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Linux/arch/xtensa/platforms/iss/simdisk.c

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  1 /*
  2  * arch/xtensa/platforms/iss/simdisk.c
  3  *
  4  * This file is subject to the terms and conditions of the GNU General Public
  5  * License.  See the file "COPYING" in the main directory of this archive
  6  * for more details.
  7  *
  8  * Copyright (C) 2001-2013 Tensilica Inc.
  9  *   Authors    Victor Prupis
 10  */
 11 
 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 
 27 struct simdisk {
 28         const char *filename;
 29         spinlock_t lock;
 30         struct request_queue *queue;
 31         struct gendisk *gd;
 32         struct proc_dir_entry *procfile;
 33         int users;
 34         unsigned long size;
 35         int fd;
 36 };
 37 
 38 
 39 static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
 40 module_param(simdisk_count, int, S_IRUGO);
 41 MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
 42 
 43 static int n_files;
 44 static const char *filename[MAX_SIMDISK_COUNT] = {
 45 #ifdef CONFIG_SIMDISK0_FILENAME
 46         CONFIG_SIMDISK0_FILENAME,
 47 #ifdef CONFIG_SIMDISK1_FILENAME
 48         CONFIG_SIMDISK1_FILENAME,
 49 #endif
 50 #endif
 51 };
 52 
 53 static int simdisk_param_set_filename(const char *val,
 54                 const struct kernel_param *kp)
 55 {
 56         if (n_files < ARRAY_SIZE(filename))
 57                 filename[n_files++] = val;
 58         else
 59                 return -EINVAL;
 60         return 0;
 61 }
 62 
 63 static const struct kernel_param_ops simdisk_param_ops_filename = {
 64         .set = simdisk_param_set_filename,
 65 };
 66 module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
 67 MODULE_PARM_DESC(filename, "Backing storage filename.");
 68 
 69 static int simdisk_major = SIMDISK_MAJOR;
 70 
 71 static void simdisk_transfer(struct simdisk *dev, unsigned long sector,
 72                 unsigned long nsect, char *buffer, int write)
 73 {
 74         unsigned long offset = sector << SECTOR_SHIFT;
 75         unsigned long nbytes = nsect << SECTOR_SHIFT;
 76 
 77         if (offset > dev->size || dev->size - offset < nbytes) {
 78                 pr_notice("Beyond-end %s (%ld %ld)\n",
 79                                 write ? "write" : "read", offset, nbytes);
 80                 return;
 81         }
 82 
 83         spin_lock(&dev->lock);
 84         while (nbytes > 0) {
 85                 unsigned long io;
 86 
 87                 simc_lseek(dev->fd, offset, SEEK_SET);
 88                 READ_ONCE(*buffer);
 89                 if (write)
 90                         io = simc_write(dev->fd, buffer, nbytes);
 91                 else
 92                         io = simc_read(dev->fd, buffer, nbytes);
 93                 if (io == -1) {
 94                         pr_err("SIMDISK: IO error %d\n", errno);
 95                         break;
 96                 }
 97                 buffer += io;
 98                 offset += io;
 99                 nbytes -= io;
100         }
101         spin_unlock(&dev->lock);
102 }
103 
104 static blk_qc_t simdisk_make_request(struct request_queue *q, struct bio *bio)
105 {
106         struct simdisk *dev = q->queuedata;
107         struct bio_vec bvec;
108         struct bvec_iter iter;
109         sector_t sector = bio->bi_iter.bi_sector;
110 
111         bio_for_each_segment(bvec, bio, iter) {
112                 char *buffer = kmap_atomic(bvec.bv_page) + bvec.bv_offset;
113                 unsigned len = bvec.bv_len >> SECTOR_SHIFT;
114 
115                 simdisk_transfer(dev, sector, len, buffer,
116                                 bio_data_dir(bio) == WRITE);
117                 sector += len;
118                 kunmap_atomic(buffer);
119         }
120 
121         bio_endio(bio);
122         return BLK_QC_T_NONE;
123 }
124 
125 static int simdisk_open(struct block_device *bdev, fmode_t mode)
126 {
127         struct simdisk *dev = bdev->bd_disk->private_data;
