1 /*
2  * Copyright (C) 2015 Free Electrons
3  * Copyright (C) 2015 NextThing Co
4  *
5  * Maxime Ripard <maxime.ripard@free-electrons.com>
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License as
9  * published by the Free Software Foundation; either version 2 of
10  * the License, or (at your option) any later version.
11  */
12 
13 #include <drm/drmP.h>
14 #include <drm/drm_atomic.h>
15 #include <drm/drm_atomic_helper.h>
16 #include <drm/drm_crtc.h>
17 #include <drm/drm_crtc_helper.h>
18 #include <drm/drm_fb_cma_helper.h>
19 #include <drm/drm_gem_cma_helper.h>
20 #include <drm/drm_plane_helper.h>
21 
22 #include <linux/component.h>
23 #include <linux/list.h>
24 #include <linux/of_device.h>
25 #include <linux/of_graph.h>
26 #include <linux/reset.h>
27 
28 #include "sun4i_backend.h"
29 #include "sun4i_drv.h"
30 #include "sun4i_frontend.h"
31 #include "sun4i_layer.h"
32 #include "sunxi_engine.h"
33 
34 struct sun4i_backend_quirks {
35 	/* backend <-> TCON muxing selection done in backend */
36 	bool needs_output_muxing;
37 
38 	/* alpha at the lowest z position is not always supported */
39 	bool supports_lowest_plane_alpha;
40 };
41 
42 static const u32 sunxi_rgb2yuv_coef[12] = {
43 	0x00000107, 0x00000204, 0x00000064, 0x00000108,
44 	0x00003f69, 0x00003ed6, 0x000001c1, 0x00000808,
45 	0x000001c1, 0x00003e88, 0x00003fb8, 0x00000808
46 };
47 
48 /*
49  * These coefficients are taken from the A33 BSP from Allwinner.
50  *
51  * The first three values of each row are coded as 13-bit signed fixed-point
52  * numbers, with 10 bits for the fractional part. The fourth value is a
53  * constant coded as a 14-bit signed fixed-point number with 4 bits for the
54  * fractional part.
55  *
56  * The values in table order give the following colorspace translation:
57  * G = 1.164 * Y - 0.391 * U - 0.813 * V + 135
58  * R = 1.164 * Y + 1.596 * V - 222
59  * B = 1.164 * Y + 2.018 * U + 276
60  *
61  * This seems to be a conversion from Y[16:235] UV[16:240] to RGB[0:255],
62  * following the BT601 spec.
63  */
64 static const u32 sunxi_bt601_yuv2rgb_coef[12] = {
65 	0x000004a7, 0x00001e6f, 0x00001cbf, 0x00000877,
66 	0x000004a7, 0x00000000, 0x00000662, 0x00003211,
67 	0x000004a7, 0x00000812, 0x00000000, 0x00002eb1,
68 };
69 
70 static void sun4i_backend_apply_color_correction(struct sunxi_engine *engine)
71 {
72 	int i;
73 
74 	DRM_DEBUG_DRIVER("Applying RGB to YUV color correction\n");
75 
76 	/* Set color correction */
77 	regmap_write(engine->regs, SUN4I_BACKEND_OCCTL_REG,
78 		     SUN4I_BACKEND_OCCTL_ENABLE);
79 
80 	for (i = 0; i < 12; i++)
81 		regmap_write(engine->regs, SUN4I_BACKEND_OCRCOEF_REG(i),
82 			     sunxi_rgb2yuv_coef[i]);
83 }
84 
85 static void sun4i_backend_disable_color_correction(struct sunxi_engine *engine)
86 {
87 	DRM_DEBUG_DRIVER("Disabling color correction\n");
88 
89 	/* Disable color correction */
90 	regmap_update_bits(engine->regs, SUN4I_BACKEND_OCCTL_REG,
91 			   SUN4I_BACKEND_OCCTL_ENABLE, 0);
92 }
93 
94 static void sun4i_backend_commit(struct sunxi_engine *engine)
95 {
96 	DRM_DEBUG_DRIVER("Committing changes\n");
97 
98 	regmap_write(engine->regs, SUN4I_BACKEND_REGBUFFCTL_REG,
99 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS |
100 		     SUN4I_BACKEND_REGBUFFCTL_LOADCTL);
101 }
102 
103 void sun4i_backend_layer_enable(struct sun4i_backend *backend,
104 				int layer, bool enable)
105 {
106 	u32 val;
107 
108 	DRM_DEBUG_DRIVER("%sabling layer %d\n", enable ? "En" : "Dis",
109 			 layer);
110 
111 	if (enable)
112 		val = SUN4I_BACKEND_MODCTL_LAY_EN(layer);
113 	else
114 		val = 0;
115 
116 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
117 			   SUN4I_BACKEND_MODCTL_LAY_EN(layer), val);
118 }
119 
120 static int sun4i_backend_drm_format_to_layer(u32 format, u32 *mode)
121 {
122 	switch (format) {
123 	case DRM_FORMAT_ARGB8888:
124 		*mode = SUN4I_BACKEND_LAY_FBFMT_ARGB8888;
125 		break;
126 
127 	case DRM_FORMAT_ARGB4444:
