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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 <asm/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 
 28 struct 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 
 40 static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
 41 module_param(simdisk_count, int, S_IRUGO);
 42 MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
 43 
 44 static int n_files;
 45 static 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 
 54 static 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 
 64 static const struct kernel_param_ops simdisk_param_ops_filename = {
 65         .set = simdisk_param_set_filename,
 66 };
 67 module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
 68 MODULE_PARM_DESC(filename, "Backing storage filename.");
 69 
 70 static int simdisk_major = SIMDISK_MAJOR;
 71 
 72 static 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                 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 int simdisk_xfer_bio(struct simdisk *dev, struct bio *bio)
105 {
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 = __bio_kmap_atomic(bio, iter);
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                 __bio_kunmap_atomic(buffer);
118         }
119         return 0;
120 }
121 
122 static void simdisk_make_request(struct request_queue *q, struct bio *bio)
123 {
124         struct simdisk *dev = q->queuedata;
125         int status = simdisk_xfer_bio(dev, bio);
126         bio_endio(bio, status);
127 }
128 
129 
130 static int simdisk_open(struct block_device *bdev, fmode_t mode)
131 {
132         struct simdisk *dev = bdev->bd_disk->private_data;
133 
134         spin_lock(&dev->lock);
135         if (!dev->users)
136                 check_disk_change(bdev);
137         ++dev->users;
138         spin_unlock(&dev->lock);
139         return 0;
140 }
141 
142 static void simdisk_release(struct gendisk *disk, fmode_t mode)
143 {
144         struct simdisk *dev = disk->private_data;
145         spin_lock(&dev->lock);
146         --dev->users;
147         spin_unlock(&dev->lock);
148 }
149 
150 static const struct block_device_operations simdisk_ops = {
151         .owner          = THIS_MODULE,
152         .open           = simdisk_open,
153         .release        = simdisk_release,
154 };
155 
156 static struct simdisk *sddev;
157 static struct proc_dir_entry *simdisk_procdir;
158 
159 static int simdisk_attach(struct simdisk *dev, const char *filename)
160 {
161         int err = 0;
162 
163         filename = kstrdup(filename, GFP_KERNEL);
164         if (filename == NULL)
165                 return -ENOMEM;
166 
167         spin_lock(&dev->lock);
168 
169         if (dev->fd != -1) {
170                 err = -EBUSY;
171                 goto out;
172         }
173         dev->fd = simc_open(filename, O_RDWR, 0);
174         if (dev->fd == -1) {
175                 pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
176                 err = -ENODEV;
177                 goto out;
178         }
179         dev->size = simc_lseek(dev->fd, 0, SEEK_END);
180         set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
181         dev->filename = filename;
182         pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
183 out:
184         if (err)
185                 kfree(filename);
186         spin_unlock(&dev->lock);
187 
188         return err;
189 }
190 
191 static int simdisk_detach(struct simdisk *dev)
192 {
193         int err = 0;
194 
195         spin_lock(&dev->lock);
196 
197         if (dev->users != 0) {
198                 err = -EBUSY;
199         } else if (dev->fd != -1) {
200                 if (simc_close(dev->fd)) {
201                         pr_err("SIMDISK: error closing %s: %d\n",
202                                         dev->filename, errno);
203                         err = -EIO;
204                 } else {
205                         pr_info("SIMDISK: %s detached from %s\n",
206                                         dev->gd->disk_name, dev->filename);
207                         dev->fd = -1;
208                         kfree(dev->filename);
209                         dev->filename = NULL;
210                 }
211         }
212         spin_unlock(&dev->lock);
213         return err;
214 }
215 
216 static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
217                         size_t size, loff_t *ppos)
218 {
219         struct simdisk *dev = PDE_DATA(file_inode(file));
220         const char *s = dev->filename;
221         if (s) {
222                 ssize_t n = simple_read_from_buffer(buf, size, ppos,
223                                                         s, strlen(s));
224                 if (n < 0)
225                         return n;
226                 buf += n;
227                 size -= n;
228         }
229         return simple_read_from_buffer(buf, size, ppos, "\n", 1);
230 }
231 
