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/kernel.h>       /* printk() */
  24 #include <linux/slab.h>         /* kmalloc() */
  25 #include <linux/fs.h>           /* everything... */
  26 #include <linux/errno.h>        /* error codes */
  27 #include <linux/types.h>        /* size_t */
  28 #include <linux/proc_fs.h>
  29 #include <linux/fcntl.h>        /* O_ACCMODE */
  30 #include <linux/pagemap.h>
  31 #include <linux/hugetlb.h>
  32 #include <linux/uaccess.h>
  33 #include <linux/platform_device.h>
  34 #include <hv/hypervisor.h>
  35 #include <linux/ioctl.h>
  36 #include <linux/cdev.h>
  37 #include <linux/delay.h>
  38 #include <hv/drv_srom_intf.h>
  39
  40 /*
  41  * Size of our hypervisor I/O requests.  We break up large transfers
  42  * so that we don't spend large uninterrupted spans of time in the
  43  * hypervisor.  Erasing an SROM sector takes a significant fraction of
  44  * a second, so if we allowed the user to, say, do one I/O to write the
  45  * entire ROM, we'd get soft lockup timeouts, or worse.
  46  */
  47 #define SROM_CHUNK_SIZE ((size_t)4096)
  48
  49 /*
  50  * When hypervisor is busy (e.g. erasing), poll the status periodically.
  51  */
  52
  53 /*
  54  * Interval to poll the state in msec
  55  */
  56 #define SROM_WAIT_TRY_INTERVAL 20
  57
  58 /*
  59  * Maximum times to poll the state
  60  */
  61 #define SROM_MAX_WAIT_TRY_TIMES 1000
  62
  63 struct srom_dev {
  64         int hv_devhdl;                  /* Handle for hypervisor device */
  65         u32 total_size;                 /* Size of this device */
  66         u32 sector_size;                /* Size of a sector */
  67         u32 page_size;                  /* Size of a page */
  68         struct mutex lock;              /* Allow only one accessor at a time */
  69 };
  70
  71 static int srom_major;                  /* Dynamic major by default */
  72 module_param(srom_major, int, 0);
  73 MODULE_AUTHOR("Tilera Corporation");
  74 MODULE_LICENSE("GPL");
  75
  76 static int srom_devs;                   /* Number of SROM partitions */
  77 static struct cdev srom_cdev;
  78 static struct platform_device *srom_parent;
  79 static struct class *srom_class;
  80 static struct srom_dev *srom_devices;
  81
  82 /*
  83  * Handle calling the hypervisor and managing EAGAIN/EBUSY.
  84  */
  85
  86 static ssize_t _srom_read(int hv_devhdl, void *buf,
  87                           loff_t off, size_t count)
  88 {
  89         int retval, retries = SROM_MAX_WAIT_TRY_TIMES;
  90         for (;;) {
  91                 retval = hv_dev_pread(hv_devhdl, 0, (HV_VirtAddr)buf,
  92                                       count, off);
  93                 if (retval >= 0)
  94                         return retval;
  95                 if (retval == HV_EAGAIN)
  96                         continue;
  97                 if (retval == HV_EBUSY && --retries > 0) {
  98                         msleep(SROM_WAIT_TRY_INTERVAL);
  99                         continue;
 100                 }
 101                 pr_err("_srom_read: error %d\n", retval);
 102                 return -EIO;
 103         }
 104 }
 105
 106 static ssize_t _srom_write(int hv_devhdl, const void *buf,
 107                            loff_t off, size_t count)
 108 {
 109         int retval, retries = SROM_MAX_WAIT_TRY_TIMES;
 110         for (;;) {
 111                 retval = hv_dev_pwrite(hv_devhdl, 0, (HV_VirtAddr)buf,
 112                                        count, off);
 113                 if (retval >= 0)
 114                         return retval;
 115                 if (retval == HV_EAGAIN)
 116                         continue;
 117                 if (retval == HV_EBUSY && --retries > 0) {
 118                         msleep(SROM_WAIT_TRY_INTERVAL);
 119                         continue;
 120                 }
 121                 pr_err("_srom_write: error %d\n", retval);
 122                 return -EIO;
 123         }
 124 }
 125
 126 /**
 127  * srom_open() - Device open routine.
 128  * @inode: Inode for this device.
 129  * @filp: File for this specific open of the device.
 130  *
 131  * Returns zero, or an error code.
 132  */
 133 static int srom_open(struct inode *inode, struct file *filp)
 134 {
 135         filp->private_data = &srom_devices[iminor(inode)];
 136         return 0;
 137 }
 138
 139
 140 /**
 141  * srom_release() - Device release routine.
 142  * @inode: Inode for this device.
 143  * @filp: File for this specific open of the device.
 144  *
 145  * Returns zero, or an error code.
