drivers/char/tpm/tpm-chip.c

   1 /*
   2  * Copyright (C) 2004 IBM Corporation
   3  * Copyright (C) 2014 Intel Corporation
   4  *
   5  * Authors:
   6  * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
   7  * Leendert van Doorn <leendert@watson.ibm.com>
   8  * Dave Safford <safford@watson.ibm.com>
   9  * Reiner Sailer <sailer@watson.ibm.com>
  10  * Kylene Hall <kjhall@us.ibm.com>
  11  *
  12  * Maintained by: <tpmdd-devel@lists.sourceforge.net>
  13  *
  14  * TPM chip management routines.
  15  *
  16  * This program is free software; you can redistribute it and/or
  17  * modify it under the terms of the GNU General Public License as
  18  * published by the Free Software Foundation, version 2 of the
  19  * License.
  20  *
  21  */
  22
  23 #include <linux/poll.h>
  24 #include <linux/slab.h>
  25 #include <linux/mutex.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/freezer.h>
  28 #include <linux/major.h>
  29 #include "tpm.h"
  30 #include "tpm_eventlog.h"
  31
  32 static DECLARE_BITMAP(dev_mask, TPM_NUM_DEVICES);
  33 static LIST_HEAD(tpm_chip_list);
  34 static DEFINE_SPINLOCK(driver_lock);
  35
  36 struct class *tpm_class;
  37 dev_t tpm_devt;
  38
  39 /**
  40  * tpm_try_get_ops() - Get a ref to the tpm_chip
  41  * @chip: Chip to ref
  42  *
  43  * The caller must already have some kind of locking to ensure that chip is
  44  * valid. This function will lock the chip so that the ops member can be
  45  * accessed safely. The locking prevents tpm_chip_unregister from
  46  * completing, so it should not be held for long periods.
  47  *
  48  * Returns -ERRNO if the chip could not be got.
  49  */
  50 int tpm_try_get_ops(struct tpm_chip *chip)
  51 {
  52         int rc = -EIO;
  53
  54         get_device(&chip->dev);
  55
  56         down_read(&chip->ops_sem);
  57         if (!chip->ops)
  58                 goto out_lock;
  59
  60         if (!try_module_get(chip->dev.parent->driver->owner))
  61                 goto out_lock;
  62
  63         return 0;
  64 out_lock:
  65         up_read(&chip->ops_sem);
  66         put_device(&chip->dev);
  67         return rc;
  68 }
  69 EXPORT_SYMBOL_GPL(tpm_try_get_ops);
  70
  71 /**
  72  * tpm_put_ops() - Release a ref to the tpm_chip
  73  * @chip: Chip to put
  74  *
  75  * This is the opposite pair to tpm_try_get_ops(). After this returns chip may
  76  * be kfree'd.
  77  */
  78 void tpm_put_ops(struct tpm_chip *chip)
  79 {
  80         module_put(chip->dev.parent->driver->owner);
  81         up_read(&chip->ops_sem);
  82         put_device(&chip->dev);
  83 }
  84 EXPORT_SYMBOL_GPL(tpm_put_ops);
  85
  86 /**
  87  * tpm_chip_find_get() - return tpm_chip for a given chip number
  88  * @chip_num: id to find
  89  *
  90  * The return'd chip has been tpm_try_get_ops'd and must be released via
  91  * tpm_put_ops
  92   */
  93 struct tpm_chip *tpm_chip_find_get(int chip_num)
  94 {
  95         struct tpm_chip *pos, *chip = NULL;
  96
  97         rcu_read_lock();
  98         list_for_each_entry_rcu(pos, &tpm_chip_list, list) {
  99                 if (chip_num != TPM_ANY_NUM && chip_num != pos->dev_num)
 100                         continue;
 101
 102                 /* rcu prevents chip from being free'd */
 103                 if (!tpm_try_get_ops(pos))
 104                         chip = pos;
 105                 break;
 106         }
 107         rcu_read_unlock();
 108         return chip;
 109 }
 110
 111 /**
 112  * tpm_dev_release() - free chip memory and the device number
 113  * @dev: the character device for the TPM chip
 114  *
 115  * This is used as the release function for the character device.
