xref: /linux/drivers/gpu/drm/sun4i/sun4i_backend.c (revision 9e56ff53b4115875667760445b028357848b4748)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2015 Free Electrons
4  * Copyright (C) 2015 NextThing Co
5  *
6  * Maxime Ripard <maxime.ripard@free-electrons.com>
7  */
8 
9 #include <linux/component.h>
10 #include <linux/list.h>
11 #include <linux/module.h>
12 #include <linux/of_device.h>
13 #include <linux/of_graph.h>
14 #include <linux/dma-mapping.h>
15 #include <linux/platform_device.h>
16 #include <linux/reset.h>
17 
18 #include <drm/drm_atomic.h>
19 #include <drm/drm_atomic_helper.h>
20 #include <drm/drm_blend.h>
21 #include <drm/drm_crtc.h>
22 #include <drm/drm_fb_dma_helper.h>
23 #include <drm/drm_fourcc.h>
24 #include <drm/drm_framebuffer.h>
25 #include <drm/drm_gem_dma_helper.h>
26 #include <drm/drm_probe_helper.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 	/* Set height and width */
177 	DRM_DEBUG_DRIVER("Layer size W: %u H: %u\n",
178 			 state->crtc_w, state->crtc_h);
179 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYSIZE_REG(layer),
180 		     SUN4I_BACKEND_LAYSIZE(state->crtc_w,
181 					   state->crtc_h));
182 
183 	/* Set base coordinates */
184 	DRM_DEBUG_DRIVER("Layer coordinates X: %d Y: %d\n",
185 			 state->crtc_x, state->crtc_y);
186 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYCOOR_REG(layer),
187 		     SUN4I_BACKEND_LAYCOOR(state->crtc_x,
188 					   state->crtc_y));
189 
190 	return 0;
191 }
192 
193 static int sun4i_backend_update_yuv_format(struct sun4i_backend *backend,
194 					   int layer, struct drm_plane *plane)
195 {
196 	struct drm_plane_state *state = plane->state;
197 	struct drm_framebuffer *fb = state->fb;
198 	const struct drm_format_info *format = fb->format;
199 	const uint32_t fmt = format->format;
200 	u32 val = SUN4I_BACKEND_IYUVCTL_EN;
201 	int i;
202 
203 	for (i = 0; i < ARRAY_SIZE(sunxi_bt601_yuv2rgb_coef); i++)
204 		regmap_write(backend->engine.regs,
205 			     SUN4I_BACKEND_YGCOEF_REG(i),
206 			     sunxi_bt601_yuv2rgb_coef[i]);
207 
208 	/*
209 	 * We should do that only for a single plane, but the
210 	 * framebuffer's atomic_check has our back on this.
211 	 */
212 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
213 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN,
214 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN);
215 
216 	/* TODO: Add support for the multi-planar YUV formats */
217 	if (drm_format_info_is_yuv_packed(format) &&
218 	    drm_format_info_is_yuv_sampling_422(format))
219 		val |= SUN4I_BACKEND_IYUVCTL_FBFMT_PACKED_YUV422;
220 	else
221 		DRM_DEBUG_DRIVER("Unsupported YUV format (0x%x)\n", fmt);
222 
223 	/*
224 	 * Allwinner seems to list the pixel sequence from right to left, while
225 	 * DRM lists it from left to right.