128 		*mode = SUN4I_BACKEND_LAY_FBFMT_ARGB4444;
129 		break;
130 
131 	case DRM_FORMAT_ARGB1555:
132 		*mode = SUN4I_BACKEND_LAY_FBFMT_ARGB1555;
133 		break;
134 
135 	case DRM_FORMAT_RGBA5551:
136 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGBA5551;
137 		break;
138 
139 	case DRM_FORMAT_RGBA4444:
140 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGBA4444;
141 		break;
142 
143 	case DRM_FORMAT_XRGB8888:
144 		*mode = SUN4I_BACKEND_LAY_FBFMT_XRGB8888;
145 		break;
146 
147 	case DRM_FORMAT_RGB888:
148 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGB888;
149 		break;
150 
151 	case DRM_FORMAT_RGB565:
152 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGB565;
153 		break;
154 
155 	default:
156 		return -EINVAL;
157 	}
158 
159 	return 0;
160 }
161 
162 static const uint32_t sun4i_backend_formats[] = {
163 	DRM_FORMAT_ARGB1555,
164 	DRM_FORMAT_ARGB4444,
165 	DRM_FORMAT_ARGB8888,
166 	DRM_FORMAT_BGRX8888,
167 	DRM_FORMAT_RGB565,
168 	DRM_FORMAT_RGB888,
169 	DRM_FORMAT_RGBA4444,
170 	DRM_FORMAT_RGBA5551,
171 	DRM_FORMAT_UYVY,
172 	DRM_FORMAT_VYUY,
173 	DRM_FORMAT_XRGB8888,
174 	DRM_FORMAT_YUYV,
175 	DRM_FORMAT_YVYU,
176 };
177 
178 bool sun4i_backend_format_is_supported(uint32_t fmt, uint64_t modifier)
179 {
180 	unsigned int i;
181 
182 	if (modifier != DRM_FORMAT_MOD_LINEAR)
183 		return false;
184 
185 	for (i = 0; i < ARRAY_SIZE(sun4i_backend_formats); i++)
186 		if (sun4i_backend_formats[i] == fmt)
187 			return true;
188 
189 	return false;
190 }
191 
192 int sun4i_backend_update_layer_coord(struct sun4i_backend *backend,
193 				     int layer, struct drm_plane *plane)
194 {
195 	struct drm_plane_state *state = plane->state;
196 
197 	DRM_DEBUG_DRIVER("Updating layer %d\n", layer);
198 
199 	if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
200 		DRM_DEBUG_DRIVER("Primary layer, updating global size W: %u H: %u\n",
201 				 state->crtc_w, state->crtc_h);
202 		regmap_write(backend->engine.regs, SUN4I_BACKEND_DISSIZE_REG,
203 			     SUN4I_BACKEND_DISSIZE(state->crtc_w,
204 						   state->crtc_h));
205 	}
206 
207 	/* Set height and width */
208 	DRM_DEBUG_DRIVER("Layer size W: %u H: %u\n",
209 			 state->crtc_w, state->crtc_h);
210 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYSIZE_REG(layer),
211 		     SUN4I_BACKEND_LAYSIZE(state->crtc_w,
212 					   state->crtc_h));
213 
214 	/* Set base coordinates */
215 	DRM_DEBUG_DRIVER("Layer coordinates X: %d Y: %d\n",
216 			 state->crtc_x, state->crtc_y);
217 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYCOOR_REG(layer),
218 		     SUN4I_BACKEND_LAYCOOR(state->crtc_x,
219 					   state->crtc_y));
220 
221 	return 0;
222 }
223 
224 static int sun4i_backend_update_yuv_format(struct sun4i_backend *backend,
225 					   int layer, struct drm_plane *plane)
226 {
227 	struct drm_plane_state *state = plane->state;
228 	struct drm_framebuffer *fb = state->fb;
229 	const struct drm_format_info *format = fb->format;
230 	const uint32_t fmt = format->format;
231 	u32 val = SUN4I_BACKEND_IYUVCTL_EN;
232 	int i;
233 
234 	for (i = 0; i < ARRAY_SIZE(sunxi_bt601_yuv2rgb_coef); i++)
235 		regmap_write(backend->engine.regs,
236 			     SUN4I_BACKEND_YGCOEF_REG(i),
237 			     sunxi_bt601_yuv2rgb_coef[i]);
238 
239 	/*
240 	 * We should do that only for a single plane, but the
241 	 * framebuffer's atomic_check has our back on this.
242 	 */
243 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
244 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN,
245 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN);
246 
247 	/* TODO: Add support for the multi-planar YUV formats */
248 	if (format->num_planes == 1)
249 		val |= SUN4I_BACKEND_IYUVCTL_FBFMT_PACKED_YUV422;
250 	else
251 		DRM_DEBUG_DRIVER("Unsupported YUV format (0x%x)\n", fmt);
252 
253 	/*
254 	 * Allwinner seems to list the pixel sequence from right to left, while
255 	 * DRM lists it from left to right.
