
117			return -EINVAL;
118	}
119
120	return drm_atomic_helper_check(dev, state);
121}
122
123static const struct drm_mode_config_funcs vkms_mode_funcs = {
124	.fb_create = drm_gem_fb_create,
125	.atomic_check = vkms_atomic_check,
126	.atomic_commit = drm_atomic_helper_commit,
127};
128
129static const struct drm_mode_config_helper_funcs vkms_mode_config_helpers = {
130	.atomic_commit_tail = vkms_atomic_commit_tail,
131};
132
133static int vkms_modeset_init(struct vkms_device *vkmsdev)
134{
135	struct drm_device *dev = &vkmsdev->drm;
136	int ret;
137
138	ret = drmm_mode_config_init(dev);
139	if (ret)
140		return ret;
141
142	dev->mode_config.funcs = &vkms_mode_funcs;
143	dev->mode_config.min_width = XRES_MIN;
144	dev->mode_config.min_height = YRES_MIN;
145	dev->mode_config.max_width = XRES_MAX;
146	dev->mode_config.max_height = YRES_MAX;
147	dev->mode_config.cursor_width = 512;
148	dev->mode_config.cursor_height = 512;
149	/*
150	 * FIXME: There's a confusion between bpp and depth between this and
151	 * fbdev helpers. We have to go with 0, meaning "pick the default",
152	 * which is XRGB8888 in all cases.
153	 */
154	dev->mode_config.preferred_depth = 0;
155	dev->mode_config.helper_private = &vkms_mode_config_helpers;
156
157	return vkms_output_init(vkmsdev);
158}
159
160int vkms_create(struct vkms_config *config)
161{
162	int ret;
163	struct faux_device *fdev;
164	struct vkms_device *vkms_device;
165	const char *dev_name;
166
167	dev_name = vkms_config_get_device_name(config);
168	fdev = faux_device_create(dev_name, NULL, NULL);
169	if (!fdev)
170		return -ENODEV;
171
172	if (!devres_open_group(&fdev->dev, NULL, GFP_KERNEL)) {
173		ret = -ENOMEM;
174		goto out_unregister;
175	}
176
177	vkms_device = devm_drm_dev_alloc(&fdev->dev, &vkms_driver,
178					 struct vkms_device, drm);
179	if (IS_ERR(vkms_device)) {
180		ret = PTR_ERR(vkms_device);
181		goto out_devres;
182	}
183	vkms_device->faux_dev = fdev;
184	vkms_device->config = config;
185	config->dev = vkms_device;
186
187	ret = dma_coerce_mask_and_coherent(vkms_device->drm.dev,
188					   DMA_BIT_MASK(64));
189
190	if (ret) {
191		DRM_ERROR("Could not initialize DMA support\n");
192		goto out_devres;
193	}
194
195	ret = drm_vblank_init(&vkms_device->drm,
196			      vkms_config_get_num_crtcs(config));
197	if (ret) {
198		DRM_ERROR("Failed to vblank\n");
199		goto out_devres;
200	}
201
202	ret = vkms_modeset_init(vkms_device);
203	if (ret)
204		goto out_devres;
205
206	vkms_config_register_debugfs(vkms_device);
207
208	ret = drm_dev_register(&vkms_device->drm, 0);
209	if (ret)
210		goto out_devres;
211
212	drm_client_setup(&vkms_device->drm, NULL);
213
214	return 0;
215
216out_devres:
217	devres_release_group(&fdev->dev, NULL);
218out_unregister:
219	faux_device_destroy(fdev);
220	return ret;
221}
222
223static int __init vkms_init(void)
224{
225	int ret;
226	struct vkms_config *config;
227
228	ret = vkms_configfs_register();
229	if (ret)
230		return ret;
231
232	if (!create_default_dev)
233		return 0;
234
235	config = vkms_config_default_create(enable_cursor, enable_writeback,
236					    enable_overlay, enable_plane_pipeline);
237	if (IS_ERR(config))
238		return PTR_ERR(config);
239
240	ret = vkms_create(config);
241	if (ret) {
242		vkms_config_destroy(config);
243		return ret;
244	}
245
246	default_config = config;
247
248	return 0;
249}
250
251void vkms_destroy(struct vkms_config *config)
252{
253	struct faux_device *fdev;
254
255	if (!config->dev) {
256		DRM_INFO("vkms_device is NULL.\n");
257		return;
258	}
259
260	fdev = config->dev->faux_dev;
261
262	drm_colorop_pipeline_destroy(&config->dev->drm);
263	drm_dev_unregister(&config->dev->drm);
264	drm_atomic_helper_shutdown(&config->dev->drm);
265	devres_release_group(&fdev->dev, NULL);
266	faux_device_destroy(fdev);
267
268	config->dev = NULL;
269}
270
271static void __exit vkms_exit(void)
272{
273	vkms_configfs_unregister();
274
275	if (!default_config)
276		return;
277
278	vkms_destroy(default_config);
279	vkms_config_destroy(default_config);
280}
281
282module_init(vkms_init);
283module_exit(vkms_exit);
284
285MODULE_AUTHOR("Haneen Mohammed <hamohammed.sa@gmail.com>");
286MODULE_AUTHOR("Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>");
287MODULE_DESCRIPTION(DRIVER_DESC);
288MODULE_LICENSE("GPL");