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_blend.h>
  8#include <drm/drm_fourcc.h>
  9#include <drm/drm_fixed.h>
 10#include <drm/drm_gem_framebuffer_helper.h>
 11#include <drm/drm_vblank.h>
 12#include <linux/minmax.h>
 13
 14#include "vkms_drv.h"
 15
 16static u16 pre_mul_blend_channel(u16 src, u16 dst, u16 alpha)
 17{
 18	u32 new_color;
 19
 20	new_color = (src * 0xffff + dst * (0xffff - alpha));
 21
 22	return DIV_ROUND_CLOSEST(new_color, 0xffff);
 23}
 24
 25/**
 26 * pre_mul_alpha_blend - alpha blending equation
 27 * @frame_info: Source framebuffer's metadata
 28 * @stage_buffer: The line with the pixels from src_plane
 29 * @output_buffer: A line buffer that receives all the blends output
 30 *
 31 * Using the information from the `frame_info`, this blends only the
 32 * necessary pixels from the `stage_buffer` to the `output_buffer`
 33 * using premultiplied blend formula.
 34 *
 35 * The current DRM assumption is that pixel color values have been already
 36 * pre-multiplied with the alpha channel values. See more
 37 * drm_plane_create_blend_mode_property(). Also, this formula assumes a
 38 * completely opaque background.
 39 */
 40static void pre_mul_alpha_blend(struct vkms_frame_info *frame_info,
 41				struct line_buffer *stage_buffer,
 42				struct line_buffer *output_buffer)
 43{
 44	int x_dst = frame_info->dst.x1;
 45	struct pixel_argb_u16 *out = output_buffer->pixels + x_dst;
 46	struct pixel_argb_u16 *in = stage_buffer->pixels;
 47	int x_limit = min_t(size_t, drm_rect_width(&frame_info->dst),
 48			    stage_buffer->n_pixels);
 49
 50	for (int x = 0; x < x_limit; x++) {
 51		out[x].a = (u16)0xffff;
 52		out[x].r = pre_mul_blend_channel(in[x].r, out[x].r, in[x].a);
 53		out[x].g = pre_mul_blend_channel(in[x].g, out[x].g, in[x].a);
 54		out[x].b = pre_mul_blend_channel(in[x].b, out[x].b, in[x].a);
 55	}
 56}
 57
 58static int get_y_pos(struct vkms_frame_info *frame_info, int y)
 59{
 60	if (frame_info->rotation & DRM_MODE_REFLECT_Y)
 61		return drm_rect_height(&frame_info->rotated) - y - 1;
 62
 63	switch (frame_info->rotation & DRM_MODE_ROTATE_MASK) {
 64	case DRM_MODE_ROTATE_90:
 65		return frame_info->rotated.x2 - y - 1;
 66	case DRM_MODE_ROTATE_270:
 67		return y + frame_info->rotated.x1;
 68	default:
 69		return y;
 70	}
 71}
 72
 73static bool check_limit(struct vkms_frame_info *frame_info, int pos)
 74{
 75	if (drm_rotation_90_or_270(frame_info->rotation)) {
 76		if (pos >= 0 && pos < drm_rect_width(&frame_info->rotated))
 77			return true;
 78	} else {
 79		if (pos >= frame_info->rotated.y1 && pos < frame_info->rotated.y2)
 80			return true;
 81	}
 82
 83	return false;
 84}
 85
 86static void fill_background(const struct pixel_argb_u16 *background_color,
 87			    struct line_buffer *output_buffer)
 88{
 89	for (size_t i = 0; i < output_buffer->n_pixels; i++)
 90		output_buffer->pixels[i] = *background_color;
 91}
 92
 93// lerp(a, b, t) = a + (b - a) * t
 94static u16 lerp_u16(u16 a, u16 b, s64 t)
 95{
 96	s64 a_fp = drm_int2fixp(a);
 97	s64 b_fp = drm_int2fixp(b);
 98
 99	s64 delta = drm_fixp_mul(b_fp - a_fp,  t);
100
101	return drm_fixp2int(a_fp + delta);
102}
103
104static s64 get_lut_index(const struct vkms_color_lut *lut, u16 channel_value)
105{
106	s64 color_channel_fp = drm_int2fixp(channel_value);
107
108	return drm_fixp_mul(color_channel_fp, lut->channel_value2index_ratio);
109}
110
111/*
112 * This enum is related to the positions of the variables inside
113 * `struct drm_color_lut`, so the order of both needs to be the same.
