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b754416b RR |
1 | /* A simple block driver for lguest. |
2 | * | |
3 | * Copyright 2006 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation; either version 2 of the License, or | |
8 | * (at your option) any later version. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program; if not, write to the Free Software | |
17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
18 | */ | |
19 | //#define DEBUG | |
20 | #include <linux/init.h> | |
21 | #include <linux/types.h> | |
22 | #include <linux/blkdev.h> | |
23 | #include <linux/interrupt.h> | |
24 | #include <linux/lguest_bus.h> | |
25 | ||
26 | static char next_block_index = 'a'; | |
27 | ||
28 | struct blockdev | |
29 | { | |
30 | spinlock_t lock; | |
31 | ||
32 | /* The disk structure for the kernel. */ | |
33 | struct gendisk *disk; | |
34 | ||
35 | /* The major number for this disk. */ | |
36 | int major; | |
37 | int irq; | |
38 | ||
39 | unsigned long phys_addr; | |
40 | /* The mapped block page. */ | |
41 | struct lguest_block_page *lb_page; | |
42 | ||
43 | /* We only have a single request outstanding at a time. */ | |
44 | struct lguest_dma dma; | |
45 | struct request *req; | |
46 | }; | |
47 | ||
48 | /* Jens gave me this nice helper to end all chunks of a request. */ | |
49 | static void end_entire_request(struct request *req, int uptodate) | |
50 | { | |
51 | if (end_that_request_first(req, uptodate, req->hard_nr_sectors)) | |
52 | BUG(); | |
53 | add_disk_randomness(req->rq_disk); | |
54 | blkdev_dequeue_request(req); | |
55 | end_that_request_last(req, uptodate); | |
56 | } | |
57 | ||
58 | static irqreturn_t lgb_irq(int irq, void *_bd) | |
59 | { | |
60 | struct blockdev *bd = _bd; | |
61 | unsigned long flags; | |
62 | ||
63 | if (!bd->req) { | |
64 | pr_debug("No work!\n"); | |
65 | return IRQ_NONE; | |
66 | } | |
67 | ||
68 | if (!bd->lb_page->result) { | |
69 | pr_debug("No result!\n"); | |
70 | return IRQ_NONE; | |
71 | } | |
72 | ||
73 | spin_lock_irqsave(&bd->lock, flags); | |
74 | end_entire_request(bd->req, bd->lb_page->result == 1); | |
75 | bd->req = NULL; | |
76 | bd->dma.used_len = 0; | |
77 | blk_start_queue(bd->disk->queue); | |
78 | spin_unlock_irqrestore(&bd->lock, flags); | |
79 | return IRQ_HANDLED; | |
80 | } | |
81 | ||
82 | static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma) | |
83 | { | |
84 | unsigned int i = 0, idx, len = 0; | |
85 | struct bio *bio; | |
86 | ||
87 | rq_for_each_bio(bio, req) { | |
88 | struct bio_vec *bvec; | |
89 | bio_for_each_segment(bvec, bio, idx) { | |
90 | BUG_ON(i == LGUEST_MAX_DMA_SECTIONS); | |
91 | BUG_ON(!bvec->bv_len); | |
92 | dma->addr[i] = page_to_phys(bvec->bv_page) | |
93 | + bvec->bv_offset; | |
94 | dma->len[i] = bvec->bv_len; | |
95 | len += bvec->bv_len; | |
96 | i++; | |
97 | } | |
98 | } | |
99 | if (i < LGUEST_MAX_DMA_SECTIONS) | |
100 | dma->len[i] = 0; | |
101 | return len; | |
102 | } | |
103 | ||
104 | static void empty_dma(struct lguest_dma *dma) | |
105 | { | |
106 | dma->len[0] = 0; | |
107 | } | |
108 | ||
109 | static void setup_req(struct blockdev *bd, | |
110 | int type, struct request *req, struct lguest_dma *dma) | |
111 | { | |
112 | bd->lb_page->type = type; | |
113 | bd->lb_page->sector = req->sector; | |
114 | bd->lb_page->result = 0; | |
115 | bd->req = req; | |
116 | bd->lb_page->bytes = req_to_dma(req, dma); | |
117 | } | |
118 | ||
119 | static void do_write(struct blockdev *bd, struct request *req) | |
120 | { | |
121 | struct lguest_dma send; | |
122 | ||
123 | pr_debug("lgb: WRITE sector %li\n", (long)req->sector); | |
124 | setup_req(bd, 1, req, &send); | |
125 | ||
126 | lguest_send_dma(bd->phys_addr, &send); | |
127 | } | |
128 | ||
129 | static void do_read(struct blockdev *bd, struct request *req) | |
130 | { | |
131 | struct lguest_dma ping; | |
132 | ||
133 | pr_debug("lgb: READ sector %li\n", (long)req->sector); | |
134 | setup_req(bd, 0, req, &bd->dma); | |
135 | ||
136 | empty_dma(&ping); | |
137 | lguest_send_dma(bd->phys_addr, &ping); | |
138 | } | |
139 | ||
140 | static void do_lgb_request(request_queue_t *q) | |
141 | { | |
142 | struct blockdev *bd; | |
