arch/xtensa/platforms/iss/simdisk.c

   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 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                 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
 105 static 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
 126 static 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
 138 static 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
 146 static const struct block_device_operations simdisk_ops = {
 147         .owner          = THIS_MODULE,
 148         .open           = simdisk_open,
 149         .release        = simdisk_release,
 150 };
 151
 152 static struct simdisk *sddev;
 153 static struct proc_dir_entry *simdisk_procdir;
 154
 155 static 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);
 179 out:
 180         if (err)
 181                 kfree(filename);
 182         spin_unlock(&dev->lock);
 183
 184         return err;
 185 }
 186
 187 static 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
 212 static 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
 228 static 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;
 250 out_free:
 251         kfree(tmp);
 252         return err;
 253 }
 254
 255 static const struct file_operations fops = {
 256         .read = proc_read_simdisk,
 257         .write = proc_write_simdisk,
 258         .llseek = default_llseek,
 259 };
 260
 261 static 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
 297 out_alloc_disk:
 298         blk_cleanup_queue(dev->queue);
 299         dev->queue = NULL;
 300 out_alloc_queue:
 301         simc_close(dev->fd);
 302         return -EIO;
 303 }
 304
 305 static 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(simdisk_count * sizeof(struct simdisk),
 321                         GFP_KERNEL);
 322         if (sddev == NULL)
 323                 goto out_unregister;
 324
 325         simdisk_procdir = proc_mkdir("simdisk", 0);
 326         if (simdisk_procdir == NULL)
 327                 goto out_free_unregister;
 328
 329         for (i = 0; i < simdisk_count; ++i) {
 330                 if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
 331                         if (filename[i] != NULL && filename[i][0] != 0 &&
 332                                         (n_files == 0 || i < n_files))
 333                                 simdisk_attach(sddev + i, filename[i]);
 334                 }
 335         }
 336
 337         return 0;
 338
 339 out_free_unregister:
 340         kfree(sddev);
 341 out_unregister:
 342         unregister_blkdev(simdisk_major, "simdisk");
 343         return -ENOMEM;
 344 }
 345 module_init(simdisk_init);
 346
 347 static void simdisk_teardown(struct simdisk *dev, int which,
 348                 struct proc_dir_entry *procdir)
 349 {
 350         char tmp[2] = { '0' + which, 0 };
 351
 352         simdisk_detach(dev);
 353         if (dev->gd)
 354                 del_gendisk(dev->gd);
 355         if (dev->queue)
 356                 blk_cleanup_queue(dev->queue);
 357         remove_proc_entry(tmp, procdir);
 358 }
 359
 360 static void __exit simdisk_exit(void)
 361 {
 362         int i;
 363
 364         for (i = 0; i < simdisk_count; ++i)
 365                 simdisk_teardown(sddev + i, i, simdisk_procdir);
 366         remove_proc_entry("simdisk", 0);
 367         kfree(sddev);
 368         unregister_blkdev(simdisk_major, "simdisk");
 369 }
 370 module_exit(simdisk_exit);
 371
 372 MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
 373
 374 MODULE_LICENSE("GPL");