226 	 */
227 	switch (fmt) {
228 	case DRM_FORMAT_YUYV:
229 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_VYUY;
230 		break;
231 	case DRM_FORMAT_YVYU:
232 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_UYVY;
233 		break;
234 	case DRM_FORMAT_UYVY:
235 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YVYU;
236 		break;
237 	case DRM_FORMAT_VYUY:
238 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YUYV;
239 		break;
240 	default:
241 		DRM_DEBUG_DRIVER("Unsupported YUV pixel sequence (0x%x)\n",
242 				 fmt);
243 	}
244 
245 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVCTL_REG, val);
246 
247 	return 0;
248 }
249 
250 int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
251 				       int layer, struct drm_plane *plane)
252 {
253 	struct drm_plane_state *state = plane->state;
254 	struct drm_framebuffer *fb = state->fb;
255 	u32 val;
256 	int ret;
257 
258 	/* Clear the YUV mode */
259 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
260 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
261 
262 	val = SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA(state->alpha >> 8);
263 	if (state->alpha != DRM_BLEND_ALPHA_OPAQUE)
264 		val |= SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN;
265 	regmap_update_bits(backend->engine.regs,
266 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
267 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_MASK |
268 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN,
269 			   val);
270 
271 	if (fb->format->is_yuv)
272 		return sun4i_backend_update_yuv_format(backend, layer, plane);
273 
274 	ret = sun4i_backend_drm_format_to_layer(fb->format->format, &val);
275 	if (ret) {
276 		DRM_DEBUG_DRIVER("Invalid format\n");
277 		return ret;
278 	}
279 
280 	regmap_update_bits(backend->engine.regs,
281 			   SUN4I_BACKEND_ATTCTL_REG1(layer),
282 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
283 
284 	return 0;
285 }
286 
287 int sun4i_backend_update_layer_frontend(struct sun4i_backend *backend,
288 					int layer, uint32_t fmt)
289 {
290 	u32 val;
291 	int ret;
292 
293 	ret = sun4i_backend_drm_format_to_layer(fmt, &val);
294 	if (ret) {
295 		DRM_DEBUG_DRIVER("Invalid format\n");
296 		return ret;
297 	}
298 
299 	regmap_update_bits(backend->engine.regs,
300 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
301 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN,
302 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN);
303 
304 	regmap_update_bits(backend->engine.regs,
305 			   SUN4I_BACKEND_ATTCTL_REG1(layer),
306 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
307 
308 	return 0;
309 }
310 
311 static int sun4i_backend_update_yuv_buffer(struct sun4i_backend *backend,
312 					   struct drm_framebuffer *fb,
313 					   dma_addr_t paddr)
314 {
315 	/* TODO: Add support for the multi-planar YUV formats */
316 	DRM_DEBUG_DRIVER("Setting packed YUV buffer address to %pad\n", &paddr);
317 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVADD_REG(0), paddr);
318 
319 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
320 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVLINEWIDTH_REG(0),
321 		     fb->pitches[0] * 8);
322 
323 	return 0;
324 }
325 
326 int sun4i_backend_update_layer_buffer(struct sun4i_backend *backend,
327 				      int layer, struct drm_plane *plane)
328 {
329 	struct drm_plane_state *state = plane->state;
330 	struct drm_framebuffer *fb = state->fb;
331 	u32 lo_paddr, hi_paddr;
332 	dma_addr_t dma_addr;
333 
334 	/* Set the line width */
335 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
336 	regmap_write(backend->engine.regs,
337 		     SUN4I_BACKEND_LAYLINEWIDTH_REG(layer),
338 		     fb->pitches[0] * 8);
339 
340 	/* Get the start of the displayed memory */
341 	dma_addr = drm_fb_dma_get_gem_addr(fb, state, 0);
342 	DRM_DEBUG_DRIVER("Setting buffer address to %pad\n", &dma_addr);
343 
344 	if (fb->format->is_yuv)
345 		return sun4i_backend_update_yuv_buffer(backend, fb, dma_addr);
346 
347 	/* Write the 32 lower bits of the address (in bits) */
348 	lo_paddr = dma_addr << 3;
349 	DRM_DEBUG_DRIVER("Setting address lower bits to 0x%x\n", lo_paddr);
350 	regmap_write(backend->engine.regs,
351 		     SUN4I_BACKEND_LAYFB_L32ADD_REG(layer),
352 		     lo_paddr);
353 
354 	/* And the upper bits */
355 	hi_paddr = dma_addr >> 29;
356 	DRM_DEBUG_DRIVER("Setting address high bits to 0x%x\n", hi_paddr);
357 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_LAYFB_H4ADD_REG,
358 			   SUN4I_BACKEND_LAYFB_H4ADD_MSK(layer),
359 			   SUN4I_BACKEND_LAYFB_H4ADD(layer, hi_paddr));
360 
361 	return 0;
362 }
363 
364 int sun4i_backend_update_layer_zpos(struct sun4i_backend *backend, int layer,
365 				    struct drm_plane *plane)
366 {
367 	struct drm_plane_state *state = plane->state;
368 	struct sun4i_layer_state *p_state = state_to_sun4i_layer_state(state);
369 	unsigned int priority = state->normalized_zpos;
370 	unsigned int pipe = p_state->pipe;
371 
372 	DRM_DEBUG_DRIVER("Setting layer %d's priority to %d and pipe %d\n",
373 			 layer, priority, pipe);
