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_crtc.h>
21 #include <drm/drm_fb_cma_helper.h>
22 #include <drm/drm_fourcc.h>
23 #include <drm/drm_gem_cma_helper.h>
24 #include <drm/drm_plane_helper.h>
25 #include <drm/drm_probe_helper.h>
26 
27 #include "sun4i_backend.h"
28 #include "sun4i_drv.h"
29 #include "sun4i_frontend.h"
30 #include "sun4i_layer.h"
31 #include "sunxi_engine.h"
32 
33 struct sun4i_backend_quirks {
34 	/* backend <-> TCON muxing selection done in backend */
35 	bool needs_output_muxing;
36 
37 	/* alpha at the lowest z position is not always supported */
38 	bool supports_lowest_plane_alpha;
39 };
40 
41 static const u32 sunxi_rgb2yuv_coef[12] = {
42 	0x00000107, 0x00000204, 0x00000064, 0x00000108,
43 	0x00003f69, 0x00003ed6, 0x000001c1, 0x00000808,
44 	0x000001c1, 0x00003e88, 0x00003fb8, 0x00000808
45 };
46 
47 static void sun4i_backend_apply_color_correction(struct sunxi_engine *engine)
48 {
49 	int i;
50 
51 	DRM_DEBUG_DRIVER("Applying RGB to YUV color correction\n");
52 
53 	/* Set color correction */
54 	regmap_write(engine->regs, SUN4I_BACKEND_OCCTL_REG,
55 		     SUN4I_BACKEND_OCCTL_ENABLE);
56 
57 	for (i = 0; i < 12; i++)
58 		regmap_write(engine->regs, SUN4I_BACKEND_OCRCOEF_REG(i),
59 			     sunxi_rgb2yuv_coef[i]);
60 }
61 
62 static void sun4i_backend_disable_color_correction(struct sunxi_engine *engine)
63 {
64 	DRM_DEBUG_DRIVER("Disabling color correction\n");
65 
66 	/* Disable color correction */
67 	regmap_update_bits(engine->regs, SUN4I_BACKEND_OCCTL_REG,
68 			   SUN4I_BACKEND_OCCTL_ENABLE, 0);
69 }
70 
71 static void sun4i_backend_commit(struct sunxi_engine *engine)
72 {
73 	DRM_DEBUG_DRIVER("Committing changes\n");
74 
75 	regmap_write(engine->regs, SUN4I_BACKEND_REGBUFFCTL_REG,
76 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS |
77 		     SUN4I_BACKEND_REGBUFFCTL_LOADCTL);
78 }
79 
80 void sun4i_backend_layer_enable(struct sun4i_backend *backend,
81 				int layer, bool enable)
82 {
83 	u32 val;
84 
85 	DRM_DEBUG_DRIVER("%sabling layer %d\n", enable ? "En" : "Dis",
86 			 layer);
87 
88 	if (enable)
89 		val = SUN4I_BACKEND_MODCTL_LAY_EN(layer);
90 	else
91 		val = 0;
92 
93 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
94 			   SUN4I_BACKEND_MODCTL_LAY_EN(layer), val);
95 }
96 
97 static int sun4i_backend_drm_format_to_layer(u32 format, u32 *mode)
98 {
99 	switch (format) {
100 	case DRM_FORMAT_ARGB8888:
101 		*mode = SUN4I_BACKEND_LAY_FBFMT_ARGB8888;
102 		break;
103 
104 	case DRM_FORMAT_ARGB4444:
105 		*mode = SUN4I_BACKEND_LAY_FBFMT_ARGB4444;
106 		break;
107 
108 	case DRM_FORMAT_ARGB1555:
109 		*mode = SUN4I_BACKEND_LAY_FBFMT_ARGB1555;
110 		break;
111 
112 	case DRM_FORMAT_RGBA5551:
113 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGBA5551;
114 		break;
115 
116 	case DRM_FORMAT_RGBA4444:
117 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGBA4444;
118 		break;
119 
120 	case DRM_FORMAT_XRGB8888:
121 		*mode = SUN4I_BACKEND_LAY_FBFMT_XRGB8888;
122 		break;
123 
124 	case DRM_FORMAT_RGB888:
125 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGB888;
126 		break;
127 
128 	case DRM_FORMAT_RGB565:
129 		*mode = SUN4I_BACKEND_LAY_FBFMT_RGB565;
130 		break;
131 
132 	default:
133 		return -EINVAL;
134 	}
135 
136 	return 0;
137 }
138 
139 static const uint32_t sun4i_backend_formats[] = {
140 	DRM_FORMAT_ARGB1555,
141 	DRM_FORMAT_ARGB4444,
142 	DRM_FORMAT_ARGB8888,
143 	DRM_FORMAT_RGB565,
144 	DRM_FORMAT_RGB888,
145 	DRM_FORMAT_RGBA4444,
146 	DRM_FORMAT_RGBA5551,
147 	DRM_FORMAT_UYVY,
148 	DRM_FORMAT_VYUY,
149 	DRM_FORMAT_XRGB8888,
150 	DRM_FORMAT_YUYV,
151 	DRM_FORMAT_YVYU,
152 };
153 
154 bool sun4i_backend_format_is_supported(uint32_t fmt, uint64_t modifier)
155 {
156 	unsigned int i;
157 
158 	if (modifier != DRM_FORMAT_MOD_LINEAR)
159 		return false;
160 
161 	for (i = 0; i < ARRAY_SIZE(sun4i_backend_formats); i++)
162 		if (sun4i_backend_formats[i] == fmt)
163 			return true;
164 
165 	return false;
166 }
167 
168 int sun4i_backend_update_layer_coord(struct sun4i_backend *backend,
169 				     int layer, struct drm_plane *plane)
170 {
171 	struct drm_plane_state *state = plane->state;
172 
173 	DRM_DEBUG_DRIVER("Updating layer %d\n", layer);
174 
175 	/* Set height and width */
176 	DRM_DEBUG_DRIVER("Layer size W: %u H: %u\n",
177 			 state->crtc_w, state->crtc_h);
