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_chip_find_get - return tpm_chip for a given chip number
  41  * @chip_num the device number for the chip
  42  */
  43 struct tpm_chip *tpm_chip_find_get(int chip_num)
  44 {
  45         struct tpm_chip *pos, *chip = NULL;
  46
  47         rcu_read_lock();
  48         list_for_each_entry_rcu(pos, &tpm_chip_list, list) {
  49                 if (chip_num != TPM_ANY_NUM && chip_num != pos->dev_num)
  50                         continue;
  51
  52                 if (try_module_get(pos->pdev->driver->owner)) {
  53                         chip = pos;
  54                         break;
  55                 }
  56         }
  57         rcu_read_unlock();
  58         return chip;
  59 }
  60
  61 /**
  62  * tpm_dev_release() - free chip memory and the device number
  63  * @dev: the character device for the TPM chip
  64  *
  65  * This is used as the release function for the character device.
  66  */
  67 static void tpm_dev_release(struct device *dev)
  68 {
  69         struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
  70
  71         spin_lock(&driver_lock);
  72         clear_bit(chip->dev_num, dev_mask);
  73         spin_unlock(&driver_lock);
  74         kfree(chip);
  75 }
  76
  77 /**
  78  * tpmm_chip_alloc() - allocate a new struct tpm_chip instance
  79  * @dev: device to which the chip is associated
  80  * @ops: struct tpm_class_ops instance
  81  *
  82  * Allocates a new struct tpm_chip instance and assigns a free
  83  * device number for it. Caller does not have to worry about
  84  * freeing the allocated resources. When the devices is removed
  85  * devres calls tpmm_chip_remove() to do the job.
  86  */
  87 struct tpm_chip *tpmm_chip_alloc(struct device *dev,
  88                                  const struct tpm_class_ops *ops)
  89 {
  90         struct tpm_chip *chip;
  91         int rc;
  92
  93         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
  94         if (chip == NULL)
  95                 return ERR_PTR(-ENOMEM);
  96
  97         mutex_init(&chip->tpm_mutex);
  98         INIT_LIST_HEAD(&chip->list);
  99
 100         chip->ops = ops;
 101
 102         spin_lock(&driver_lock);
 103         chip->dev_num = find_first_zero_bit(dev_mask, TPM_NUM_DEVICES);
 104         spin_unlock(&driver_lock);
 105
 106         if (chip->dev_num >= TPM_NUM_DEVICES) {
 107                 dev_err(dev, "No available tpm device numbers\n");
 108                 kfree(chip);
 109                 return ERR_PTR(-ENOMEM);
 110         }
 111
 112         set_bit(chip->dev_num, dev_mask);
 113
 114         scnprintf(chip->devname, sizeof(chip->devname), "tpm%d", chip->dev_num);
 115
 116         chip->pdev = dev;
 117
 118         dev_set_drvdata(dev, chip);
 119
 120         chip->dev.class = tpm_class;
 121         chip->dev.release = tpm_dev_release;
 122         chip->dev.parent = chip->pdev;
 123 #ifdef CONFIG_ACPI
 124         chip->dev.groups = chip->groups;
 125 #endif
 126
 127         if (chip->dev_num == 0)
 128                 chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR);
 129         else
 130                 chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num);
 131
 132         dev_set_name(&chip->dev, "%s", chip->devname);
 133
 134         device_initialize(&chip->dev);
 135
 136         cdev_init(&chip->cdev, &tpm_fops);
 137         chip->cdev.owner = chip->pdev->driver->owner;
 138         chip->cdev.kobj.parent = &chip->dev.kobj;
 139
 140         rc = devm_add_action(dev, (void (*)(void *)) put_device, &chip->dev);
 141         if (rc) {
 142                 put_device(&chip->dev);
 143                 return ERR_PTR(rc);
 144         }
 145
 146         return chip;
 147 }
 148 EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
 149
 150 static int tpm_add_char_device(struct tpm_chip *chip)
 151 {
 152         int rc;
 153
 154         rc = cdev_add(&chip->cdev, chip->dev.devt, 1);
 155         if (rc) {
 156                 dev_err(&chip->dev,
 157                         "unable to cdev_add() %s, major %d, minor %d, err=%d\n",
