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 	if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
176 		DRM_DEBUG_DRIVER("Primary layer, updating global size W: %u H: %u\n",
177 				 state->crtc_w, state->crtc_h);
178 		regmap_write(backend->engine.regs, SUN4I_BACKEND_DISSIZE_REG,
179 			     SUN4I_BACKEND_DISSIZE(state->crtc_w,
180 						   state->crtc_h));
181 	}
182 
183 	/* Set height and width */
184 	DRM_DEBUG_DRIVER("Layer size W: %u H: %u\n",
185 			 state->crtc_w, state->crtc_h);
186 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYSIZE_REG(layer),
187 		     SUN4I_BACKEND_LAYSIZE(state->crtc_w,
188 					   state->crtc_h));
189 
190 	/* Set base coordinates */
191 	DRM_DEBUG_DRIVER("Layer coordinates X: %d Y: %d\n",
192 			 state->crtc_x, state->crtc_y);
193 	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYCOOR_REG(layer),
194 		     SUN4I_BACKEND_LAYCOOR(state->crtc_x,
195 					   state->crtc_y));
196 
197 	return 0;
198 }
199 
200 static int sun4i_backend_update_yuv_format(struct sun4i_backend *backend,
201 					   int layer, struct drm_plane *plane)
202 {
203 	struct drm_plane_state *state = plane->state;
204 	struct drm_framebuffer *fb = state->fb;
205 	const struct drm_format_info *format = fb->format;
206 	const uint32_t fmt = format->format;
207 	u32 val = SUN4I_BACKEND_IYUVCTL_EN;
208 	int i;
209 
210 	for (i = 0; i < ARRAY_SIZE(sunxi_bt601_yuv2rgb_coef); i++)
211 		regmap_write(backend->engine.regs,
212 			     SUN4I_BACKEND_YGCOEF_REG(i),
213 			     sunxi_bt601_yuv2rgb_coef[i]);
214 
215 	/*
216 	 * We should do that only for a single plane, but the
217 	 * framebuffer's atomic_check has our back on this.
218 	 */
219 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
220 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN,
221 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN);
222 
223 	/* TODO: Add support for the multi-planar YUV formats */
224 	if (drm_format_info_is_yuv_packed(format) &&
225 	    drm_format_info_is_yuv_sampling_422(format))
226 		val |= SUN4I_BACKEND_IYUVCTL_FBFMT_PACKED_YUV422;
227 	else
228 		DRM_DEBUG_DRIVER("Unsupported YUV format (0x%x)\n", fmt);
229 
230 	/*
231 	 * Allwinner seems to list the pixel sequence from right to left, while
232 	 * DRM lists it from left to right.
233 	 */
234 	switch (fmt) {
235 	case DRM_FORMAT_YUYV:
236 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_VYUY;
237 		break;
238 	case DRM_FORMAT_YVYU:
239 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_UYVY;
240 		break;
241 	case DRM_FORMAT_UYVY:
242 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YVYU;
243 		break;
244 	case DRM_FORMAT_VYUY:
245 		val |= SUN4I_BACKEND_IYUVCTL_FBPS_YUYV;
246 		break;
247 	default:
248 		DRM_DEBUG_DRIVER("Unsupported YUV pixel sequence (0x%x)\n",
249 				 fmt);
250 	}
251 
252 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVCTL_REG, val);
253 
254 	return 0;
255 }
256 
257 int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
258 				       int layer, struct drm_plane *plane)
259 {
260 	struct drm_plane_state *state = plane->state;
261 	struct drm_framebuffer *fb = state->fb;
262 	bool interlaced = false;
263 	u32 val;
264 	int ret;
265 
266 	/* Clear the YUV mode */
267 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
268 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
269 
270 	if (plane->state->crtc)
271 		interlaced = plane->state->crtc->state->adjusted_mode.flags
272 			& DRM_MODE_FLAG_INTERLACE;
273 
274 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
275 			   SUN4I_BACKEND_MODCTL_ITLMOD_EN,
276 			   interlaced ? SUN4I_BACKEND_MODCTL_ITLMOD_EN : 0);
277 
278 	DRM_DEBUG_DRIVER("Switching display backend interlaced mode %s\n",
279 			 interlaced ? "on" : "off");
280 
281 	val = SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA(state->alpha >> 8);
282 	if (state->alpha != DRM_BLEND_ALPHA_OPAQUE)
283 		val |= SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN;
284 	regmap_update_bits(backend->engine.regs,
285 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
286 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_MASK |
287 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_GLBALPHA_EN,
288 			   val);
289 
290 	if (fb->format->is_yuv)