178 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYSIZE_REG(layer),
179 		     SUN4I_BACKEND_LAYSIZE(state->crtc_w,
180 					   state->crtc_h));
181 
182 	/* Set base coordinates */
183 	DRM_DEBUG_DRIVER("Layer coordinates X: %d Y: %d\n",
184 			 state->crtc_x, state->crtc_y);
185 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYCOOR_REG(layer),
186 		     SUN4I_BACKEND_LAYCOOR(state->crtc_x,
187 					   state->crtc_y));
188 
189 	return 0;
190 }
191 
192 static int sun4i_backend_update_yuv_format(struct sun4i_backend *backend,
193 					   int layer, struct drm_plane *plane)
194 {
195 	struct drm_plane_state *state = plane->state;
196 	struct drm_framebuffer *fb = state->fb;
197 	const struct drm_format_info *format = fb->format;
198 	const uint32_t fmt = format->format;
199 	u32 val = SUN4I_BACKEND_IYUVCTL_EN;
200 	int i;
201 
202 	for (i = 0; i < ARRAY_SIZE(sunxi_bt601_yuv2rgb_coef); i++)
203 		regmap_write(backend->engine.regs,
204 			     SUN4I_BACKEND_YGCOEF_REG(i),
205 			     sunxi_bt601_yuv2rgb_coef[i]);
206 
207 	/*
208 	 * We should do that only for a single plane, but the
209 	 * framebuffer's atomic_check has our back on this.
210 	 */
211 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
212 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN,
213 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN);
214 
215 	/* TODO: Add support for the multi-planar YUV formats */
216 	if (drm_format_info_is_yuv_packed(format) &&
217 	    drm_format_info_is_yuv_sampling_422(format))
218 		val |= SUN4I_BACKEND_IYUVCTL_FBFMT_PACKED_YUV422;
219 	else
220 		DRM_DEBUG_DRIVER("Unsupported YUV format (0x%x)\n", fmt);
221 
222 	/*
223 	 * Allwinner seems to list the pixel sequence from right to left, while
224 	 * DRM lists it from left to right.
225 	 */
226 	switch (fmt) {
227 	case DRM_FORMAT_YUYV:
228 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_VYUY;
229 		break;
230 	case DRM_FORMAT_YVYU:
231 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_UYVY;
232 		break;
233 	case DRM_FORMAT_UYVY:
234 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YVYU;
235 		break;
236 	case DRM_FORMAT_VYUY:
237 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YUYV;
238 		break;
239 	default:
240 		DRM_DEBUG_DRIVER("Unsupported YUV pixel sequence (0x%x)\n",
241 				 fmt);
242 	}
243 
244 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVCTL_REG, val);
245 
246 	return 0;
247 }
248 
249 int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
250 				       int layer, struct drm_plane *plane)
251 {
252 	struct drm_plane_state *state = plane->state;
253 	struct drm_framebuffer *fb = state->fb;
254 	u32 val;
255 	int ret;
256 
257 	/* Clear the YUV mode */
258 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
259 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
260 
261 	val = SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA(state->alpha >> 8);
262 	if (state->alpha != DRM_BLEND_ALPHA_OPAQUE)
263 		val |= SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN;
264 	regmap_update_bits(backend->engine.regs,
265 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
266 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_MASK |
267 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN,
268 			   val);
269 
270 	if (fb->format->is_yuv)
271 		return sun4i_backend_update_yuv_format(backend, layer, plane);
272 
273 	ret = sun4i_backend_drm_format_to_layer(fb->format->format, &val);
274 	if (ret) {
275 		DRM_DEBUG_DRIVER("Invalid format\n");
276 		return ret;
277 	}
278 
279 	regmap_update_bits(backend->engine.regs,
280 			   SUN4I_BACKEND_ATTCTL_REG1(layer),
281 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
282 
283 	return 0;
284 }
285 
286 int sun4i_backend_update_layer_frontend(struct sun4i_backend *backend,
287 					int layer, uint32_t fmt)
288 {
289 	u32 val;
290 	int ret;
291 
292 	ret = sun4i_backend_drm_format_to_layer(fmt, &val);
293 	if (ret) {
294 		DRM_DEBUG_DRIVER("Invalid format\n");
295 		return ret;
296 	}
297 
298 	regmap_update_bits(backend->engine.regs,
299 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
300 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN,
301 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN);
302 
303 	regmap_update_bits(backend->engine.regs,
