Rusty Russell | b754416 | 2007-07-19 01:49:29 -0700 | [diff] [blame] | 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 | |
Jens Axboe | 165125e | 2007-07-24 09:28:11 +0200 | [diff] [blame^] | 140 | static void do_lgb_request(struct request_queue *q) |
Rusty Russell | b754416 | 2007-07-19 01:49:29 -0700 | [diff] [blame] | 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"); |