256 	 */
257 	switch (fmt) {
258 	case DRM_FORMAT_YUYV:
259 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_VYUY;
260 		break;
261 	case DRM_FORMAT_YVYU:
262 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_UYVY;
263 		break;
264 	case DRM_FORMAT_UYVY:
265 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YVYU;
266 		break;
267 	case DRM_FORMAT_VYUY:
268 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YUYV;
269 		break;
270 	default:
271 		DRM_DEBUG_DRIVER("Unsupported YUV pixel sequence (0x%x)\n",
272 				 fmt);
273 	}
274 
275 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVCTL_REG, val);
276 
277 	return 0;
278 }
279 
280 int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
281 				       int layer, struct drm_plane *plane)
282 {
283 	struct drm_plane_state *state = plane->state;
284 	struct drm_framebuffer *fb = state->fb;
285 	bool interlaced = false;
286 	u32 val;
287 	int ret;
288 
289 	/* Clear the YUV mode */
290 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
291 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
292 
293 	if (plane->state->crtc)
294 		interlaced = plane->state->crtc->state->adjusted_mode.flags
295 			& DRM_MODE_FLAG_INTERLACE;
296 
297 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
298 			   SUN4I_BACKEND_MODCTL_ITLMOD_EN,
299 			   interlaced ? SUN4I_BACKEND_MODCTL_ITLMOD_EN : 0);
300 
301 	DRM_DEBUG_DRIVER("Switching display backend interlaced mode %s\n",
302 			 interlaced ? "on" : "off");
303 
304 	val = SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA(state->alpha >> 8);
305 	if (state->alpha != DRM_BLEND_ALPHA_OPAQUE)
306 		val |= SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN;
307 	regmap_update_bits(backend->engine.regs,
308 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
309 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_MASK |
310 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN,
311 			   val);
312 
313 	if (fb->format->is_yuv)
314 		return sun4i_backend_update_yuv_format(backend, layer, plane);
315 
316 	ret = sun4i_backend_drm_format_to_layer(fb->format->format, &val);
317 	if (ret) {
318 		DRM_DEBUG_DRIVER("Invalid format\n");
319 		return ret;
320 	}
321 
322 	regmap_update_bits(backend->engine.regs,
323 			   SUN4I_BACKEND_ATTCTL_REG1(layer),
324 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
325 
326 	return 0;
327 }
328 
329 int sun4i_backend_update_layer_frontend(struct sun4i_backend *backend,
330 					int layer, uint32_t fmt)
331 {
332 	u32 val;
333 	int ret;
334 
335 	ret = sun4i_backend_drm_format_to_layer(fmt, &val);
336 	if (ret) {
337 		DRM_DEBUG_DRIVER("Invalid format\n");
338 		return ret;
339 	}
340 
341 	regmap_update_bits(backend->engine.regs,
342 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
343 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN,
344 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN);
345 
346 	regmap_update_bits(backend->engine.regs,
347 			   SUN4I_BACKEND_ATTCTL_REG1(layer),
348 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
349 
350 	return 0;
351 }
352 
353 static int sun4i_backend_update_yuv_buffer(struct sun4i_backend *backend,
354 					   struct drm_framebuffer *fb,
355 					   dma_addr_t paddr)
356 {
357 	/* TODO: Add support for the multi-planar YUV formats */
358 	DRM_DEBUG_DRIVER("Setting packed YUV buffer address to %pad\n", &paddr);
359 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVADD_REG(0), paddr);
360 
361 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
362 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVLINEWIDTH_REG(0),
363 		     fb->pitches[0] * 8);
364 
365 	return 0;
366 }
367 
368 int sun4i_backend_update_layer_buffer(struct sun4i_backend *backend,
369 				      int layer, struct drm_plane *plane)
370 {
371 	struct drm_plane_state *state = plane->state;
372 	struct drm_framebuffer *fb = state->fb;
373 	u32 lo_paddr, hi_paddr;
374 	dma_addr_t paddr;
375 
376 	/* Set the line width */
377 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
378 	regmap_write(backend->engine.regs,
379 		     SUN4I_BACKEND_LAYLINEWIDTH_REG(layer),
380 		     fb->pitches[0] * 8);
381 
382 	/* Get the start of the displayed memory */
383 	paddr = drm_fb_cma_get_gem_addr(fb, state, 0);
384 	DRM_DEBUG_DRIVER("Setting buffer address to %pad\n", &paddr);
385 
386 	/*
387 	 * backend DMA accesses DRAM directly, bypassing the system
388 	 * bus. As such, the address range is different and the buffer
389 	 * address needs to be corrected.