374 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
375 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL_MASK |
376 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL_MASK,
377 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL(p_state->pipe) |
378 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL(priority));
379 
380 	return 0;
381 }
382 
383 void sun4i_backend_cleanup_layer(struct sun4i_backend *backend,
384 				 int layer)
385 {
386 	regmap_update_bits(backend->engine.regs,
387 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
388 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN |
389 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
390 }
391 
392 static bool sun4i_backend_plane_uses_scaler(struct drm_plane_state *state)
393 {
394 	u16 src_h = state->src_h >> 16;
395 	u16 src_w = state->src_w >> 16;
396 
397 	DRM_DEBUG_DRIVER("Input size %dx%d, output size %dx%d\n",
398 			 src_w, src_h, state->crtc_w, state->crtc_h);
399 
400 	if ((state->crtc_h != src_h) || (state->crtc_w != src_w))
401 		return true;
402 
403 	return false;
404 }
405 
406 static bool sun4i_backend_plane_uses_frontend(struct drm_plane_state *state)
407 {
408 	struct sun4i_layer *layer = plane_to_sun4i_layer(state->plane);
409 	struct sun4i_backend *backend = layer->backend;
410 	uint32_t format = state->fb->format->format;
411 	uint64_t modifier = state->fb->modifier;
412 
413 	if (IS_ERR(backend->frontend))
414 		return false;
415 
416 	if (!sun4i_frontend_format_is_supported(format, modifier))
417 		return false;
418 
419 	if (!sun4i_backend_format_is_supported(format, modifier))
420 		return true;
421 
422 	/*
423 	 * TODO: The backend alone allows 2x and 4x integer scaling, including
424 	 * support for an alpha component (which the frontend doesn't support).
425 	 * Use the backend directly instead of the frontend in this case, with
426 	 * another test to return false.
427 	 */
428 
429 	if (sun4i_backend_plane_uses_scaler(state))
430 		return true;
431 
432 	/*
433 	 * Here the format is supported by both the frontend and the backend
434 	 * and no frontend scaling is required, so use the backend directly.
435 	 */
436 	return false;
437 }
438 
439 static bool sun4i_backend_plane_is_supported(struct drm_plane_state *state,
440 					     bool *uses_frontend)
441 {
442 	if (sun4i_backend_plane_uses_frontend(state)) {
443 		*uses_frontend = true;
444 		return true;
445 	}
446 
447 	*uses_frontend = false;
448 
449 	/* Scaling is not supported without the frontend. */
450 	if (sun4i_backend_plane_uses_scaler(state))
451 		return false;
452 
453 	return true;
454 }
455 
456 static void sun4i_backend_atomic_begin(struct sunxi_engine *engine,
457 				       struct drm_crtc_state *old_state)
458 {
459 	u32 val;
460 
461 	WARN_ON(regmap_read_poll_timeout(engine->regs,
462 					 SUN4I_BACKEND_REGBUFFCTL_REG,
463 					 val, !(val & SUN4I_BACKEND_REGBUFFCTL_LOADCTL),
464 					 100, 50000));
465 }
466 
467 static int sun4i_backend_atomic_check(struct sunxi_engine *engine,
468 				      struct drm_crtc_state *crtc_state)
469 {
470 	struct drm_plane_state *plane_states[SUN4I_BACKEND_NUM_LAYERS] = { 0 };
471 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
472 	struct drm_atomic_state *state = crtc_state->state;
473 	struct drm_device *drm = state->dev;
474 	struct drm_plane *plane;
475 	unsigned int num_planes = 0;
476 	unsigned int num_alpha_planes = 0;
477 	unsigned int num_frontend_planes = 0;
478 	unsigned int num_alpha_planes_max = 1;
479 	unsigned int num_yuv_planes = 0;
480 	unsigned int current_pipe = 0;
481 	unsigned int i;
482 
483 	DRM_DEBUG_DRIVER("Starting checking our planes\n");
484 
485 	if (!crtc_state->planes_changed)
486 		return 0;
487 
488 	drm_for_each_plane_mask(plane, drm, crtc_state->plane_mask) {
489 		struct drm_plane_state *plane_state =
490 			drm_atomic_get_plane_state(state, plane);
491 		struct sun4i_layer_state *layer_state =
492 			state_to_sun4i_layer_state(plane_state);
493 		struct drm_framebuffer *fb = plane_state->fb;
494 
495 		if (!sun4i_backend_plane_is_supported(plane_state,
496 						      &layer_state->uses_frontend))
497 			return -EINVAL;
498 
499 		if (layer_state->uses_frontend) {
500 			DRM_DEBUG_DRIVER("Using the frontend for plane %d\n",
501 					 plane->index);
502 			num_frontend_planes++;
503 		} else {
504 			if (fb->format->is_yuv) {
505 				DRM_DEBUG_DRIVER("Plane FB format is YUV\n");
506 				num_yuv_planes++;
507 			}
508 		}
509 
510 		DRM_DEBUG_DRIVER("Plane FB format is %p4cc\n",
511 				 &fb->format->format);
512 		if (fb->format->has_alpha || (plane_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
513 			num_alpha_planes++;
514 
515 		DRM_DEBUG_DRIVER("Plane zpos is %d\n",
516 				 plane_state->normalized_zpos);
517 
518 		/* Sort our planes by Zpos */
519 		plane_states[plane_state->normalized_zpos] = plane_state;
520 
521 		num_planes++;
522 	}
523 
524 	/* All our planes were disabled, bail out */
525 	if (!num_planes)
526 		return 0;
527 
528 	/*
529 	 * The hardware is a bit unusual here.