304 			   SUN4I_BACKEND_ATTCTL_REG1(layer),
305 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
306 
307 	return 0;
308 }
309 
310 static int sun4i_backend_update_yuv_buffer(struct sun4i_backend *backend,
311 					   struct drm_framebuffer *fb,
312 					   dma_addr_t paddr)
313 {
314 	/* TODO: Add support for the multi-planar YUV formats */
315 	DRM_DEBUG_DRIVER("Setting packed YUV buffer address to %pad\n", &paddr);
316 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVADD_REG(0), paddr);
317 
318 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
319 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVLINEWIDTH_REG(0),
320 		     fb->pitches[0] * 8);
321 
322 	return 0;
323 }
324 
325 int sun4i_backend_update_layer_buffer(struct sun4i_backend *backend,
326 				      int layer, struct drm_plane *plane)
327 {
328 	struct drm_plane_state *state = plane->state;
329 	struct drm_framebuffer *fb = state->fb;
330 	u32 lo_paddr, hi_paddr;
331 	dma_addr_t paddr;
332 
333 	/* Set the line width */
334 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
335 	regmap_write(backend->engine.regs,
336 		     SUN4I_BACKEND_LAYLINEWIDTH_REG(layer),
337 		     fb->pitches[0] * 8);
338 
339 	/* Get the start of the displayed memory */
340 	paddr = drm_fb_cma_get_gem_addr(fb, state, 0);
341 	DRM_DEBUG_DRIVER("Setting buffer address to %pad\n", &paddr);
342 
343 	if (fb->format->is_yuv)
344 		return sun4i_backend_update_yuv_buffer(backend, fb, paddr);
345 
346 	/* Write the 32 lower bits of the address (in bits) */
347 	lo_paddr = paddr << 3;
348 	DRM_DEBUG_DRIVER("Setting address lower bits to 0x%x\n", lo_paddr);
349 	regmap_write(backend->engine.regs,
350 		     SUN4I_BACKEND_LAYFB_L32ADD_REG(layer),
351 		     lo_paddr);
352 
353 	/* And the upper bits */
354 	hi_paddr = paddr >> 29;
355 	DRM_DEBUG_DRIVER("Setting address high bits to 0x%x\n", hi_paddr);
356 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_LAYFB_H4ADD_REG,
357 			   SUN4I_BACKEND_LAYFB_H4ADD_MSK(layer),
358 			   SUN4I_BACKEND_LAYFB_H4ADD(layer, hi_paddr));
359 
360 	return 0;
361 }
362 
363 int sun4i_backend_update_layer_zpos(struct sun4i_backend *backend, int layer,
364 				    struct drm_plane *plane)
365 {
366 	struct drm_plane_state *state = plane->state;
367 	struct sun4i_layer_state *p_state = state_to_sun4i_layer_state(state);
368 	unsigned int priority = state->normalized_zpos;
369 	unsigned int pipe = p_state->pipe;
370 
371 	DRM_DEBUG_DRIVER("Setting layer %d's priority to %d and pipe %d\n",
372 			 layer, priority, pipe);
373 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
374 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL_MASK |
375 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL_MASK,
376 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL(p_state->pipe) |
377 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL(priority));
378 
379 	return 0;
380 }
381 
382 void sun4i_backend_cleanup_layer(struct sun4i_backend *backend,
383 				 int layer)
384 {
385 	regmap_update_bits(backend->engine.regs,
386 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
387 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN |
388 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
389 }
390 
391 static bool sun4i_backend_plane_uses_scaler(struct drm_plane_state *state)
392 {
393 	u16 src_h = state->src_h >> 16;
394 	u16 src_w = state->src_w >> 16;
395 
396 	DRM_DEBUG_DRIVER("Input size %dx%d, output size %dx%d\n",
397 			 src_w, src_h, state->crtc_w, state->crtc_h);
398 
399 	if ((state->crtc_h != src_h) || (state->crtc_w != src_w))
400 		return true;
401 
402 	return false;
403 }
404 
405 static bool sun4i_backend_plane_uses_frontend(struct drm_plane_state *state)
406 {
407 	struct sun4i_layer *layer = plane_to_sun4i_layer(state->plane);
408 	struct sun4i_backend *backend = layer->backend;
409 	uint32_t format = state->fb->format->format;
410 	uint64_t modifier = state->fb->modifier;
411 
412 	if (IS_ERR(backend->frontend))
413 		return false;
414 
415 	if (!sun4i_frontend_format_is_supported(format, modifier))
416 		return false;
417 
418 	if (!sun4i_backend_format_is_supported(format, modifier))
419 		return true;
420 
421 	/*
422 	 * TODO: The backend alone allows 2x and 4x integer scaling, including
423 	 * support for an alpha component (which the frontend doesn't support).
