xref: /netbsd-src/sys/external/bsd/drm2/drm/drm_scatter.c (revision b7b7574d3bf8eeb51a1fa3977b59142ec6434a55)
1 /*	$NetBSD: drm_scatter.c,v 1.2 2014/03/18 18:20:42 riastradh Exp $	*/
2 
3 /*-
4  * Copyright (c) 2013 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Taylor R. Campbell.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #include <sys/cdefs.h>
33 __KERNEL_RCSID(0, "$NetBSD: drm_scatter.c,v 1.2 2014/03/18 18:20:42 riastradh Exp $");
34 
35 #include <sys/types.h>
36 #include <sys/bus.h>
37 #include <sys/errno.h>
38 #include <sys/systm.h>
39 
40 #include <linux/slab.h>
41 
42 #include <drm/drmP.h>
43 
44 static int	drm_sg_alloc_mem(struct drm_device *, size_t,
45 		    struct drm_sg_mem **);
46 
47 int
48 drm_sg_alloc_ioctl(struct drm_device *dev, void *data,
49     struct drm_file *file __unused)
50 {
51 	struct drm_scatter_gather *const request = data;
52 	struct drm_sg_mem *sg;
53 	int error;
54 
55 	/*
56 	 * XXX Should not hold this mutex during drm_sg_alloc.  For
57 	 * now, we'll just use non-blocking allocations.
58 	 */
59 	KASSERT(mutex_is_locked(&drm_global_mutex));
60 
61 	/*
62 	 * Sanity-check the inputs.
63 	 */
64 	if (!drm_core_check_feature(dev, DRIVER_SG))
65 		return -ENODEV;
66 	if (dev->sg != NULL)
67 		return -EBUSY;
68 	if (request->size > 0xffffffffUL)
69 		return -ENOMEM;
70 
71 	/*
72 	 * Do the allocation.
73 	 *
74 	 * XXX Would it be safe to drop drm_global_mutex here to avoid
75 	 * holding it during allocation?
76 	 */
77 	error = drm_sg_alloc_mem(dev, request->size, &sg);
78 	if (error)
79 		return error;
80 
81 	/* Set it up to be the device's scatter-gather memory.  */
82 	dev->sg = sg;
83 
84 	/* Success!  */
85 	request->handle = sg->handle;
86 	return 0;
87 }
88 
89 int
90 drm_sg_free(struct drm_device *dev, void *data, struct drm_file *file)
91 {
92 	struct drm_scatter_gather *const request = data;
93 	struct drm_sg_mem *sg;
94 
95 	KASSERT(mutex_is_locked(&drm_global_mutex));
96 
97 	/*
98 	 * Sanity-check the inputs.
99 	 */
100 	if (!drm_core_check_feature(dev, DRIVER_SG))
101 		return -ENODEV;
102 
103 	sg = dev->sg;
104 	if (sg == NULL)
105 		return -ENXIO;
106 	if (sg->handle != request->handle)
107 		return -EINVAL;
108 
109 	/* Remove dev->sg.  */
110 	dev->sg = NULL;
111 
112 	/* Success!  */
113 	drm_sg_cleanup(sg);
114 	return 0;
115 }
116 
117 static int
118 drm_sg_alloc_mem(struct drm_device *dev, size_t size, struct drm_sg_mem **sgp)
119 {
120 	int nsegs;
121 	int error;
122 
123 	KASSERT(drm_core_check_feature(dev, DRIVER_SG));
124 
125 	KASSERT(size <= (size_t)0xffffffffUL); /* XXX 32-bit sizes only?  */
126 	const size_t nbytes = PAGE_ALIGN(size);
127 	const size_t npages = nbytes >> PAGE_SHIFT;
128 	KASSERT(npages <= (size_t)INT_MAX);
129 
130 	/*
131 	 * Allocate a drm_sg_mem record.
132 	 */
133 	struct drm_sg_mem *const sg =
134 	    kmem_zalloc(offsetof(struct drm_sg_mem, sg_segs[npages]),
135 		KM_NOSLEEP);
136 	if (sg == NULL)
137 		return -ENOMEM;
138 	sg->sg_tag = dev->dmat;
139 	sg->sg_nsegs_max = (unsigned int)npages;
140 
141 	/*
142 	 * Allocate the requested amount of DMA-safe memory.
