xref: /linux/drivers/gpu/drm/sun4i/sun4i_backend.c (revision 2b64b2ed277ff23e785fbdb65098ee7e1252d64f)
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_fb_cma_helper.h>
18 #include <drm/drm_gem_cma_helper.h>
19 #include <drm/drm_plane_helper.h>
20 #include <drm/drm_probe_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 static void sun4i_backend_apply_color_correction(struct sunxi_engine *engine)
49 {
50 	int i;
51 
52 	DRM_DEBUG_DRIVER("Applying RGB to YUV color correction\n");
53 
54 	/* Set color correction */
55 	regmap_write(engine->regs, SUN4I_BACKEND_OCCTL_REG,
56 		     SUN4I_BACKEND_OCCTL_ENABLE);
57 
58 	for (i = 0; i < 12; i++)
59 		regmap_write(engine->regs, SUN4I_BACKEND_OCRCOEF_REG(i),
60 			     sunxi_rgb2yuv_coef[i]);
61 }
62 
63 static void sun4i_backend_disable_color_correction(struct sunxi_engine *engine)
64 {
65 	DRM_DEBUG_DRIVER("Disabling color correction\n");
66 
67 	/* Disable color correction */
68 	regmap_update_bits(engine->regs, SUN4I_BACKEND_OCCTL_REG,
69 			   SUN4I_BACKEND_OCCTL_ENABLE, 0);
70 }
71 
72 static void sun4i_backend_commit(struct sunxi_engine *engine)
73 {
74 	DRM_DEBUG_DRIVER("Committing changes\n");
75 
76 	regmap_write(engine->regs, SUN4I_BACKEND_REGBUFFCTL_REG,
77 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS |
78 		     SUN4I_BACKEND_REGBUFFCTL_LOADCTL);
79 }
80 
81 void sun4i_backend_layer_enable(struct sun4i_backend *backend,
82 				int layer, bool enable)
83 {
84 	u32 val;
85 
86 	DRM_DEBUG_DRIVER("%sabling layer %d\n", enable ? "En" : "Dis",
87 			 layer);
88 
89 	if (enable)
90 		val = SUN4I_BACKEND_MODCTL_LAY_EN(layer);
91 	else
92 		val = 0;
93 
94 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
95 			   SUN4I_BACKEND_MODCTL_LAY_EN(layer), val);
96 }
97 
98 static int sun4i_backend_drm_format_to_layer(u32 format, u32 *mode)
99 {
100 	switch (format) {
101 	case DRM_FORMAT_ARGB8888:
102 		*mode = SUN4I_BACKEND_LAY_FBFMT_ARGB8888;
103 		break;
104 
105 	case DRM_FORMAT_ARGB4444:
106 		*mode = SUN4I_BACKEND_LAY_FBFMT_ARGB4444;
107 		break;
108 
109 	case DRM_FORMAT_ARGB1555:
110 		*mode = SUN4I_BACKEND_LAY_FBFMT_ARGB1555;
111 		break;
112 
113 	case DRM_FORMAT_RGBA5551:
114 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGBA5551;
115 		break;
116 
117 	case DRM_FORMAT_RGBA4444:
118 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGBA4444;
119 		break;
120 
121 	case DRM_FORMAT_XRGB8888:
122 		*mode = SUN4I_BACKEND_LAY_FBFMT_XRGB8888;
123 		break;
124 
125 	case DRM_FORMAT_RGB888:
126 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGB888;
127 		break;
128 
129 	case DRM_FORMAT_RGB565:
130 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGB565;
131 		break;
132 
133 	default:
134 		return -EINVAL;
135 	}
136 
137 	return 0;
138 }
139 
140 static const uint32_t sun4i_backend_formats[] = {
141 	DRM_FORMAT_ARGB1555,
142 	DRM_FORMAT_ARGB4444,
143 	DRM_FORMAT_ARGB8888,
144 	DRM_FORMAT_RGB565,
145 	DRM_FORMAT_RGB888,
146 	DRM_FORMAT_RGBA4444,
147 	DRM_FORMAT_RGBA5551,
148 	DRM_FORMAT_UYVY,
149 	DRM_FORMAT_VYUY,
150 	DRM_FORMAT_XRGB8888,
151 	DRM_FORMAT_YUYV,
152 	DRM_FORMAT_YVYU,
153 };
154 
155 bool sun4i_backend_format_is_supported(uint32_t fmt, uint64_t modifier)
156 {
157 	unsigned int i;
158 
159 	if (modifier != DRM_FORMAT_MOD_LINEAR)
160 		return false;
161 
162 	for (i = 0; i < ARRAY_SIZE(sun4i_backend_formats); i++)
163 		if (sun4i_backend_formats[i] == fmt)
164 			return true;
165 
166 	return false;
167 }
168 
169 int sun4i_backend_update_layer_coord(struct sun4i_backend *backend,
170 				     int layer, struct drm_plane *plane)
171 {
172 	struct drm_plane_state *state = plane->state;
173 
174 	DRM_DEBUG_DRIVER("Updating layer %d\n", layer);
175 
176 	if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
177 		DRM_DEBUG_DRIVER("Primary layer, updating global size W: %u H: %u\n",
178 				 state->crtc_w, state->crtc_h);
179 		regmap_write(backend->engine.regs, SUN4I_BACKEND_DISSIZE_REG,
180 			     SUN4I_BACKEND_DISSIZE(state->crtc_w,
181 						   state->crtc_h));
182 	}
183 
184 	/* Set height and width */
185 	DRM_DEBUG_DRIVER("Layer size W: %u H: %u\n",
186 			 state->crtc_w, state->crtc_h);
187 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYSIZE_REG(layer),
188 		     SUN4I_BACKEND_LAYSIZE(state->crtc_w,
189 					   state->crtc_h));
190 
191 	/* Set base coordinates */
192 	DRM_DEBUG_DRIVER("Layer coordinates X: %d Y: %d\n",
193 			 state->crtc_x, state->crtc_y);
194 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYCOOR_REG(layer),