291 		return sun4i_backend_update_yuv_format(backend, layer, plane);
292 
293 	ret = sun4i_backend_drm_format_to_layer(fb->format->format, &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_REG1(layer),
301 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
302 
303 	return 0;
304 }
305 
306 int sun4i_backend_update_layer_frontend(struct sun4i_backend *backend,
307 					int layer, uint32_t fmt)
308 {
309 	u32 val;
310 	int ret;
311 
312 	ret = sun4i_backend_drm_format_to_layer(fmt, &val);
313 	if (ret) {
314 		DRM_DEBUG_DRIVER("Invalid format\n");
315 		return ret;
316 	}
317 
318 	regmap_update_bits(backend->engine.regs,
319 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
320 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN,
321 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN);
322 
323 	regmap_update_bits(backend->engine.regs,
324 			   SUN4I_BACKEND_ATTCTL_REG1(layer),
325 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
326 
327 	return 0;
328 }
329 
330 static int sun4i_backend_update_yuv_buffer(struct sun4i_backend *backend,
331 					   struct drm_framebuffer *fb,
332 					   dma_addr_t paddr)
333 {
334 	/* TODO: Add support for the multi-planar YUV formats */
335 	DRM_DEBUG_DRIVER("Setting packed YUV buffer address to %pad\n", &paddr);
336 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVADD_REG(0), paddr);
337 
338 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
339 	regmap_write(backend->engine.regs, SUN4I_BACKEND_IYUVLINEWIDTH_REG(0),
340 		     fb->pitches[0] * 8);
341 
342 	return 0;
343 }
344 
345 int sun4i_backend_update_layer_buffer(struct sun4i_backend *backend,
346 				      int layer, struct drm_plane *plane)
347 {
348 	struct drm_plane_state *state = plane->state;
349 	struct drm_framebuffer *fb = state->fb;
350 	u32 lo_paddr, hi_paddr;
351 	dma_addr_t paddr;
352 
353 	/* Set the line width */
354 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
355 	regmap_write(backend->engine.regs,
356 		     SUN4I_BACKEND_LAYLINEWIDTH_REG(layer),
357 		     fb->pitches[0] * 8);
358 
359 	/* Get the start of the displayed memory */
360 	paddr = drm_fb_cma_get_gem_addr(fb, state, 0);
361 	DRM_DEBUG_DRIVER("Setting buffer address to %pad\n", &paddr);
362 
363 	if (fb->format->is_yuv)
364 		return sun4i_backend_update_yuv_buffer(backend, fb, paddr);
365 
366 	/* Write the 32 lower bits of the address (in bits) */
367 	lo_paddr = paddr << 3;
368 	DRM_DEBUG_DRIVER("Setting address lower bits to 0x%x\n", lo_paddr);
369 	regmap_write(backend->engine.regs,
370 		     SUN4I_BACKEND_LAYFB_L32ADD_REG(layer),
371 		     lo_paddr);
372 
373 	/* And the upper bits */
374 	hi_paddr = paddr >> 29;
375 	DRM_DEBUG_DRIVER("Setting address high bits to 0x%x\n", hi_paddr);
376 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_LAYFB_H4ADD_REG,
377 			   SUN4I_BACKEND_LAYFB_H4ADD_MSK(layer),
378 			   SUN4I_BACKEND_LAYFB_H4ADD(layer, hi_paddr));
379 
380 	return 0;
381 }
382 
383 int sun4i_backend_update_layer_zpos(struct sun4i_backend *backend, int layer,
384 				    struct drm_plane *plane)
385 {
386 	struct drm_plane_state *state = plane->state;
387 	struct sun4i_layer_state *p_state = state_to_sun4i_layer_state(state);
388 	unsigned int priority = state->normalized_zpos;
389 	unsigned int pipe = p_state->pipe;
390 
391 	DRM_DEBUG_DRIVER("Setting layer %d's priority to %d and pipe %d\n",
392 			 layer, priority, pipe);
393 	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_ATTCTL_REG0(layer),
394 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL_MASK |
395 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL_MASK,
396 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL(p_state->pipe) |
397 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_PRISEL(priority));
398 
399 	return 0;
400 }
401 
402 void sun4i_backend_cleanup_layer(struct sun4i_backend *backend,
403 				 int layer)
404 {
405 	regmap_update_bits(backend->engine.regs,
406 			   SUN4I_BACKEND_ATTCTL_REG0(layer),
407 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_VDOEN |
408 			   SUN4I_BACKEND_ATTCTL_REG0_LAY_YUVEN, 0);
409 }
410 
411 static bool sun4i_backend_plane_uses_scaler(struct drm_plane_state *state)
412 {
413 	u16 src_h = state->src_h >> 16;
414 	u16 src_w = state->src_w >> 16;
415 