390 	 */
391 	paddr -= PHYS_OFFSET;
392 
393 	if (fb->format->is_yuv)
394 		return sun4i_backend_update_yuv_buffer(backend, fb, paddr);
395 
396 	/* Write the 32 lower bits of the address (in bits) */
397 	lo_paddr = paddr << 3;
398 	DRM_DEBUG_DRIVER("Setting address lower bits to 0x%x\n", lo_paddr);
399 	regmap_write(backend->engine.regs,
400 		     SUN4I_BACKEND_LAYFB_L32ADD_REG(layer),
401 		     lo_paddr);
402 
403 	/* And the upper bits */
404 	hi_paddr = paddr >> 29;
405 	DRM_DEBUG_DRIVER("Setting address high bits to 0x%x\n", hi_paddr);
406 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_LAYFB_H4ADD_REG,
407 			   SUN4I_BACKEND_LAYFB_H4ADD_MSK(layer),
408 			   SUN4I_BACKEND_LAYFB_H4ADD(layer, hi_paddr));
409 
410 	return 0;
411 }
412 
413 int sun4i_backend_update_layer_zpos(struct sun4i_backend *backend, int layer,
414 				    struct drm_plane *plane)
415 {
416 	struct drm_plane_state *state = plane->state;
417 	struct sun4i_layer_state *p_state = state_to_sun4i_layer_state(state);
418 	unsigned int priority = state->normalized_zpos;
419 	unsigned int pipe = p_state->pipe;
420 
421 	DRM_DEBUG_DRIVER("Setting layer %d's priority to %d and pipe %d\n",
422 			 layer, priority, pipe);
423 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
424 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL_MASK |
425 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL_MASK,
426 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL(p_state->pipe) |
427 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL(priority));
428 
429 	return 0;
430 }
431 
432 void sun4i_backend_cleanup_layer(struct sun4i_backend *backend,
433 				 int layer)
434 {
435 	regmap_update_bits(backend->engine.regs,
436 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
437 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN |
438 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
439 }
440 
441 static bool sun4i_backend_plane_uses_scaler(struct drm_plane_state *state)
442 {
443 	u16 src_h = state->src_h >> 16;
444 	u16 src_w = state->src_w >> 16;
445 
446 	DRM_DEBUG_DRIVER("Input size %dx%d, output size %dx%d\n",
447 			 src_w, src_h, state->crtc_w, state->crtc_h);
448 
449 	if ((state->crtc_h != src_h) || (state->crtc_w != src_w))
450 		return true;
451 
452 	return false;
453 }
454 
455 static bool sun4i_backend_plane_uses_frontend(struct drm_plane_state *state)
456 {
457 	struct sun4i_layer *layer = plane_to_sun4i_layer(state->plane);
458 	struct sun4i_backend *backend = layer->backend;
459 	uint32_t format = state->fb->format->format;
460 	uint64_t modifier = state->fb->modifier;
461 
462 	if (IS_ERR(backend->frontend))
463 		return false;
464 
465 	if (!sun4i_frontend_format_is_supported(format, modifier))
466 		return false;
467 
468 	if (!sun4i_backend_format_is_supported(format, modifier))
469 		return true;
470 
471 	/*
472 	 * TODO: The backend alone allows 2x and 4x integer scaling, including
473 	 * support for an alpha component (which the frontend doesn't support).
474 	 * Use the backend directly instead of the frontend in this case, with
475 	 * another test to return false.
476 	 */
477 
478 	if (sun4i_backend_plane_uses_scaler(state))
479 		return true;
480 
481 	/*
482 	 * Here the format is supported by both the frontend and the backend
483 	 * and no frontend scaling is required, so use the backend directly.
484 	 */
485 	return false;
486 }
487 
488 static bool sun4i_backend_plane_is_supported(struct drm_plane_state *state,
489 					     bool *uses_frontend)
490 {
491 	if (sun4i_backend_plane_uses_frontend(state)) {
492 		*uses_frontend = true;
493 		return true;
494 	}
495 
496 	*uses_frontend = false;
497 
498 	/* Scaling is not supported without the frontend. */
499 	if (sun4i_backend_plane_uses_scaler(state))
500 		return false;
501 
502 	return true;
503 }
504 
505 static void sun4i_backend_atomic_begin(struct sunxi_engine *engine,
506 				       struct drm_crtc_state *old_state)
507 {
508 	u32 val;
509 
510 	WARN_ON(regmap_read_poll_timeout(engine->regs,
511 					 SUN4I_BACKEND_REGBUFFCTL_REG,
512 					 val, !(val & SUN4I_BACKEND_REGBUFFCTL_LOADCTL),
513 					 100, 50000));
514 }
515 
516 static int sun4i_backend_atomic_check(struct sunxi_engine *engine,
517 				      struct drm_crtc_state *crtc_state)
518 {
519 	struct drm_plane_state *plane_states[SUN4I_BACKEND_NUM_LAYERS] = { 0 };
520 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
521 	struct drm_atomic_state *state = crtc_state->state;
522 	struct drm_device *drm = state->dev;
523 	struct drm_plane *plane;
524 	unsigned int num_planes = 0;
525 	unsigned int num_alpha_planes = 0;
526 	unsigned int num_frontend_planes = 0;
527 	unsigned int num_alpha_planes_max = 1;
528 	unsigned int num_yuv_planes = 0;
529 	unsigned int current_pipe = 0;
530 	unsigned int i;
531 
532 	DRM_DEBUG_DRIVER("Starting checking our planes\n");
533 
534 	if (!crtc_state->planes_changed)
535 		return 0;
536 