143 | struct request *req; | |
144 | ||
145 | again: | |
146 | req = elv_next_request(q); | |
147 | if (!req) | |
148 | return; | |
149 | ||
150 | bd = req->rq_disk->private_data; | |
151 | /* Sometimes we get repeated requests after blk_stop_queue. */ | |
152 | if (bd->req) | |
153 | return; | |
154 | ||
155 | if (!blk_fs_request(req)) { | |
156 | pr_debug("Got non-command 0x%08x\n", req->cmd_type); | |
157 | req->errors++; | |
158 | end_entire_request(req, 0); | |
159 | goto again; | |
160 | } | |
161 | ||
162 | if (rq_data_dir(req) == WRITE) | |
163 | do_write(bd, req); | |
164 | else | |
165 | do_read(bd, req); | |
166 | ||
167 | /* Wait for interrupt to tell us it's done. */ | |
168 | blk_stop_queue(q); | |
169 | } | |
170 | ||
171 | static struct block_device_operations lguestblk_fops = { | |
172 | .owner = THIS_MODULE, | |
173 | }; | |
174 | ||
175 | static int lguestblk_probe(struct lguest_device *lgdev) | |
176 | { | |
177 | struct blockdev *bd; | |
178 | int err; | |
179 | int irqflags = IRQF_SHARED; | |
180 | ||
181 | bd = kmalloc(sizeof(*bd), GFP_KERNEL); | |
182 | if (!bd) | |
183 | return -ENOMEM; | |
184 | ||
185 | spin_lock_init(&bd->lock); | |
186 | bd->irq = lgdev_irq(lgdev); | |
187 | bd->req = NULL; | |
188 | bd->dma.used_len = 0; | |
189 | bd->dma.len[0] = 0; | |
190 | bd->phys_addr = (lguest_devices[lgdev->index].pfn << PAGE_SHIFT); | |
191 | ||
192 | bd->lb_page = lguest_map(bd->phys_addr, 1); | |
193 | if (!bd->lb_page) { | |
194 | err = -ENOMEM; | |
195 | goto out_free_bd; | |
196 | } | |
197 | ||
198 | bd->major = register_blkdev(0, "lguestblk"); | |
199 | if (bd->major < 0) { | |
200 | err = bd->major; | |
201 | goto out_unmap; | |
202 | } | |
203 | ||
204 | bd->disk = alloc_disk(1); | |
205 | if (!bd->disk) { | |
206 | err = -ENOMEM; | |
207 | goto out_unregister_blkdev; | |
208 | } | |
209 | ||
210 | bd->disk->queue = blk_init_queue(do_lgb_request, &bd->lock); | |
211 | if (!bd->disk->queue) { | |
212 | err = -ENOMEM; | |
213 | goto out_put_disk; | |
214 | } | |
215 | ||
216 | /* We can only handle a certain number of sg entries */ | |
217 | blk_queue_max_hw_segments(bd->disk->queue, LGUEST_MAX_DMA_SECTIONS); | |
218 | /* Buffers must not cross page boundaries */ | |
219 | blk_queue_segment_boundary(bd->disk->queue, PAGE_SIZE-1); | |
220 | ||
221 | sprintf(bd->disk->disk_name, "lgb%c", next_block_index++); | |
222 | if (lguest_devices[lgdev->index].features & LGUEST_DEVICE_F_RANDOMNESS) | |
223 | irqflags |= IRQF_SAMPLE_RANDOM; | |
224 | err = request_irq(bd->irq, lgb_irq, irqflags, bd->disk->disk_name, bd); | |
225 | if (err) | |
226 | goto out_cleanup_queue; | |
227 | ||
228 | err = lguest_bind_dma(bd->phys_addr, &bd->dma, 1, bd->irq); | |
229 | if (err) | |
230 | goto out_free_irq; | |
231 | ||
232 | bd->disk->major = bd->major; | |
233 | bd->disk->first_minor = 0; | |
234 | bd->disk->private_data = bd; | |
235 | bd->disk->fops = &lguestblk_fops; | |
236 | /* This is initialized to the disk size by the other end. */ | |
237 | set_capacity(bd->disk, bd->lb_page->num_sectors); | |
238 | add_disk(bd->disk); | |
239 | ||
240 | printk(KERN_INFO "%s: device %i at major %d\n", | |
241 | bd->disk->disk_name, lgdev->index, bd->major); | |
242 | ||
243 | lgdev->private = bd; | |
244 | return 0; | |
245 | ||
246 | out_free_irq: | |
247 | free_irq(bd->irq, bd); | |
248 | out_cleanup_queue: | |
249 | blk_cleanup_queue(bd->disk->queue); | |
250 | out_put_disk: | |
251 | put_disk(bd->disk); | |
252 | out_unregister_blkdev: | |
253 | unregister_blkdev(bd->major, "lguestblk"); | |
254 | out_unmap: | |
255 | lguest_unmap(bd->lb_page); | |
256 | out_free_bd: | |
257 | kfree(bd); | |
258 | return err; | |
259 | } | |
260 | ||
261 | static struct lguest_driver lguestblk_drv = { | |
262 | .name = "lguestblk", | |
263 | .owner = THIS_MODULE, | |
264 | .device_type = LGUEST_DEVICE_T_BLOCK, | |
265 | .probe = lguestblk_probe, | |
266 | }; | |
267 | ||
268 | static __init int lguestblk_init(void) | |
269 | { | |
270 | return register_lguest_driver(&lguestblk_drv); | |
271 | } | |
272 | module_init(lguestblk_init); | |
273 | ||
274 | MODULE_DESCRIPTION("Lguest block driver"); | |
275 | MODULE_LICENSE("GPL"); |