416 	DRM_DEBUG_DRIVER("Input size %dx%d, output size %dx%d\n",
417 			 src_w, src_h, state->crtc_w, state->crtc_h);
418 
419 	if ((state->crtc_h != src_h) || (state->crtc_w != src_w))
420 		return true;
421 
422 	return false;
423 }
424 
425 static bool sun4i_backend_plane_uses_frontend(struct drm_plane_state *state)
426 {
427 	struct sun4i_layer *layer = plane_to_sun4i_layer(state->plane);
428 	struct sun4i_backend *backend = layer->backend;
429 	uint32_t format = state->fb->format->format;
430 	uint64_t modifier = state->fb->modifier;
431 
432 	if (IS_ERR(backend->frontend))
433 		return false;
434 
435 	if (!sun4i_frontend_format_is_supported(format, modifier))
436 		return false;
437 
438 	if (!sun4i_backend_format_is_supported(format, modifier))
439 		return true;
440 
441 	/*
442 	 * TODO: The backend alone allows 2x and 4x integer scaling, including
443 	 * support for an alpha component (which the frontend doesn't support).
444 	 * Use the backend directly instead of the frontend in this case, with
445 	 * another test to return false.
446 	 */
447 
448 	if (sun4i_backend_plane_uses_scaler(state))
449 		return true;
450 
451 	/*
452 	 * Here the format is supported by both the frontend and the backend
453 	 * and no frontend scaling is required, so use the backend directly.
454 	 */
455 	return false;
456 }
457 
458 static bool sun4i_backend_plane_is_supported(struct drm_plane_state *state,
459 					     bool *uses_frontend)
460 {
461 	if (sun4i_backend_plane_uses_frontend(state)) {
462 		*uses_frontend = true;
463 		return true;
464 	}
465 
466 	*uses_frontend = false;
467 
468 	/* Scaling is not supported without the frontend. */
469 	if (sun4i_backend_plane_uses_scaler(state))
470 		return false;
471 
472 	return true;
473 }
474 
475 static void sun4i_backend_atomic_begin(struct sunxi_engine *engine,
476 				       struct drm_crtc_state *old_state)
477 {
478 	u32 val;
479 
480 	WARN_ON(regmap_read_poll_timeout(engine->regs,
481 					 SUN4I_BACKEND_REGBUFFCTL_REG,
482 					 val, !(val & SUN4I_BACKEND_REGBUFFCTL_LOADCTL),
483 					 100, 50000));
484 }
485 
486 static int sun4i_backend_atomic_check(struct sunxi_engine *engine,
487 				      struct drm_crtc_state *crtc_state)
488 {
489 	struct drm_plane_state *plane_states[SUN4I_BACKEND_NUM_LAYERS] = { 0 };
490 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
491 	struct drm_atomic_state *state = crtc_state->state;
492 	struct drm_device *drm = state->dev;
493 	struct drm_plane *plane;
494 	unsigned int num_planes = 0;
495 	unsigned int num_alpha_planes = 0;
496 	unsigned int num_frontend_planes = 0;
497 	unsigned int num_alpha_planes_max = 1;
498 	unsigned int num_yuv_planes = 0;
499 	unsigned int current_pipe = 0;
500 	unsigned int i;
501 
502 	DRM_DEBUG_DRIVER("Starting checking our planes\n");
503 
504 	if (!crtc_state->planes_changed)
505 		return 0;
506 
507 	drm_for_each_plane_mask(plane, drm, crtc_state->plane_mask) {
508 		struct drm_plane_state *plane_state =
509 			drm_atomic_get_plane_state(state, plane);
510 		struct sun4i_layer_state *layer_state =
511 			state_to_sun4i_layer_state(plane_state);
512 		struct drm_framebuffer *fb = plane_state->fb;
513 		struct drm_format_name_buf format_name;
514 
515 		if (!sun4i_backend_plane_is_supported(plane_state,
516 						      &layer_state->uses_frontend))
517 			return -EINVAL;
518 
519 		if (layer_state->uses_frontend) {
520 			DRM_DEBUG_DRIVER("Using the frontend for plane %d\n",
521 					 plane->index);
522 			num_frontend_planes++;
523 		} else {
524 			if (fb->format->is_yuv) {
525 				DRM_DEBUG_DRIVER("Plane FB format is YUV\n");
526 				num_yuv_planes++;
527 			}
528 		}
529 
530 		DRM_DEBUG_DRIVER("Plane FB format is %s\n",
531 				 drm_get_format_name(fb->format->format,
532 						     &format_name));
533 		if (fb->format->has_alpha || (plane_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
534 			num_alpha_planes++;
535 
536 		DRM_DEBUG_DRIVER("Plane zpos is %d\n",
537 				 plane_state->normalized_zpos);
538 
539 		/* Sort our planes by Zpos */
540 		plane_states[plane_state->normalized_zpos] = plane_state;
541 
542 		num_planes++;
543 	}
544 
545 	/* All our planes were disabled, bail out */
546 	if (!num_planes)
547 		return 0;
548 
549 	/*
550 	 * The hardware is a bit unusual here.