424 	 * Use the backend directly instead of the frontend in this case, with
425 	 * another test to return false.
426 	 */
427 
428 	if (sun4i_backend_plane_uses_scaler(state))
429 		return true;
430 
431 	/*
432 	 * Here the format is supported by both the frontend and the backend
433 	 * and no frontend scaling is required, so use the backend directly.
434 	 */
435 	return false;
436 }
437 
438 static bool sun4i_backend_plane_is_supported(struct drm_plane_state *state,
439 					     bool *uses_frontend)
440 {
441 	if (sun4i_backend_plane_uses_frontend(state)) {
442 		*uses_frontend = true;
443 		return true;
444 	}
445 
446 	*uses_frontend = false;
447 
448 	/* Scaling is not supported without the frontend. */
449 	if (sun4i_backend_plane_uses_scaler(state))
450 		return false;
451 
452 	return true;
453 }
454 
455 static void sun4i_backend_atomic_begin(struct sunxi_engine *engine,
456 				       struct drm_crtc_state *old_state)
457 {
458 	u32 val;
459 
460 	WARN_ON(regmap_read_poll_timeout(engine->regs,
461 					 SUN4I_BACKEND_REGBUFFCTL_REG,
462 					 val, !(val & SUN4I_BACKEND_REGBUFFCTL_LOADCTL),
463 					 100, 50000));
464 }
465 
466 static int sun4i_backend_atomic_check(struct sunxi_engine *engine,
467 				      struct drm_crtc_state *crtc_state)
468 {
469 	struct drm_plane_state *plane_states[SUN4I_BACKEND_NUM_LAYERS] = { 0 };
470 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
471 	struct drm_atomic_state *state = crtc_state->state;
472 	struct drm_device *drm = state->dev;
473 	struct drm_plane *plane;
474 	unsigned int num_planes = 0;
475 	unsigned int num_alpha_planes = 0;
476 	unsigned int num_frontend_planes = 0;
477 	unsigned int num_alpha_planes_max = 1;
478 	unsigned int num_yuv_planes = 0;
479 	unsigned int current_pipe = 0;
480 	unsigned int i;
481 
482 	DRM_DEBUG_DRIVER("Starting checking our planes\n");
483 
484 	if (!crtc_state->planes_changed)
485 		return 0;
486 
487 	drm_for_each_plane_mask(plane, drm, crtc_state->plane_mask) {
488 		struct drm_plane_state *plane_state =
489 			drm_atomic_get_plane_state(state, plane);
490 		struct sun4i_layer_state *layer_state =
491 			state_to_sun4i_layer_state(plane_state);
492 		struct drm_framebuffer *fb = plane_state->fb;
493 
494 		if (!sun4i_backend_plane_is_supported(plane_state,
495 						      &layer_state->uses_frontend))
496 			return -EINVAL;
497 
498 		if (layer_state->uses_frontend) {
499 			DRM_DEBUG_DRIVER("Using the frontend for plane %d\n",
500 					 plane->index);
501 			num_frontend_planes++;
502 		} else {
503 			if (fb->format->is_yuv) {
504 				DRM_DEBUG_DRIVER("Plane FB format is YUV\n");
505 				num_yuv_planes++;
506 			}
507 		}
508 
509 		DRM_DEBUG_DRIVER("Plane FB format is %p4cc\n",
510 				 &fb->format->format);
511 		if (fb->format->has_alpha || (plane_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
512 			num_alpha_planes++;
513 
514 		DRM_DEBUG_DRIVER("Plane zpos is %d\n",
515 				 plane_state->normalized_zpos);
516 
517 		/* Sort our planes by Zpos */
518 		plane_states[plane_state->normalized_zpos] = plane_state;
519 
520 		num_planes++;
521 	}
522 
523 	/* All our planes were disabled, bail out */
524 	if (!num_planes)
525 		return 0;
526 
527 	/*
528 	 * The hardware is a bit unusual here.
529 	 *
530 	 * Even though it supports 4 layers, it does the composition
531 	 * in two separate steps.
532 	 *
533 	 * The first one is assigning a layer to one of its two
534 	 * pipes. If more that 1 layer is assigned to the same pipe,
535 	 * and if pixels overlaps, the pipe will take the pixel from
536 	 * the layer with the highest priority.
537 	 *
538 	 * The second step is the actual alpha blending, that takes
539 	 * the two pipes as input, and uses the potential alpha
540 	 * component to do the transparency between the two.
541 	 *
542 	 * This two-step scenario makes us unable to guarantee a
543 	 * robust alpha blending between the 4 layers in all
544 	 * situations, since this means that we need to have one layer
545 	 * with alpha at the lowest position of our two pipes.