195 		     SUN4I_BACKEND_LAYCOOR(state->crtc_x,
196 					   state->crtc_y));
197 
198 	return 0;
199 }
200 
201 static int sun4i_backend_update_yuv_format(struct sun4i_backend *backend,
202 					   int layer, struct drm_plane *plane)
203 {
204 	struct drm_plane_state *state = plane->state;
205 	struct drm_framebuffer *fb = state->fb;
206 	const struct drm_format_info *format = fb->format;
207 	const uint32_t fmt = format->format;
208 	u32 val = SUN4I_BACKEND_IYUVCTL_EN;
209 	int i;
210 
211 	for (i = 0; i < ARRAY_SIZE(sunxi_bt601_yuv2rgb_coef); i++)
212 		regmap_write(backend->engine.regs,
213 			     SUN4I_BACKEND_YGCOEF_REG(i),
214 			     sunxi_bt601_yuv2rgb_coef[i]);
215 
216 	/*
217 	 * We should do that only for a single plane, but the
218 	 * framebuffer's atomic_check has our back on this.
219 	 */
220 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
221 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN,
222 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN);
223 
224 	/* TODO: Add support for the multi-planar YUV formats */
225 	if (drm_format_info_is_yuv_packed(format) &&
226 	    drm_format_info_is_yuv_sampling_422(format))
227 		val |= SUN4I_BACKEND_IYUVCTL_FBFMT_PACKED_YUV422;
228 	else
229 		DRM_DEBUG_DRIVER("Unsupported YUV format (0x%x)\n", fmt);
230 
231 	/*
232 	 * Allwinner seems to list the pixel sequence from right to left, while
233 	 * DRM lists it from left to right.
234 	 */
235 	switch (fmt) {
236 	case DRM_FORMAT_YUYV:
237 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_VYUY;
238 		break;
239 	case DRM_FORMAT_YVYU:
240 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_UYVY;
241 		break;
242 	case DRM_FORMAT_UYVY:
243 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YVYU;
244 		break;
245 	case DRM_FORMAT_VYUY:
246 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YUYV;
247 		break;
248 	default:
249 		DRM_DEBUG_DRIVER("Unsupported YUV pixel sequence (0x%x)\n",
250 				 fmt);
251 	}
252 
253 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVCTL_REG, val);
254 
255 	return 0;
256 }
257 
258 int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
259 				       int layer, struct drm_plane *plane)
260 {
261 	struct drm_plane_state *state = plane->state;
262 	struct drm_framebuffer *fb = state->fb;
263 	bool interlaced = false;
264 	u32 val;
265 	int ret;
266 
267 	/* Clear the YUV mode */
268 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
269 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
270 
271 	if (plane->state->crtc)
272 		interlaced = plane->state->crtc->state->adjusted_mode.flags
273 			& DRM_MODE_FLAG_INTERLACE;
274 
275 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
276 			   SUN4I_BACKEND_MODCTL_ITLMOD_EN,
277 			   interlaced ? SUN4I_BACKEND_MODCTL_ITLMOD_EN : 0);
278 
279 	DRM_DEBUG_DRIVER("Switching display backend interlaced mode %s\n",
280 			 interlaced ? "on" : "off");
281 
282 	val = SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA(state->alpha >> 8);
283 	if (state->alpha != DRM_BLEND_ALPHA_OPAQUE)
284 		val |= SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN;
285 	regmap_update_bits(backend->engine.regs,
286 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
287 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_MASK |
288 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN,
289 			   val);
290 
291 	if (fb->format->is_yuv)
292 		return sun4i_backend_update_yuv_format(backend, layer, plane);
293 
294 	ret = sun4i_backend_drm_format_to_layer(fb->format->format, &val);
295 	if (ret) {
296 		DRM_DEBUG_DRIVER("Invalid format\n");
297 		return ret;
298 	}
299 
300 	regmap_update_bits(backend->engine.regs,
301 			   SUN4I_BACKEND_ATTCTL_REG1(layer),
302 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
303 
304 	return 0;
305 }
306 
307 int sun4i_backend_update_layer_frontend(struct sun4i_backend *backend,
308 					int layer, uint32_t fmt)
309 {
310 	u32 val;
311 	int ret;
312 
313 	ret = sun4i_backend_drm_format_to_layer(fmt, &val);
314 	if (ret) {
315 		DRM_DEBUG_DRIVER("Invalid format\n");
316 		return ret;
317 	}
318 
319 	regmap_update_bits(backend->engine.regs,
320 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
321 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN,
322 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN);
323 
324 	regmap_update_bits(backend->engine.regs,
325 			   SUN4I_BACKEND_ATTCTL_REG1(layer),
326 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