551 	 *
552 	 * Even though it supports 4 layers, it does the composition
553 	 * in two separate steps.
554 	 *
555 	 * The first one is assigning a layer to one of its two
556 	 * pipes. If more that 1 layer is assigned to the same pipe,
557 	 * and if pixels overlaps, the pipe will take the pixel from
558 	 * the layer with the highest priority.
559 	 *
560 	 * The second step is the actual alpha blending, that takes
561 	 * the two pipes as input, and uses the potential alpha
562 	 * component to do the transparency between the two.
563 	 *
564 	 * This two-step scenario makes us unable to guarantee a
565 	 * robust alpha blending between the 4 layers in all
566 	 * situations, since this means that we need to have one layer
567 	 * with alpha at the lowest position of our two pipes.
568 	 *
569 	 * However, we cannot even do that on every platform, since
570 	 * the hardware has a bug where the lowest plane of the lowest
571 	 * pipe (pipe 0, priority 0), if it has any alpha, will
572 	 * discard the pixel data entirely and just display the pixels
573 	 * in the background color (black by default).
574 	 *
575 	 * This means that on the affected platforms, we effectively
576 	 * have only three valid configurations with alpha, all of
577 	 * them with the alpha being on pipe1 with the lowest
578 	 * position, which can be 1, 2 or 3 depending on the number of
579 	 * planes and their zpos.
580 	 */
581 
582 	/* For platforms that are not affected by the issue described above. */
583 	if (backend->quirks->supports_lowest_plane_alpha)
584 		num_alpha_planes_max++;
585 
586 	if (num_alpha_planes > num_alpha_planes_max) {
587 		DRM_DEBUG_DRIVER("Too many planes with alpha, rejecting...\n");
588 		return -EINVAL;
589 	}
590 
591 	/* We can't have an alpha plane at the lowest position */
592 	if (!backend->quirks->supports_lowest_plane_alpha &&
593 	    (plane_states[0]->alpha != DRM_BLEND_ALPHA_OPAQUE))
594 		return -EINVAL;
595 
596 	for (i = 1; i < num_planes; i++) {
597 		struct drm_plane_state *p_state = plane_states[i];
598 		struct drm_framebuffer *fb = p_state->fb;
599 		struct sun4i_layer_state *s_state = state_to_sun4i_layer_state(p_state);
600 
601 		/*
602 		 * The only alpha position is the lowest plane of the
603 		 * second pipe.
