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 blk_qc_t 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         return BLK_QC_T_NONE;
 122 }
 123
 124 static int simdisk_open(struct block_device *bdev, fmode_t mode)
 125 {
 126         struct simdisk *dev = bdev->bd_disk->private_data;
 127
 128         spin_lock(&dev->lock);
 129         ++dev->users;
 130         spin_unlock(&dev->lock);
 131         return 0;
 132 }
 133
 134 static void simdisk_release(struct gendisk *disk, fmode_t mode)
 135 {
 136         struct simdisk *dev = disk->private_data;
 137         spin_lock(&dev->lock);
 138         --dev->users;
 139         spin_unlock(&dev->lock);
 140 }
 141
 142 static const struct block_device_operations simdisk_ops = {
 143         .owner          = THIS_MODULE,
 144         .submit_bio     = simdisk_submit_bio,
 145         .open           = simdisk_open,
 146         .release        = simdisk_release,
 147 };
 148
 149 static struct simdisk *sddev;
 150 static struct proc_dir_entry *simdisk_procdir;
 151
 152 static int simdisk_attach(struct simdisk *dev, const char *filename)
 153 {
 154         int err = 0;
 155
 156         filename = kstrdup(filename, GFP_KERNEL);
 157         if (filename == NULL)
 158                 return -ENOMEM;
 159
 160         spin_lock(&dev->lock);
 161
 162         if (dev->fd != -1) {
 163                 err = -EBUSY;
 164                 goto out;
 165         }
 166         dev->fd = simc_open(filename, O_RDWR, 0);
 167         if (dev->fd == -1) {
 168                 pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
 169                 err = -ENODEV;
 170                 goto out;
 171         }
 172         dev->size = simc_lseek(dev->fd, 0, SEEK_END);
 173         set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
 174         dev->filename = filename;
 175         pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
 176 out:
 177         if (err)
 178                 kfree(filename);
 179         spin_unlock(&dev->lock);
 180
 181         return err;
 182 }
 183
 184 static int simdisk_detach(struct simdisk *dev)
 185 {
 186         int err = 0;
 187
 188         spin_lock(&dev->lock);
 189
 190         if (dev->users != 0) {
 191                 err = -EBUSY;
 192         } else if (dev->fd != -1) {
 193                 if (simc_close(dev->fd)) {
 194                         pr_err("SIMDISK: error closing %s: %d\n",
 195                                         dev->filename, errno);
 196                         err = -EIO;
 197                 } else {
 198                         pr_info("SIMDISK: %s detached from %s\n",
 199                                         dev->gd->disk_name, dev->filename);
 200                         dev->fd = -1;
 201                         kfree(dev->filename);
 202                         dev->filename = NULL;
 203                 }
 204         }
 205         spin_unlock(&dev->lock);
 206         return err;
 207 }
 208
 209 static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
 210                         size_t size, loff_t *ppos)
 211 {
 212         struct simdisk *dev = PDE_DATA(file_inode(file));
 213         const char *s = dev->filename;
 214         if (s) {
 215                 ssize_t n = simple_read_from_buffer(buf, size, ppos,
 216                                                         s, strlen(s));
 217                 if (n < 0)
 218                         return n;
 219                 buf += n;
 220                 size -= n;
 221         }
 222         return simple_read_from_buffer(buf, size, ppos, "\n", 1);
 223 }
 224
 225 static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
 226                         size_t count, loff_t *ppos)
 227 {
 228         char *tmp = memdup_user_nul(buf, count);
 229         struct simdisk *dev = PDE_DATA(file_inode(file));
 230         int err;
 231
 232         if (IS_ERR(tmp))
 233                 return PTR_ERR(tmp);
 234
 235         err = simdisk_detach(dev);
 236         if (err != 0)
 237                 goto out_free;
 238
 239         if (count > 0 && tmp[count - 1] == '\n')
 240                 tmp[count - 1] = 0;
 241
 242         if (tmp[0])
 243                 err = simdisk_attach(dev, tmp);
 244
 245         if (err == 0)
 246                 err = count;
 247 out_free:
 248         kfree(tmp);
 249         return err;
 250 }
 251
 252 static const struct proc_ops simdisk_proc_ops = {
 253         .proc_read      = proc_read_simdisk,
 254         .proc_write     = proc_write_simdisk,
 255         .proc_lseek     = default_llseek,
 256 };
 257
 258 static int __init simdisk_setup(struct simdisk *dev, int which,
 259                 struct proc_dir_entry *procdir)
 260 {
 261         char tmp[2] = { '0' + which, 0 };
 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                 return -ENOMEM;
 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         add_disk(dev->gd);
 279
 280         dev->procfile = proc_create_data(tmp, 0644, procdir, &simdisk_proc_ops, dev);
 281         return 0;
 282 }
 283
 284 static int __init simdisk_init(void)
 285 {
 286         int i;
 287
 288         if (register_blkdev(simdisk_major, "simdisk") < 0) {
 289                 pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
 290                 return -EIO;
 291         }
 292         pr_info("SIMDISK: major: %d\n", simdisk_major);
 293
 294         if (n_files > simdisk_count)
 295                 simdisk_count = n_files;
 296         if (simdisk_count > MAX_SIMDISK_COUNT)
 297                 simdisk_count = MAX_SIMDISK_COUNT;
 298
 299         sddev = kmalloc_array(simdisk_count, sizeof(*sddev), GFP_KERNEL);
 300         if (sddev == NULL)
 301                 goto out_unregister;
 302
 303         simdisk_procdir = proc_mkdir("simdisk", 0);
 304         if (simdisk_procdir == NULL)
 305                 goto out_free_unregister;
 306
 307         for (i = 0; i < simdisk_count; ++i) {
 308                 if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
 309                         if (filename[i] != NULL && filename[i][0] != 0 &&
 310                                         (n_files == 0 || i < n_files))
 311                                 simdisk_attach(sddev + i, filename[i]);
 312                 }
 313         }
 314
 315         return 0;
 316
 317 out_free_unregister:
 318         kfree(sddev);
 319 out_unregister:
 320         unregister_blkdev(simdisk_major, "simdisk");
 321         return -ENOMEM;
 322 }
 323 module_init(simdisk_init);
 324
 325 static void simdisk_teardown(struct simdisk *dev, int which,
 326                 struct proc_dir_entry *procdir)
 327 {
 328         char tmp[2] = { '0' + which, 0 };
 329
 330         simdisk_detach(dev);
 331         if (dev->gd) {
 332                 del_gendisk(dev->gd);
 333                 blk_cleanup_disk(dev->gd);
 334         }
 335         remove_proc_entry(tmp, procdir);
 336 }
 337
 338 static void __exit simdisk_exit(void)
 339 {
 340         int i;
 341
 342         for (i = 0; i < simdisk_count; ++i)
 343                 simdisk_teardown(sddev + i, i, simdisk_procdir);
 344         remove_proc_entry("simdisk", 0);
 345         kfree(sddev);
 346         unregister_blkdev(simdisk_major, "simdisk");
 347 }
 348 module_exit(simdisk_exit);
 349
 350 MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
 351
 352 MODULE_LICENSE("GPL");