327 
328 	return 0;
329 }
330 
331 static int sun4i_backend_update_yuv_buffer(struct sun4i_backend *backend,
332 					   struct drm_framebuffer *fb,
333 					   dma_addr_t paddr)
334 {
335 	/* TODO: Add support for the multi-planar YUV formats */
336 	DRM_DEBUG_DRIVER("Setting packed YUV buffer address to %pad\n", &paddr);
337 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVADD_REG(0), paddr);
338 
339 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
340 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVLINEWIDTH_REG(0),
341 		     fb->pitches[0] * 8);
342 
343 	return 0;
344 }
345 
346 int sun4i_backend_update_layer_buffer(struct sun4i_backend *backend,
347 				      int layer, struct drm_plane *plane)
348 {
349 	struct drm_plane_state *state = plane->state;
350 	struct drm_framebuffer *fb = state->fb;
351 	u32 lo_paddr, hi_paddr;
352 	dma_addr_t paddr;
353 
354 	/* Set the line width */
355 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
356 	regmap_write(backend->engine.regs,
357 		     SUN4I_BACKEND_LAYLINEWIDTH_REG(layer),
358 		     fb->pitches[0] * 8);
359 
360 	/* Get the start of the displayed memory */
361 	paddr = drm_fb_cma_get_gem_addr(fb, state, 0);
362 	DRM_DEBUG_DRIVER("Setting buffer address to %pad\n", &paddr);
363 
364 	/*
365 	 * backend DMA accesses DRAM directly, bypassing the system
366 	 * bus. As such, the address range is different and the buffer
367 	 * address needs to be corrected.
368 	 */
369 	paddr -= PHYS_OFFSET;
370 
371 	if (fb->format->is_yuv)
372 		return sun4i_backend_update_yuv_buffer(backend, fb, paddr);
373 
374 	/* Write the 32 lower bits of the address (in bits) */
375 	lo_paddr = paddr << 3;
376 	DRM_DEBUG_DRIVER("Setting address lower bits to 0x%x\n", lo_paddr);
377 	regmap_write(backend->engine.regs,
378 		     SUN4I_BACKEND_LAYFB_L32ADD_REG(layer),
379 		     lo_paddr);
380 
381 	/* And the upper bits */
382 	hi_paddr = paddr >> 29;
383 	DRM_DEBUG_DRIVER("Setting address high bits to 0x%x\n", hi_paddr);
384 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_LAYFB_H4ADD_REG,
385 			   SUN4I_BACKEND_LAYFB_H4ADD_MSK(layer),
386 			   SUN4I_BACKEND_LAYFB_H4ADD(layer, hi_paddr));
387 
388 	return 0;
389 }
390 
391 int sun4i_backend_update_layer_zpos(struct sun4i_backend *backend, int layer,
392 				    struct drm_plane *plane)
393 {
394 	struct drm_plane_state *state = plane->state;
395 	struct sun4i_layer_state *p_state = state_to_sun4i_layer_state(state);
396 	unsigned int priority = state->normalized_zpos;
397 	unsigned int pipe = p_state->pipe;
398 
399 	DRM_DEBUG_DRIVER("Setting layer %d's priority to %d and pipe %d\n",
400 			 layer, priority, pipe);
401 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
402 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL_MASK |
403 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL_MASK,
404 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL(p_state->pipe) |
405 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL(priority));
406 
407 	return 0;
408 }
409 
410 void sun4i_backend_cleanup_layer(struct sun4i_backend *backend,
411 				 int layer)
412 {
413 	regmap_update_bits(backend->engine.regs,
414 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
415 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN |
416 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
417 }
418 
419 static bool sun4i_backend_plane_uses_scaler(struct drm_plane_state *state)
420 {
421 	u16 src_h = state->src_h >> 16;
422 	u16 src_w = state->src_w >> 16;
423 
424 	DRM_DEBUG_DRIVER("Input size %dx%d, output size %dx%d\n",
425 			 src_w, src_h, state->crtc_w, state->crtc_h);
426 
427 	if ((state->crtc_h != src_h) || (state->crtc_w != src_w))
428 		return true;
429 
430 	return false;
431 }
432 
433 static bool sun4i_backend_plane_uses_frontend(struct drm_plane_state *state)
434 {
435 	struct sun4i_layer *layer = plane_to_sun4i_layer(state->plane);
436 	struct sun4i_backend *backend = layer->backend;
437 	uint32_t format = state->fb->format->format;
438 	uint64_t modifier = state->fb->modifier;
439 
440 	if (IS_ERR(backend->frontend))
441 		return false;
442 
443 	if (!sun4i_frontend_format_is_supported(format, modifier))
444 		return false;
445 
446 	if (!sun4i_backend_format_is_supported(format, modifier))
447 		return true;
448 
449 	/*
450 	 * TODO: The backend alone allows 2x and 4x integer scaling, including
451 	 * support for an alpha component (which the frontend doesn't support).