537 	drm_for_each_plane_mask(plane, drm, crtc_state->plane_mask) {
538 		struct drm_plane_state *plane_state =
539 			drm_atomic_get_plane_state(state, plane);
540 		struct sun4i_layer_state *layer_state =
541 			state_to_sun4i_layer_state(plane_state);
542 		struct drm_framebuffer *fb = plane_state->fb;
543 		struct drm_format_name_buf format_name;
544 
545 		if (!sun4i_backend_plane_is_supported(plane_state,
546 						      &layer_state->uses_frontend))
547 			return -EINVAL;
548 
549 		if (layer_state->uses_frontend) {
550 			DRM_DEBUG_DRIVER("Using the frontend for plane %d\n",
551 					 plane->index);
552 			num_frontend_planes++;
553 		} else {
554 			if (fb->format->is_yuv) {
555 				DRM_DEBUG_DRIVER("Plane FB format is YUV\n");
556 				num_yuv_planes++;
557 			}
558 		}
559 
560 		DRM_DEBUG_DRIVER("Plane FB format is %s\n",
561 				 drm_get_format_name(fb->format->format,
562 						     &format_name));
563 		if (fb->format->has_alpha || (plane_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
564 			num_alpha_planes++;
565 
566 		DRM_DEBUG_DRIVER("Plane zpos is %d\n",
567 				 plane_state->normalized_zpos);
568 
569 		/* Sort our planes by Zpos */
570 		plane_states[plane_state->normalized_zpos] = plane_state;
571 
572 		num_planes++;
573 	}
574 
575 	/* All our planes were disabled, bail out */
576 	if (!num_planes)
577 		return 0;
578 
579 	/*
580 	 * The hardware is a bit unusual here.
581 	 *
582 	 * Even though it supports 4 layers, it does the composition
583 	 * in two separate steps.
584 	 *
585 	 * The first one is assigning a layer to one of its two
586 	 * pipes. If more that 1 layer is assigned to the same pipe,
587 	 * and if pixels overlaps, the pipe will take the pixel from
588 	 * the layer with the highest priority.
589 	 *
590 	 * The second step is the actual alpha blending, that takes
591 	 * the two pipes as input, and uses the potential alpha
592 	 * component to do the transparency between the two.
593 	 *
594 	 * This two-step scenario makes us unable to guarantee a
595 	 * robust alpha blending between the 4 layers in all
596 	 * situations, since this means that we need to have one layer
597 	 * with alpha at the lowest position of our two pipes.
598 	 *
599 	 * However, we cannot even do that on every platform, since
600 	 * the hardware has a bug where the lowest plane of the lowest
601 	 * pipe (pipe 0, priority 0), if it has any alpha, will
602 	 * discard the pixel data entirely and just display the pixels
603 	 * in the background color (black by default).
604 	 *
605 	 * This means that on the affected platforms, we effectively
606 	 * have only three valid configurations with alpha, all of
607 	 * them with the alpha being on pipe1 with the lowest
608 	 * position, which can be 1, 2 or 3 depending on the number of
609 	 * planes and their zpos.
610 	 */
611 
612 	/* For platforms that are not affected by the issue described above. */
613 	if (backend->quirks->supports_lowest_plane_alpha)
614 		num_alpha_planes_max++;
615 
616 	if (num_alpha_planes > num_alpha_planes_max) {
617 		DRM_DEBUG_DRIVER("Too many planes with alpha, rejecting...\n");
618 		return -EINVAL;
619 	}
620 
621 	/* We can't have an alpha plane at the lowest position */
622 	if (!backend->quirks->supports_lowest_plane_alpha &&
623 	    (plane_states[0]->fb->format->has_alpha ||
624 	    (plane_states[0]->alpha != DRM_BLEND_ALPHA_OPAQUE)))
625 		return -EINVAL;
626 
627 	for (i = 1; i < num_planes; i++) {
628 		struct drm_plane_state *p_state = plane_states[i];
629 		struct drm_framebuffer *fb = p_state->fb;
630 		struct sun4i_layer_state *s_state = state_to_sun4i_layer_state(p_state);
631 
632 		/*
633 		 * The only alpha position is the lowest plane of the
634 		 * second pipe.
635 		 */
636 		if (fb->format->has_alpha || (p_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
637 			current_pipe++;
638 
639 		s_state->pipe = current_pipe;
640 	}
641 
642 	/* We can only have a single YUV plane at a time */
643 	if (num_yuv_planes > SUN4I_BACKEND_NUM_YUV_PLANES) {
644 		DRM_DEBUG_DRIVER("Too many planes with YUV, rejecting...\n");
645 		return -EINVAL;
646 	}
647 
648 	if (num_frontend_planes > SUN4I_BACKEND_NUM_FRONTEND_LAYERS) {
649 		DRM_DEBUG_DRIVER("Too many planes going through the frontend, rejecting\n");
650 		return -EINVAL;
651 	}
652 
653 	DRM_DEBUG_DRIVER("State valid with %u planes, %u alpha, %u video, %u YUV\n",
654 			 num_planes, num_alpha_planes, num_frontend_planes,
655 			 num_yuv_planes);
656 
657 	return 0;
658 }
659 
660 static void sun4i_backend_vblank_quirk(struct sunxi_engine *engine)
661 {
662 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
663 	struct sun4i_frontend *frontend = backend->frontend;
664 
665 	if (!frontend)
666 		return;
667 
668 	/*
669 	 * In a teardown scenario with the frontend involved, we have
670 	 * to keep the frontend enabled until the next vblank, and
671 	 * only then disable it.
