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