452 	 * Use the backend directly instead of the frontend in this case, with
453 	 * another test to return false.
454 	 */
455 
456 	if (sun4i_backend_plane_uses_scaler(state))
457 		return true;
458 
459 	/*
460 	 * Here the format is supported by both the frontend and the backend
461 	 * and no frontend scaling is required, so use the backend directly.
462 	 */
463 	return false;
464 }
465 
466 static bool sun4i_backend_plane_is_supported(struct drm_plane_state *state,
467 					     bool *uses_frontend)
468 {
469 	if (sun4i_backend_plane_uses_frontend(state)) {
470 		*uses_frontend = true;
471 		return true;
472 	}
473 
474 	*uses_frontend = false;
475 
476 	/* Scaling is not supported without the frontend. */
477 	if (sun4i_backend_plane_uses_scaler(state))
478 		return false;
479 
480 	return true;
481 }
482 
483 static void sun4i_backend_atomic_begin(struct sunxi_engine *engine,
484 				       struct drm_crtc_state *old_state)
485 {
486 	u32 val;
487 
488 	WARN_ON(regmap_read_poll_timeout(engine->regs,
489 					 SUN4I_BACKEND_REGBUFFCTL_REG,
490 					 val, !(val & SUN4I_BACKEND_REGBUFFCTL_LOADCTL),
491 					 100, 50000));
492 }
493 
494 static int sun4i_backend_atomic_check(struct sunxi_engine *engine,
495 				      struct drm_crtc_state *crtc_state)
496 {
497 	struct drm_plane_state *plane_states[SUN4I_BACKEND_NUM_LAYERS] = { 0 };
498 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
499 	struct drm_atomic_state *state = crtc_state->state;
500 	struct drm_device *drm = state->dev;
501 	struct drm_plane *plane;
502 	unsigned int num_planes = 0;
503 	unsigned int num_alpha_planes = 0;
504 	unsigned int num_frontend_planes = 0;
505 	unsigned int num_alpha_planes_max = 1;
506 	unsigned int num_yuv_planes = 0;
507 	unsigned int current_pipe = 0;
508 	unsigned int i;
509 
510 	DRM_DEBUG_DRIVER("Starting checking our planes\n");
511 
512 	if (!crtc_state->planes_changed)
513 		return 0;
514 
515 	drm_for_each_plane_mask(plane, drm, crtc_state->plane_mask) {
516 		struct drm_plane_state *plane_state =
517 			drm_atomic_get_plane_state(state, plane);
518 		struct sun4i_layer_state *layer_state =
519 			state_to_sun4i_layer_state(plane_state);
520 		struct drm_framebuffer *fb = plane_state->fb;
521 		struct drm_format_name_buf format_name;
522 
523 		if (!sun4i_backend_plane_is_supported(plane_state,
524 						      &layer_state->uses_frontend))
525 			return -EINVAL;
526 
527 		if (layer_state->uses_frontend) {
528 			DRM_DEBUG_DRIVER("Using the frontend for plane %d\n",
529 					 plane->index);
530 			num_frontend_planes++;
531 		} else {
532 			if (fb->format->is_yuv) {
533 				DRM_DEBUG_DRIVER("Plane FB format is YUV\n");
534 				num_yuv_planes++;
535 			}
536 		}
537 
538 		DRM_DEBUG_DRIVER("Plane FB format is %s\n",
539 				 drm_get_format_name(fb->format->format,
540 						     &format_name));
541 		if (fb->format->has_alpha || (plane_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
542 			num_alpha_planes++;
543 
544 		DRM_DEBUG_DRIVER("Plane zpos is %d\n",
545 				 plane_state->normalized_zpos);
546 
547 		/* Sort our planes by Zpos */
548 		plane_states[plane_state->normalized_zpos] = plane_state;
549 
550 		num_planes++;
551 	}
552 
553 	/* All our planes were disabled, bail out */
554 	if (!num_planes)
555 		return 0;
556 
557 	/*
558 	 * The hardware is a bit unusual here.
