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1 /*
2  * DMA region bookkeeping routines
3  *
4  * Copyright (C) 2002 Maas Digital LLC
5  *
6  * This code is licensed under the GPL.  See the file COPYING in the root
7  * directory of the kernel sources for details.
8  */
9
10 #include <linux/mm.h>
11 #include <linux/module.h>
12 #include <linux/pci.h>
13 #include <linux/slab.h>
14 #include <linux/vmalloc.h>
15 #include <asm/scatterlist.h>
16
17 #include "dma.h"
18
19 /* dma_prog_region */
20
21 void dma_prog_region_init(struct dma_prog_region *prog)
22 {
23         prog->kvirt = NULL;
24         prog->dev = NULL;
25         prog->n_pages = 0;
26         prog->bus_addr = 0;
27 }
28
29 int dma_prog_region_alloc(struct dma_prog_region *prog, unsigned long n_bytes,
30                           struct pci_dev *dev)
31 {
32         /* round up to page size */
33         n_bytes = PAGE_ALIGN(n_bytes);
34
35         prog->n_pages = n_bytes >> PAGE_SHIFT;
36
37         prog->kvirt = pci_alloc_consistent(dev, n_bytes, &prog->bus_addr);
38         if (!prog->kvirt) {
39                 printk(KERN_ERR
40                        "dma_prog_region_alloc: pci_alloc_consistent() failed\n");
41                 dma_prog_region_free(prog);
42                 return -ENOMEM;
43         }
44
45         prog->dev = dev;
46
47         return 0;
48 }
49
50 void dma_prog_region_free(struct dma_prog_region *prog)
51 {
52         if (prog->kvirt) {
53                 pci_free_consistent(prog->dev, prog->n_pages << PAGE_SHIFT,
54                                     prog->kvirt, prog->bus_addr);
55         }
56
57         prog->kvirt = NULL;
58         prog->dev = NULL;
59         prog->n_pages = 0;
60         prog->bus_addr = 0;
61 }
62
63 /* dma_region */
64
65 /**
66  * dma_region_init - clear out all fields but do not allocate anything
67  */
68 void dma_region_init(struct dma_region *dma)
69 {
70         dma->kvirt = NULL;
71         dma->dev = NULL;
72         dma->n_pages = 0;
73         dma->n_dma_pages = 0;
74         dma->sglist = NULL;
75 }
76
77 /**
78  * dma_region_alloc - allocate the buffer and map it to the IOMMU
79  */
80 int dma_region_alloc(struct dma_region *dma, unsigned long n_bytes,
81                      struct pci_dev *dev, int direction)
82 {
83         unsigned int i;
84
85         /* round up to page size */
86         n_bytes = PAGE_ALIGN(n_bytes);
87
88         dma->n_pages = n_bytes >> PAGE_SHIFT;
89
90         dma->kvirt = vmalloc_32(n_bytes);
91         if (!dma->kvirt) {
92                 printk(KERN_ERR "dma_region_alloc: vmalloc_32() failed\n");
93                 goto err;
94         }
95
96         /* Clear the ram out, no junk to the user */
97         memset(dma->kvirt, 0, n_bytes);
98
99         /* allocate scatter/gather list */
100         dma->sglist = vmalloc(dma->n_pages * sizeof(*dma->sglist));
101         if (!dma->sglist) {
102                 printk(KERN_ERR "dma_region_alloc: vmalloc(sglist) failed\n");
103                 goto err;
104         }
105
106         /* just to be safe - this will become unnecessary once sglist->address goes away */
107         memset(dma->sglist, 0, dma->n_pages * sizeof(*dma->sglist));
108
109         /* fill scatter/gather list with pages */
110         for (i = 0; i < dma->n_pages; i++) {
111                 unsigned long va =
112                     (unsigned long)dma->kvirt + (i << PAGE_SHIFT);
113
114                 dma->sglist[i].page = vmalloc_to_page((void *)va);
115                 dma->sglist[i].length = PAGE_SIZE;
116         }
117
118         /* map sglist to the IOMMU */
119         dma->n_dma_pages =
120             pci_map_sg(dev, dma->sglist, dma->n_pages, direction);
121
122         if (dma->n_dma_pages == 0) {
123                 printk(KERN_ERR "dma_region_alloc: pci_map_sg() failed\n");
124                 goto err;
125         }
126
127         dma->dev = dev;
128         dma->direction = direction;
129
130         return 0;
131
132       err:
133         dma_region_free(dma);
134         return -ENOMEM;
135 }
136
137 /**
138  * dma_region_free - unmap and free the buffer
139  */
140 void dma_region_free(struct dma_region *dma)
141 {
142         if (dma->n_dma_pages) {
143                 pci_unmap_sg(dma->dev, dma->sglist, dma->n_pages,
144                              dma->direction);
145                 dma->n_dma_pages = 0;
146                 dma->dev = NULL;
147         }
148
149         vfree(dma->sglist);
150         dma->sglist = NULL;
151
152         vfree(dma->kvirt);
153         dma->kvirt = NULL;
154         dma->n_pages = 0;
155 }
156
157 /* find the scatterlist index and remaining offset corresponding to a
158    given offset from the beginning of the buffer */
159 static inline int dma_region_find(struct dma_region *dma, unsigned long offset,
160                                   unsigned int start, unsigned long *rem)
161 {
162         int i;
163         unsigned long off = offset;
164
165         for (i = start; i < dma->n_dma_pages; i++) {
166                 if (off < sg_dma_len(&dma->sglist[i])) {
167                         *rem = off;
168                         break;
169                 }
170
171                 off -= sg_dma_len(&dma->sglist[i]);
172         }
173
174         BUG_ON(i >= dma->n_dma_pages);
175
176         return i;
177 }
178
179 /**
180  * dma_region_offset_to_bus - get bus address of an offset within a DMA region
181  *
182  * Returns the DMA bus address of the byte with the given @offset relative to
183  * the beginning of the @dma.
