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 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] = { '0' + 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] = { '0' + 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");