drivers/char/tile-srom.c

   1 /*
   2  * Copyright 2011 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  *
  14  * SPI Flash ROM driver
  15  *
  16  * This source code is derived from code provided in "Linux Device
  17  * Drivers, Third Edition", by Jonathan Corbet, Alessandro Rubini, and
  18  * Greg Kroah-Hartman, published by O'Reilly Media, Inc.
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>       /* printk() */
  25 #include <linux/slab.h>         /* kmalloc() */
  26 #include <linux/fs.h>           /* everything... */
  27 #include <linux/errno.h>        /* error codes */
  28 #include <linux/types.h>        /* size_t */
  29 #include <linux/proc_fs.h>
  30 #include <linux/fcntl.h>        /* O_ACCMODE */
  31 #include <linux/aio.h>
  32 #include <linux/pagemap.h>
  33 #include <linux/hugetlb.h>
  34 #include <linux/uaccess.h>
  35 #include <linux/platform_device.h>
  36 #include <hv/hypervisor.h>
  37 #include <linux/ioctl.h>
  38 #include <linux/cdev.h>
  39 #include <linux/delay.h>
  40 #include <hv/drv_srom_intf.h>
  41
  42 /*
  43  * Size of our hypervisor I/O requests.  We break up large transfers
  44  * so that we don't spend large uninterrupted spans of time in the
  45  * hypervisor.  Erasing an SROM sector takes a significant fraction of
  46  * a second, so if we allowed the user to, say, do one I/O to write the
  47  * entire ROM, we'd get soft lockup timeouts, or worse.
  48  */
  49 #define SROM_CHUNK_SIZE ((size_t)4096)
  50
  51 /*
  52  * When hypervisor is busy (e.g. erasing), poll the status periodically.
  53  */
  54
  55 /*
  56  * Interval to poll the state in msec
  57  */
  58 #define SROM_WAIT_TRY_INTERVAL 20
  59
  60 /*
  61  * Maximum times to poll the state
  62  */
  63 #define SROM_MAX_WAIT_TRY_TIMES 1000
  64
  65 struct srom_dev {
  66         int hv_devhdl;                  /* Handle for hypervisor device */
  67         u32 total_size;                 /* Size of this device */
  68         u32 sector_size;                /* Size of a sector */
  69         u32 page_size;                  /* Size of a page */
  70         struct mutex lock;              /* Allow only one accessor at a time */
  71 };
  72
  73 static int srom_major;                  /* Dynamic major by default */
  74 module_param(srom_major, int, 0);
  75 MODULE_AUTHOR("Tilera Corporation");
  76 MODULE_LICENSE("GPL");
  77
  78 static int srom_devs;                   /* Number of SROM partitions */
  79 static struct cdev srom_cdev;
  80 static struct class *srom_class;
  81 static struct srom_dev *srom_devices;
  82
  83 /*
  84  * Handle calling the hypervisor and managing EAGAIN/EBUSY.
  85  */
  86
  87 static ssize_t _srom_read(int hv_devhdl, void *buf,
  88                           loff_t off, size_t count)
  89 {
  90         int retval, retries = SROM_MAX_WAIT_TRY_TIMES;
  91         for (;;) {
  92                 retval = hv_dev_pread(hv_devhdl, 0, (HV_VirtAddr)buf,
  93                                       count, off);
  94                 if (retval >= 0)
  95                         return retval;
  96                 if (retval == HV_EAGAIN)
  97                         continue;
  98                 if (retval == HV_EBUSY && --retries > 0) {
  99                         msleep(SROM_WAIT_TRY_INTERVAL);
 100                         continue;
 101                 }
 102                 pr_err("_srom_read: error %d\n", retval);
 103                 return -EIO;
 104         }
 105 }
 106
 107 static ssize_t _srom_write(int hv_devhdl, const void *buf,
 108                            loff_t off, size_t count)
 109 {
 110         int retval, retries = SROM_MAX_WAIT_TRY_TIMES;
 111         for (;;) {
 112                 retval = hv_dev_pwrite(hv_devhdl, 0, (HV_VirtAddr)buf,
 113                                        count, off);
 114                 if (retval >= 0)
 115                         return retval;
 116                 if (retval == HV_EAGAIN)
 117                         continue;
 118                 if (retval == HV_EBUSY && --retries > 0) {
 119                         msleep(SROM_WAIT_TRY_INTERVAL);
 120                         continue;
 121                 }
 122                 pr_err("_srom_write: error %d\n", retval);
 123                 return -EIO;
 124         }
 125 }
 126
 127 /**
 128  * srom_open() - Device open routine.