 116  */
 117 static void tpm_dev_release(struct device *dev)
 118 {
 119         struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
 120
 121         spin_lock(&driver_lock);
 122         clear_bit(chip->dev_num, dev_mask);
 123         spin_unlock(&driver_lock);
 124         kfree(chip);
 125 }
 126
 127 /**
 128  * tpmm_chip_alloc() - allocate a new struct tpm_chip instance
 129  * @dev: device to which the chip is associated
 130  * @ops: struct tpm_class_ops instance
 131  *
 132  * Allocates a new struct tpm_chip instance and assigns a free
 133  * device number for it. Caller does not have to worry about
 134  * freeing the allocated resources. When the devices is removed
 135  * devres calls tpmm_chip_remove() to do the job.
 136  */
 137 struct tpm_chip *tpmm_chip_alloc(struct device *dev,
 138                                  const struct tpm_class_ops *ops)
 139 {
 140         struct tpm_chip *chip;
 141         int rc;
 142
 143         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
 144         if (chip == NULL)
 145                 return ERR_PTR(-ENOMEM);
 146
 147         mutex_init(&chip->tpm_mutex);
 148         init_rwsem(&chip->ops_sem);
 149         INIT_LIST_HEAD(&chip->list);
 150
 151         chip->ops = ops;
 152
 153         spin_lock(&driver_lock);
 154         chip->dev_num = find_first_zero_bit(dev_mask, TPM_NUM_DEVICES);
 155         spin_unlock(&driver_lock);
 156
 157         if (chip->dev_num >= TPM_NUM_DEVICES) {
 158                 dev_err(dev, "No available tpm device numbers\n");
 159                 kfree(chip);
 160                 return ERR_PTR(-ENOMEM);
 161         }
 162
 163         set_bit(chip->dev_num, dev_mask);
 164
 165         device_initialize(&chip->dev);
 166
 167         dev_set_drvdata(dev, chip);
 168
 169         chip->dev.class = tpm_class;
 170         chip->dev.release = tpm_dev_release;
 171         chip->dev.parent = dev;
 172 #ifdef CONFIG_ACPI
 173         chip->dev.groups = chip->groups;
 174 #endif
 175
 176         if (chip->dev_num == 0)
 177                 chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR);
 178         else
 179                 chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num);
 180
 181         rc = dev_set_name(&chip->dev, "tpm%d", chip->dev_num);
 182         if (rc)
 183                 goto out;
 184
 185         cdev_init(&chip->cdev, &tpm_fops);
 186         chip->cdev.owner = dev->driver->owner;
 187         chip->cdev.kobj.parent = &chip->dev.kobj;
 188
 189         rc = devm_add_action(dev, (void (*)(void *)) put_device, &chip->dev);
 190         if (rc) {
 191                 put_device(&chip->dev);
 192                 return ERR_PTR(rc);
 193         }
 194
 195         return chip;
 196
 197 out:
 198         put_device(&chip->dev);
 199         return ERR_PTR(rc);
 200 }
 201 EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
 202
 203 static int tpm_add_char_device(struct tpm_chip *chip)
 204 {
 205         int rc;
 206
 207         rc = cdev_add(&chip->cdev, chip->dev.devt, 1);
 208         if (rc) {
 209                 dev_err(&chip->dev,
 210                         "unable to cdev_add() %s, major %d, minor %d, err=%d\n",
 211                         dev_name(&chip->dev), MAJOR(chip->dev.devt),
 212                         MINOR(chip->dev.devt), rc);
 213
 214                 return rc;
 215         }
 216
 217         rc = device_add(&chip->dev);
 218         if (rc) {
 219                 dev_err(&chip->dev,
 220                         "unable to device_register() %s, major %d, minor %d, err=%d\n",
 221                         dev_name(&chip->dev), MAJOR(chip->dev.devt),
 222                         MINOR(chip->dev.devt), rc);
 223
 224                 cdev_del(&chip->cdev);