530 	 *
531 	 * Even though it supports 4 layers, it does the composition
532 	 * in two separate steps.
533 	 *
534 	 * The first one is assigning a layer to one of its two
535 	 * pipes. If more that 1 layer is assigned to the same pipe,
536 	 * and if pixels overlaps, the pipe will take the pixel from
537 	 * the layer with the highest priority.
538 	 *
539 	 * The second step is the actual alpha blending, that takes
540 	 * the two pipes as input, and uses the potential alpha
541 	 * component to do the transparency between the two.
542 	 *
543 	 * This two-step scenario makes us unable to guarantee a
544 	 * robust alpha blending between the 4 layers in all
545 	 * situations, since this means that we need to have one layer
546 	 * with alpha at the lowest position of our two pipes.
547 	 *
548 	 * However, we cannot even do that on every platform, since
549 	 * the hardware has a bug where the lowest plane of the lowest
550 	 * pipe (pipe 0, priority 0), if it has any alpha, will
551 	 * discard the pixel data entirely and just display the pixels
552 	 * in the background color (black by default).
553 	 *
554 	 * This means that on the affected platforms, we effectively
555 	 * have only three valid configurations with alpha, all of
556 	 * them with the alpha being on pipe1 with the lowest
557 	 * position, which can be 1, 2 or 3 depending on the number of
558 	 * planes and their zpos.
559 	 */
560 
561 	/* For platforms that are not affected by the issue described above. */
562 	if (backend->quirks->supports_lowest_plane_alpha)
563 		num_alpha_planes_max++;
564 
565 	if (num_alpha_planes > num_alpha_planes_max) {
566 		DRM_DEBUG_DRIVER("Too many planes with alpha, rejecting...\n");
567 		return -EINVAL;
568 	}
569 
570 	/* We can't have an alpha plane at the lowest position */
571 	if (!backend->quirks->supports_lowest_plane_alpha &&
572 	    (plane_states[0]->alpha != DRM_BLEND_ALPHA_OPAQUE))
573 		return -EINVAL;
574 
575 	for (i = 1; i < num_planes; i++) {
576 		struct drm_plane_state *p_state = plane_states[i];
577 		struct drm_framebuffer *fb = p_state->fb;
578 		struct sun4i_layer_state *s_state = state_to_sun4i_layer_state(p_state);
579 
580 		/*
581 		 * The only alpha position is the lowest plane of the
582 		 * second pipe.
583 		 */
584 		if (fb->format->has_alpha || (p_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
585 			current_pipe++;
586 
587 		s_state->pipe = current_pipe;
588 	}
589 
590 	/* We can only have a single YUV plane at a time */
591 	if (num_yuv_planes > SUN4I_BACKEND_NUM_YUV_PLANES) {
592 		DRM_DEBUG_DRIVER("Too many planes with YUV, rejecting...\n");
593 		return -EINVAL;
594 	}
595 
596 	if (num_frontend_planes > SUN4I_BACKEND_NUM_FRONTEND_LAYERS) {
597 		DRM_DEBUG_DRIVER("Too many planes going through the frontend, rejecting\n");
598 		return -EINVAL;
599 	}
600 
601 	DRM_DEBUG_DRIVER("State valid with %u planes, %u alpha, %u video, %u YUV\n",
602 			 num_planes, num_alpha_planes, num_frontend_planes,
603 			 num_yuv_planes);
604 
605 	return 0;
606 }
607 
608 static void sun4i_backend_vblank_quirk(struct sunxi_engine *engine)
609 {
610 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
611 	struct sun4i_frontend *frontend = backend->frontend;
612 
613 	if (!frontend)
614 		return;
615 
616 	/*
617 	 * In a teardown scenario with the frontend involved, we have
618 	 * to keep the frontend enabled until the next vblank, and
619 	 * only then disable it.