 129  * @inode: Inode for this device.
 130  * @filp: File for this specific open of the device.
 131  *
 132  * Returns zero, or an error code.
 133  */
 134 static int srom_open(struct inode *inode, struct file *filp)
 135 {
 136         filp->private_data = &srom_devices[iminor(inode)];
 137         return 0;
 138 }
 139
 140
 141 /**
 142  * srom_release() - Device release routine.
 143  * @inode: Inode for this device.
 144  * @filp: File for this specific open of the device.
 145  *
 146  * Returns zero, or an error code.
 147  */
 148 static int srom_release(struct inode *inode, struct file *filp)
 149 {
 150         struct srom_dev *srom = filp->private_data;
 151         char dummy;
 152
 153         /* Make sure we've flushed anything written to the ROM. */
 154         mutex_lock(&srom->lock);
 155         if (srom->hv_devhdl >= 0)
 156                 _srom_write(srom->hv_devhdl, &dummy, SROM_FLUSH_OFF, 1);
 157         mutex_unlock(&srom->lock);
 158
 159         filp->private_data = NULL;
 160
 161         return 0;
 162 }
 163
 164
 165 /**
 166  * srom_read() - Read data from the device.
 167  * @filp: File for this specific open of the device.
 168  * @buf: User's data buffer.
 169  * @count: Number of bytes requested.
 170  * @f_pos: File position.
 171  *
 172  * Returns number of bytes read, or an error code.
 173  */
 174 static ssize_t srom_read(struct file *filp, char __user *buf,
 175                          size_t count, loff_t *f_pos)
 176 {
 177         int retval = 0;
 178         void *kernbuf;
 179         struct srom_dev *srom = filp->private_data;
 180
 181         kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL);
 182         if (!kernbuf)
 183                 return -ENOMEM;
 184
 185         if (mutex_lock_interruptible(&srom->lock)) {
 186                 retval = -ERESTARTSYS;
 187                 kfree(kernbuf);
 188                 return retval;
 189         }
 190
 191         while (count) {
 192                 int hv_retval;
 193                 int bytes_this_pass = min(count, SROM_CHUNK_SIZE);
 194
 195                 hv_retval = _srom_read(srom->hv_devhdl, kernbuf,
 196                                        *f_pos, bytes_this_pass);
 197                 if (hv_retval <= 0) {
 198                         if (retval == 0)
 199                                 retval = hv_retval;
 200                         break;
 201                 }
 202
 203                 if (copy_to_user(buf, kernbuf, hv_retval) != 0) {
 204                         retval = -EFAULT;
 205                         break;
 206                 }
 207
 208                 retval += hv_retval;
 209                 *f_pos += hv_retval;
 210                 buf += hv_retval;
 211                 count -= hv_retval;
 212         }
 213
 214         mutex_unlock(&srom->lock);
 215         kfree(kernbuf);
 216
 217         return retval;
 218 }
 219
 220 /**
 221  * srom_write() - Write data to the device.
 222  * @filp: File for this specific open of the device.
 223  * @buf: User's data buffer.
 224  * @count: Number of bytes requested.
 225  * @f_pos: File position.
 226  *
 227  * Returns number of bytes written, or an error code.
