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_panic.h>
19#include <drm/drm_plane.h>
20
21#include <linux/dma-mapping.h>
22#include <linux/export.h>
23#include <linux/module.h>
24
25/**
26 * DOC: framebuffer dma helper functions
27 *
28 * Provides helper functions for creating a DMA-contiguous framebuffer.
29 *
30 * Depending on the platform, the buffers may be physically non-contiguous and
31 * mapped through an IOMMU or a similar mechanism, or allocated from
32 * physically-contiguous memory (using, for instance, CMA or a pool of memory
33 * reserved at early boot). This is handled behind the scenes by the DMA mapping
34 * API.
35 *
36 * drm_gem_fb_create() is used in the &drm_mode_config_funcs.fb_create
37 * callback function to create a DMA-contiguous framebuffer.
38 */
39
40/**
41 * drm_fb_dma_get_gem_obj() - Get DMA GEM object for framebuffer
42 * @fb: The framebuffer
43 * @plane: Which plane
44 *
45 * Return the DMA GEM object for given framebuffer.
46 *
47 * This function will usually be called from the CRTC callback functions.
48 */
49struct drm_gem_dma_object *drm_fb_dma_get_gem_obj(struct drm_framebuffer *fb,
50 unsigned int plane)
51{
52 struct drm_gem_object *gem;
53
54 gem = drm_gem_fb_get_obj(fb, plane);
55 if (!gem)
56 return NULL;
57
58 return to_drm_gem_dma_obj(gem);
59}
60EXPORT_SYMBOL_GPL(drm_fb_dma_get_gem_obj);
61
62/**
63 * drm_fb_dma_get_gem_addr() - Get DMA (bus) address for framebuffer, for pixel
64 * formats where values are grouped in blocks this will get you the beginning of
65 * the block
66 * @fb: The framebuffer
67 * @state: Which state of drm plane
68 * @plane: Which plane
69 * Return the DMA GEM address for given framebuffer.
70 *
71 * This function will usually be called from the PLANE callback functions.
72 */
73dma_addr_t drm_fb_dma_get_gem_addr(struct drm_framebuffer *fb,
74 struct drm_plane_state *state,
75 unsigned int plane)
76{
77 struct drm_gem_dma_object *obj;
78 dma_addr_t dma_addr;
79 u8 h_div = 1, v_div = 1;
80 u32 block_w = drm_format_info_block_width(info: fb->format, plane);
81 u32 block_h = drm_format_info_block_height(info: fb->format, plane);
82 u32 block_size = fb->format->char_per_block[plane];
83 u32 sample_x;
84 u32 sample_y;
85 u32 block_start_y;
86 u32 num_hblocks;
87
88 obj = drm_fb_dma_get_gem_obj(fb, plane);
89 if (!obj)
90 return 0;
91
92 dma_addr = obj->dma_addr + fb->offsets[plane];
93
94 if (plane > 0) {
95 h_div = fb->format->hsub;
96 v_div = fb->format->vsub;
97 }
98
99 sample_x = (state->src_x >> 16) / h_div;
100 sample_y = (state->src_y >> 16) / v_div;
101 block_start_y = (sample_y / block_h) * block_h;
102 num_hblocks = sample_x / block_w;
103
104 dma_addr += fb->pitches[plane] * block_start_y;
105 dma_addr += block_size * num_hblocks;
106
107 return dma_addr;
108}
109EXPORT_SYMBOL_GPL(drm_fb_dma_get_gem_addr);
110
111/**
112 * drm_fb_dma_sync_non_coherent - Sync GEM object to non-coherent backing
113 * memory
114 * @drm: DRM device
115 * @old_state: Old plane state
116 * @state: New plane state
117 *
118 * This function can be used by drivers that use damage clips and have
119 * DMA GEM objects backed by non-coherent memory. Calling this function
120 * in a plane's .atomic_update ensures that all the data in the backing
121 * memory have been written to RAM.
122 */
123void drm_fb_dma_sync_non_coherent(struct drm_device *drm,
124 struct drm_plane_state *old_state,
125 struct drm_plane_state *state)
126{
127 const struct drm_format_info *finfo = state->fb->format;
128 struct drm_atomic_helper_damage_iter iter;
129 const struct drm_gem_dma_object *dma_obj;
130 unsigned int offset, i;
131 struct drm_rect clip;
132 dma_addr_t daddr;
133 size_t nb_bytes;
134
135 for (i = 0; i < finfo->num_planes; i++) {
136 dma_obj = drm_fb_dma_get_gem_obj(state->fb, i);
137 if (!dma_obj->map_noncoherent)
138 continue;
139
140 daddr = drm_fb_dma_get_gem_addr(state->fb, state, i);
141 drm_atomic_helper_damage_iter_init(iter: &iter, old_state, new_state: state);
142
143 drm_atomic_for_each_plane_damage(&iter, &clip) {
144 /* Ignore x1/x2 values, invalidate complete lines */
145 offset = clip.y1 * state->fb->pitches[i];
146
147 nb_bytes = (clip.y2 - clip.y1) * state->fb->pitches[i];
148 dma_sync_single_for_device(dev: drm->dev, addr: daddr + offset,
149 size: nb_bytes, dir: DMA_TO_DEVICE);
150 }
151 }
152}
153EXPORT_SYMBOL_GPL(drm_fb_dma_sync_non_coherent);
154
155/**
156 * drm_fb_dma_get_scanout_buffer - Provide a scanout buffer in case of panic
157 * @plane: DRM primary plane
158 * @sb: scanout buffer for the panic handler
159 * Returns: 0 or negative error code
160 *
161 * Generic get_scanout_buffer() implementation, for drivers that uses the
162 * drm_fb_dma_helper. It won't call vmap in the panic context, so the driver
163 * should make sure the primary plane is vmapped, otherwise the panic screen
164 * won't get displayed.
165 */
166int drm_fb_dma_get_scanout_buffer(struct drm_plane *plane,
167 struct drm_scanout_buffer *sb)
168{
169 struct drm_gem_dma_object *dma_obj;
170 struct drm_framebuffer *fb;
171
172 if (!plane->state || !plane->state->fb)
173 return -EINVAL;
174
175 fb = plane->state->fb;
176 /* Only support linear modifier */
177 if (fb->modifier != DRM_FORMAT_MOD_LINEAR)
178 return -ENODEV;
179
180 dma_obj = drm_fb_dma_get_gem_obj(fb, 0);
181
182 /* Buffer should be accessible from the CPU */
183 if (drm_gem_is_imported(obj: &dma_obj->base))
184 return -ENODEV;
185
186 /* Buffer should be already mapped to CPU */
187 if (!dma_obj->vaddr)
188 return -ENODEV;
189
190 iosys_map_set_vaddr(map: &sb->map[0], vaddr: dma_obj->vaddr);
191 sb->format = fb->format;
192 sb->height = fb->height;
193 sb->width = fb->width;
194 sb->pitch[0] = fb->pitches[0];
195 return 0;
196}
197EXPORT_SYMBOL(drm_fb_dma_get_scanout_buffer);
198

source code of linux/drivers/gpu/drm/drm_fb_dma_helper.c