604 		 */
605 		if (fb->format->has_alpha || (p_state->alpha != DRM_BLEND_ALPHA_OPAQUE))
606 			current_pipe++;
607 
608 		s_state->pipe = current_pipe;
609 	}
610 
611 	/* We can only have a single YUV plane at a time */
612 	if (num_yuv_planes > SUN4I_BACKEND_NUM_YUV_PLANES) {
613 		DRM_DEBUG_DRIVER("Too many planes with YUV, rejecting...\n");
614 		return -EINVAL;
615 	}
616 
617 	if (num_frontend_planes > SUN4I_BACKEND_NUM_FRONTEND_LAYERS) {
618 		DRM_DEBUG_DRIVER("Too many planes going through the frontend, rejecting\n");
619 		return -EINVAL;
620 	}
621 
622 	DRM_DEBUG_DRIVER("State valid with %u planes, %u alpha, %u video, %u YUV\n",
623 			 num_planes, num_alpha_planes, num_frontend_planes,
624 			 num_yuv_planes);
625 
626 	return 0;
627 }
628 
629 static void sun4i_backend_vblank_quirk(struct sunxi_engine *engine)
630 {
631 	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
632 	struct sun4i_frontend *frontend = backend->frontend;
633 
634 	if (!frontend)
635 		return;
636 
637 	/*
638 	 * In a teardown scenario with the frontend involved, we have
639 	 * to keep the frontend enabled until the next vblank, and
640 	 * only then disable it.
641 	 *
642 	 * This is due to the fact that the backend will not take into
643 	 * account the new configuration (with the plane that used to
644 	 * be fed by the frontend now disabled) until we write to the
645 	 * commit bit and the hardware fetches the new configuration
646 	 * during the next vblank.
647 	 *
648 	 * So we keep the frontend around in order to prevent any
649 	 * visual artifacts.
650 	 */
651 	spin_lock(&backend->frontend_lock);
652 	if (backend->frontend_teardown) {
653 		sun4i_frontend_exit(frontend);
654 		backend->frontend_teardown = false;
655 	}
656 	spin_unlock(&backend->frontend_lock);
657 };
658 
659 static int sun4i_backend_init_sat(struct device *dev) {
660 	struct sun4i_backend *backend = dev_get_drvdata(dev);
661 	int ret;
662 
663 	backend->sat_reset = devm_reset_control_get(dev, "sat");
664 	if (IS_ERR(backend->sat_reset)) {
665 		dev_err(dev, "Couldn't get the SAT reset line\n");
666 		return PTR_ERR(backend->sat_reset);
667 	}
668 
669 	ret = reset_control_deassert(backend->sat_reset);
670 	if (ret) {
671 		dev_err(dev, "Couldn't deassert the SAT reset line\n");
672 		return ret;
673 	}
674 
675 	backend->sat_clk = devm_clk_get(dev, "sat");
676 	if (IS_ERR(backend->sat_clk)) {
677 		dev_err(dev, "Couldn't get our SAT clock\n");
678 		ret = PTR_ERR(backend->sat_clk);
679 		goto err_assert_reset;
680 	}
681 
682 	ret = clk_prepare_enable(backend->sat_clk);
683 	if (ret) {
684 		dev_err(dev, "Couldn't enable the SAT clock\n");
685 		return ret;
686 	}
687 
688 	return 0;
689 
690 err_assert_reset:
691 	reset_control_assert(backend->sat_reset);
692 	return ret;
693 }
694 
695 static int sun4i_backend_free_sat(struct device *dev) {
696 	struct sun4i_backend *backend = dev_get_drvdata(dev);
697 
698 	clk_disable_unprepare(backend->sat_clk);
699 	reset_control_assert(backend->sat_reset);
700 
701 	return 0;
702 }
703 
704 /*
705  * The display backend can take video output from the display frontend, or
706  * the display enhancement unit on the A80, as input for one it its layers.
707  * This relationship within the display pipeline is encoded in the device
708  * tree with of_graph, and we use it here to figure out which backend, if
709  * there are 2 or more, we are currently probing. The number would be in
710  * the "reg" property of the upstream output port endpoint.