672 	 *
673 	 * This is due to the fact that the backend will not take into
674 	 * account the new configuration (with the plane that used to
675 	 * be fed by the frontend now disabled) until we write to the
676 	 * commit bit and the hardware fetches the new configuration
677 	 * during the next vblank.
678 	 *
679 	 * So we keep the frontend around in order to prevent any
680 	 * visual artifacts.
681 	 */
682 	spin_lock(&backend->frontend_lock);
683 	if (backend->frontend_teardown) {
684 		sun4i_frontend_exit(frontend);
685 		backend->frontend_teardown = false;
686 	}
687 	spin_unlock(&backend->frontend_lock);
688 };
689 
690 static int sun4i_backend_init_sat(struct device *dev) {
691 	struct sun4i_backend *backend = dev_get_drvdata(dev);
692 	int ret;
693 
694 	backend->sat_reset = devm_reset_control_get(dev, "sat");
695 	if (IS_ERR(backend->sat_reset)) {
696 		dev_err(dev, "Couldn't get the SAT reset line\n");
697 		return PTR_ERR(backend->sat_reset);
698 	}
699 
700 	ret = reset_control_deassert(backend->sat_reset);
701 	if (ret) {
702 		dev_err(dev, "Couldn't deassert the SAT reset line\n");
703 		return ret;
704 	}
705 
706 	backend->sat_clk = devm_clk_get(dev, "sat");
707 	if (IS_ERR(backend->sat_clk)) {
708 		dev_err(dev, "Couldn't get our SAT clock\n");
709 		ret = PTR_ERR(backend->sat_clk);
710 		goto err_assert_reset;
711 	}
712 
713 	ret = clk_prepare_enable(backend->sat_clk);
714 	if (ret) {
715 		dev_err(dev, "Couldn't enable the SAT clock\n");
716 		return ret;
717 	}
718 
719 	return 0;
720 
721 err_assert_reset:
722 	reset_control_assert(backend->sat_reset);
723 	return ret;
724 }
725 
726 static int sun4i_backend_free_sat(struct device *dev) {
727 	struct sun4i_backend *backend = dev_get_drvdata(dev);
728 
729 	clk_disable_unprepare(backend->sat_clk);
730 	reset_control_assert(backend->sat_reset);
731 
732 	return 0;
733 }
734 
735 /*
736  * The display backend can take video output from the display frontend, or
737  * the display enhancement unit on the A80, as input for one it its layers.
738  * This relationship within the display pipeline is encoded in the device
739  * tree with of_graph, and we use it here to figure out which backend, if
740  * there are 2 or more, we are currently probing. The number would be in
741  * the "reg" property of the upstream output port endpoint.
742  */
743 static int sun4i_backend_of_get_id(struct device_node *node)
744 {
745 	struct device_node *port, *ep;
746 	int ret = -EINVAL;
747 
748 	/* input is port 0 */
749 	port = of_graph_get_port_by_id(node, 0);
750 	if (!port)
751 		return -EINVAL;
752 
753 	/* try finding an upstream endpoint */
754 	for_each_available_child_of_node(port, ep) {
755 		struct device_node *remote;
756 		u32 reg;
757 
758 		remote = of_graph_get_remote_endpoint(ep);
759 		if (!remote)
760 			continue;
761 
762 		ret = of_property_read_u32(remote, "reg", &reg);
763 		if (ret)
764 			continue;
765 
766 		ret = reg;
767 	}
768 
769 	of_node_put(port);
770 
771 	return ret;
772 }
773 
774 /* TODO: This needs to take multiple pipelines into account */
775 static struct sun4i_frontend *sun4i_backend_find_frontend(struct sun4i_drv *drv,
776 							  struct device_node *node)
777 {
778 	struct device_node *port, *ep, *remote;
779 	struct sun4i_frontend *frontend;
780 
781 	port = of_graph_get_port_by_id(node, 0);
782 	if (!port)
783 		return ERR_PTR(-EINVAL);
784 
785 	for_each_available_child_of_node(port, ep) {
786 		remote = of_graph_get_remote_port_parent(ep);
787 		if (!remote)
788 			continue;
789 
790 		/* does this node match any registered engines? */
791 		list_for_each_entry(frontend, &drv->frontend_list, list) {
792 			if (remote == frontend->node) {
793 				of_node_put(remote);
794 				of_node_put(port);
795 				return frontend;
796 			}
797 		}
798 	}
799 
800 	return ERR_PTR(-EINVAL);
801 }
802 
803 static const struct sunxi_engine_ops sun4i_backend_engine_ops = {
804 	.atomic_begin			= sun4i_backend_atomic_begin,
805 	.atomic_check			= sun4i_backend_atomic_check,
806 	.commit				= sun4i_backend_commit,
807 	.layers_init			= sun4i_layers_init,
808 	.apply_color_correction		= sun4i_backend_apply_color_correction,
809 	.disable_color_correction	= sun4i_backend_disable_color_correction,