620 	 *
621 	 * This is due to the fact that the backend will not take into
622 	 * account the new configuration (with the plane that used to
623 	 * be fed by the frontend now disabled) until we write to the
624 	 * commit bit and the hardware fetches the new configuration
625 	 * during the next vblank.
626 	 *
627 	 * So we keep the frontend around in order to prevent any
628 	 * visual artifacts.
629 	 */
630 	spin_lock(&backend->frontend_lock);
631 	if (backend->frontend_teardown) {
632 		sun4i_frontend_exit(frontend);
633 		backend->frontend_teardown = false;
634 	}
635 	spin_unlock(&backend->frontend_lock);
636 };
637 
638 static void sun4i_backend_mode_set(struct sunxi_engine *engine,
639 				   const struct drm_display_mode *mode)
640 {
641 	bool interlaced = !!(mode->flags & DRM_MODE_FLAG_INTERLACE);
642 
643 	DRM_DEBUG_DRIVER("Updating global size W: %u H: %u\n",
644 			 mode->hdisplay, mode->vdisplay);
645 
646 	regmap_write(engine->regs, SUN4I_BACKEND_DISSIZE_REG,
647 		     SUN4I_BACKEND_DISSIZE(mode->hdisplay, mode->vdisplay));
648 
649 	regmap_update_bits(engine->regs, SUN4I_BACKEND_MODCTL_REG,
650 			   SUN4I_BACKEND_MODCTL_ITLMOD_EN,
651 			   interlaced ? SUN4I_BACKEND_MODCTL_ITLMOD_EN : 0);
652 
653 	DRM_DEBUG_DRIVER("Switching display backend interlaced mode %s\n",
654 			 interlaced ? "on" : "off");
655 }
656 
657 static int sun4i_backend_init_sat(struct device *dev) {
658 	struct sun4i_backend *backend = dev_get_drvdata(dev);
659 	int ret;
660 
661 	backend->sat_reset = devm_reset_control_get(dev, "sat");
662 	if (IS_ERR(backend->sat_reset)) {
663 		dev_err(dev, "Couldn't get the SAT reset line\n");
664 		return PTR_ERR(backend->sat_reset);
665 	}
666 
667 	ret = reset_control_deassert(backend->sat_reset);
668 	if (ret) {
669 		dev_err(dev, "Couldn't deassert the SAT reset line\n");
670 		return ret;
671 	}
672 
673 	backend->sat_clk = devm_clk_get(dev, "sat");
674 	if (IS_ERR(backend->sat_clk)) {
675 		dev_err(dev, "Couldn't get our SAT clock\n");
676 		ret = PTR_ERR(backend->sat_clk);
677 		goto err_assert_reset;
678 	}
679 
680 	ret = clk_prepare_enable(backend->sat_clk);
681 	if (ret) {
682 		dev_err(dev, "Couldn't enable the SAT clock\n");
683 		return ret;
684 	}
685 
686 	return 0;
687 
688 err_assert_reset:
689 	reset_control_assert(backend->sat_reset);
690 	return ret;
691 }
692 
693 static int sun4i_backend_free_sat(struct device *dev) {
694 	struct sun4i_backend *backend = dev_get_drvdata(dev);
695 
696 	clk_disable_unprepare(backend->sat_clk);
697 	reset_control_assert(backend->sat_reset);
698 
699 	return 0;
700 }
701 
702 /*
703  * The display backend can take video output from the display frontend, or
704  * the display enhancement unit on the A80, as input for one it its layers.
705  * This relationship within the display pipeline is encoded in the device
706  * tree with of_graph, and we use it here to figure out which backend, if
707  * there are 2 or more, we are currently probing. The number would be in
708  * the "reg" property of the upstream output port endpoint.
