1// SPDX-License-Identifier: GPL-2.0+
  2
  3#include <linux/crc32.h>
  4
  5#include <drm/drm_atomic.h>
  6#include <drm/drm_atomic_helper.h>
  7#include <drm/drm_fourcc.h>
  8#include <drm/drm_gem_framebuffer_helper.h>
  9#include <drm/drm_gem_shmem_helper.h>
 10#include <drm/drm_vblank.h>
 11
 12#include "vkms_drv.h"
 13
 14static u32 get_pixel_from_buffer(int x, int y, const u8 *buffer,
 15				 const struct vkms_composer *composer)
 16{
 17	u32 pixel;
 18	int src_offset = composer->offset + (y * composer->pitch)
 19				      + (x * composer->cpp);
 20
 21	pixel = *(u32 *)&buffer[src_offset];
 22
 23	return pixel;
 24}
 25
 26/**
 27 * compute_crc - Compute CRC value on output frame
 28 *
 29 * @vaddr: address to final framebuffer
 30 * @composer: framebuffer's metadata
 31 *
 32 * returns CRC value computed using crc32 on the visible portion of
 33 * the final framebuffer at vaddr_out
 34 */
 35static uint32_t compute_crc(const u8 *vaddr,
 36			    const struct vkms_composer *composer)
 37{
 38	int x, y;
 39	u32 crc = 0, pixel = 0;
 40	int x_src = composer->src.x1 >> 16;
 41	int y_src = composer->src.y1 >> 16;
 42	int h_src = drm_rect_height(&composer->src) >> 16;
 43	int w_src = drm_rect_width(&composer->src) >> 16;
 44
 45	for (y = y_src; y < y_src + h_src; ++y) {
 46		for (x = x_src; x < x_src + w_src; ++x) {
 47			pixel = get_pixel_from_buffer(x, y, vaddr, composer);
 48			crc = crc32_le(crc, (void *)&pixel, sizeof(u32));
 49		}
 50	}
 51
 52	return crc;
 53}
 54
 55static u8 blend_channel(u8 src, u8 dst, u8 alpha)
 56{
 57	u32 pre_blend;
 58	u8 new_color;
 59
 60	pre_blend = (src * 255 + dst * (255 - alpha));
 61
 62	/* Faster div by 255 */
 63	new_color = ((pre_blend + ((pre_blend + 257) >> 8)) >> 8);
 64
 65	return new_color;
 66}
 67
 68/**
 69 * alpha_blend - alpha blending equation
 70 * @argb_src: src pixel on premultiplied alpha mode
 71 * @argb_dst: dst pixel completely opaque
 72 *
 73 * blend pixels using premultiplied blend formula. The current DRM assumption
 74 * is that pixel color values have been already pre-multiplied with the alpha
 75 * channel values. See more drm_plane_create_blend_mode_property(). Also, this
 76 * formula assumes a completely opaque background.
 77 */
 78static void alpha_blend(const u8 *argb_src, u8 *argb_dst)
 79{
 80	u8 alpha;
 81
 82	alpha = argb_src[3];
 83	argb_dst[0] = blend_channel(argb_src[0], argb_dst[0], alpha);
 84	argb_dst[1] = blend_channel(argb_src[1], argb_dst[1], alpha);
 85	argb_dst[2] = blend_channel(argb_src[2], argb_dst[2], alpha);
 86}
 87
 88/**
 89 * x_blend - blending equation that ignores the pixel alpha
 90 *
 91 * overwrites RGB color value from src pixel to dst pixel.
 92 */
 93static void x_blend(const u8 *xrgb_src, u8 *xrgb_dst)
 94{
 95	memcpy(xrgb_dst, xrgb_src, sizeof(u8) * 3);
 96}
 97
 98/**
 99 * blend - blend value at vaddr_src with value at vaddr_dst
100 * @vaddr_dst: destination address
101 * @vaddr_src: source address
102 * @dst_composer: destination framebuffer's metadata
103 * @src_composer: source framebuffer's metadata
104 * @pixel_blend: blending equation based on plane format
105 *
106 * Blend the vaddr_src value with the vaddr_dst value using a pixel blend
107 * equation according to the supported plane formats DRM_FORMAT_(A/XRGB8888)
108 * and clearing alpha channel to an completely opaque background. This function
109 * uses buffer's metadata to locate the new composite values at vaddr_dst.
