2 * Copyright (c) 1990 University of Utah.
3 * Copyright (c) 1991, 1993
4 * The Regents of the University of California. All rights reserved.
6 * This code is derived from software contributed to Berkeley by
7 * the Systems Programming Group of the University of Utah Computer
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20 * This product includes software developed by the University of
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38 * @(#)device_pager.c 8.1 (Berkeley) 6/11/93
39 * $FreeBSD: src/sys/vm/device_pager.c,v 1.46.2.1 2000/08/02 21:54:37 peter Exp $
40 * $DragonFly: src/sys/vm/device_pager.c,v 1.13 2008/01/21 10:25:18 corecode Exp $
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/kernel.h>
48 #include <sys/device.h>
49 #include <sys/queue.h>
50 #include <sys/malloc.h>
51 #include <sys/thread2.h>
54 #include <vm/vm_object.h>
55 #include <vm/vm_page.h>
56 #include <vm/vm_pager.h>
57 #include <vm/vm_zone.h>
59 static void dev_pager_init (void);
60 static vm_object_t dev_pager_alloc (void *, off_t, vm_prot_t, off_t);
61 static void dev_pager_dealloc (vm_object_t);
62 static int dev_pager_getpage (vm_object_t, vm_page_t *, int);
63 static void dev_pager_putpages (vm_object_t, vm_page_t *, int,
65 static boolean_t dev_pager_haspage (vm_object_t, vm_pindex_t);
67 /* list of device pager objects */
68 static struct pagerlst dev_pager_object_list;
69 static TAILQ_HEAD(, vm_page) dev_freepages_list;
70 static MALLOC_DEFINE(M_FICTITIOUS_PAGES, "device-mapped pages", "Device mapped pages");
72 static vm_page_t dev_pager_getfake (vm_paddr_t);
73 static void dev_pager_putfake (vm_page_t);
75 static int dev_pager_alloc_lock, dev_pager_alloc_lock_want;
77 struct pagerops devicepagerops = {
90 TAILQ_INIT(&dev_pager_object_list);
91 TAILQ_INIT(&dev_freepages_list);
95 dev_pager_alloc(void *handle, off_t size, vm_prot_t prot, off_t foff)
103 * Make sure this device can be mapped.
108 * Offset should be page aligned.
110 if (foff & PAGE_MASK)
113 size = round_page(size);
116 * Check that the specified range of the device allows the desired
119 * XXX assumes VM_PROT_* == PROT_*
121 npages = OFF_TO_IDX(size);
122 for (off = foff; npages--; off += PAGE_SIZE) {
123 if (dev_dmmap(dev, off, (int)prot) == -1)
128 * Lock to prevent object creation race condition.
130 while (dev_pager_alloc_lock) {
131 dev_pager_alloc_lock_want++;
132 tsleep(&dev_pager_alloc_lock, 0, "dvpall", 0);
133 dev_pager_alloc_lock_want--;
135 dev_pager_alloc_lock = 1;
138 * Look up pager, creating as necessary.
140 object = vm_pager_object_lookup(&dev_pager_object_list, handle);
141 if (object == NULL) {
143 * Allocate object and associate it with the pager.
145 object = vm_object_allocate(OBJT_DEVICE,
146 OFF_TO_IDX(foff + size));
147 object->handle = handle;
148 TAILQ_INIT(&object->un_pager.devp.devp_pglist);
149 TAILQ_INSERT_TAIL(&dev_pager_object_list, object, pager_object_list);
152 * Gain a reference to the object.
154 vm_object_reference(object);
155 if (OFF_TO_IDX(foff + size) > object->size)
156 object->size = OFF_TO_IDX(foff + size);
159 dev_pager_alloc_lock = 0;
160 if (dev_pager_alloc_lock_want)
161 wakeup(&dev_pager_alloc_lock);
167 dev_pager_dealloc(vm_object_t object)
171 TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
173 * Free up our fake pages.
175 while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist)) != 0) {
176 TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
177 dev_pager_putfake(m);
182 dev_pager_getpage(vm_object_t object, vm_page_t *mpp, int seqaccess)
191 dev = object->handle;
192 offset = page->pindex;
193 prot = PROT_READ; /* XXX should pass in? */
195 paddr = pmap_phys_address(
196 dev_dmmap(dev, (vm_offset_t)offset << PAGE_SHIFT, prot));
197 KASSERT(paddr != -1,("dev_pager_getpage: map function returns error"));
199 if (page->flags & PG_FICTITIOUS) {
201 * If the passed in reqpage page is a fake page, update it
202 * with the new physical address.
204 page->phys_addr = paddr;
205 page->valid = VM_PAGE_BITS_ALL;
208 * Replace the passed in reqpage page with our own fake page
209 * and free up all the original pages.
211 page = dev_pager_getfake(paddr);
212 TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist, page, pageq);
215 vm_page_insert(page, object, offset);
218 return (VM_PAGER_OK);
222 dev_pager_putpages(vm_object_t object, vm_page_t *m,
223 int count, boolean_t sync, int *rtvals)
225 panic("dev_pager_putpage called");
229 dev_pager_haspage(vm_object_t object, vm_pindex_t pindex)
235 dev_pager_getfake(vm_paddr_t paddr)
239 if ((m = TAILQ_FIRST(&dev_freepages_list)) != NULL) {
240 TAILQ_REMOVE(&dev_freepages_list, m, pageq);
242 m = kmalloc(sizeof(*m), M_FICTITIOUS_PAGES, M_WAITOK);
244 bzero(m, sizeof(*m));
246 m->flags = PG_BUSY | PG_FICTITIOUS;
247 m->valid = VM_PAGE_BITS_ALL;
255 m->phys_addr = paddr;
261 * Synthesized VM pages must be structurally stable for lockless lookups to
265 dev_pager_putfake(vm_page_t m)
267 if (!(m->flags & PG_FICTITIOUS))
268 panic("dev_pager_putfake: bad page");
269 KKASSERT(m->object == NULL);
270 TAILQ_INSERT_HEAD(&dev_freepages_list, m, pageq);