 146  */
 147 static int srom_release(struct inode *inode, struct file *filp)
 148 {
 149         struct srom_dev *srom = filp->private_data;
 150         char dummy;
 151
 152         /* Make sure we've flushed anything written to the ROM. */
 153         mutex_lock(&srom->lock);
 154         if (srom->hv_devhdl >= 0)
 155                 _srom_write(srom->hv_devhdl, &dummy, SROM_FLUSH_OFF, 1);
 156         mutex_unlock(&srom->lock);
 157
 158         filp->private_data = NULL;
 159
 160         return 0;
 161 }
 162
 163
 164 /**
 165  * srom_read() - Read data from the device.
 166  * @filp: File for this specific open of the device.
 167  * @buf: User's data buffer.
 168  * @count: Number of bytes requested.
 169  * @f_pos: File position.
 170  *
 171  * Returns number of bytes read, or an error code.
 172  */
 173 static ssize_t srom_read(struct file *filp, char __user *buf,
 174                          size_t count, loff_t *f_pos)
 175 {
 176         int retval = 0;
 177         void *kernbuf;
 178         struct srom_dev *srom = filp->private_data;
 179
 180         kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL);
 181         if (!kernbuf)
 182                 return -ENOMEM;
 183
 184         if (mutex_lock_interruptible(&srom->lock)) {
 185                 retval = -ERESTARTSYS;
 186                 kfree(kernbuf);
 187                 return retval;
 188         }
 189
 190         while (count) {
 191                 int hv_retval;
 192                 int bytes_this_pass = min(count, SROM_CHUNK_SIZE);
 193
 194                 hv_retval = _srom_read(srom->hv_devhdl, kernbuf,
 195                                        *f_pos, bytes_this_pass);
 196                 if (hv_retval <= 0) {
 197                         if (retval == 0)
 198                                 retval = hv_retval;
 199                         break;
 200                 }
 201
 202                 if (copy_to_user(buf, kernbuf, hv_retval) != 0) {
 203                         retval = -EFAULT;
 204                         break;
 205                 }
 206
 207                 retval += hv_retval;
 208                 *f_pos += hv_retval;
 209                 buf += hv_retval;
 210                 count -= hv_retval;
 211         }
 212
 213         mutex_unlock(&srom->lock);
 214         kfree(kernbuf);
 215
 216         return retval;
 217 }
 218
 219 /**
 220  * srom_write() - Write data to the device.
 221  * @filp: File for this specific open of the device.
 222  * @buf: User's data buffer.
 223  * @count: Number of bytes requested.
 224  * @f_pos: File position.
 225  *
 226  * Returns number of bytes written, or an error code.
 227  */
 228 static ssize_t srom_write(struct file *filp, const char __user *buf,
 229                           size_t count, loff_t *f_pos)
 230 {
 231         int retval = 0;
 232         void *kernbuf;
 233         struct srom_dev *srom = filp->private_data;
 234
 235         kernbuf = kmalloc(SROM_CHUNK_SIZE, GFP_KERNEL);
 236         if (!kernbuf)
 237                 return -ENOMEM;
 238
 239         if (mutex_lock_interruptible(&srom->lock)) {
 240                 retval = -ERESTARTSYS;
 241                 kfree(kernbuf);
 242                 return retval;
 243         }
 244
 245         while (count) {
 246                 int hv_retval;
 247                 int bytes_this_pass = min(count, SROM_CHUNK_SIZE);
 248
 249                 if (copy_from_user(kernbuf, buf, bytes_this_pass) != 0) {
 250                         retval = -EFAULT;
 251                         break;
 252                 }
 253
 254                 hv_retval = _srom_write(srom->hv_devhdl, kernbuf,
 255                                         *f_pos, bytes_this_pass);
 256                 if (hv_retval <= 0) {
 257                         if (retval == 0)
 258                                 retval = hv_retval;
 259                         break;
 260                 }
 261
 262                 retval += hv_retval;
 263                 *f_pos += hv_retval;
 264                 buf += hv_retval;
 265                 count -= hv_retval;
 266         }
 267
 268         mutex_unlock(&srom->lock);
 269         kfree(kernbuf);
 270
 271         return retval;
 272 }
 273
 274 /* Provide our own implementation so we can use srom->total_size. */
 275 loff_t srom_llseek(struct file *file, loff_t offset, int origin)
 276 {
 277         struct srom_dev *srom = file->private_data;
 278         return fixed_size_llseek(file, offset, origin, srom->total_size);
 279 }
 280
 281 static ssize_t total_size_show(struct device *dev,
 282                                struct device_attribute *attr, char *buf)
 283 {
 284         struct srom_dev *srom = dev_get_drvdata(dev);
 285         return sprintf(buf, "%u\n", srom->total_size);
 286 }
 287 static DEVICE_ATTR_RO(total_size);
 288
 289 static ssize_t sector_size_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 static DEVICE_ATTR_RO(sector_size);
 296
 297 static ssize_t page_size_show(struct device *dev,
 298                               struct device_attribute *attr, char *buf)
 299 {
 300         struct srom_dev *srom = dev_get_drvdata(dev);
 301         return sprintf(buf, "%u\n", srom->page_size);
 302 }
 303 static DEVICE_ATTR_RO(page_size);
 304
 305 static struct attribute *srom_dev_attrs[] = {
 306         &dev_attr_total_size.attr,
 307         &dev_attr_sector_size.attr,
 308         &dev_attr_page_size.attr,
 309         NULL,
 310 };
 311 ATTRIBUTE_GROUPS(srom_dev);
 312
 313 static char *srom_devnode(struct device *dev, umode_t *mode)
 314 {
 315         if (mode)
 316                 *mode = 0644;
 317         return kasprintf(GFP_KERNEL, "srom/%s", dev_name(dev));
 318 }
 319
 320 /*
 321  * The fops
 322  */
 323 static const struct file_operations srom_fops = {
 324         .owner =     THIS_MODULE,
 325         .llseek =    srom_llseek,
 326         .read =      srom_read,
 327         .write =     srom_write,
 328         .open =      srom_open,
 329         .release =   srom_release,
 330 };
 331
 332 /**
 333  * srom_setup_minor() - Initialize per-minor information.
