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
  92         chip = kzalloc(sizeof(*chip), GFP_KERNEL);
  93         if (chip == NULL)
  94                 return ERR_PTR(-ENOMEM);
  95
  96         mutex_init(&chip->tpm_mutex);
  97         INIT_LIST_HEAD(&chip->list);
  98
  99         chip->ops = ops;
 100
 101         spin_lock(&driver_lock);
 102         chip->dev_num = find_first_zero_bit(dev_mask, TPM_NUM_DEVICES);
 103         spin_unlock(&driver_lock);
 104
 105         if (chip->dev_num >= TPM_NUM_DEVICES) {
 106                 dev_err(dev, "No available tpm device numbers\n");
 107                 kfree(chip);
 108                 return ERR_PTR(-ENOMEM);
 109         }
 110
 111         set_bit(chip->dev_num, dev_mask);
 112
 113         scnprintf(chip->devname, sizeof(chip->devname), "tpm%d", chip->dev_num);
 114
 115         chip->pdev = dev;
 116
 117         dev_set_drvdata(dev, chip);
 118
 119         chip->dev.class = tpm_class;
 120         chip->dev.release = tpm_dev_release;
 121         chip->dev.parent = chip->pdev;
 122
 123         if (chip->dev_num == 0)
 124                 chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR);
 125         else
 126                 chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num);
 127
 128         dev_set_name(&chip->dev, "%s", chip->devname);
 129
 130         device_initialize(&chip->dev);
 131
 132         chip->cdev.owner = chip->pdev->driver->owner;
 133         cdev_init(&chip->cdev, &tpm_fops);
 134
 135         return chip;
 136 }
 137 EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
 138
 139 static int tpm_dev_add_device(struct tpm_chip *chip)
 140 {
 141         int rc;
 142
 143         rc = cdev_add(&chip->cdev, chip->dev.devt, 1);
 144         if (rc) {
 145                 dev_err(&chip->dev,
 146                         "unable to cdev_add() %s, major %d, minor %d, err=%d\n",
 147                         chip->devname, MAJOR(chip->dev.devt),
 148                         MINOR(chip->dev.devt), rc);
 149
 150                 device_unregister(&chip->dev);
 151                 return rc;
 152         }
 153
 154         rc = device_add(&chip->dev);
 155         if (rc) {
 156                 dev_err(&chip->dev,
 157                         "unable to device_register() %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         return rc;
 165 }
 166
 167 static void tpm_dev_del_device(struct tpm_chip *chip)
 168 {
 169         cdev_del(&chip->cdev);
 170         device_unregister(&chip->dev);
 171 }
 172
 173 /*
 174  * tpm_chip_register() - create a character device for the TPM chip
 175  * @chip: TPM chip to use.
 176  *
 177  * Creates a character device for the TPM chip and adds sysfs attributes for
 178  * the device. As the last step this function adds the chip to the list of TPM
 179  * chips available for in-kernel use.
 180  *
 181  * This function should be only called after the chip initialization is
 182  * complete.
 183  */
 184 int tpm_chip_register(struct tpm_chip *chip)
 185 {
 186         int rc;
 187
 188         /* Populate sysfs for TPM1 devices. */
 189         if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
 190                 rc = tpm_sysfs_add_device(chip);
 191                 if (rc)
 192                         goto del_misc;
 193
 194                 rc = tpm_add_ppi(chip);
 195                 if (rc)
 196                         goto del_sysfs;
 197
 198                 chip->bios_dir = tpm_bios_log_setup(chip->devname);
 199         }
 200
 201         rc = tpm_dev_add_device(chip);
 202         if (rc)
 203                 return rc;
 204
 205         /* Make the chip available. */
 206         spin_lock(&driver_lock);
 207         list_add_rcu(&chip->list, &tpm_chip_list);
 208         spin_unlock(&driver_lock);
 209
 210         chip->flags |= TPM_CHIP_FLAG_REGISTERED;
 211
 212         return 0;
 213 del_sysfs:
 214         tpm_sysfs_del_device(chip);
 215 del_misc:
 216         tpm_dev_del_device(chip);
 217         return rc;
 218 }
 219 EXPORT_SYMBOL_GPL(tpm_chip_register);
 220
 221 /*
 222  * tpm_chip_unregister() - release the TPM driver
 223  * @chip: TPM chip to use.
 224  *
 225  * Takes the chip first away from the list of available TPM chips and then
 226  * cleans up all the resources reserved by tpm_chip_register().
 227  *
 228  * NOTE: This function should be only called before deinitializing chip
 229  * resources.
 230  */
 231 void tpm_chip_unregister(struct tpm_chip *chip)
 232 {
 233         if (!(chip->flags & TPM_CHIP_FLAG_REGISTERED))
 234                 return;
 235
 236         spin_lock(&driver_lock);
 237         list_del_rcu(&chip->list);
 238         spin_unlock(&driver_lock);
 239         synchronize_rcu();
 240
 241         if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
 242                 if (chip->bios_dir)
 243                         tpm_bios_log_teardown(chip->bios_dir);
 244                 tpm_remove_ppi(chip);
 245                 tpm_sysfs_del_device(chip);
 246         }
 247
 248         tpm_dev_del_device(chip);
 249 }
 250 EXPORT_SYMBOL_GPL(tpm_chip_unregister);