184  */
185 dma_addr_t dma_region_offset_to_bus(struct dma_region * dma,
186                                     unsigned long offset)
187 {
188         unsigned long rem = 0;
189
190         struct scatterlist *sg =
191             &dma->sglist[dma_region_find(dma, offset, 0, &rem)];
192         return sg_dma_address(sg) + rem;
193 }
194
195 /**
196  * dma_region_sync_for_cpu - sync the CPU's view of the buffer
197  */
198 void dma_region_sync_for_cpu(struct dma_region *dma, unsigned long offset,
199                              unsigned long len)
200 {
201         int first, last;
202         unsigned long rem = 0;
203
204         if (!len)
205                 len = 1;
206
207         first = dma_region_find(dma, offset, 0, &rem);
208         last = dma_region_find(dma, rem + len - 1, first, &rem);
209
210         pci_dma_sync_sg_for_cpu(dma->dev, &dma->sglist[first], last - first + 1,
211                                 dma->direction);
212 }
213
214 /**
215  * dma_region_sync_for_device - sync the IO bus' view of the buffer
216  */
217 void dma_region_sync_for_device(struct dma_region *dma, unsigned long offset,
218                                 unsigned long len)
219 {
220         int first, last;
221         unsigned long rem = 0;
222
223         if (!len)
224                 len = 1;
225
226         first = dma_region_find(dma, offset, 0, &rem);
227         last = dma_region_find(dma, rem + len - 1, first, &rem);
228
229         pci_dma_sync_sg_for_device(dma->dev, &dma->sglist[first],
230                                    last - first + 1, dma->direction);
231 }
232
233 #ifdef CONFIG_MMU
234
235 /* nopage() handler for mmap access */
236
237 static struct page *dma_region_pagefault(struct vm_area_struct *area,
238                                          unsigned long address, int *type)
239 {
240         unsigned long offset;
241         unsigned long kernel_virt_addr;
242         struct page *ret = NOPAGE_SIGBUS;
243
244         struct dma_region *dma = (struct dma_region *)area->vm_private_data;
245
246         if (!dma->kvirt)
247                 goto out;
248
249         if ((address < (unsigned long)area->vm_start) ||
250             (address >
251              (unsigned long)area->vm_start + (dma->n_pages << PAGE_SHIFT)))
252                 goto out;
253
254         if (type)
255                 *type = VM_FAULT_MINOR;
256         offset = address - area->vm_start;
257         kernel_virt_addr = (unsigned long)dma->kvirt + offset;
258         ret = vmalloc_to_page((void *)kernel_virt_addr);
259         get_page(ret);
260       out:
261         return ret;
262 }
263
264 static struct vm_operations_struct dma_region_vm_ops = {
265         .nopage = dma_region_pagefault,
266 };
267
268 /**
269  * dma_region_mmap - map the buffer into a user space process
270  */
271 int dma_region_mmap(struct dma_region *dma, struct file *file,
272                     struct vm_area_struct *vma)
273 {
274         unsigned long size;
275
276         if (!dma->kvirt)
277                 return -EINVAL;
278
279         /* must be page-aligned */
280         if (vma->vm_pgoff != 0)
281                 return -EINVAL;
282
283         /* check the length */
284         size = vma->vm_end - vma->vm_start;
285         if (size > (dma->n_pages << PAGE_SHIFT))
286                 return -EINVAL;
287
288         vma->vm_ops = &dma_region_vm_ops;
289         vma->vm_private_data = dma;
290         vma->vm_file = file;
291         vma->vm_flags |= VM_RESERVED;
292
293         return 0;
294 }
295
296 #else                           /* CONFIG_MMU */
297
298 int dma_region_mmap(struct dma_region *dma, struct file *file,
299                     struct vm_area_struct *vma)
300 {
301         return -EINVAL;
302 }
303
304 #endif                          /* CONFIG_MMU */