 334  * @srom: Per-device SROM state.
 335  * @devhdl: Partition device handle.
 336  */
 337 static int srom_setup_minor(struct srom_dev *srom, int devhdl)
 338 {
 339         srom->hv_devhdl = devhdl;
 340         mutex_init(&srom->lock);
 341
 342         if (_srom_read(devhdl, &srom->total_size,
 343                        SROM_TOTAL_SIZE_OFF, sizeof(srom->total_size)) < 0)
 344                 return -EIO;
 345         if (_srom_read(devhdl, &srom->sector_size,
 346                        SROM_SECTOR_SIZE_OFF, sizeof(srom->sector_size)) < 0)
 347                 return -EIO;
 348         if (_srom_read(devhdl, &srom->page_size,
 349                        SROM_PAGE_SIZE_OFF, sizeof(srom->page_size)) < 0)
 350                 return -EIO;
 351
 352         return 0;
 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 = kmalloc(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);
 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                 result = srom_setup_minor(&srom_devices[i], devhdl);
 388                 if (result != 0)
 389                         goto fail_mem;
 390         }
 391         srom_devs = i;
 392
 393         /* Bail out early if we have no partitions at all. */
 394         if (srom_devs == 0) {
 395                 result = -ENODEV;
 396                 goto fail_mem;
 397         }
 398
 399         /* Register our major, and accept a dynamic number. */
 400         if (srom_major)
 401                 result = register_chrdev_region(dev, srom_devs, "srom");
 402         else {
 403                 result = alloc_chrdev_region(&dev, 0, srom_devs, "srom");
 404                 srom_major = MAJOR(dev);
 405         }
 406         if (result < 0)
 407                 goto fail_mem;
 408
 409         /* Register a character device. */
 410         cdev_init(&srom_cdev, &srom_fops);
 411         srom_cdev.owner = THIS_MODULE;
 412         srom_cdev.ops = &srom_fops;
 413         result = cdev_add(&srom_cdev, dev, srom_devs);
 414         if (result < 0)
 415                 goto fail_chrdev;
 416
 417         /* Create a parent device */
 418         srom_parent = platform_device_register_simple("srom", -1, NULL, 0);
 419         if (IS_ERR(srom_parent)) {
 420                 result = PTR_ERR(srom_parent);
 421                 goto fail_pdev;
 422         }
 423
 424         /* Create a sysfs class. */
 425         srom_class = class_create(THIS_MODULE, "srom");
 426         if (IS_ERR(srom_class)) {
 427                 result = PTR_ERR(srom_class);
 428                 goto fail_cdev;
 429         }
 430         srom_class->dev_groups = srom_dev_groups;
 431         srom_class->devnode = srom_devnode;
 432
 433         /* Create per-partition devices */
 434         for (i = 0; i < srom_devs; i++) {
 435                 struct device *dev =
 436                         device_create(srom_class, &srom_parent->dev,
 437                                       MKDEV(srom_major, i), srom_devices + i,
 438                                       "%d", i);
 439                 result = PTR_ERR_OR_ZERO(dev);
 440                 if (result < 0)
 441                         goto fail_class;
 442         }
 443
 444         return 0;
 445
 446 fail_class:
 447         for (i = 0; i < srom_devs; i++)
 448                 device_destroy(srom_class, MKDEV(srom_major, i));
 449         class_destroy(srom_class);
 450 fail_cdev:
 451         platform_device_unregister(srom_parent);
 452 fail_pdev:
 453         cdev_del(&srom_cdev);
 454 fail_chrdev:
 455         unregister_chrdev_region(dev, srom_devs);
 456 fail_mem:
 457         kfree(srom_devices);
 458         return result;
 459 }
 460
 461 /** srom_cleanup() - Clean up the driver's module. */
 462 static void srom_cleanup(void)
 463 {
 464         int i;
 465         for (i = 0; i < srom_devs; i++)
 466                 device_destroy(srom_class, MKDEV(srom_major, i));
 467         class_destroy(srom_class);
 468         cdev_del(&srom_cdev);
 469         platform_device_unregister(srom_parent);
 470         unregister_chrdev_region(MKDEV(srom_major, 0), srom_devs);
 471         kfree(srom_devices);
 472 }
 473
 474 module_init(srom_init);
 475 module_exit(srom_cleanup);