 228  */
 229 static ssize_t srom_write(struct file *filp, const char __user *buf,
 230                           size_t count, loff_t *f_pos)
 231 {
 232         int retval = 0;
 233         void *kernbuf;
 234         struct srom_dev *srom = filp->private_data;
 235
 236         kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL);
 237         if (!kernbuf)
 238                 return -ENOMEM;
 239
 240         if (mutex_lock_interruptible(&srom->lock)) {
 241                 retval = -ERESTARTSYS;
 242                 kfree(kernbuf);
 243                 return retval;
 244         }
 245
 246         while (count) {
 247                 int hv_retval;
 248                 int bytes_this_pass = min(count, SROM_CHUNK_SIZE);
 249
 250                 if (copy_from_user(kernbuf, buf, bytes_this_pass) != 0) {
 251                         retval = -EFAULT;
 252                         break;
 253                 }
 254
 255                 hv_retval = _srom_write(srom->hv_devhdl, kernbuf,
 256                                         *f_pos, bytes_this_pass);
 257                 if (hv_retval <= 0) {
 258                         if (retval == 0)
 259                                 retval = hv_retval;
 260                         break;
 261                 }
 262
 263                 retval += hv_retval;
 264                 *f_pos += hv_retval;
 265                 buf += hv_retval;
 266                 count -= hv_retval;
 267         }
 268
 269         mutex_unlock(&srom->lock);
 270         kfree(kernbuf);
 271
 272         return retval;
 273 }
 274
 275 /* Provide our own implementation so we can use srom->total_size. */
 276 loff_t srom_llseek(struct file *file, loff_t offset, int origin)
 277 {
 278         struct srom_dev *srom = file->private_data;
 279         return fixed_size_llseek(file, offset, origin, srom->total_size);
 280 }
 281
 282 static ssize_t total_show(struct device *dev,
 283                           struct device_attribute *attr, char *buf)
 284 {
 285         struct srom_dev *srom = dev_get_drvdata(dev);
 286         return sprintf(buf, "%u\n", srom->total_size);
 287 }
 288
 289 static ssize_t sector_show(struct device *dev,
 290                            struct device_attribute *attr, char *buf)
 291 {
 292         struct srom_dev *srom = dev_get_drvdata(dev);
 293         return sprintf(buf, "%u\n", srom->sector_size);
 294 }
 295
 296 static ssize_t page_show(struct device *dev,
 297                          struct device_attribute *attr, char *buf)
 298 {
 299         struct srom_dev *srom = dev_get_drvdata(dev);
 300         return sprintf(buf, "%u\n", srom->page_size);
 301 }
 302
 303 static struct device_attribute srom_dev_attrs[] = {
 304         __ATTR(total_size, S_IRUGO, total_show, NULL),
 305         __ATTR(sector_size, S_IRUGO, sector_show, NULL),
 306         __ATTR(page_size, S_IRUGO, page_show, NULL),
 307         __ATTR_NULL
 308 };
 309
 310 static char *srom_devnode(struct device *dev, umode_t *mode)
 311 {
 312         *mode = S_IRUGO | S_IWUSR;
 313         return kasprintf(GFP_KERNEL, "srom/%s", dev_name(dev));
 314 }
 315
 316 /*
 317  * The fops
 318  */
 319 static const struct file_operations srom_fops = {
 320         .owner =     THIS_MODULE,
 321         .llseek =    srom_llseek,
 322         .read =      srom_read,
 323         .write =     srom_write,
 324         .open =      srom_open,
 325         .release =   srom_release,
 326 };
 327
 328 /**
 329  * srom_setup_minor() - Initialize per-minor information.
 330  * @srom: Per-device SROM state.
 331  * @index: Device to set up.
 332  */
 333 static int srom_setup_minor(struct srom_dev *srom, int index)
 334 {
 335         struct device *dev;
 336         int devhdl = srom->hv_devhdl;
 337
 338         mutex_init(&srom->lock);
 339
 340         if (_srom_read(devhdl, &srom->total_size,
 341                        SROM_TOTAL_SIZE_OFF, sizeof(srom->total_size)) < 0)
 342                 return -EIO;
 343         if (_srom_read(devhdl, &srom->sector_size,
 344                        SROM_SECTOR_SIZE_OFF, sizeof(srom->sector_size)) < 0)
 345                 return -EIO;
 346         if (_srom_read(devhdl, &srom->page_size,
 347                        SROM_PAGE_SIZE_OFF, sizeof(srom->page_size)) < 0)
 348                 return -EIO;
 349
 350         dev = device_create(srom_class, &platform_bus,
 351                             MKDEV(srom_major, index), srom, "%d", index);
 352         return PTR_RET(dev);
 353 }
 354
 355 /** srom_init() - Initialize the driver's module. */
 356 static int srom_init(void)
 357 {
 358         int result, i;
 359         dev_t dev = MKDEV(srom_major, 0);
 360
 361         /*
 362          * Start with a plausible number of partitions; the krealloc() call
 363          * below will yield about log(srom_devs) additional allocations.