114 */
115enum lut_channel {
116	LUT_RED = 0,
117	LUT_GREEN,
118	LUT_BLUE,
119	LUT_RESERVED
120};
121
122static u16 apply_lut_to_channel_value(const struct vkms_color_lut *lut, u16 channel_value,
123				      enum lut_channel channel)
124{
125	s64 lut_index = get_lut_index(lut, channel_value);
126
127	/*
128	 * This checks if `struct drm_color_lut` has any gap added by the compiler
129	 * between the struct fields.
130	 */
131	static_assert(sizeof(struct drm_color_lut) == sizeof(__u16) * 4);
132
133	u16 *floor_lut_value = (__u16 *)&lut->base[drm_fixp2int(lut_index)];
134	u16 *ceil_lut_value = (__u16 *)&lut->base[drm_fixp2int_ceil(lut_index)];
135
136	u16 floor_channel_value = floor_lut_value[channel];
137	u16 ceil_channel_value = ceil_lut_value[channel];
138
139	return lerp_u16(floor_channel_value, ceil_channel_value,
140			lut_index & DRM_FIXED_DECIMAL_MASK);
141}
142
143static void apply_lut(const struct vkms_crtc_state *crtc_state, struct line_buffer *output_buffer)
144{
145	if (!crtc_state->gamma_lut.base)
146		return;
147
148	if (!crtc_state->gamma_lut.lut_length)
149		return;
150
151	for (size_t x = 0; x < output_buffer->n_pixels; x++) {
152		struct pixel_argb_u16 *pixel = &output_buffer->pixels[x];
153
154		pixel->r = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->r, LUT_RED);
155		pixel->g = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->g, LUT_GREEN);
156		pixel->b = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->b, LUT_BLUE);
157	}
158}
159
160/**
161 * blend - blend the pixels from all planes and compute crc
162 * @wb: The writeback frame buffer metadata
163 * @crtc_state: The crtc state
164 * @crc32: The crc output of the final frame
165 * @output_buffer: A buffer of a row that will receive the result of the blend(s)
166 * @stage_buffer: The line with the pixels from plane being blend to the output
167 * @row_size: The size, in bytes, of a single row
168 *
169 * This function blends the pixels (Using the `pre_mul_alpha_blend`)
170 * from all planes, calculates the crc32 of the output from the former step,
171 * and, if necessary, convert and store the output to the writeback buffer.
