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 <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         int i;
 107         struct bio_vec *bvec;
 108         sector_t sector = bio->bi_sector;
 109
 110         bio_for_each_segment(bvec, bio, i) {
 111                 char *buffer = __bio_kmap_atomic(bio, i, KM_USER0);
 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(bio, KM_USER0);
 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] = { '0' + 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] = { '0' + 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");