711  */
712 static int sun4i_backend_of_get_id(struct device_node *node)
713 {
714 	struct device_node *ep, *remote;
715 	struct of_endpoint of_ep;
716 
717 	/* Input port is 0, and we want the first endpoint. */
718 	ep = of_graph_get_endpoint_by_regs(node, 0, -1);
719 	if (!ep)
720 		return -EINVAL;
721 
722 	remote = of_graph_get_remote_endpoint(ep);
723 	of_node_put(ep);
724 	if (!remote)
725 		return -EINVAL;
726 
727 	of_graph_parse_endpoint(remote, &of_ep);
728 	of_node_put(remote);
729 	return of_ep.id;
730 }
731 
732 /* TODO: This needs to take multiple pipelines into account */
733 static struct sun4i_frontend *sun4i_backend_find_frontend(struct sun4i_drv *drv,
734 							  struct device_node *node)
735 {
736 	struct device_node *port, *ep, *remote;
737 	struct sun4i_frontend *frontend;
738 
739 	port = of_graph_get_port_by_id(node, 0);
740 	if (!port)
741 		return ERR_PTR(-EINVAL);
742 
743 	for_each_available_child_of_node(port, ep) {
744 		remote = of_graph_get_remote_port_parent(ep);
745 		if (!remote)
746 			continue;
747 		of_node_put(remote);
748 
749 		/* does this node match any registered engines? */
750 		list_for_each_entry(frontend, &drv->frontend_list, list) {
751 			if (remote == frontend->node) {
752 				of_node_put(port);
753 				of_node_put(ep);
754 				return frontend;
755 			}
756 		}
757 	}
758 	of_node_put(port);
759 	return ERR_PTR(-EINVAL);
760 }
761 
762 static const struct sunxi_engine_ops sun4i_backend_engine_ops = {
763 	.atomic_begin			= sun4i_backend_atomic_begin,
764 	.atomic_check			= sun4i_backend_atomic_check,
765 	.commit				= sun4i_backend_commit,
766 	.layers_init			= sun4i_layers_init,
767 	.apply_color_correction		= sun4i_backend_apply_color_correction,
768 	.disable_color_correction	= sun4i_backend_disable_color_correction,
769 	.vblank_quirk			= sun4i_backend_vblank_quirk,
770 };
771 
772 static const struct regmap_config sun4i_backend_regmap_config = {
773 	.reg_bits	= 32,
774 	.val_bits	= 32,
775 	.reg_stride	= 4,
776 	.max_register	= 0x5800,
777 };
778 
779 static int sun4i_backend_bind(struct device *dev, struct device *master,
780 			      void *data)
781 {
782 	struct platform_device *pdev = to_platform_device(dev);
783 	struct drm_device *drm = data;
784 	struct sun4i_drv *drv = drm->dev_private;
785 	struct sun4i_backend *backend;
786 	const struct sun4i_backend_quirks *quirks;
787 	struct resource *res;
788 	void __iomem *regs;
789 	int i, ret;
790 
791 	backend = devm_kzalloc(dev, sizeof(*backend), GFP_KERNEL);
792 	if (!backend)
793 		return -ENOMEM;
794 	dev_set_drvdata(dev, backend);
795 	spin_lock_init(&backend->frontend_lock);
796 
797 	if (of_find_property(dev->of_node, "interconnects", NULL)) {
798 		/*
799 		 * This assume we have the same DMA constraints for all our the
800 		 * devices in our pipeline (all the backends, but also the
801 		 * frontends). This sounds bad, but it has always been the case
802 		 * for us, and DRM doesn't do per-device allocation either, so
803 		 * we would need to fix DRM first...
804 		 */
805 		ret = of_dma_configure(drm->dev, dev->of_node, true);
806 		if (ret)
807 			return ret;
808 	} else {
809 		/*
810 		 * If we don't have the interconnect property, most likely
811 		 * because of an old DT, we need to set the DMA offset by hand
812 		 * on our device since the RAM mapping is at 0 for the DMA bus,
813 		 * unlike the CPU.
814 		 *
815 		 * XXX(hch): this has no business in a driver and needs to move
816 		 * to the device tree.
817 		 *
818 		 * If we have two subsequent calls to dma_direct_set_offset
819 		 * returns -EINVAL. Unfortunately, this happens when we have two
820 		 * backends in the system, and will result in the driver
821 		 * reporting an error while it has been setup properly before.
822 		 * Ignore EINVAL, but it should really be removed eventually.