232 static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
233                         size_t count, loff_t *ppos)
234 {
235         char *tmp = kmalloc(count + 1, GFP_KERNEL);
236         struct simdisk *dev = PDE_DATA(file_inode(file));
237         int err;
238 
239         if (tmp == NULL)
240                 return -ENOMEM;
241         if (copy_from_user(tmp, buf, count)) {
242                 err = -EFAULT;
243                 goto out_free;
244         }
245 
246         err = simdisk_detach(dev);
247         if (err != 0)
248                 goto out_free;
249 
250         if (count > 0 && tmp[count - 1] == '\n')
251                 tmp[count - 1] = 0;
252         else
253                 tmp[count] = 0;
254 
255         if (tmp[0])
256                 err = simdisk_attach(dev, tmp);
257 
258         if (err == 0)
259                 err = count;
260 out_free:
261         kfree(tmp);
262         return err;
263 }
264 
265 static const struct file_operations fops = {
266         .read = proc_read_simdisk,
267         .write = proc_write_simdisk,
268         .llseek = default_llseek,
269 };
270 
271 static int __init simdisk_setup(struct simdisk *dev, int which,
272                 struct proc_dir_entry *procdir)
273 {
274         char tmp[2] = { '' + which, 0 };
275 
276         dev->fd = -1;
277         dev->filename = NULL;
278         spin_lock_init(&dev->lock);
279         dev->users = 0;
280 
281         dev->queue = blk_alloc_queue(GFP_KERNEL);
282         if (dev->queue == NULL) {
283                 pr_err("blk_alloc_queue failed\n");
284                 goto out_alloc_queue;
285         }
286 
287         blk_queue_make_request(dev->queue, simdisk_make_request);
288         dev->queue->queuedata = dev;
289 
290         dev->gd = alloc_disk(SIMDISK_MINORS);
291         if (dev->gd == NULL) {
292                 pr_err("alloc_disk failed\n");
293                 goto out_alloc_disk;
294         }
295         dev->gd->major = simdisk_major;
296         dev->gd->first_minor = which;
297         dev->gd->fops = &simdisk_ops;
298         dev->gd->queue = dev->queue;
299         dev->gd->private_data = dev;
300         snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
301         set_capacity(dev->gd, 0);
302         add_disk(dev->gd);
303 
304         dev->procfile = proc_create_data(tmp, 0644, procdir, &fops, dev);
305         return 0;
306 
307 out_alloc_disk:
308         blk_cleanup_queue(dev->queue);
309         dev->queue = NULL;
310 out_alloc_queue:
311         simc_close(dev->fd);
312         return -EIO;
313 }
314 
315 static int __init simdisk_init(void)
316 {
317         int i;
318 
319         if (register_blkdev(simdisk_major, "simdisk") < 0) {
320                 pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
321                 return -EIO;
322         }
323         pr_info("SIMDISK: major: %d\n", simdisk_major);
324 
325         if (n_files > simdisk_count)
326                 simdisk_count = n_files;
327         if (simdisk_count > MAX_SIMDISK_COUNT)
328                 simdisk_count = MAX_SIMDISK_COUNT;
329 
330         sddev = kmalloc(simdisk_count * sizeof(struct simdisk),
331                         GFP_KERNEL);
332         if (sddev == NULL)
333                 goto out_unregister;
334 
335         simdisk_procdir = proc_mkdir("simdisk", 0);
336         if (simdisk_procdir == NULL)
337                 goto out_free_unregister;
338 
339         for (i = 0; i < simdisk_count; ++i) {
340                 if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
341                         if (filename[i] != NULL && filename[i][0] != 0 &&
342                                         (n_files == 0 || i < n_files))
343                                 simdisk_attach(sddev + i, filename[i]);
344                 }
345         }
346 
347         return 0;
348 
349 out_free_unregister:
350         kfree(sddev);
351 out_unregister:
352         unregister_blkdev(simdisk_major, "simdisk");
353         return -ENOMEM;
354 }
355 module_init(simdisk_init);
356 
357 static void simdisk_teardown(struct simdisk *dev, int which,
358                 struct proc_dir_entry *procdir)
359 {
360         char tmp[2] = { '' + which, 0 };
361 
362         simdisk_detach(dev);
363         if (dev->gd)
364                 del_gendisk(dev->gd);
365         if (dev->queue)
366                 blk_cleanup_queue(dev->queue);
367         remove_proc_entry(tmp, procdir);
368 }
369 
370 static void __exit simdisk_exit(void)
371 {
372         int i;
373 
374         for (i = 0; i < simdisk_count; ++i)
375                 simdisk_teardown(sddev + i, i, simdisk_procdir);
376         remove_proc_entry("simdisk", 0);
377         kfree(sddev);
378         unregister_blkdev(simdisk_major, "simdisk");
379 }
380 module_exit(simdisk_exit);
381 
382 MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
383 
384 MODULE_LICENSE("GPL");
385 

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