 364          */
 365         srom_devices = kzalloc(4 * sizeof(struct srom_dev), GFP_KERNEL);
 366
 367         /* Discover the number of srom partitions. */
 368         for (i = 0; ; i++) {
 369                 int devhdl;
 370                 char buf[20];
 371                 struct srom_dev *new_srom_devices =
 372                         krealloc(srom_devices, (i+1) * sizeof(struct srom_dev),
 373                                  GFP_KERNEL | __GFP_ZERO);
 374                 if (!new_srom_devices) {
 375                         result = -ENOMEM;
 376                         goto fail_mem;
 377                 }
 378                 srom_devices = new_srom_devices;
 379                 sprintf(buf, "srom/0/%d", i);
 380                 devhdl = hv_dev_open((HV_VirtAddr)buf, 0);
 381                 if (devhdl < 0) {
 382                         if (devhdl != HV_ENODEV)
 383                                 pr_notice("srom/%d: hv_dev_open failed: %d.\n",
 384                                           i, devhdl);
 385                         break;
 386                 }
 387                 srom_devices[i].hv_devhdl = devhdl;
 388         }
 389         srom_devs = i;
 390
 391         /* Bail out early if we have no partitions at all. */
 392         if (srom_devs == 0) {
 393                 result = -ENODEV;
 394                 goto fail_mem;
 395         }
 396
 397         /* Register our major, and accept a dynamic number. */
 398         if (srom_major)
 399                 result = register_chrdev_region(dev, srom_devs, "srom");
 400         else {
 401                 result = alloc_chrdev_region(&dev, 0, srom_devs, "srom");
 402                 srom_major = MAJOR(dev);
 403         }
 404         if (result < 0)
 405                 goto fail_mem;
 406
 407         /* Register a character device. */
 408         cdev_init(&srom_cdev, &srom_fops);
 409         srom_cdev.owner = THIS_MODULE;
 410         srom_cdev.ops = &srom_fops;
 411         result = cdev_add(&srom_cdev, dev, srom_devs);
 412         if (result < 0)
 413                 goto fail_chrdev;
 414
 415         /* Create a sysfs class. */
 416         srom_class = class_create(THIS_MODULE, "srom");
 417         if (IS_ERR(srom_class)) {
 418                 result = PTR_ERR(srom_class);
 419                 goto fail_cdev;
 420         }
 421         srom_class->dev_attrs = srom_dev_attrs;
 422         srom_class->devnode = srom_devnode;
 423
 424         /* Do per-partition initialization */
 425         for (i = 0; i < srom_devs; i++) {
 426                 result = srom_setup_minor(srom_devices + i, i);
 427                 if (result < 0)
 428                         goto fail_class;
 429         }
 430
 431         return 0;
 432
 433 fail_class:
 434         for (i = 0; i < srom_devs; i++)
 435                 device_destroy(srom_class, MKDEV(srom_major, i));
 436         class_destroy(srom_class);
 437 fail_cdev:
 438         cdev_del(&srom_cdev);
 439 fail_chrdev:
 440         unregister_chrdev_region(dev, srom_devs);
 441 fail_mem:
 442         kfree(srom_devices);
 443         return result;
 444 }
 445
 446 /** srom_cleanup() - Clean up the driver's module. */
 447 static void srom_cleanup(void)
 448 {
 449         int i;
 450         for (i = 0; i < srom_devs; i++)
 451                 device_destroy(srom_class, MKDEV(srom_major, i));
 452         class_destroy(srom_class);
 453         cdev_del(&srom_cdev);
 454         unregister_chrdev_region(MKDEV(srom_major, 0), srom_devs);
 455         kfree(srom_devices);
 456 }
 457
 458 module_init(srom_init);
 459 module_exit(srom_cleanup);