823 		 */
824 		ret = dma_direct_set_offset(drm->dev, PHYS_OFFSET, 0, SZ_4G);
825 		if (ret && ret != -EINVAL)
826 			return ret;
827 	}
828 
829 	backend->engine.node = dev->of_node;
830 	backend->engine.ops = &sun4i_backend_engine_ops;
831 	backend->engine.id = sun4i_backend_of_get_id(dev->of_node);
832 	if (backend->engine.id < 0)
833 		return backend->engine.id;
834 
835 	backend->frontend = sun4i_backend_find_frontend(drv, dev->of_node);
836 	if (IS_ERR(backend->frontend))
837 		dev_warn(dev, "Couldn't find matching frontend, frontend features disabled\n");
838 
839 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
840 	regs = devm_ioremap_resource(dev, res);
841 	if (IS_ERR(regs))
842 		return PTR_ERR(regs);
843 
844 	backend->reset = devm_reset_control_get(dev, NULL);
845 	if (IS_ERR(backend->reset)) {
846 		dev_err(dev, "Couldn't get our reset line\n");
847 		return PTR_ERR(backend->reset);
848 	}
849 
850 	ret = reset_control_deassert(backend->reset);
851 	if (ret) {
852 		dev_err(dev, "Couldn't deassert our reset line\n");
853 		return ret;
854 	}
855 
856 	backend->bus_clk = devm_clk_get(dev, "ahb");
857 	if (IS_ERR(backend->bus_clk)) {
858 		dev_err(dev, "Couldn't get the backend bus clock\n");
859 		ret = PTR_ERR(backend->bus_clk);
860 		goto err_assert_reset;
861 	}
862 	clk_prepare_enable(backend->bus_clk);
863 
864 	backend->mod_clk = devm_clk_get(dev, "mod");
865 	if (IS_ERR(backend->mod_clk)) {
866 		dev_err(dev, "Couldn't get the backend module clock\n");
867 		ret = PTR_ERR(backend->mod_clk);
868 		goto err_disable_bus_clk;
869 	}
870 
871 	ret = clk_set_rate_exclusive(backend->mod_clk, 300000000);
872 	if (ret) {
873 		dev_err(dev, "Couldn't set the module clock frequency\n");
874 		goto err_disable_bus_clk;
875 	}
876 
877 	clk_prepare_enable(backend->mod_clk);
878 
879 	backend->ram_clk = devm_clk_get(dev, "ram");
880 	if (IS_ERR(backend->ram_clk)) {
881 		dev_err(dev, "Couldn't get the backend RAM clock\n");
882 		ret = PTR_ERR(backend->ram_clk);
883 		goto err_disable_mod_clk;
884 	}
885 	clk_prepare_enable(backend->ram_clk);
886 
887 	if (of_device_is_compatible(dev->of_node,
888 				    "allwinner,sun8i-a33-display-backend")) {
889 		ret = sun4i_backend_init_sat(dev);
890 		if (ret) {
891 			dev_err(dev, "Couldn't init SAT resources\n");
892 			goto err_disable_ram_clk;
893 		}
894 	}
895 
896 	backend->engine.regs = devm_regmap_init_mmio(dev, regs,
897 						     &sun4i_backend_regmap_config);
898 	if (IS_ERR(backend->engine.regs)) {
899 		dev_err(dev, "Couldn't create the backend regmap\n");
900 		return PTR_ERR(backend->engine.regs);
901 	}
902 
903 	list_add_tail(&backend->engine.list, &drv->engine_list);
904 
905 	/*
906 	 * Many of the backend's layer configuration registers have
907 	 * undefined default values. This poses a risk as we use
908 	 * regmap_update_bits in some places, and don't overwrite
909 	 * the whole register.
910 	 *
911 	 * Clear the registers here to have something predictable.
912 	 */
913 	for (i = 0x800; i < 0x1000; i += 4)
914 		regmap_write(backend->engine.regs, i, 0);
915 
916 	/* Disable registers autoloading */
917 	regmap_write(backend->engine.regs, SUN4I_BACKEND_REGBUFFCTL_REG,
918 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS);
919 
920 	/* Enable the backend */
921 	regmap_write(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
922 		     SUN4I_BACKEND_MODCTL_DEBE_EN |
923 		     SUN4I_BACKEND_MODCTL_START_CTL);
924 
925 	/* Set output selection if needed */
926 	quirks = of_device_get_match_data(dev);
927 	if (quirks->needs_output_muxing) {
928 		/*
929 		 * We assume there is no dynamic muxing of backends
930 		 * and TCONs, so we select the backend with same ID.
931 		 *
932 		 * While dynamic selection might be interesting, since
933 		 * the CRTC is tied to the TCON, while the layers are
934 		 * tied to the backends, this means, we will need to
935 		 * switch between groups of layers. There might not be
936 		 * a way to represent this constraint in DRM.