110 *
111 * TODO: completely clear the primary plane (a = 0xff) before starting to blend
112 * pixel color values
113 */
114static void blend(void *vaddr_dst, void *vaddr_src,
115		  struct vkms_composer *dst_composer,
116		  struct vkms_composer *src_composer,
117		  void (*pixel_blend)(const u8 *, u8 *))
118{
119	int i, j, j_dst, i_dst;
120	int offset_src, offset_dst;
121	u8 *pixel_dst, *pixel_src;
122
123	int x_src = src_composer->src.x1 >> 16;
124	int y_src = src_composer->src.y1 >> 16;
125
126	int x_dst = src_composer->dst.x1;
127	int y_dst = src_composer->dst.y1;
128	int h_dst = drm_rect_height(&src_composer->dst);
129	int w_dst = drm_rect_width(&src_composer->dst);
130
131	int y_limit = y_src + h_dst;
132	int x_limit = x_src + w_dst;
133
134	for (i = y_src, i_dst = y_dst; i < y_limit; ++i) {
135		for (j = x_src, j_dst = x_dst; j < x_limit; ++j) {
136			offset_dst = dst_composer->offset
137				     + (i_dst * dst_composer->pitch)
138				     + (j_dst++ * dst_composer->cpp);
139			offset_src = src_composer->offset
140				     + (i * src_composer->pitch)
141				     + (j * src_composer->cpp);
142
143			pixel_src = (u8 *)(vaddr_src + offset_src);
144			pixel_dst = (u8 *)(vaddr_dst + offset_dst);
145			pixel_blend(pixel_src, pixel_dst);
146			/* clearing alpha channel (0xff)*/
147			pixel_dst[3] = 0xff;
148		}
149		i_dst++;
150	}
151}
152
153static void compose_plane(struct vkms_composer *primary_composer,
154			  struct vkms_composer *plane_composer,
155			  void *vaddr_out)
156{
157	struct drm_gem_object *plane_obj;
158	struct drm_gem_shmem_object *plane_shmem_obj;
159	struct drm_framebuffer *fb = &plane_composer->fb;
160	void (*pixel_blend)(const u8 *p_src, u8 *p_dst);
161
162	plane_obj = drm_gem_fb_get_obj(&plane_composer->fb, 0);
163	plane_shmem_obj = to_drm_gem_shmem_obj(plane_obj);
164
165	if (WARN_ON(!plane_shmem_obj->vaddr))
166		return;
167
168	if (fb->format->format == DRM_FORMAT_ARGB8888)
169		pixel_blend = &alpha_blend;
170	else
171		pixel_blend = &x_blend;
172
173	blend(vaddr_out, plane_shmem_obj->vaddr, primary_composer,
174	      plane_composer, pixel_blend);
175}
176
177static int compose_active_planes(void **vaddr_out,
178				 struct vkms_composer *primary_composer,
179				 struct vkms_crtc_state *crtc_state)
180{
181	struct drm_framebuffer *fb = &primary_composer->fb;
182	struct drm_gem_object *gem_obj = drm_gem_fb_get_obj(fb, 0);
183	struct drm_gem_shmem_object *shmem_obj = to_drm_gem_shmem_obj(gem_obj);
184	int i;
185
186	if (!*vaddr_out) {
187		*vaddr_out = kzalloc(shmem_obj->base.size, GFP_KERNEL);
188		if (!*vaddr_out) {
189			DRM_ERROR("Cannot allocate memory for output frame.");
190			return -ENOMEM;
191		}
192	}
193
194	if (WARN_ON(!shmem_obj->vaddr))
195		return -EINVAL;
196
197	memcpy(*vaddr_out, shmem_obj->vaddr, shmem_obj->base.size);
198
199	/* If there are other planes besides primary, we consider the active
200	 * planes should be in z-order and compose them associatively:
201	 * ((primary <- overlay) <- cursor)
202	 */
203	for (i = 1; i < crtc_state->num_active_planes; i++)
204		compose_plane(primary_composer,
205			      crtc_state->active_planes[i]->composer,
206			      *vaddr_out);
207
208	return 0;
209}
210
211/**
212 * vkms_composer_worker - ordered work_struct to compute CRC
213 *
214 * @work: work_struct
215 *
216 * Work handler for composing and computing CRCs. work_struct scheduled in
217 * an ordered workqueue that's periodically scheduled to run by
218 * _vblank_handle() and flushed at vkms_atomic_crtc_destroy_state().