172 */
173static void blend(struct vkms_writeback_job *wb,
174		  struct vkms_crtc_state *crtc_state,
175		  u32 *crc32, struct line_buffer *stage_buffer,
176		  struct line_buffer *output_buffer, size_t row_size)
177{
178	struct vkms_plane_state **plane = crtc_state->active_planes;
179	u32 n_active_planes = crtc_state->num_active_planes;
180	int y_pos;
181
182	const struct pixel_argb_u16 background_color = { .a = 0xffff };
183
184	size_t crtc_y_limit = crtc_state->base.crtc->mode.vdisplay;
185
186	for (size_t y = 0; y < crtc_y_limit; y++) {
187		fill_background(&background_color, output_buffer);
188
189		/* The active planes are composed associatively in z-order. */
190		for (size_t i = 0; i < n_active_planes; i++) {
191			y_pos = get_y_pos(plane[i]->frame_info, y);
192
193			if (!check_limit(plane[i]->frame_info, y_pos))
194				continue;
195
196			vkms_compose_row(stage_buffer, plane[i], y_pos);
197			pre_mul_alpha_blend(plane[i]->frame_info, stage_buffer,
198					    output_buffer);
199		}
200
201		apply_lut(crtc_state, output_buffer);
202
203		*crc32 = crc32_le(*crc32, (void *)output_buffer->pixels, row_size);
204
205		if (wb)
206			vkms_writeback_row(wb, output_buffer, y_pos);
207	}
208}
209
210static int check_format_funcs(struct vkms_crtc_state *crtc_state,
211			      struct vkms_writeback_job *active_wb)
212{
213	struct vkms_plane_state **planes = crtc_state->active_planes;
214	u32 n_active_planes = crtc_state->num_active_planes;
215
216	for (size_t i = 0; i < n_active_planes; i++)
217		if (!planes[i]->pixel_read)
218			return -1;
219
220	if (active_wb && !active_wb->pixel_write)
221		return -1;
222
223	return 0;
224}
225
226static int check_iosys_map(struct vkms_crtc_state *crtc_state)
227{
228	struct vkms_plane_state **plane_state = crtc_state->active_planes;
229	u32 n_active_planes = crtc_state->num_active_planes;
230
231	for (size_t i = 0; i < n_active_planes; i++)
232		if (iosys_map_is_null(&plane_state[i]->frame_info->map[0]))
233			return -1;
234
235	return 0;
236}
237
238static int compose_active_planes(struct vkms_writeback_job *active_wb,
239				 struct vkms_crtc_state *crtc_state,
240				 u32 *crc32)
241{
242	size_t line_width, pixel_size = sizeof(struct pixel_argb_u16);
243	struct line_buffer output_buffer, stage_buffer;
244	int ret = 0;
245
246	/*
247	 * This check exists so we can call `crc32_le` for the entire line
248	 * instead doing it for each channel of each pixel in case
249	 * `struct `pixel_argb_u16` had any gap added by the compiler
250	 * between the struct fields.
251	 */
252	static_assert(sizeof(struct pixel_argb_u16) == 8);
253
254	if (WARN_ON(check_iosys_map(crtc_state)))
255		return -EINVAL;
256
257	if (WARN_ON(check_format_funcs(crtc_state, active_wb)))
258		return -EINVAL;
259
260	line_width = crtc_state->base.crtc->mode.hdisplay;
261	stage_buffer.n_pixels = line_width;
262	output_buffer.n_pixels = line_width;
263
264	stage_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL);
265	if (!stage_buffer.pixels) {
266		DRM_ERROR("Cannot allocate memory for the output line buffer");
267		return -ENOMEM;
268	}
269
270	output_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL);
271	if (!output_buffer.pixels) {
272		DRM_ERROR("Cannot allocate memory for intermediate line buffer");
273		ret = -ENOMEM;
274		goto free_stage_buffer;
275	}
276
277	blend(active_wb, crtc_state, crc32, &stage_buffer,
278	      &output_buffer, line_width * pixel_size);
279
280	kvfree(output_buffer.pixels);
281free_stage_buffer:
282	kvfree(stage_buffer.pixels);
283
284	return ret;
285}
286
287/**
288 * vkms_composer_worker - ordered work_struct to compute CRC
289 *
290 * @work: work_struct
291 *
292 * Work handler for composing and computing CRCs. work_struct scheduled in
293 * an ordered workqueue that's periodically scheduled to run by
294 * vkms_vblank_simulate() and flushed at vkms_atomic_commit_tail().
