1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * drm kms/fb dma helper functions
4  *
5  * Copyright (C) 2012 Analog Devices Inc.
6  *   Author: Lars-Peter Clausen <lars@metafoo.de>
7  *
8  * Based on udl_fbdev.c
9  *  Copyright (C) 2012 Red Hat
10  */
11 
12 #include <drm/drm_damage_helper.h>
13 #include <drm/drm_fb_dma_helper.h>
14 #include <drm/drm_fourcc.h>
15 #include <drm/drm_framebuffer.h>
16 #include <drm/drm_gem_dma_helper.h>
17 #include <drm/drm_gem_framebuffer_helper.h>
18 #include <drm/drm_plane.h>
19 #include <linux/dma-mapping.h>
20 #include <linux/module.h>
21 
22 /**
23  * DOC: framebuffer dma helper functions
24  *
25  * Provides helper functions for creating a DMA-contiguous framebuffer.
26  *
27  * Depending on the platform, the buffers may be physically non-contiguous and
28  * mapped through an IOMMU or a similar mechanism, or allocated from
29  * physically-contiguous memory (using, for instance, CMA or a pool of memory
30  * reserved at early boot). This is handled behind the scenes by the DMA mapping
31  * API.
32  *
33  * drm_gem_fb_create() is used in the &drm_mode_config_funcs.fb_create
34  * callback function to create a DMA-contiguous framebuffer.
35  */
36 
37 /**
38  * drm_fb_dma_get_gem_obj() - Get DMA GEM object for framebuffer
39  * @fb: The framebuffer
40  * @plane: Which plane
41  *
42  * Return the DMA GEM object for given framebuffer.
43  *
44  * This function will usually be called from the CRTC callback functions.
45  */
46 struct drm_gem_dma_object *drm_fb_dma_get_gem_obj(struct drm_framebuffer *fb,
47 						  unsigned int plane)
48 {
49 	struct drm_gem_object *gem;
50 
51 	gem = drm_gem_fb_get_obj(fb, plane);
52 	if (!gem)
53 		return NULL;
54 
55 	return to_drm_gem_dma_obj(gem);
56 }
57 EXPORT_SYMBOL_GPL(drm_fb_dma_get_gem_obj);
58 
59 /**
60  * drm_fb_dma_get_gem_addr() - Get DMA (bus) address for framebuffer, for pixel
61  * formats where values are grouped in blocks this will get you the beginning of
62  * the block
63  * @fb: The framebuffer
64  * @state: Which state of drm plane
65  * @plane: Which plane
66  * Return the DMA GEM address for given framebuffer.
67  *
68  * This function will usually be called from the PLANE callback functions.
69  */
70 dma_addr_t drm_fb_dma_get_gem_addr(struct drm_framebuffer *fb,
71 				   struct drm_plane_state *state,
72 				   unsigned int plane)
73 {
74 	struct drm_gem_dma_object *obj;
75 	dma_addr_t dma_addr;
76 	u8 h_div = 1, v_div = 1;
77 	u32 block_w = drm_format_info_block_width(fb->format, plane);
78 	u32 block_h = drm_format_info_block_height(fb->format, plane);
79 	u32 block_size = fb->format->char_per_block[plane];
80 	u32 sample_x;
81 	u32 sample_y;
82 	u32 block_start_y;
83 	u32 num_hblocks;
84 
85 	obj = drm_fb_dma_get_gem_obj(fb, plane);
86 	if (!obj)
87 		return 0;
88 
89 	dma_addr = obj->dma_addr + fb->offsets[plane];
90 
91 	if (plane > 0) {
92 		h_div = fb->format->hsub;
93 		v_div = fb->format->vsub;
94 	}
95 
96 	sample_x = (state->src_x >> 16) / h_div;
97 	sample_y = (state->src_y >> 16) / v_div;
98 	block_start_y = (sample_y / block_h) * block_h;
99 	num_hblocks = sample_x / block_w;
100 
101 	dma_addr += fb->pitches[plane] * block_start_y;
102 	dma_addr += block_size * num_hblocks;
103 
104 	return dma_addr;
105 }
106 EXPORT_SYMBOL_GPL(drm_fb_dma_get_gem_addr);
107 
108 /**
109  * drm_fb_dma_sync_non_coherent - Sync GEM object to non-coherent backing
110  *	memory
111  * @drm: DRM device
112  * @old_state: Old plane state
113  * @state: New plane state
114  *
115  * This function can be used by drivers that use damage clips and have
116  * DMA GEM objects backed by non-coherent memory. Calling this function
117  * in a plane's .atomic_update ensures that all the data in the backing
118  * memory have been written to RAM.
119  */
120 void drm_fb_dma_sync_non_coherent(struct drm_device *drm,
121 				  struct drm_plane_state *old_state,
122 				  struct drm_plane_state *state)
123 {
124 	const struct drm_format_info *finfo = state->fb->format;
125 	struct drm_atomic_helper_damage_iter iter;
126 	const struct drm_gem_dma_object *dma_obj;
127 	unsigned int offset, i;
128 	struct drm_rect clip;
129 	dma_addr_t daddr;
130 	size_t nb_bytes;
131 
132 	for (i = 0; i < finfo->num_planes; i++) {
133 		dma_obj = drm_fb_dma_get_gem_obj(state->fb, i);
134 		if (!dma_obj->map_noncoherent)
135 			continue;
136 
137 		daddr = drm_fb_dma_get_gem_addr(state->fb, state, i);
138 		drm_atomic_helper_damage_iter_init(&iter, old_state, state);
139 
140 		drm_atomic_for_each_plane_damage(&iter, &clip) {
141 			/* Ignore x1/x2 values, invalidate complete lines */
142 			offset = clip.y1 * state->fb->pitches[i];
143 
144 			nb_bytes = (clip.y2 - clip.y1) * state->fb->pitches[i];
145 			dma_sync_single_for_device(drm->dev, daddr + offset,
146 						   nb_bytes, DMA_TO_DEVICE);
147 		}
148 	}
149 }
150 EXPORT_SYMBOL_GPL(drm_fb_dma_sync_non_coherent);
151