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12#include <linux/module.h>
13#include <linux/moduleparam.h>
14#include <linux/kernel.h>
15#include <linux/init.h>
16#include <linux/string.h>
17#include <linux/blkdev.h>
18#include <linux/bio.h>
19#include <linux/proc_fs.h>
20#include <linux/uaccess.h>
21#include <platform/simcall.h>
22
23#define SIMDISK_MAJOR 240
24#define SECTOR_SHIFT 9
25#define SIMDISK_MINORS 1
26#define MAX_SIMDISK_COUNT 10
27
28struct simdisk {
29 const char *filename;
30 spinlock_t lock;
31 struct request_queue *queue;
32 struct gendisk *gd;
33 struct proc_dir_entry *procfile;
34 int users;
35 unsigned long size;
36 int fd;
37};
38
39
40static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
41module_param(simdisk_count, int, S_IRUGO);
42MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
43
44static int n_files;
45static const char *filename[MAX_SIMDISK_COUNT] = {
46#ifdef CONFIG_SIMDISK0_FILENAME
47 CONFIG_SIMDISK0_FILENAME,
48#ifdef CONFIG_SIMDISK1_FILENAME
49 CONFIG_SIMDISK1_FILENAME,
50#endif
51#endif
52};
53
54static int simdisk_param_set_filename(const char *val,
55 const struct kernel_param *kp)
56{
57 if (n_files < ARRAY_SIZE(filename))
58 filename[n_files++] = val;
59 else
60 return -EINVAL;
61 return 0;
62}
63
64static const struct kernel_param_ops simdisk_param_ops_filename = {
65 .set = simdisk_param_set_filename,
66};
67module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
68MODULE_PARM_DESC(filename, "Backing storage filename.");
69
70static int simdisk_major = SIMDISK_MAJOR;
71
72static void simdisk_transfer(struct simdisk *dev, unsigned long sector,
73 unsigned long nsect, char *buffer, int write)
74{
75 unsigned long offset = sector << SECTOR_SHIFT;
76 unsigned long nbytes = nsect << SECTOR_SHIFT;
77
78 if (offset > dev->size || dev->size - offset < nbytes) {
79 pr_notice("Beyond-end %s (%ld %ld)\n",
80 write ? "write" : "read", offset, nbytes);
81 return;
82 }
83
84 spin_lock(&dev->lock);
85 while (nbytes > 0) {
86 unsigned long io;
87
88 simc_lseek(dev->fd, offset, SEEK_SET);
89 READ_ONCE(*buffer);
90 if (write)
91 io = simc_write(dev->fd, buffer, nbytes);
92 else
93 io = simc_read(dev->fd, buffer, nbytes);
94 if (io == -1) {
95 pr_err("SIMDISK: IO error %d\n", errno);
96 break;
97 }
98 buffer += io;
99 offset += io;
100 nbytes -= io;
101 }
102 spin_unlock(&dev->lock);
103}
104
105static blk_qc_t simdisk_make_request(struct request_queue *q, struct bio *bio)
106{
107 struct simdisk *dev = q->queuedata;
108 struct bio_vec bvec;
109 struct bvec_iter iter;
110 sector_t sector = bio->bi_iter.bi_sector;
111
112 bio_for_each_segment(bvec, bio, iter) {
113 char *buffer = __bio_kmap_atomic(bio, iter);
114 unsigned len = bvec.bv_len >> SECTOR_SHIFT;
115
116 simdisk_transfer(dev, sector, len, buffer,
117 bio_data_dir(bio) == WRITE);
118 sector += len;
119 __bio_kunmap_atomic(buffer);
120 }
121
122 bio_endio(bio);
123 return BLK_QC_T_NONE;
124}
125
126static int simdisk_open(struct block_device *bdev, fmode_t mode)
127{
128 struct simdisk *dev = bdev->bd_disk->private_data;
129
130 spin_lock(&dev->lock);
131 if (!dev->users)
132 check_disk_change(bdev);
133 ++dev->users;
134 spin_unlock(&dev->lock);
135 return 0;
136}
137
138static void simdisk_release(struct gendisk *disk, fmode_t mode)
139{
140 struct simdisk *dev = disk->private_data;
141 spin_lock(&dev->lock);
142 --dev->users;
143 spin_unlock(&dev->lock);
144}
145
146static const struct block_device_operations simdisk_ops = {
147 .owner = THIS_MODULE,
148 .open = simdisk_open,
149 .release = simdisk_release,
150};
151
152static struct simdisk *sddev;
153static struct proc_dir_entry *simdisk_procdir;
154
155static int simdisk_attach(struct simdisk *dev, const char *filename)
156{
157 int err = 0;
158
159 filename = kstrdup(filename, GFP_KERNEL);
160 if (filename == NULL)
161 return -ENOMEM;
162
163 spin_lock(&dev->lock);
164
165 if (dev->fd != -1) {
166 err = -EBUSY;
167 goto out;
168 }
169 dev->fd = simc_open(filename, O_RDWR, 0);
170 if (dev->fd == -1) {
171 pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
172 err = -ENODEV;
173 goto out;
174 }
175 dev->size = simc_lseek(dev->fd, 0, SEEK_END);
176 set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
177 dev->filename = filename;
178 pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
179out:
180 if (err)
181 kfree(filename);
182 spin_unlock(&dev->lock);
183
184 return err;
185}
186
187static int simdisk_detach(struct simdisk *dev)
188{
189 int err = 0;
190
