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