559 	 *
560 	 * Even though it supports 4 layers, it does the composition
561 	 * in two separate steps.
562 	 *
563 	 * The first one is assigning a layer to one of its two
564 	 * pipes. If more that 1 layer is assigned to the same pipe,
565 	 * and if pixels overlaps, the pipe will take the pixel from
566 	 * the layer with the highest priority.
567 	 *
568 	 * The second step is the actual alpha blending, that takes
569 	 * the two pipes as input, and uses the potential alpha
570 	 * component to do the transparency between the two.
571 	 *
572 	 * This two-step scenario makes us unable to guarantee a
573 	 * robust alpha blending between the 4 layers in all
574 	 * situations, since this means that we need to have one layer
575 	 * with alpha at the lowest position of our two pipes.
576 	 *
577 	 * However, we cannot even do that on every platform, since
578 	 * the hardware has a bug where the lowest plane of the lowest
579 	 * pipe (pipe 0, priority 0), if it has any alpha, will
580 	 * discard the pixel data entirely and just display the pixels
581 	 * in the background color (black by default).
582 	 *
583 	 * This means that on the affected platforms, we effectively
584 	 * have only three valid configurations with alpha, all of
585 	 * them with the alpha being on pipe1 with the lowest
586 	 * position, which can be 1, 2 or 3 depending on the number of
587 	 * planes and their zpos.
588 	 */
589 
590 	/* For platforms that are not affected by the issue described above. */
591 	if (backend->quirks->supports_lowest_plane_alpha)
592 		num_alpha_planes_max++;
593 
594 	if (num_alpha_planes > num_alpha_planes_max) {
595 		DRM_DEBUG_DRIVER("Too many planes with alpha, rejecting...\n");
596 		return -EINVAL;
597 	}
598 
599 	/* We can't have an alpha plane at the lowest position */
600 	if (!backend->quirks->supports_lowest_plane_alpha &&
601 	    (plane_states[0]->fb->format->has_alpha ||
602 	    (plane_states[0]->alpha != DRM_BLEND_ALPHA_OPAQUE)))
603 		return -EINVAL;
604 
605 	for (i = 1; i < num_planes; i++) {
606 		struct drm_plane_state *p_state = plane_states[i];
607 		struct drm_framebuffer *fb = p_state->fb;
608 		struct sun4i_layer_state *s_state = state_to_sun4i_layer_state(p_state);
609 
610 		/*
611 		 * The only alpha position is the lowest plane of the
612 		 * second pipe.
613 		 */
614 		if (fb->format->has_alpha || (p_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
615 			current_pipe++;
616 
617 		s_state->pipe = current_pipe;
618 	}
619 
620 	/* We can only have a single YUV plane at a time */
621 	if (num_yuv_planes > SUN4I_BACKEND_NUM_YUV_PLANES) {
622 		DRM_DEBUG_DRIVER("Too many planes with YUV, rejecting...\n");
623 		return -EINVAL;
624 	}
625 
626 	if (num_frontend_planes > SUN4I_BACKEND_NUM_FRONTEND_LAYERS) {
627 		DRM_DEBUG_DRIVER("Too many planes going through the frontend, rejecting\n");
628 		return -EINVAL;
629 	}
630 
631 	DRM_DEBUG_DRIVER("State valid with %u planes, %u alpha, %u video, %u YUV\n",
632 			 num_planes, num_alpha_planes, num_frontend_planes,
633 			 num_yuv_planes);
634 
635 	return 0;
636 }
637 
638 static void sun4i_backend_vblank_quirk(struct sunxi_engine *engine)
639 {
640 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
641 	struct sun4i_frontend *frontend = backend->frontend;
642 
643 	if (!frontend)
644 		return;
645 
646 	/*
647 	 * In a teardown scenario with the frontend involved, we have
648 	 * to keep the frontend enabled until the next vblank, and
649 	 * only then disable it.
650 	 *
651 	 * This is due to the fact that the backend will not take into
652 	 * account the new configuration (with the plane that used to
653 	 * be fed by the frontend now disabled) until we write to the
654 	 * commit bit and the hardware fetches the new configuration
655 	 * during the next vblank.
656 	 *
657 	 * So we keep the frontend around in order to prevent any
658 	 * visual artifacts.