546 	 *
547 	 * However, we cannot even do that on every platform, since
548 	 * the hardware has a bug where the lowest plane of the lowest
549 	 * pipe (pipe 0, priority 0), if it has any alpha, will
550 	 * discard the pixel data entirely and just display the pixels
551 	 * in the background color (black by default).
552 	 *
553 	 * This means that on the affected platforms, we effectively
554 	 * have only three valid configurations with alpha, all of
555 	 * them with the alpha being on pipe1 with the lowest
556 	 * position, which can be 1, 2 or 3 depending on the number of
557 	 * planes and their zpos.
558 	 */
559 
560 	/* For platforms that are not affected by the issue described above. */
561 	if (backend->quirks->supports_lowest_plane_alpha)
562 		num_alpha_planes_max++;
563 
564 	if (num_alpha_planes > num_alpha_planes_max) {
565 		DRM_DEBUG_DRIVER("Too many planes with alpha, rejecting...\n");
566 		return -EINVAL;
567 	}
568 
569 	/* We can't have an alpha plane at the lowest position */
570 	if (!backend->quirks->supports_lowest_plane_alpha &&
571 	    (plane_states[0]->alpha != DRM_BLEND_ALPHA_OPAQUE))
572 		return -EINVAL;
573 
574 	for (i = 1; i < num_planes; i++) {
575 		struct drm_plane_state *p_state = plane_states[i];
576 		struct drm_framebuffer *fb = p_state->fb;
577 		struct sun4i_layer_state *s_state = state_to_sun4i_layer_state(p_state);
578 
579 		/*
580 		 * The only alpha position is the lowest plane of the
581 		 * second pipe.
582 		 */
583 		if (fb->format->has_alpha || (p_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
584 			current_pipe++;
585 
586 		s_state->pipe = current_pipe;
587 	}
588 
589 	/* We can only have a single YUV plane at a time */
590 	if (num_yuv_planes > SUN4I_BACKEND_NUM_YUV_PLANES) {
591 		DRM_DEBUG_DRIVER("Too many planes with YUV, rejecting...\n");
592 		return -EINVAL;
593 	}
594 
595 	if (num_frontend_planes > SUN4I_BACKEND_NUM_FRONTEND_LAYERS) {
596 		DRM_DEBUG_DRIVER("Too many planes going through the frontend, rejecting\n");
597 		return -EINVAL;
598 	}
599 
600 	DRM_DEBUG_DRIVER("State valid with %u planes, %u alpha, %u video, %u YUV\n",
601 			 num_planes, num_alpha_planes, num_frontend_planes,
602 			 num_yuv_planes);
603 
604 	return 0;
605 }
606 
607 static void sun4i_backend_vblank_quirk(struct sunxi_engine *engine)
608 {
609 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
610 	struct sun4i_frontend *frontend = backend->frontend;
611 
612 	if (!frontend)
613 		return;
614 
615 	/*
616 	 * In a teardown scenario with the frontend involved, we have
617 	 * to keep the frontend enabled until the next vblank, and
618 	 * only then disable it.
619 	 *
620 	 * This is due to the fact that the backend will not take into
621 	 * account the new configuration (with the plane that used to
622 	 * be fed by the frontend now disabled) until we write to the
623 	 * commit bit and the hardware fetches the new configuration
624 	 * during the next vblank.
625 	 *
626 	 * So we keep the frontend around in order to prevent any
627 	 * visual artifacts.
628 	 */
629 	spin_lock(&backend->frontend_lock);
630 	if (backend->frontend_teardown) {
631 		sun4i_frontend_exit(frontend);
632 		backend->frontend_teardown = false;
633 	}
634 	spin_unlock(&backend->frontend_lock);
635 };
636 
637 static void sun4i_backend_mode_set(struct sunxi_engine *engine,
638 				   const struct drm_display_mode *mode)
639 {
640 	bool interlaced = !!(mode->flags & DRM_MODE_FLAG_INTERLACE);
641 
642 	DRM_DEBUG_DRIVER("Updating global size W: %u H: %u\n",
643 			 mode->hdisplay, mode->vdisplay);
644 
645 	regmap_write(engine->regs, SUN4I_BACKEND_DISSIZE_REG,
646 		     SUN4I_BACKEND_DISSIZE(mode->hdisplay, mode->vdisplay));
647 
648 	regmap_update_bits(engine->regs, SUN4I_BACKEND_MODCTL_REG,
649 			   SUN4I_BACKEND_MODCTL_ITLMOD_EN,
650 			   interlaced ? SUN4I_BACKEND_MODCTL_ITLMOD_EN : 0);
651 
652 	DRM_DEBUG_DRIVER("Switching display backend interlaced mode %s\n",
653 			 interlaced ? "on" : "off");
654 }
655 
656 static int sun4i_backend_init_sat(struct device *dev) {
657 	struct sun4i_backend *backend = dev_get_drvdata(dev);
658 	int ret;
659 
660 	backend->sat_reset = devm_reset_control_get(dev, "sat");
661 	if (IS_ERR(backend->sat_reset)) {
662 		dev_err(dev, "Couldn't get the SAT reset line\n");
663 		return PTR_ERR(backend->sat_reset);
664 	}
665 