128 
129         spin_lock(&dev->lock);
130         if (!dev->users)
131                 check_disk_change(bdev);
132         ++dev->users;
133         spin_unlock(&dev->lock);
134         return 0;
135 }
136 
137 static void simdisk_release(struct gendisk *disk, fmode_t mode)
138 {
139         struct simdisk *dev = disk->private_data;
140         spin_lock(&dev->lock);
141         --dev->users;
142         spin_unlock(&dev->lock);
143 }
144 
145 static const struct block_device_operations simdisk_ops = {
146         .owner          = THIS_MODULE,
147         .open           = simdisk_open,
148         .release        = simdisk_release,
149 };
150 
151 static struct simdisk *sddev;
152 static struct proc_dir_entry *simdisk_procdir;
153 
154 static int simdisk_attach(struct simdisk *dev, const char *filename)
155 {
156         int err = 0;
157 
158         filename = kstrdup(filename, GFP_KERNEL);
159         if (filename == NULL)
160                 return -ENOMEM;
161 
162         spin_lock(&dev->lock);
163 
164         if (dev->fd != -1) {
165                 err = -EBUSY;
166                 goto out;
167         }
168         dev->fd = simc_open(filename, O_RDWR, 0);
169         if (dev->fd == -1) {
170                 pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
171                 err = -ENODEV;
172                 goto out;
173         }
174         dev->size = simc_lseek(dev->fd, 0, SEEK_END);
175         set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
176         dev->filename = filename;
177         pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
178 out:
179         if (err)
180                 kfree(filename);
181         spin_unlock(&dev->lock);
182 
183         return err;
184 }
185 
186 static int simdisk_detach(struct simdisk *dev)
187 {
188         int err = 0;
189 
190         spin_lock(&dev->lock);
191 
192         if (dev->users != 0) {
193                 err = -EBUSY;
194         } else if (dev->fd != -1) {
195                 if (simc_close(dev->fd)) {
196                         pr_err("SIMDISK: error closing %s: %d\n",
197                                         dev->filename, errno);
198                         err = -EIO;
199                 } else {
200                         pr_info("SIMDISK: %s detached from %s\n",
201                                         dev->gd->disk_name, dev->filename);
202                         dev->fd = -1;
203                         kfree(dev->filename);
204                         dev->filename = NULL;
205                 }
206         }
207         spin_unlock(&dev->lock);
208         return err;
209 }
210 
211 static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
212                         size_t size, loff_t *ppos)
213 {
214         struct simdisk *dev = PDE_DATA(file_inode(file));
215         const char *s = dev->filename;
216         if (s) {
217                 ssize_t n = simple_read_from_buffer(buf, size, ppos,
218                                                         s, strlen(s));
219                 if (n < 0)
220                         return n;
221                 buf += n;
222                 size -= n;
223         }
224         return simple_read_from_buffer(buf, size, ppos, "\n", 1);
225 }
226 
227 static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
228                         size_t count, loff_t *ppos)
229 {
230         char *tmp = memdup_user_nul(buf, count);
231         struct simdisk *dev = PDE_DATA(file_inode(file));
232         int err;
233 
234         if (IS_ERR(tmp))
235                 return PTR_ERR(tmp);
236 
237         err = simdisk_detach(dev);
238         if (err != 0)
239                 goto out_free;
240 
241         if (count > 0 && tmp[count - 1] == '\n')
242                 tmp[count - 1] = 0;
243 
244         if (tmp[0])
245                 err = simdisk_attach(dev, tmp);
246 
247         if (err == 0)
248                 err = count;
249 out_free:
250         kfree(tmp);