659 	 */
660 	spin_lock(&backend->frontend_lock);
661 	if (backend->frontend_teardown) {
662 		sun4i_frontend_exit(frontend);
663 		backend->frontend_teardown = false;
664 	}
665 	spin_unlock(&backend->frontend_lock);
666 };
667 
668 static int sun4i_backend_init_sat(struct device *dev) {
669 	struct sun4i_backend *backend = dev_get_drvdata(dev);
670 	int ret;
671 
672 	backend->sat_reset = devm_reset_control_get(dev, "sat");
673 	if (IS_ERR(backend->sat_reset)) {
674 		dev_err(dev, "Couldn't get the SAT reset line\n");
675 		return PTR_ERR(backend->sat_reset);
676 	}
677 
678 	ret = reset_control_deassert(backend->sat_reset);
679 	if (ret) {
680 		dev_err(dev, "Couldn't deassert the SAT reset line\n");
681 		return ret;
682 	}
683 
684 	backend->sat_clk = devm_clk_get(dev, "sat");
685 	if (IS_ERR(backend->sat_clk)) {
686 		dev_err(dev, "Couldn't get our SAT clock\n");
687 		ret = PTR_ERR(backend->sat_clk);
688 		goto err_assert_reset;
689 	}
690 
691 	ret = clk_prepare_enable(backend->sat_clk);
692 	if (ret) {
693 		dev_err(dev, "Couldn't enable the SAT clock\n");
694 		return ret;
695 	}
696 
697 	return 0;
698 
699 err_assert_reset:
700 	reset_control_assert(backend->sat_reset);
701 	return ret;
702 }
703 
704 static int sun4i_backend_free_sat(struct device *dev) {
705 	struct sun4i_backend *backend = dev_get_drvdata(dev);
706 
707 	clk_disable_unprepare(backend->sat_clk);
708 	reset_control_assert(backend->sat_reset);
709 
710 	return 0;
711 }
712 
713 /*
714  * The display backend can take video output from the display frontend, or
715  * the display enhancement unit on the A80, as input for one it its layers.
716  * This relationship within the display pipeline is encoded in the device
717  * tree with of_graph, and we use it here to figure out which backend, if
718  * there are 2 or more, we are currently probing. The number would be in
719  * the "reg" property of the upstream output port endpoint.
720  */
721 static int sun4i_backend_of_get_id(struct device_node *node)
722 {
723 	struct device_node *port, *ep;
724 	int ret = -EINVAL;
725 
726 	/* input is port 0 */
727 	port = of_graph_get_port_by_id(node, 0);
728 	if (!port)
729 		return -EINVAL;
730 
731 	/* try finding an upstream endpoint */
732 	for_each_available_child_of_node(port, ep) {
733 		struct device_node *remote;
734 		u32 reg;
735 
736 		remote = of_graph_get_remote_endpoint(ep);
737 		if (!remote)
738 			continue;
739 
740 		ret = of_property_read_u32(remote, "reg", &reg);
741 		if (ret)
742 			continue;
743 
744 		ret = reg;
745 	}
746 
747 	of_node_put(port);
748 
749 	return ret;
750 }
751 
752 /* TODO: This needs to take multiple pipelines into account */
753 static struct sun4i_frontend *sun4i_backend_find_frontend(struct sun4i_drv *drv,
754 							  struct device_node *node)
755 {
756 	struct device_node *port, *ep, *remote;
757 	struct sun4i_frontend *frontend;
758 
759 	port = of_graph_get_port_by_id(node, 0);
760 	if (!port)
761 		return ERR_PTR(-EINVAL);
762 
763 	for_each_available_child_of_node(port, ep) {
764 		remote = of_graph_get_remote_port_parent(ep);
765 		if (!remote)
766 			continue;
767 		of_node_put(remote);
768 
769 		/* does this node match any registered engines? */
770 		list_for_each_entry(frontend, &drv->frontend_list, list) {
771 			if (remote == frontend->node) {
772 				of_node_put(port);
773 				of_node_put(ep);
774 				return frontend;
775 			}
776 		}
777 	}
778 	of_node_put(port);
779 	return ERR_PTR(-EINVAL);
780 }
781 
782 static const struct sunxi_engine_ops sun4i_backend_engine_ops = {
783 	.atomic_begin			= sun4i_backend_atomic_begin,
784 	.atomic_check			= sun4i_backend_atomic_check,
785 	.commit				= sun4i_backend_commit,
786 	.layers_init			= sun4i_layers_init,
787 	.apply_color_correction		= sun4i_backend_apply_color_correction,
788 	.disable_color_correction	= sun4i_backend_disable_color_correction,
789 	.vblank_quirk			= sun4i_backend_vblank_quirk,
790 };
791 
792 static struct regmap_config sun4i_backend_regmap_config = {
793 	.reg_bits	= 32,
794 	.val_bits	= 32,
795 	.reg_stride	= 4,
796 	.max_register	= 0x5800,
797 };
798 
799 static int sun4i_backend_bind(struct device *dev, struct device *master,