219 */
220void vkms_composer_worker(struct work_struct *work)
221{
222	struct vkms_crtc_state *crtc_state = container_of(work,
223						struct vkms_crtc_state,
224						composer_work);
225	struct drm_crtc *crtc = crtc_state->base.crtc;
226	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
227	struct vkms_composer *primary_composer = NULL;
228	struct vkms_plane_state *act_plane = NULL;
229	bool crc_pending, wb_pending;
230	void *vaddr_out = NULL;
231	u32 crc32 = 0;
232	u64 frame_start, frame_end;
233	int ret;
234
235	spin_lock_irq(&out->composer_lock);
236	frame_start = crtc_state->frame_start;
237	frame_end = crtc_state->frame_end;
238	crc_pending = crtc_state->crc_pending;
239	wb_pending = crtc_state->wb_pending;
240	crtc_state->frame_start = 0;
241	crtc_state->frame_end = 0;
242	crtc_state->crc_pending = false;
243	spin_unlock_irq(&out->composer_lock);
244
245	/*
246	 * We raced with the vblank hrtimer and previous work already computed
247	 * the crc, nothing to do.
248	 */
249	if (!crc_pending)
250		return;
251
252	if (crtc_state->num_active_planes >= 1) {
253		act_plane = crtc_state->active_planes[0];
254		if (act_plane->base.plane->type == DRM_PLANE_TYPE_PRIMARY)
255			primary_composer = act_plane->composer;
256	}
257
258	if (!primary_composer)
259		return;
260
261	if (wb_pending)
262		vaddr_out = crtc_state->active_writeback;
263
264	ret = compose_active_planes(&vaddr_out, primary_composer,
265				    crtc_state);
266	if (ret) {
267		if (ret == -EINVAL && !wb_pending)
268			kfree(vaddr_out);
269		return;
270	}
271
272	crc32 = compute_crc(vaddr_out, primary_composer);
273
274	if (wb_pending) {
275		drm_writeback_signal_completion(&out->wb_connector, 0);
276		spin_lock_irq(&out->composer_lock);
277		crtc_state->wb_pending = false;
278		spin_unlock_irq(&out->composer_lock);
279	} else {
280		kfree(vaddr_out);
281	}
282
283	/*
284	 * The worker can fall behind the vblank hrtimer, make sure we catch up.
285	 */
286	while (frame_start <= frame_end)
287		drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
288}
289
290static const char * const pipe_crc_sources[] = {"auto"};
291
292const char *const *vkms_get_crc_sources(struct drm_crtc *crtc,
293					size_t *count)
294{
295	*count = ARRAY_SIZE(pipe_crc_sources);
296	return pipe_crc_sources;
297}
298
299static int vkms_crc_parse_source(const char *src_name, bool *enabled)
300{
301	int ret = 0;
302
303	if (!src_name) {
304		*enabled = false;
305	} else if (strcmp(src_name, "auto") == 0) {
306		*enabled = true;
307	} else {
308		*enabled = false;
309		ret = -EINVAL;
310	}
311
312	return ret;
313}
314
315int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
316			   size_t *values_cnt)
317{
318	bool enabled;
319
320	if (vkms_crc_parse_source(src_name, &enabled) < 0) {
321		DRM_DEBUG_DRIVER("unknown source %s\n", src_name);
322		return -EINVAL;
323	}
324
325	*values_cnt = 1;
326
327	return 0;
328}
329
330void vkms_set_composer(struct vkms_output *out, bool enabled)
331{
332	bool old_enabled;
333
334	if (enabled)
335		drm_crtc_vblank_get(&out->crtc);
336
337	spin_lock_irq(&out->lock);
338	old_enabled = out->composer_enabled;
339	out->composer_enabled = enabled;
340	spin_unlock_irq(&out->lock);
341
342	if (old_enabled)
343		drm_crtc_vblank_put(&out->crtc);
344}
345
346int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
347{
348	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
349	bool enabled = false;
350	int ret = 0;
351
352	ret = vkms_crc_parse_source(src_name, &enabled);
353
354	vkms_set_composer(out, enabled);
355
356	return ret;
357}