 225                 return rc;
 226         }
 227
 228         return rc;
 229 }
 230
 231 static void tpm_del_char_device(struct tpm_chip *chip)
 232 {
 233         cdev_del(&chip->cdev);
 234
 235         /* Make the driver uncallable. */
 236         down_write(&chip->ops_sem);
 237         chip->ops = NULL;
 238         up_write(&chip->ops_sem);
 239
 240         device_del(&chip->dev);
 241 }
 242
 243 static int tpm1_chip_register(struct tpm_chip *chip)
 244 {
 245         int rc;
 246
 247         if (chip->flags & TPM_CHIP_FLAG_TPM2)
 248                 return 0;
 249
 250         rc = tpm_sysfs_add_device(chip);
 251         if (rc)
 252                 return rc;
 253
 254         chip->bios_dir = tpm_bios_log_setup(dev_name(&chip->dev));
 255
 256         return 0;
 257 }
 258
 259 static void tpm1_chip_unregister(struct tpm_chip *chip)
 260 {
 261         if (chip->flags & TPM_CHIP_FLAG_TPM2)
 262                 return;
 263
 264         if (chip->bios_dir)
 265                 tpm_bios_log_teardown(chip->bios_dir);
 266
 267         tpm_sysfs_del_device(chip);
 268 }
 269
 270 /*
 271  * tpm_chip_register() - create a character device for the TPM chip
 272  * @chip: TPM chip to use.
 273  *
 274  * Creates a character device for the TPM chip and adds sysfs attributes for
 275  * the device. As the last step this function adds the chip to the list of TPM
 276  * chips available for in-kernel use.
 277  *
 278  * This function should be only called after the chip initialization is
 279  * complete.
 280  */
 281 int tpm_chip_register(struct tpm_chip *chip)
 282 {
 283         int rc;
 284
 285         rc = tpm1_chip_register(chip);
 286         if (rc)
 287                 return rc;
 288
 289         tpm_add_ppi(chip);
 290
 291         rc = tpm_add_char_device(chip);
 292         if (rc)
 293                 goto out_err;
 294
 295         /* Make the chip available. */
 296         spin_lock(&driver_lock);
 297         list_add_tail_rcu(&chip->list, &tpm_chip_list);
 298         spin_unlock(&driver_lock);
 299
 300         chip->flags |= TPM_CHIP_FLAG_REGISTERED;
 301
 302         if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
 303                 rc = __compat_only_sysfs_link_entry_to_kobj(
 304                     &chip->dev.parent->kobj, &chip->dev.kobj, "ppi");
 305                 if (rc && rc != -ENOENT) {
 306                         tpm_chip_unregister(chip);
 307                         return rc;
 308                 }
 309         }
 310
 311         return 0;
 312 out_err:
 313         tpm1_chip_unregister(chip);
 314         return rc;
 315 }
 316 EXPORT_SYMBOL_GPL(tpm_chip_register);
 317
 318 /*
 319  * tpm_chip_unregister() - release the TPM driver
 320  * @chip: TPM chip to use.
 321  *
 322  * Takes the chip first away from the list of available TPM chips and then
 323  * cleans up all the resources reserved by tpm_chip_register().
 324  *
 325  * Once this function returns the driver call backs in 'op's will not be
 326  * running and will no longer start.
 327  *
 328  * NOTE: This function should be only called before deinitializing chip
 329  * resources.
 330  */
 331 void tpm_chip_unregister(struct tpm_chip *chip)
 332 {
 333         if (!(chip->flags & TPM_CHIP_FLAG_REGISTERED))
 334                 return;
 335
 336         spin_lock(&driver_lock);
 337         list_del_rcu(&chip->list);
 338         spin_unlock(&driver_lock);
 339         synchronize_rcu();
 340
 341         if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
 342                 sysfs_remove_link(&chip->dev.parent->kobj, "ppi");
 343
 344         tpm1_chip_unregister(chip);
 345         tpm_del_char_device(chip);
 346 }
 347 EXPORT_SYMBOL_GPL(tpm_chip_unregister);