709  */
710 static int sun4i_backend_of_get_id(struct device_node *node)
711 {
712 	struct device_node *ep, *remote;
713 	struct of_endpoint of_ep;
714 
715 	/* Input port is 0, and we want the first endpoint. */
716 	ep = of_graph_get_endpoint_by_regs(node, 0, -1);
717 	if (!ep)
718 		return -EINVAL;
719 
720 	remote = of_graph_get_remote_endpoint(ep);
721 	of_node_put(ep);
722 	if (!remote)
723 		return -EINVAL;
724 
725 	of_graph_parse_endpoint(remote, &of_ep);
726 	of_node_put(remote);
727 	return of_ep.id;
728 }
729 
730 /* TODO: This needs to take multiple pipelines into account */
731 static struct sun4i_frontend *sun4i_backend_find_frontend(struct sun4i_drv *drv,
732 							  struct device_node *node)
733 {
734 	struct device_node *port, *ep, *remote;
735 	struct sun4i_frontend *frontend;
736 
737 	port = of_graph_get_port_by_id(node, 0);
738 	if (!port)
739 		return ERR_PTR(-EINVAL);
740 
741 	for_each_available_child_of_node(port, ep) {
742 		remote = of_graph_get_remote_port_parent(ep);
743 		if (!remote)
744 			continue;
745 		of_node_put(remote);
746 
747 		/* does this node match any registered engines? */
748 		list_for_each_entry(frontend, &drv->frontend_list, list) {
749 			if (remote == frontend->node) {
750 				of_node_put(port);
751 				of_node_put(ep);
752 				return frontend;
753 			}
754 		}
755 	}
756 	of_node_put(port);
757 	return ERR_PTR(-EINVAL);
758 }
759 
760 static const struct sunxi_engine_ops sun4i_backend_engine_ops = {
761 	.atomic_begin			= sun4i_backend_atomic_begin,
762 	.atomic_check			= sun4i_backend_atomic_check,
763 	.commit				= sun4i_backend_commit,
764 	.layers_init			= sun4i_layers_init,
765 	.apply_color_correction		= sun4i_backend_apply_color_correction,
766 	.disable_color_correction	= sun4i_backend_disable_color_correction,
767 	.vblank_quirk			= sun4i_backend_vblank_quirk,
768 	.mode_set			= sun4i_backend_mode_set,
769 };
770 
771 static const struct regmap_config sun4i_backend_regmap_config = {
772 	.reg_bits	= 32,
773 	.val_bits	= 32,
774 	.reg_stride	= 4,
775 	.max_register	= 0x5800,
776 };
777 
778 static int sun4i_backend_bind(struct device *dev, struct device *master,
779 			      void *data)
780 {
781 	struct platform_device *pdev = to_platform_device(dev);
782 	struct drm_device *drm = data;
783 	struct sun4i_drv *drv = drm->dev_private;
784 	struct sun4i_backend *backend;
785 	const struct sun4i_backend_quirks *quirks;
786 	void __iomem *regs;
787 	int i, ret;
788 
789 	backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
790 	if (!backend)
791 		return -ENOMEM;
792 	dev_set_drvdata(dev, backend);
793 	spin_lock_init(&backend->frontend_lock);
794 
795 	if (of_property_present(dev->of_node, "interconnects")) {
796 		/*
797 		 * This assume we have the same DMA constraints for all our the
798 		 * devices in our pipeline (all the backends, but also the
799 		 * frontends). This sounds bad, but it has always been the case
800 		 * for us, and DRM doesn't do per-device allocation either, so
801 		 * we would need to fix DRM first...