143 	 */
144 	KASSERT(sg->sg_nsegs_max <= (unsigned int)INT_MAX);
145 	/* XXX errno NetBSD->Linux */
146 	error = -bus_dmamem_alloc(sg->sg_tag, nbytes, PAGE_SIZE, 0,
147 	    sg->sg_segs, (int)sg->sg_nsegs_max, &nsegs, BUS_DMA_NOWAIT);
148 	if (error)
149 		goto fail0;
150 	KASSERT(0 <= nsegs);
151 	sg->sg_nsegs = (unsigned int)nsegs;
152 
153 	/*
154 	 * XXX Old drm passed DRM_BUS_NOWAIT below but BUS_DMA_WAITOK
155 	 * above.  WTF?
156 	 */
157 
158 	/*
159 	 * Map the DMA-safe memory into kernel virtual address space.
160 	 */
161 	/* XXX errno NetBSD->Linux */
162 	error = -bus_dmamem_map(sg->sg_tag, sg->sg_segs, nsegs, nbytes,
163 	    &sg->virtual,
164 	    (BUS_DMA_NOWAIT | BUS_DMA_COHERENT | BUS_DMA_NOCACHE));
165 	if (error)
166 		goto fail1;
167 	sg->sg_size = nbytes;
168 
169 	/*
170 	 * Create a map for DMA transfers.
171 	 */
172 	/* XXX errno NetBSD->Linux */
173 	error = -bus_dmamap_create(sg->sg_tag, nbytes, nsegs, nbytes, 0,
174 	    BUS_DMA_NOWAIT, &sg->sg_map);
175 	if (error)
176 		goto fail2;
177 
178 	/*
179 	 * Load the kva buffer into the map for DMA transfers.
180 	 */
181 	/* XXX errno NetBSD->Linux */
182 	error = -bus_dmamap_load(sg->sg_tag, sg->sg_map, sg->virtual, nbytes,
183 	    NULL, (BUS_DMA_NOWAIT | BUS_DMA_NOCACHE));
184 	if (error)
185 		goto fail3;
186 
187 	/*
188 	 * Use the kernel virtual address as the userland handle.
189 	 *
190 	 * XXX This leaks some information about kernel virtual
191 	 * addresses to userland; should we use an idr instead?
192 	 */
193 	sg->handle = (unsigned long)(uintptr_t)sg->virtual;
194 	KASSERT(sg->virtual == (void *)(uintptr_t)sg->handle);
195 
196 	/* Success!  */
197 	*sgp = sg;
198 	return 0;
199 
200 fail3:	bus_dmamap_destroy(sg->sg_tag, sg->sg_map);
201 fail2:	bus_dmamem_unmap(sg->sg_tag, sg->virtual, sg->sg_size);
202 fail1:	KASSERT(sg->sg_nsegs <= (unsigned int)INT_MAX);
203 	bus_dmamem_free(sg->sg_tag, sg->sg_segs, (int)sg->sg_nsegs);
204 fail0:	sg->sg_tag = NULL;	/* XXX paranoia */
205 	kfree(sg);
206 	return error;
207 }
208 
209 void
210 drm_sg_cleanup(struct drm_sg_mem *sg)
211 {
212 
213 	bus_dmamap_unload(sg->sg_tag, sg->sg_map);
214 	bus_dmamap_destroy(sg->sg_tag, sg->sg_map);
215 	bus_dmamem_unmap(sg->sg_tag, sg->virtual, sg->sg_size);
216 	KASSERT(sg->sg_nsegs <= (unsigned int)INT_MAX);
217 	bus_dmamem_free(sg->sg_tag, sg->sg_segs, (int)sg->sg_nsegs);
218 	sg->sg_tag = NULL;	/* XXX paranoia */
219 	kmem_free(sg, offsetof(struct drm_sg_mem, sg_segs[sg->sg_nsegs_max]));
220 }
221