drm_fb_dma_helper.c

  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(fb->format, plane);
 81	u32 block_h = drm_format_info_block_height(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, old_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(drm->dev, daddr + offset,
149						   nb_bytes, 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(&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(&sb->map[0], 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);