937 		 */
938 		regmap_update_bits(backend->engine.regs,
939 				   SUN4I_BACKEND_MODCTL_REG,
940 				   SUN4I_BACKEND_MODCTL_OUT_SEL,
941 				   (backend->engine.id
942 				    ? SUN4I_BACKEND_MODCTL_OUT_LCD1
943 				    : SUN4I_BACKEND_MODCTL_OUT_LCD0));
944 	}
945 
946 	backend->quirks = quirks;
947 
948 	return 0;
949 
950 err_disable_ram_clk:
951 	clk_disable_unprepare(backend->ram_clk);
952 err_disable_mod_clk:
953 	clk_rate_exclusive_put(backend->mod_clk);
954 	clk_disable_unprepare(backend->mod_clk);
955 err_disable_bus_clk:
956 	clk_disable_unprepare(backend->bus_clk);
957 err_assert_reset:
958 	reset_control_assert(backend->reset);
959 	return ret;
960 }
961 
962 static void sun4i_backend_unbind(struct device *dev, struct device *master,
963 				 void *data)
964 {
965 	struct sun4i_backend *backend = dev_get_drvdata(dev);
966 
967 	list_del(&backend->engine.list);
968 
969 	if (of_device_is_compatible(dev->of_node,
970 				    "allwinner,sun8i-a33-display-backend"))
971 		sun4i_backend_free_sat(dev);
972 
973 	clk_disable_unprepare(backend->ram_clk);
974 	clk_rate_exclusive_put(backend->mod_clk);
975 	clk_disable_unprepare(backend->mod_clk);
976 	clk_disable_unprepare(backend->bus_clk);
977 	reset_control_assert(backend->reset);
978 }
979 
980 static const struct component_ops sun4i_backend_ops = {
981 	.bind	= sun4i_backend_bind,
982 	.unbind	= sun4i_backend_unbind,
983 };
984 
985 static int sun4i_backend_probe(struct platform_device *pdev)
986 {
987 	return component_add(&pdev->dev, &sun4i_backend_ops);
988 }
989 
990 static int sun4i_backend_remove(struct platform_device *pdev)
991 {
992 	component_del(&pdev->dev, &sun4i_backend_ops);
993 
994 	return 0;
995 }
996 
997 static const struct sun4i_backend_quirks sun4i_backend_quirks = {
998 	.needs_output_muxing = true,
999 };
1000 
1001 static const struct sun4i_backend_quirks sun5i_backend_quirks = {
1002 };
1003 
1004 static const struct sun4i_backend_quirks sun6i_backend_quirks = {
1005 };
1006 
1007 static const struct sun4i_backend_quirks sun7i_backend_quirks = {
1008 	.needs_output_muxing = true,
1009 };
1010 
1011 static const struct sun4i_backend_quirks sun8i_a33_backend_quirks = {
1012 	.supports_lowest_plane_alpha = true,
1013 };
1014 
1015 static const struct sun4i_backend_quirks sun9i_backend_quirks = {
1016 };
1017 
1018 static const struct of_device_id sun4i_backend_of_table[] = {
1019 	{
1020 		.compatible = "allwinner,sun4i-a10-display-backend",
1021 		.data = &sun4i_backend_quirks,
1022 	},
1023 	{
1024 		.compatible = "allwinner,sun5i-a13-display-backend",
1025 		.data = &sun5i_backend_quirks,
1026 	},
1027 	{
1028 		.compatible = "allwinner,sun6i-a31-display-backend",
1029 		.data = &sun6i_backend_quirks,
1030 	},
1031 	{
1032 		.compatible = "allwinner,sun7i-a20-display-backend",
1033 		.data = &sun7i_backend_quirks,
1034 	},
1035 	{
1036 		.compatible = "allwinner,sun8i-a23-display-backend",
1037 		.data = &sun8i_a33_backend_quirks,
1038 	},
1039 	{
1040 		.compatible = "allwinner,sun8i-a33-display-backend",
1041 		.data = &sun8i_a33_backend_quirks,
1042 	},
1043 	{
1044 		.compatible = "allwinner,sun9i-a80-display-backend",
1045 		.data = &sun9i_backend_quirks,
1046 	},
1047 	{ }
1048 };
1049 MODULE_DEVICE_TABLE(of, sun4i_backend_of_table);
1050 
1051 static struct platform_driver sun4i_backend_platform_driver = {
1052 	.probe		= sun4i_backend_probe,
1053 	.remove		= sun4i_backend_remove,
1054 	.driver		= {
1055 		.name		= "sun4i-backend",
1056 		.of_match_table	= sun4i_backend_of_table,
1057 	},
1058 };
1059 module_platform_driver(sun4i_backend_platform_driver);
1060 
1061 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
1062 MODULE_DESCRIPTION("Allwinner A10 Display Backend Driver");
1063 MODULE_LICENSE("GPL");
1064