191 spin_lock(&dev->lock);
192
193 if (dev->users != 0) {
194 err = -EBUSY;
195 } else if (dev->fd != -1) {
196 if (simc_close(dev->fd)) {
197 pr_err("SIMDISK: error closing %s: %d\n",
198 dev->filename, errno);
199 err = -EIO;
200 } else {
201 pr_info("SIMDISK: %s detached from %s\n",
202 dev->gd->disk_name, dev->filename);
203 dev->fd = -1;
204 kfree(dev->filename);
205 dev->filename = NULL;
206 }
207 }
208 spin_unlock(&dev->lock);
209 return err;
210}
211
212static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
213 size_t size, loff_t *ppos)
214{
215 struct simdisk *dev = PDE_DATA(file_inode(file));
216 const char *s = dev->filename;
217 if (s) {
218 ssize_t n = simple_read_from_buffer(buf, size, ppos,
219 s, strlen(s));
220 if (n < 0)
221 return n;
222 buf += n;
223 size -= n;
224 }
225 return simple_read_from_buffer(buf, size, ppos, "\n", 1);
226}
227
228static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
229 size_t count, loff_t *ppos)
230{
231 char *tmp = memdup_user_nul(buf, count);
232 struct simdisk *dev = PDE_DATA(file_inode(file));
233 int err;
234
235 if (IS_ERR(tmp))
236 return PTR_ERR(tmp);
237
238 err = simdisk_detach(dev);
239 if (err != 0)
240 goto out_free;
241
242 if (count > 0 && tmp[count - 1] == '\n')
243 tmp[count - 1] = 0;
244
245 if (tmp[0])
246 err = simdisk_attach(dev, tmp);
247
248 if (err == 0)
249 err = count;
250out_free:
251 kfree(tmp);
252 return err;
253}
254
255static const struct file_operations fops = {
256 .read = proc_read_simdisk,
257 .write = proc_write_simdisk,
258 .llseek = default_llseek,
259};
260
261static int __init simdisk_setup(struct simdisk *dev, int which,
262 struct proc_dir_entry *procdir)
263{
264 char tmp[2] = { '0' + which, 0 };
265
266 dev->fd = -1;
267 dev->filename = NULL;
268 spin_lock_init(&dev->lock);
269 dev->users = 0;
270
271 dev->queue = blk_alloc_queue(GFP_KERNEL);
272 if (dev->queue == NULL) {
273 pr_err("blk_alloc_queue failed\n");
274 goto out_alloc_queue;
275 }
276
277 blk_queue_make_request(dev->queue, simdisk_make_request);
278 dev->queue->queuedata = dev;
279
280 dev->gd = alloc_disk(SIMDISK_MINORS);
281 if (dev->gd == NULL) {
282 pr_err("alloc_disk failed\n");
283 goto out_alloc_disk;
284 }
285 dev->gd->major = simdisk_major;
286 dev->gd->first_minor = which;
287 dev->gd->fops = &simdisk_ops;
288 dev->gd->queue = dev->queue;
289 dev->gd->private_data = dev;
290 snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
291 set_capacity(dev->gd, 0);
292 add_disk(dev->gd);
293
294 dev->procfile = proc_create_data(tmp, 0644, procdir, &fops, dev);
295 return 0;
296
297out_alloc_disk:
298 blk_cleanup_queue(dev->queue);
299 dev->queue = NULL;
300out_alloc_queue:
301 simc_close(dev->fd);
302 return -EIO;
303}
304
305static int __init simdisk_init(void)
306{
307 int i;
308
309 if (register_blkdev(simdisk_major, "simdisk") < 0) {
310 pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
311 return -EIO;
312 }
313 pr_info("SIMDISK: major: %d\n", simdisk_major);
314
315 if (n_files > simdisk_count)
316 simdisk_count = n_files;
317 if (simdisk_count > MAX_SIMDISK_COUNT)
318 simdisk_count = MAX_SIMDISK_COUNT;
319
320 sddev = kmalloc_array(simdisk_count, sizeof(*sddev), GFP_KERNEL);
321 if (sddev == NULL)
322 goto out_unregister;
323
324 simdisk_procdir = proc_mkdir("simdisk", 0);
325 if (simdisk_procdir == NULL)
326 goto out_free_unregister;
327
328 for (i = 0; i < simdisk_count; ++i) {
329 if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
330 if (filename[i] != NULL && filename[i][0] != 0 &&
331 (n_files == 0 || i < n_files))
332 simdisk_attach(sddev + i, filename[i]);
333 }
334 }
335
336 return 0;
337
338out_free_unregister:
339 kfree(sddev);
340out_unregister:
341 unregister_blkdev(simdisk_major, "simdisk");
342 return -ENOMEM;
343}
344module_init(simdisk_init);
345
346static void simdisk_teardown(struct simdisk *dev, int which,
347 struct proc_dir_entry *procdir)
348{
349 char tmp[2] = { '0' + which, 0 };
350
351 simdisk_detach(dev);
352 if (dev->gd)
353 del_gendisk(dev->gd);
354 if (dev->queue)
355 blk_cleanup_queue(dev->queue);
356 remove_proc_entry(tmp, procdir);
357}
358
359static void __exit simdisk_exit(void)
360{
361 int i;
362
363 for (i = 0; i < simdisk_count; ++i)
364 simdisk_teardown(sddev + i, i, simdisk_procdir);
365 remove_proc_entry("simdisk", 0);
366 kfree(sddev);
367 unregister_blkdev(simdisk_major, "simdisk");
368}
369module_exit(simdisk_exit);
370
371MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
372
373MODULE_LICENSE("GPL");
374