802 		 */
803 		ret = of_dma_configure(drm->dev, dev->of_node, true);
804 		if (ret)
805 			return ret;
806 	}
807 
808 	backend->engine.node = dev->of_node;
809 	backend->engine.ops = &sun4i_backend_engine_ops;
810 	backend->engine.id = sun4i_backend_of_get_id(dev->of_node);
811 	if (backend->engine.id < 0)
812 		return backend->engine.id;
813 
814 	backend->frontend = sun4i_backend_find_frontend(drv, dev->of_node);
815 	if (IS_ERR(backend->frontend))
816 		dev_warn(dev, "Couldn't find matching frontend, frontend features disabled\n");
817 
818 	regs = devm_platform_ioremap_resource(pdev, 0);
819 	if (IS_ERR(regs))
820 		return PTR_ERR(regs);
821 
822 	backend->reset = devm_reset_control_get(dev, NULL);
823 	if (IS_ERR(backend->reset)) {
824 		dev_err(dev, "Couldn't get our reset line\n");
825 		return PTR_ERR(backend->reset);
826 	}
827 
828 	ret = reset_control_deassert(backend->reset);
829 	if (ret) {
830 		dev_err(dev, "Couldn't deassert our reset line\n");
831 		return ret;
832 	}
833 
834 	backend->bus_clk = devm_clk_get(dev, "ahb");
835 	if (IS_ERR(backend->bus_clk)) {
836 		dev_err(dev, "Couldn't get the backend bus clock\n");
837 		ret = PTR_ERR(backend->bus_clk);
838 		goto err_assert_reset;
839 	}
840 	clk_prepare_enable(backend->bus_clk);
841 
842 	backend->mod_clk = devm_clk_get(dev, "mod");
843 	if (IS_ERR(backend->mod_clk)) {
844 		dev_err(dev, "Couldn't get the backend module clock\n");
845 		ret = PTR_ERR(backend->mod_clk);
846 		goto err_disable_bus_clk;
847 	}
848 
849 	ret = clk_set_rate_exclusive(backend->mod_clk, 300000000);
850 	if (ret) {
851 		dev_err(dev, "Couldn't set the module clock frequency\n");
852 		goto err_disable_bus_clk;
853 	}
854 
855 	clk_prepare_enable(backend->mod_clk);
856 
857 	backend->ram_clk = devm_clk_get(dev, "ram");
858 	if (IS_ERR(backend->ram_clk)) {
859 		dev_err(dev, "Couldn't get the backend RAM clock\n");
860 		ret = PTR_ERR(backend->ram_clk);
861 		goto err_disable_mod_clk;
862 	}
863 	clk_prepare_enable(backend->ram_clk);
864 
865 	if (of_device_is_compatible(dev->of_node,
866 				    "allwinner,sun8i-a33-display-backend")) {
867 		ret = sun4i_backend_init_sat(dev);
868 		if (ret) {
869 			dev_err(dev, "Couldn't init SAT resources\n");
870 			goto err_disable_ram_clk;
871 		}
872 	}
873 
874 	backend->engine.regs = devm_regmap_init_mmio(dev, regs,
875 						     &sun4i_backend_regmap_config);
876 	if (IS_ERR(backend->engine.regs)) {
877 		dev_err(dev, "Couldn't create the backend regmap\n");
878 		return PTR_ERR(backend->engine.regs);
879 	}
880 
881 	list_add_tail(&backend->engine.list, &drv->engine_list);
882 
883 	/*
884 	 * Many of the backend's layer configuration registers have
885 	 * undefined default values. This poses a risk as we use
886 	 * regmap_update_bits in some places, and don't overwrite
887 	 * the whole register.
888 	 *
889 	 * Clear the registers here to have something predictable.
890 	 */
891 	for (i = 0x800; i < 0x1000; i += 4)
892 		regmap_write(backend->engine.regs, i, 0);
893 
894 	/* Disable registers autoloading */
895 	regmap_write(backend->engine.regs, SUN4I_BACKEND_REGBUFFCTL_REG,
896 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS);
897 
898 	/* Enable the backend */
899 	regmap_write(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
900 		     SUN4I_BACKEND_MODCTL_DEBE_EN |
901 		     SUN4I_BACKEND_MODCTL_START_CTL);
902 
903 	/* Set output selection if needed */
904 	quirks = of_device_get_match_data(dev);
905 	if (quirks->needs_output_muxing) {
906 		/*
907 		 * We assume there is no dynamic muxing of backends
908 		 * and TCONs, so we select the backend with same ID.
909 		 *
910 		 * While dynamic selection might be interesting, since
911 		 * the CRTC is tied to the TCON, while the layers are
912 		 * tied to the backends, this means, we will need to
913 		 * switch between groups of layers. There might not be
914 		 * a way to represent this constraint in DRM.