666 	ret = reset_control_deassert(backend->sat_reset);
667 	if (ret) {
668 		dev_err(dev, "Couldn't deassert the SAT reset line\n");
669 		return ret;
670 	}
671 
672 	backend->sat_clk = devm_clk_get(dev, "sat");
673 	if (IS_ERR(backend->sat_clk)) {
674 		dev_err(dev, "Couldn't get our SAT clock\n");
675 		ret = PTR_ERR(backend->sat_clk);
676 		goto err_assert_reset;
677 	}
678 
679 	ret = clk_prepare_enable(backend->sat_clk);
680 	if (ret) {
681 		dev_err(dev, "Couldn't enable the SAT clock\n");
682 		return ret;
683 	}
684 
685 	return 0;
686 
687 err_assert_reset:
688 	reset_control_assert(backend->sat_reset);
689 	return ret;
690 }
691 
692 static int sun4i_backend_free_sat(struct device *dev) {
693 	struct sun4i_backend *backend = dev_get_drvdata(dev);
694 
695 	clk_disable_unprepare(backend->sat_clk);
696 	reset_control_assert(backend->sat_reset);
697 
698 	return 0;
699 }
700 
701 /*
702  * The display backend can take video output from the display frontend, or
703  * the display enhancement unit on the A80, as input for one it its layers.
704  * This relationship within the display pipeline is encoded in the device
705  * tree with of_graph, and we use it here to figure out which backend, if
706  * there are 2 or more, we are currently probing. The number would be in
707  * the "reg" property of the upstream output port endpoint.
708  */
709 static int sun4i_backend_of_get_id(struct device_node *node)
710 {
711 	struct device_node *ep, *remote;
712 	struct of_endpoint of_ep;
713 
714 	/* Input port is 0, and we want the first endpoint. */
715 	ep = of_graph_get_endpoint_by_regs(node, 0, -1);
716 	if (!ep)
717 		return -EINVAL;
718 
719 	remote = of_graph_get_remote_endpoint(ep);
720 	of_node_put(ep);
721 	if (!remote)
722 		return -EINVAL;
723 
724 	of_graph_parse_endpoint(remote, &of_ep);
725 	of_node_put(remote);
726 	return of_ep.id;
727 }
728 
729 /* TODO: This needs to take multiple pipelines into account */
730 static struct sun4i_frontend *sun4i_backend_find_frontend(struct sun4i_drv *drv,
731 							  struct device_node *node)
732 {
733 	struct device_node *port, *ep, *remote;
734 	struct sun4i_frontend *frontend;
735 
736 	port = of_graph_get_port_by_id(node, 0);
737 	if (!port)
738 		return ERR_PTR(-EINVAL);
739 
740 	for_each_available_child_of_node(port, ep) {
741 		remote = of_graph_get_remote_port_parent(ep);
742 		if (!remote)
743 			continue;
744 		of_node_put(remote);
745 
746 		/* does this node match any registered engines? */
747 		list_for_each_entry(frontend, &drv->frontend_list, list) {
748 			if (remote == frontend->node) {
749 				of_node_put(port);
750 				of_node_put(ep);
751 				return frontend;
752 			}
753 		}
754 	}
755 	of_node_put(port);
756 	return ERR_PTR(-EINVAL);
757 }
758 
759 static const struct sunxi_engine_ops sun4i_backend_engine_ops = {
760 	.atomic_begin			= sun4i_backend_atomic_begin,
761 	.atomic_check			= sun4i_backend_atomic_check,
762 	.commit				= sun4i_backend_commit,
763 	.layers_init			= sun4i_layers_init,
764 	.apply_color_correction		= sun4i_backend_apply_color_correction,
765 	.disable_color_correction	= sun4i_backend_disable_color_correction,
766 	.vblank_quirk			= sun4i_backend_vblank_quirk,
767 	.mode_set			= sun4i_backend_mode_set,
768 };
769 
770 static const struct regmap_config sun4i_backend_regmap_config = {
771 	.reg_bits	= 32,
772 	.val_bits	= 32,
773 	.reg_stride	= 4,
774 	.max_register	= 0x5800,
775 };
776 
777 static int sun4i_backend_bind(struct device *dev, struct device *master,
778 			      void *data)
779 {
780 	struct platform_device *pdev = to_platform_device(dev);
781 	struct drm_device *drm = data;
782 	struct sun4i_drv *drv = drm->dev_private;
783 	struct sun4i_backend *backend;
784 	const struct sun4i_backend_quirks *quirks;
785 	void __iomem *regs;
786 	int i, ret;
787 
788 	backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
789 	if (!backend)
790 		return -ENOMEM;
791 	dev_set_drvdata(dev, backend);
792 	spin_lock_init(&backend->frontend_lock);
793 
794 	if (of_find_property(dev->of_node, "interconnects", NULL)) {
795 		/*
796 		 * This assume we have the same DMA constraints for all our the
797 		 * devices in our pipeline (all the backends, but also the
798 		 * frontends). This sounds bad, but it has always been the case
799 		 * for us, and DRM doesn't do per-device allocation either, so
800 		 * we would need to fix DRM first...