 158                         chip->devname, MAJOR(chip->dev.devt),
 159                         MINOR(chip->dev.devt), rc);
 160
 161                 return rc;
 162         }
 163
 164         rc = device_add(&chip->dev);
 165         if (rc) {
 166                 dev_err(&chip->dev,
 167                         "unable to device_register() %s, major %d, minor %d, err=%d\n",
 168                         chip->devname, MAJOR(chip->dev.devt),
 169                         MINOR(chip->dev.devt), rc);
 170
 171                 cdev_del(&chip->cdev);
 172                 return rc;
 173         }
 174
 175         return rc;
 176 }
 177
 178 static void tpm_del_char_device(struct tpm_chip *chip)
 179 {
 180         cdev_del(&chip->cdev);
 181         device_del(&chip->dev);
 182 }
 183
 184 static int tpm1_chip_register(struct tpm_chip *chip)
 185 {
 186         int rc;
 187
 188         if (chip->flags & TPM_CHIP_FLAG_TPM2)
 189                 return 0;
 190
 191         rc = tpm_sysfs_add_device(chip);
 192         if (rc)
 193                 return rc;
 194
 195         chip->bios_dir = tpm_bios_log_setup(chip->devname);
 196
 197         return 0;
 198 }
 199
 200 static void tpm1_chip_unregister(struct tpm_chip *chip)
 201 {
 202         if (chip->flags & TPM_CHIP_FLAG_TPM2)
 203                 return;
 204
 205         if (chip->bios_dir)
 206                 tpm_bios_log_teardown(chip->bios_dir);
 207
 208         tpm_sysfs_del_device(chip);
 209 }
 210
 211 /*
 212  * tpm_chip_register() - create a character device for the TPM chip
 213  * @chip: TPM chip to use.
 214  *
 215  * Creates a character device for the TPM chip and adds sysfs attributes for
 216  * the device. As the last step this function adds the chip to the list of TPM
 217  * chips available for in-kernel use.
 218  *
 219  * This function should be only called after the chip initialization is
 220  * complete.
 221  */
 222 int tpm_chip_register(struct tpm_chip *chip)
 223 {
 224         int rc;
 225
 226         rc = tpm1_chip_register(chip);
 227         if (rc)
 228                 return rc;
 229
 230         tpm_add_ppi(chip);
 231
 232         rc = tpm_add_char_device(chip);
 233         if (rc)
 234                 goto out_err;
 235
 236         /* Make the chip available. */
 237         spin_lock(&driver_lock);
 238         list_add_tail_rcu(&chip->list, &tpm_chip_list);
 239         spin_unlock(&driver_lock);
 240
 241         chip->flags |= TPM_CHIP_FLAG_REGISTERED;
 242
 243         if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
 244                 rc = __compat_only_sysfs_link_entry_to_kobj(&chip->pdev->kobj,
 245                                                             &chip->dev.kobj,
 246                                                             "ppi");
 247                 if (rc && rc != -ENOENT) {
 248                         tpm_chip_unregister(chip);
 249                         return rc;
 250                 }
 251         }
 252
 253         return 0;
 254 out_err:
 255         tpm1_chip_unregister(chip);
 256         return rc;
 257 }
 258 EXPORT_SYMBOL_GPL(tpm_chip_register);
 259
 260 /*
 261  * tpm_chip_unregister() - release the TPM driver
 262  * @chip: TPM chip to use.
 263  *
 264  * Takes the chip first away from the list of available TPM chips and then
 265  * cleans up all the resources reserved by tpm_chip_register().
 266  *
 267  * NOTE: This function should be only called before deinitializing chip
 268  * resources.
 269  */
 270 void tpm_chip_unregister(struct tpm_chip *chip)
 271 {
 272         if (!(chip->flags & TPM_CHIP_FLAG_REGISTERED))
 273                 return;
 274
 275         spin_lock(&driver_lock);
 276         list_del_rcu(&chip->list);
 277         spin_unlock(&driver_lock);
 278         synchronize_rcu();
 279
 280         if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
 281                 sysfs_remove_link(&chip->pdev->kobj, "ppi");
 282
 283         tpm1_chip_unregister(chip);
 284         tpm_del_char_device(chip);
 285 }
 286 EXPORT_SYMBOL_GPL(tpm_chip_unregister);