810 	.vblank_quirk			= sun4i_backend_vblank_quirk,
811 };
812 
813 static struct regmap_config sun4i_backend_regmap_config = {
814 	.reg_bits	= 32,
815 	.val_bits	= 32,
816 	.reg_stride	= 4,
817 	.max_register	= 0x5800,
818 };
819 
820 static int sun4i_backend_bind(struct device *dev, struct device *master,
821 			      void *data)
822 {
823 	struct platform_device *pdev = to_platform_device(dev);
824 	struct drm_device *drm = data;
825 	struct sun4i_drv *drv = drm->dev_private;
826 	struct sun4i_backend *backend;
827 	const struct sun4i_backend_quirks *quirks;
828 	struct resource *res;
829 	void __iomem *regs;
830 	int i, ret;
831 
832 	backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
833 	if (!backend)
834 		return -ENOMEM;
835 	dev_set_drvdata(dev, backend);
836 	spin_lock_init(&backend->frontend_lock);
837 
838 	backend->engine.node = dev->of_node;
839 	backend->engine.ops = &sun4i_backend_engine_ops;
840 	backend->engine.id = sun4i_backend_of_get_id(dev->of_node);
841 	if (backend->engine.id < 0)
842 		return backend->engine.id;
843 
844 	backend->frontend = sun4i_backend_find_frontend(drv, dev->of_node);
845 	if (IS_ERR(backend->frontend))
846 		dev_warn(dev, "Couldn't find matching frontend, frontend features disabled\n");
847 
848 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
849 	regs = devm_ioremap_resource(dev, res);
850 	if (IS_ERR(regs))
851 		return PTR_ERR(regs);
852 
853 	backend->reset = devm_reset_control_get(dev, NULL);
854 	if (IS_ERR(backend->reset)) {
855 		dev_err(dev, "Couldn't get our reset line\n");
856 		return PTR_ERR(backend->reset);
857 	}
858 
859 	ret = reset_control_deassert(backend->reset);
860 	if (ret) {
861 		dev_err(dev, "Couldn't deassert our reset line\n");
862 		return ret;
863 	}
864 
865 	backend->bus_clk = devm_clk_get(dev, "ahb");
866 	if (IS_ERR(backend->bus_clk)) {
867 		dev_err(dev, "Couldn't get the backend bus clock\n");
868 		ret = PTR_ERR(backend->bus_clk);
869 		goto err_assert_reset;
870 	}
871 	clk_prepare_enable(backend->bus_clk);
872 
873 	backend->mod_clk = devm_clk_get(dev, "mod");
874 	if (IS_ERR(backend->mod_clk)) {
875 		dev_err(dev, "Couldn't get the backend module clock\n");
876 		ret = PTR_ERR(backend->mod_clk);
877 		goto err_disable_bus_clk;
878 	}
879 	clk_prepare_enable(backend->mod_clk);
880 
881 	backend->ram_clk = devm_clk_get(dev, "ram");
882 	if (IS_ERR(backend->ram_clk)) {
883 		dev_err(dev, "Couldn't get the backend RAM clock\n");
884 		ret = PTR_ERR(backend->ram_clk);
885 		goto err_disable_mod_clk;
886 	}
887 	clk_prepare_enable(backend->ram_clk);
888 
889 	if (of_device_is_compatible(dev->of_node,
890 				    "allwinner,sun8i-a33-display-backend")) {
891 		ret = sun4i_backend_init_sat(dev);
892 		if (ret) {
893 			dev_err(dev, "Couldn't init SAT resources\n");
894 			goto err_disable_ram_clk;
895 		}
896 	}
897 
898 	backend->engine.regs = devm_regmap_init_mmio(dev, regs,
899 						     &sun4i_backend_regmap_config);
900 	if (IS_ERR(backend->engine.regs)) {
901 		dev_err(dev, "Couldn't create the backend regmap\n");
902 		return PTR_ERR(backend->engine.regs);
903 	}
904 
905 	list_add_tail(&backend->engine.list, &drv->engine_list);
906 
907 	/*
908 	 * Many of the backend's layer configuration registers have
909 	 * undefined default values. This poses a risk as we use
910 	 * regmap_update_bits in some places, and don't overwrite
911 	 * the whole register.
912 	 *
913 	 * Clear the registers here to have something predictable.
914 	 */
915 	for (i = 0x800; i < 0x1000; i += 4)
916 		regmap_write(backend->engine.regs, i, 0);
917 
918 	/* Disable registers autoloading */
919 	regmap_write(backend->engine.regs, SUN4I_BACKEND_REGBUFFCTL_REG,
920 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS);
921 
922 	/* Enable the backend */
923 	regmap_write(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
924 		     SUN4I_BACKEND_MODCTL_DEBE_EN |
925 		     SUN4I_BACKEND_MODCTL_START_CTL);
926 
927 	/* Set output selection if needed */
928 	quirks = of_device_get_match_data(dev);
929 	if (quirks->needs_output_muxing) {
930 		/*
931 		 * We assume there is no dynamic muxing of backends
932 		 * and TCONs, so we select the backend with same ID.