801 		 */
802 		ret = of_dma_configure(drm->dev, dev->of_node, true);
803 		if (ret)
804 			return ret;
805 	}
806 
807 	backend->engine.node = dev->of_node;
808 	backend->engine.ops = &sun4i_backend_engine_ops;
809 	backend->engine.id = sun4i_backend_of_get_id(dev->of_node);
810 	if (backend->engine.id < 0)
811 		return backend->engine.id;
812 
813 	backend->frontend = sun4i_backend_find_frontend(drv, dev->of_node);
814 	if (IS_ERR(backend->frontend))
815 		dev_warn(dev, "Couldn't find matching frontend, frontend features disabled\n");
816 
817 	regs = devm_platform_ioremap_resource(pdev, 0);
818 	if (IS_ERR(regs))
819 		return PTR_ERR(regs);
820 
821 	backend->reset = devm_reset_control_get(dev, NULL);
822 	if (IS_ERR(backend->reset)) {
823 		dev_err(dev, "Couldn't get our reset line\n");
824 		return PTR_ERR(backend->reset);
825 	}
826 
827 	ret = reset_control_deassert(backend->reset);
828 	if (ret) {
829 		dev_err(dev, "Couldn't deassert our reset line\n");
830 		return ret;
831 	}
832 
833 	backend->bus_clk = devm_clk_get(dev, "ahb");
834 	if (IS_ERR(backend->bus_clk)) {
835 		dev_err(dev, "Couldn't get the backend bus clock\n");
836 		ret = PTR_ERR(backend->bus_clk);
837 		goto err_assert_reset;
838 	}
839 	clk_prepare_enable(backend->bus_clk);
840 
841 	backend->mod_clk = devm_clk_get(dev, "mod");
842 	if (IS_ERR(backend->mod_clk)) {
843 		dev_err(dev, "Couldn't get the backend module clock\n");
844 		ret = PTR_ERR(backend->mod_clk);
845 		goto err_disable_bus_clk;
846 	}
847 
848 	ret = clk_set_rate_exclusive(backend->mod_clk, 300000000);
849 	if (ret) {
850 		dev_err(dev, "Couldn't set the module clock frequency\n");
851 		goto err_disable_bus_clk;
852 	}
853 
854 	clk_prepare_enable(backend->mod_clk);
855 
856 	backend->ram_clk = devm_clk_get(dev, "ram");
857 	if (IS_ERR(backend->ram_clk)) {
858 		dev_err(dev, "Couldn't get the backend RAM clock\n");
859 		ret = PTR_ERR(backend->ram_clk);
860 		goto err_disable_mod_clk;
861 	}
862 	clk_prepare_enable(backend->ram_clk);
863 
864 	if (of_device_is_compatible(dev->of_node,
865 				    "allwinner,sun8i-a33-display-backend")) {
866 		ret = sun4i_backend_init_sat(dev);
867 		if (ret) {
868 			dev_err(dev, "Couldn't init SAT resources\n");
869 			goto err_disable_ram_clk;
870 		}
871 	}
872 
873 	backend->engine.regs = devm_regmap_init_mmio(dev, regs,
874 						     &sun4i_backend_regmap_config);
875 	if (IS_ERR(backend->engine.regs)) {
876 		dev_err(dev, "Couldn't create the backend regmap\n");
877 		return PTR_ERR(backend->engine.regs);
878 	}
879 
880 	list_add_tail(&backend->engine.list, &drv->engine_list);
881 
882 	/*
883 	 * Many of the backend's layer configuration registers have
884 	 * undefined default values. This poses a risk as we use
885 	 * regmap_update_bits in some places, and don't overwrite
886 	 * the whole register.
887 	 *
888 	 * Clear the registers here to have something predictable.
889 	 */
890 	for (i = 0x800; i < 0x1000; i += 4)
891 		regmap_write(backend->engine.regs, i, 0);
892 
893 	/* Disable registers autoloading */
894 	regmap_write(backend->engine.regs, SUN4I_BACKEND_REGBUFFCTL_REG,
895 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS);
896 
897 	/* Enable the backend */
898 	regmap_write(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
899 		     SUN4I_BACKEND_MODCTL_DEBE_EN |
900 		     SUN4I_BACKEND_MODCTL_START_CTL);
901 
902 	/* Set output selection if needed */
903 	quirks = of_device_get_match_data(dev);
904 	if (quirks->needs_output_muxing) {
905 		/*
906 		 * We assume there is no dynamic muxing of backends
907 		 * and TCONs, so we select the backend with same ID.