800 			      void *data)
801 {
802 	struct platform_device *pdev = to_platform_device(dev);
803 	struct drm_device *drm = data;
804 	struct sun4i_drv *drv = drm->dev_private;
805 	struct sun4i_backend *backend;
806 	const struct sun4i_backend_quirks *quirks;
807 	struct resource *res;
808 	void __iomem *regs;
809 	int i, ret;
810 
811 	backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
812 	if (!backend)
813 		return -ENOMEM;
814 	dev_set_drvdata(dev, backend);
815 	spin_lock_init(&backend->frontend_lock);
816 
817 	backend->engine.node = dev->of_node;
818 	backend->engine.ops = &sun4i_backend_engine_ops;
819 	backend->engine.id = sun4i_backend_of_get_id(dev->of_node);
820 	if (backend->engine.id < 0)
821 		return backend->engine.id;
822 
823 	backend->frontend = sun4i_backend_find_frontend(drv, dev->of_node);
824 	if (IS_ERR(backend->frontend))
825 		dev_warn(dev, "Couldn't find matching frontend, frontend features disabled\n");
826 
827 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
828 	regs = devm_ioremap_resource(dev, res);
829 	if (IS_ERR(regs))
830 		return PTR_ERR(regs);
831 
832 	backend->reset = devm_reset_control_get(dev, NULL);
833 	if (IS_ERR(backend->reset)) {
834 		dev_err(dev, "Couldn't get our reset line\n");
835 		return PTR_ERR(backend->reset);
836 	}
837 
838 	ret = reset_control_deassert(backend->reset);
839 	if (ret) {
840 		dev_err(dev, "Couldn't deassert our reset line\n");
841 		return ret;
842 	}
843 
844 	backend->bus_clk = devm_clk_get(dev, "ahb");
845 	if (IS_ERR(backend->bus_clk)) {
846 		dev_err(dev, "Couldn't get the backend bus clock\n");
847 		ret = PTR_ERR(backend->bus_clk);
848 		goto err_assert_reset;
849 	}
850 	clk_prepare_enable(backend->bus_clk);
851 
852 	backend->mod_clk = devm_clk_get(dev, "mod");
853 	if (IS_ERR(backend->mod_clk)) {
854 		dev_err(dev, "Couldn't get the backend module clock\n");
855 		ret = PTR_ERR(backend->mod_clk);
856 		goto err_disable_bus_clk;
857 	}
858 	clk_prepare_enable(backend->mod_clk);
859 
860 	backend->ram_clk = devm_clk_get(dev, "ram");
861 	if (IS_ERR(backend->ram_clk)) {
862 		dev_err(dev, "Couldn't get the backend RAM clock\n");
863 		ret = PTR_ERR(backend->ram_clk);
864 		goto err_disable_mod_clk;
865 	}
866 	clk_prepare_enable(backend->ram_clk);
867 
868 	if (of_device_is_compatible(dev->of_node,
869 				    "allwinner,sun8i-a33-display-backend")) {
870 		ret = sun4i_backend_init_sat(dev);
871 		if (ret) {
872 			dev_err(dev, "Couldn't init SAT resources\n");
873 			goto err_disable_ram_clk;
874 		}
875 	}
876 
877 	backend->engine.regs = devm_regmap_init_mmio(dev, regs,
878 						     &sun4i_backend_regmap_config);
879 	if (IS_ERR(backend->engine.regs)) {
880 		dev_err(dev, "Couldn't create the backend regmap\n");
881 		return PTR_ERR(backend->engine.regs);
882 	}
883 
884 	list_add_tail(&backend->engine.list, &drv->engine_list);
885 
886 	/*
887 	 * Many of the backend's layer configuration registers have
888 	 * undefined default values. This poses a risk as we use
889 	 * regmap_update_bits in some places, and don't overwrite
890 	 * the whole register.
891 	 *
892 	 * Clear the registers here to have something predictable.
893 	 */
894 	for (i = 0x800; i < 0x1000; i += 4)
895 		regmap_write(backend->engine.regs, i, 0);
896 
897 	/* Disable registers autoloading */
898 	regmap_write(backend->engine.regs, SUN4I_BACKEND_REGBUFFCTL_REG,
899 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS);
900 
901 	/* Enable the backend */
902 	regmap_write(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
903 		     SUN4I_BACKEND_MODCTL_DEBE_EN |
904 		     SUN4I_BACKEND_MODCTL_START_CTL);
905 
906 	/* Set output selection if needed */
907 	quirks = of_device_get_match_data(dev);
908 	if (quirks->needs_output_muxing) {
909 		/*
910 		 * We assume there is no dynamic muxing of backends
911 		 * and TCONs, so we select the backend with same ID.
912 		 *
913 		 * While dynamic selection might be interesting, since
914 		 * the CRTC is tied to the TCON, while the layers are
915 		 * tied to the backends, this means, we will need to
916 		 * switch between groups of layers. There might not be
917 		 * a way to represent this constraint in DRM.