933 		 *
934 		 * While dynamic selection might be interesting, since
935 		 * the CRTC is tied to the TCON, while the layers are
936 		 * tied to the backends, this means, we will need to
937 		 * switch between groups of layers. There might not be
938 		 * a way to represent this constraint in DRM.
939 		 */
940 		regmap_update_bits(backend->engine.regs,
941 				   SUN4I_BACKEND_MODCTL_REG,
942 				   SUN4I_BACKEND_MODCTL_OUT_SEL,
943 				   (backend->engine.id
944 				    ? SUN4I_BACKEND_MODCTL_OUT_LCD1
945 				    : SUN4I_BACKEND_MODCTL_OUT_LCD0));
946 	}
947 
948 	backend->quirks = quirks;
949 
950 	return 0;
951 
952 err_disable_ram_clk:
953 	clk_disable_unprepare(backend->ram_clk);
954 err_disable_mod_clk:
955 	clk_disable_unprepare(backend->mod_clk);
956 err_disable_bus_clk:
957 	clk_disable_unprepare(backend->bus_clk);
958 err_assert_reset:
959 	reset_control_assert(backend->reset);
960 	return ret;
961 }
962 
963 static void sun4i_backend_unbind(struct device *dev, struct device *master,
964 				 void *data)
965 {
966 	struct sun4i_backend *backend = dev_get_drvdata(dev);
967 
968 	list_del(&backend->engine.list);
969 
970 	if (of_device_is_compatible(dev->of_node,
971 				    "allwinner,sun8i-a33-display-backend"))
972 		sun4i_backend_free_sat(dev);
973 
974 	clk_disable_unprepare(backend->ram_clk);
975 	clk_disable_unprepare(backend->mod_clk);
976 	clk_disable_unprepare(backend->bus_clk);
977 	reset_control_assert(backend->reset);
978 }
979 
980 static const struct component_ops sun4i_backend_ops = {
981 	.bind	= sun4i_backend_bind,
982 	.unbind	= sun4i_backend_unbind,
983 };
984 
985 static int sun4i_backend_probe(struct platform_device *pdev)
986 {
987 	return component_add(&pdev->dev, &sun4i_backend_ops);
988 }
989 
990 static int sun4i_backend_remove(struct platform_device *pdev)
991 {
992 	component_del(&pdev->dev, &sun4i_backend_ops);
993 
994 	return 0;
995 }
996 
997 static const struct sun4i_backend_quirks sun4i_backend_quirks = {
998 	.needs_output_muxing = true,
999 };
1000 
1001 static const struct sun4i_backend_quirks sun5i_backend_quirks = {
1002 };
1003 
1004 static const struct sun4i_backend_quirks sun6i_backend_quirks = {
1005 };
1006 
1007 static const struct sun4i_backend_quirks sun7i_backend_quirks = {
1008 	.needs_output_muxing = true,
1009 	.supports_lowest_plane_alpha = true,
1010 };
1011 
1012 static const struct sun4i_backend_quirks sun8i_a33_backend_quirks = {
1013 	.supports_lowest_plane_alpha = true,
1014 };
1015 
1016 static const struct sun4i_backend_quirks sun9i_backend_quirks = {
1017 };
1018 
1019 static const struct of_device_id sun4i_backend_of_table[] = {
1020 	{
1021 		.compatible = "allwinner,sun4i-a10-display-backend",
1022 		.data = &sun4i_backend_quirks,
1023 	},
1024 	{
1025 		.compatible = "allwinner,sun5i-a13-display-backend",
1026 		.data = &sun5i_backend_quirks,
1027 	},
1028 	{
1029 		.compatible = "allwinner,sun6i-a31-display-backend",
1030 		.data = &sun6i_backend_quirks,
1031 	},
1032 	{
1033 		.compatible = "allwinner,sun7i-a20-display-backend",
1034 		.data = &sun7i_backend_quirks,
1035 	},
1036 	{
1037 		.compatible = "allwinner,sun8i-a33-display-backend",
1038 		.data = &sun8i_a33_backend_quirks,
1039 	},
1040 	{
1041 		.compatible = "allwinner,sun9i-a80-display-backend",
1042 		.data = &sun9i_backend_quirks,
1043 	},
1044 	{ }
1045 };
1046 MODULE_DEVICE_TABLE(of, sun4i_backend_of_table);
1047 
1048 static struct platform_driver sun4i_backend_platform_driver = {
1049 	.probe		= sun4i_backend_probe,
1050 	.remove		= sun4i_backend_remove,
1051 	.driver		= {
1052 		.name		= "sun4i-backend",
1053 		.of_match_table	= sun4i_backend_of_table,
1054 	},
1055 };
1056 module_platform_driver(sun4i_backend_platform_driver);
1057 
1058 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
1059 MODULE_DESCRIPTION("Allwinner A10 Display Backend Driver");
1060 MODULE_LICENSE("GPL");
1061