251         return err;
252 }
253 
254 static const struct file_operations fops = {
255         .read = proc_read_simdisk,
256         .write = proc_write_simdisk,
257         .llseek = default_llseek,
258 };
259 
260 static int __init simdisk_setup(struct simdisk *dev, int which,
261                 struct proc_dir_entry *procdir)
262 {
263         char tmp[2] = { '' + which, 0 };
264 
265         dev->fd = -1;
266         dev->filename = NULL;
267         spin_lock_init(&dev->lock);
268         dev->users = 0;
269 
270         dev->queue = blk_alloc_queue(GFP_KERNEL);
271         if (dev->queue == NULL) {
272                 pr_err("blk_alloc_queue failed\n");
273                 goto out_alloc_queue;
274         }
275 
276         blk_queue_make_request(dev->queue, simdisk_make_request);
277         dev->queue->queuedata = dev;
278 
279         dev->gd = alloc_disk(SIMDISK_MINORS);
280         if (dev->gd == NULL) {
281                 pr_err("alloc_disk failed\n");
282                 goto out_alloc_disk;
283         }
284         dev->gd->major = simdisk_major;
285         dev->gd->first_minor = which;
286         dev->gd->fops = &simdisk_ops;
287         dev->gd->queue = dev->queue;
288         dev->gd->private_data = dev;
289         snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
290         set_capacity(dev->gd, 0);
291         add_disk(dev->gd);
292 
293         dev->procfile = proc_create_data(tmp, 0644, procdir, &fops, dev);
294         return 0;
295 
296 out_alloc_disk:
297         blk_cleanup_queue(dev->queue);
298         dev->queue = NULL;
299 out_alloc_queue:
300         return -ENOMEM;
301 }
302 
303 static int __init simdisk_init(void)
304 {
305         int i;
306 
307         if (register_blkdev(simdisk_major, "simdisk") < 0) {
308                 pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
309                 return -EIO;
310         }
311         pr_info("SIMDISK: major: %d\n", simdisk_major);
312 
313         if (n_files > simdisk_count)
314                 simdisk_count = n_files;
315         if (simdisk_count > MAX_SIMDISK_COUNT)
316                 simdisk_count = MAX_SIMDISK_COUNT;
317 
318         sddev = kmalloc_array(simdisk_count, sizeof(*sddev), GFP_KERNEL);
319         if (sddev == NULL)
320                 goto out_unregister;
321 
322         simdisk_procdir = proc_mkdir("simdisk", 0);
323         if (simdisk_procdir == NULL)
324                 goto out_free_unregister;
325 
326         for (i = 0; i < simdisk_count; ++i) {
327                 if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
328                         if (filename[i] != NULL && filename[i][0] != 0 &&
329                                         (n_files == 0 || i < n_files))
330                                 simdisk_attach(sddev + i, filename[i]);
331                 }
332         }
333 
334         return 0;
335 
336 out_free_unregister:
337         kfree(sddev);
338 out_unregister:
339         unregister_blkdev(simdisk_major, "simdisk");
340         return -ENOMEM;
341 }
342 module_init(simdisk_init);
343 
344 static void simdisk_teardown(struct simdisk *dev, int which,
345                 struct proc_dir_entry *procdir)
346 {
347         char tmp[2] = { '' + which, 0 };
348 
349         simdisk_detach(dev);
350         if (dev->gd)
351                 del_gendisk(dev->gd);
352         if (dev->queue)
353                 blk_cleanup_queue(dev->queue);
354         remove_proc_entry(tmp, procdir);
355 }
356 
357 static void __exit simdisk_exit(void)
358 {
359         int i;
360 
361         for (i = 0; i < simdisk_count; ++i)
362                 simdisk_teardown(sddev + i, i, simdisk_procdir);
363         remove_proc_entry("simdisk", 0);
364         kfree(sddev);
365         unregister_blkdev(simdisk_major, "simdisk");
366 }
367 module_exit(simdisk_exit);
368 
369 MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
370 
371 MODULE_LICENSE("GPL");
372 

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