908 		 *
909 		 * While dynamic selection might be interesting, since
910 		 * the CRTC is tied to the TCON, while the layers are
911 		 * tied to the backends, this means, we will need to
912 		 * switch between groups of layers. There might not be
913 		 * a way to represent this constraint in DRM.
914 		 */
915 		regmap_update_bits(backend->engine.regs,
916 				   SUN4I_BACKEND_MODCTL_REG,
917 				   SUN4I_BACKEND_MODCTL_OUT_SEL,
918 				   (backend->engine.id
919 				    ? SUN4I_BACKEND_MODCTL_OUT_LCD1
920 				    : SUN4I_BACKEND_MODCTL_OUT_LCD0));
921 	}
922 
923 	backend->quirks = quirks;
924 
925 	return 0;
926 
927 err_disable_ram_clk:
928 	clk_disable_unprepare(backend->ram_clk);
929 err_disable_mod_clk:
930 	clk_rate_exclusive_put(backend->mod_clk);
931 	clk_disable_unprepare(backend->mod_clk);
932 err_disable_bus_clk:
933 	clk_disable_unprepare(backend->bus_clk);
934 err_assert_reset:
935 	reset_control_assert(backend->reset);
936 	return ret;
937 }
938 
939 static void sun4i_backend_unbind(struct device *dev, struct device *master,
940 				 void *data)
941 {
942 	struct sun4i_backend *backend = dev_get_drvdata(dev);
943 
944 	list_del(&backend->engine.list);
945 
946 	if (of_device_is_compatible(dev->of_node,
947 				    "allwinner,sun8i-a33-display-backend"))
948 		sun4i_backend_free_sat(dev);
949 
950 	clk_disable_unprepare(backend->ram_clk);
951 	clk_rate_exclusive_put(backend->mod_clk);
952 	clk_disable_unprepare(backend->mod_clk);
953 	clk_disable_unprepare(backend->bus_clk);
954 	reset_control_assert(backend->reset);
955 }
956 
957 static const struct component_ops sun4i_backend_ops = {
958 	.bind	= sun4i_backend_bind,
959 	.unbind	= sun4i_backend_unbind,
960 };
961 
962 static int sun4i_backend_probe(struct platform_device *pdev)
963 {
964 	return component_add(&pdev->dev, &sun4i_backend_ops);
965 }
966 
967 static int sun4i_backend_remove(struct platform_device *pdev)
968 {
969 	component_del(&pdev->dev, &sun4i_backend_ops);
970 
971 	return 0;
972 }
973 
974 static const struct sun4i_backend_quirks sun4i_backend_quirks = {
975 	.needs_output_muxing = true,
976 };
977 
978 static const struct sun4i_backend_quirks sun5i_backend_quirks = {
979 };
980 
981 static const struct sun4i_backend_quirks sun6i_backend_quirks = {
982 };
983 
984 static const struct sun4i_backend_quirks sun7i_backend_quirks = {
985 	.needs_output_muxing = true,
986 };
987 
988 static const struct sun4i_backend_quirks sun8i_a33_backend_quirks = {
989 	.supports_lowest_plane_alpha = true,
990 };
991 
992 static const struct sun4i_backend_quirks sun9i_backend_quirks = {
993 };
994 
995 static const struct of_device_id sun4i_backend_of_table[] = {
996 	{
997 		.compatible = "allwinner,sun4i-a10-display-backend",
998 		.data = &sun4i_backend_quirks,
999 	},
1000 	{
1001 		.compatible = "allwinner,sun5i-a13-display-backend",
1002 		.data = &sun5i_backend_quirks,
1003 	},
1004 	{
1005 		.compatible = "allwinner,sun6i-a31-display-backend",
1006 		.data = &sun6i_backend_quirks,
1007 	},
1008 	{
1009 		.compatible = "allwinner,sun7i-a20-display-backend",
1010 		.data = &sun7i_backend_quirks,
1011 	},
1012 	{
1013 		.compatible = "allwinner,sun8i-a23-display-backend",
1014 		.data = &sun8i_a33_backend_quirks,
1015 	},
1016 	{
1017 		.compatible = "allwinner,sun8i-a33-display-backend",
1018 		.data = &sun8i_a33_backend_quirks,
1019 	},
1020 	{
1021 		.compatible = "allwinner,sun9i-a80-display-backend",
1022 		.data = &sun9i_backend_quirks,
1023 	},
1024 	{ }
1025 };
1026 MODULE_DEVICE_TABLE(of, sun4i_backend_of_table);
1027 
1028 static struct platform_driver sun4i_backend_platform_driver = {
1029 	.probe		= sun4i_backend_probe,
1030 	.remove		= sun4i_backend_remove,
1031 	.driver		= {
1032 		.name		= "sun4i-backend",
1033 		.of_match_table	= sun4i_backend_of_table,
1034 	},
1035 };
1036 module_platform_driver(sun4i_backend_platform_driver);
1037 
1038 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
1039 MODULE_DESCRIPTION("Allwinner A10 Display Backend Driver");
1040 MODULE_LICENSE("GPL");
1041