918 		 */
919 		regmap_update_bits(backend->engine.regs,
920 				   SUN4I_BACKEND_MODCTL_REG,
921 				   SUN4I_BACKEND_MODCTL_OUT_SEL,
922 				   (backend->engine.id
923 				    ? SUN4I_BACKEND_MODCTL_OUT_LCD1
924 				    : SUN4I_BACKEND_MODCTL_OUT_LCD0));
925 	}
926 
927 	backend->quirks = quirks;
928 
929 	return 0;
930 
931 err_disable_ram_clk:
932 	clk_disable_unprepare(backend->ram_clk);
933 err_disable_mod_clk:
934 	clk_disable_unprepare(backend->mod_clk);
935 err_disable_bus_clk:
936 	clk_disable_unprepare(backend->bus_clk);
937 err_assert_reset:
938 	reset_control_assert(backend->reset);
939 	return ret;
940 }
941 
942 static void sun4i_backend_unbind(struct device *dev, struct device *master,
943 				 void *data)
944 {
945 	struct sun4i_backend *backend = dev_get_drvdata(dev);
946 
947 	list_del(&backend->engine.list);
948 
949 	if (of_device_is_compatible(dev->of_node,
950 				    "allwinner,sun8i-a33-display-backend"))
951 		sun4i_backend_free_sat(dev);
952 
953 	clk_disable_unprepare(backend->ram_clk);
954 	clk_disable_unprepare(backend->mod_clk);
955 	clk_disable_unprepare(backend->bus_clk);
956 	reset_control_assert(backend->reset);
957 }
958 
959 static const struct component_ops sun4i_backend_ops = {
960 	.bind	= sun4i_backend_bind,
961 	.unbind	= sun4i_backend_unbind,
962 };
963 
964 static int sun4i_backend_probe(struct platform_device *pdev)
965 {
966 	return component_add(&pdev->dev, &sun4i_backend_ops);
967 }
968 
969 static int sun4i_backend_remove(struct platform_device *pdev)
970 {
971 	component_del(&pdev->dev, &sun4i_backend_ops);
972 
973 	return 0;
974 }
975 
976 static const struct sun4i_backend_quirks sun4i_backend_quirks = {
977 	.needs_output_muxing = true,
978 };
979 
980 static const struct sun4i_backend_quirks sun5i_backend_quirks = {
981 };
982 
983 static const struct sun4i_backend_quirks sun6i_backend_quirks = {
984 };
985 
986 static const struct sun4i_backend_quirks sun7i_backend_quirks = {
987 	.needs_output_muxing = true,
988 	.supports_lowest_plane_alpha = true,
989 };
990 
991 static const struct sun4i_backend_quirks sun8i_a33_backend_quirks = {
992 	.supports_lowest_plane_alpha = true,
993 };
994 
995 static const struct sun4i_backend_quirks sun9i_backend_quirks = {
996 };
997 
998 static const struct of_device_id sun4i_backend_of_table[] = {
999 	{
1000 		.compatible = "allwinner,sun4i-a10-display-backend",
1001 		.data = &sun4i_backend_quirks,
1002 	},
1003 	{
1004 		.compatible = "allwinner,sun5i-a13-display-backend",
1005 		.data = &sun5i_backend_quirks,
1006 	},
1007 	{
1008 		.compatible = "allwinner,sun6i-a31-display-backend",
1009 		.data = &sun6i_backend_quirks,
1010 	},
1011 	{
1012 		.compatible = "allwinner,sun7i-a20-display-backend",
1013 		.data = &sun7i_backend_quirks,
1014 	},
1015 	{
1016 		.compatible = "allwinner,sun8i-a23-display-backend",
1017 		.data = &sun8i_a33_backend_quirks,
1018 	},
1019 	{
1020 		.compatible = "allwinner,sun8i-a33-display-backend",
1021 		.data = &sun8i_a33_backend_quirks,
1022 	},
1023 	{
1024 		.compatible = "allwinner,sun9i-a80-display-backend",
1025 		.data = &sun9i_backend_quirks,
1026 	},
1027 	{ }
1028 };
1029 MODULE_DEVICE_TABLE(of, sun4i_backend_of_table);
1030 
1031 static struct platform_driver sun4i_backend_platform_driver = {
1032 	.probe		= sun4i_backend_probe,
1033 	.remove		= sun4i_backend_remove,
1034 	.driver		= {
1035 		.name		= "sun4i-backend",
1036 		.of_match_table	= sun4i_backend_of_table,
1037 	},
1038 };
1039 module_platform_driver(sun4i_backend_platform_driver);
1040 
1041 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
1042 MODULE_DESCRIPTION("Allwinner A10 Display Backend Driver");
1043 MODULE_LICENSE("GPL");
1044