915 		 */
916 		regmap_update_bits(backend->engine.regs,
917 				   SUN4I_BACKEND_MODCTL_REG,
918 				   SUN4I_BACKEND_MODCTL_OUT_SEL,
919 				   (backend->engine.id
920 				    ? SUN4I_BACKEND_MODCTL_OUT_LCD1
921 				    : SUN4I_BACKEND_MODCTL_OUT_LCD0));
922 	}
923 
924 	backend->quirks = quirks;
925 
926 	return 0;
927 
928 err_disable_ram_clk:
929 	clk_disable_unprepare(backend->ram_clk);
930 err_disable_mod_clk:
931 	clk_rate_exclusive_put(backend->mod_clk);
932 	clk_disable_unprepare(backend->mod_clk);
933 err_disable_bus_clk:
934 	clk_disable_unprepare(backend->bus_clk);
935 err_assert_reset:
936 	reset_control_assert(backend->reset);
937 	return ret;
938 }
939 
940 static void sun4i_backend_unbind(struct device *dev, struct device *master,
941 				 void *data)
942 {
943 	struct sun4i_backend *backend = dev_get_drvdata(dev);
944 
945 	list_del(&backend->engine.list);
946 
947 	if (of_device_is_compatible(dev->of_node,
948 				    "allwinner,sun8i-a33-display-backend"))
949 		sun4i_backend_free_sat(dev);
950 
951 	clk_disable_unprepare(backend->ram_clk);
952 	clk_rate_exclusive_put(backend->mod_clk);
953 	clk_disable_unprepare(backend->mod_clk);
954 	clk_disable_unprepare(backend->bus_clk);
955 	reset_control_assert(backend->reset);
956 }
957 
958 static const struct component_ops sun4i_backend_ops = {
959 	.bind	= sun4i_backend_bind,
960 	.unbind	= sun4i_backend_unbind,
961 };
962 
963 static int sun4i_backend_probe(struct platform_device *pdev)
964 {
965 	return component_add(&pdev->dev, &sun4i_backend_ops);
966 }
967 
968 static void sun4i_backend_remove(struct platform_device *pdev)
969 {
970 	component_del(&pdev->dev, &sun4i_backend_ops);
971 }
972 
973 static const struct sun4i_backend_quirks sun4i_backend_quirks = {
974 	.needs_output_muxing = true,
975 };
976 
977 static const struct sun4i_backend_quirks sun5i_backend_quirks = {
978 };
979 
980 static const struct sun4i_backend_quirks sun6i_backend_quirks = {
981 };
982 
983 static const struct sun4i_backend_quirks sun7i_backend_quirks = {
984 	.needs_output_muxing = true,
985 };
986 
987 static const struct sun4i_backend_quirks sun8i_a33_backend_quirks = {
988 	.supports_lowest_plane_alpha = true,
989 };
990 
991 static const struct sun4i_backend_quirks sun9i_backend_quirks = {
992 };
993 
994 static const struct of_device_id sun4i_backend_of_table[] = {
995 	{
996 		.compatible = "allwinner,sun4i-a10-display-backend",
997 		.data = &sun4i_backend_quirks,
998 	},
999 	{
1000 		.compatible = "allwinner,sun5i-a13-display-backend",
1001 		.data = &sun5i_backend_quirks,
1002 	},
1003 	{
1004 		.compatible = "allwinner,sun6i-a31-display-backend",
1005 		.data = &sun6i_backend_quirks,
1006 	},
1007 	{
1008 		.compatible = "allwinner,sun7i-a20-display-backend",
1009 		.data = &sun7i_backend_quirks,
1010 	},
1011 	{
1012 		.compatible = "allwinner,sun8i-a23-display-backend",
1013 		.data = &sun8i_a33_backend_quirks,
1014 	},
1015 	{
1016 		.compatible = "allwinner,sun8i-a33-display-backend",
1017 		.data = &sun8i_a33_backend_quirks,
1018 	},
1019 	{
1020 		.compatible = "allwinner,sun9i-a80-display-backend",
1021 		.data = &sun9i_backend_quirks,
1022 	},
1023 	{ }
1024 };
1025 MODULE_DEVICE_TABLE(of, sun4i_backend_of_table);
1026 
1027 static struct platform_driver sun4i_backend_platform_driver = {
1028 	.probe		= sun4i_backend_probe,
1029 	.remove_new	= sun4i_backend_remove,
1030 	.driver		= {
1031 		.name		= "sun4i-backend",
1032 		.of_match_table	= sun4i_backend_of_table,
1033 	},
1034 };
1035 module_platform_driver(sun4i_backend_platform_driver);
1036 
1037 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
1038 MODULE_DESCRIPTION("Allwinner A10 Display Backend Driver");
1039 MODULE_LICENSE("GPL");
1040