295 */
296void vkms_composer_worker(struct work_struct *work)
297{
298	struct vkms_crtc_state *crtc_state = container_of(work,
299						struct vkms_crtc_state,
300						composer_work);
301	struct drm_crtc *crtc = crtc_state->base.crtc;
302	struct vkms_writeback_job *active_wb = crtc_state->active_writeback;
303	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
304	bool crc_pending, wb_pending;
305	u64 frame_start, frame_end;
306	u32 crc32 = 0;
307	int ret;
308
309	spin_lock_irq(&out->composer_lock);
310	frame_start = crtc_state->frame_start;
311	frame_end = crtc_state->frame_end;
312	crc_pending = crtc_state->crc_pending;
313	wb_pending = crtc_state->wb_pending;
314	crtc_state->frame_start = 0;
315	crtc_state->frame_end = 0;
316	crtc_state->crc_pending = false;
317
318	if (crtc->state->gamma_lut) {
319		s64 max_lut_index_fp;
320		s64 u16_max_fp = drm_int2fixp(0xffff);
321
322		crtc_state->gamma_lut.base = (struct drm_color_lut *)crtc->state->gamma_lut->data;
323		crtc_state->gamma_lut.lut_length =
324			crtc->state->gamma_lut->length / sizeof(struct drm_color_lut);
325		max_lut_index_fp = drm_int2fixp(crtc_state->gamma_lut.lut_length  - 1);
326		crtc_state->gamma_lut.channel_value2index_ratio = drm_fixp_div(max_lut_index_fp,
327									       u16_max_fp);
328
329	} else {
330		crtc_state->gamma_lut.base = NULL;
331	}
332
333	spin_unlock_irq(&out->composer_lock);
334
335	/*
336	 * We raced with the vblank hrtimer and previous work already computed
337	 * the crc, nothing to do.
338	 */
339	if (!crc_pending)
340		return;
341
342	if (wb_pending)
343		ret = compose_active_planes(active_wb, crtc_state, &crc32);
344	else
345		ret = compose_active_planes(NULL, crtc_state, &crc32);
346
347	if (ret)
348		return;
349
350	if (wb_pending) {
351		drm_writeback_signal_completion(&out->wb_connector, 0);
352		spin_lock_irq(&out->composer_lock);
353		crtc_state->wb_pending = false;
354		spin_unlock_irq(&out->composer_lock);
355	}
356
357	/*
358	 * The worker can fall behind the vblank hrtimer, make sure we catch up.
359	 */
360	while (frame_start <= frame_end)
361		drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
362}
363
364static const char * const pipe_crc_sources[] = {"auto"};
365
366const char *const *vkms_get_crc_sources(struct drm_crtc *crtc,
367					size_t *count)
368{
369	*count = ARRAY_SIZE(pipe_crc_sources);
370	return pipe_crc_sources;
371}
372
373static int vkms_crc_parse_source(const char *src_name, bool *enabled)
374{
375	int ret = 0;
376
377	if (!src_name) {
378		*enabled = false;
379	} else if (strcmp(src_name, "auto") == 0) {
380		*enabled = true;
381	} else {
382		*enabled = false;
383		ret = -EINVAL;
384	}
385
386	return ret;
387}
388
389int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
390			   size_t *values_cnt)
391{
392	bool enabled;
393
394	if (vkms_crc_parse_source(src_name, &enabled) < 0) {
395		DRM_DEBUG_DRIVER("unknown source %s\n", src_name);
396		return -EINVAL;
397	}
398
399	*values_cnt = 1;
400
401	return 0;
402}
403
404void vkms_set_composer(struct vkms_output *out, bool enabled)
405{
406	bool old_enabled;
407
408	if (enabled)
409		drm_crtc_vblank_get(&out->crtc);
410
411	spin_lock_irq(&out->lock);
412	old_enabled = out->composer_enabled;
413	out->composer_enabled = enabled;
414	spin_unlock_irq(&out->lock);
415
416	if (old_enabled)
417		drm_crtc_vblank_put(&out->crtc);
418}
419
420int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
421{
422	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
423	bool enabled = false;
424	int ret = 0;
425
426	ret = vkms_crc_parse_source(src_name, &enabled);
427
428	vkms_set_composer(out, enabled);
429
430	return ret;
431}