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