![Jason Gunthorpe](/assets/img/avatar_default.png)
The tpm-rng.c approach is completely inconsistent with how the kernel handles hotplug. Instead manage a hwrng device for each TPM. This will cause the kernel to read entropy from the TPM when it is plugged in, and allow access to the TPM rng via /dev/hwrng. Signed-off-by: Jason Gunthorpe <jgg@ziepe.ca> Tested-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
497 lines
12 KiB
C
497 lines
12 KiB
C
/*
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* Copyright (C) 2004 IBM Corporation
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* Copyright (C) 2014 Intel Corporation
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*
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* Authors:
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* Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
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* Leendert van Doorn <leendert@watson.ibm.com>
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* Dave Safford <safford@watson.ibm.com>
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* Reiner Sailer <sailer@watson.ibm.com>
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* Kylene Hall <kjhall@us.ibm.com>
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*
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* Maintained by: <tpmdd-devel@lists.sourceforge.net>
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*
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* TPM chip management routines.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*
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*/
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#include <linux/poll.h>
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#include <linux/slab.h>
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#include <linux/mutex.h>
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#include <linux/spinlock.h>
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#include <linux/freezer.h>
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#include <linux/major.h>
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#include <linux/tpm_eventlog.h>
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#include <linux/hw_random.h>
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#include "tpm.h"
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DEFINE_IDR(dev_nums_idr);
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static DEFINE_MUTEX(idr_lock);
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struct class *tpm_class;
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struct class *tpmrm_class;
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dev_t tpm_devt;
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/**
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* tpm_try_get_ops() - Get a ref to the tpm_chip
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* @chip: Chip to ref
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*
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* The caller must already have some kind of locking to ensure that chip is
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* valid. This function will lock the chip so that the ops member can be
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* accessed safely. The locking prevents tpm_chip_unregister from
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* completing, so it should not be held for long periods.
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*
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* Returns -ERRNO if the chip could not be got.
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*/
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int tpm_try_get_ops(struct tpm_chip *chip)
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{
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int rc = -EIO;
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get_device(&chip->dev);
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down_read(&chip->ops_sem);
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if (!chip->ops)
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goto out_lock;
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return 0;
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out_lock:
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up_read(&chip->ops_sem);
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put_device(&chip->dev);
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return rc;
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}
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EXPORT_SYMBOL_GPL(tpm_try_get_ops);
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/**
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* tpm_put_ops() - Release a ref to the tpm_chip
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* @chip: Chip to put
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*
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* This is the opposite pair to tpm_try_get_ops(). After this returns chip may
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* be kfree'd.
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*/
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void tpm_put_ops(struct tpm_chip *chip)
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{
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up_read(&chip->ops_sem);
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put_device(&chip->dev);
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}
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EXPORT_SYMBOL_GPL(tpm_put_ops);
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/**
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* tpm_chip_find_get() - find and reserve a TPM chip
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* @chip: a &struct tpm_chip instance, %NULL for the default chip
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*
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* Finds a TPM chip and reserves its class device and operations. The chip must
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* be released with tpm_chip_put_ops() after use.
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*
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* Return:
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* A reserved &struct tpm_chip instance.
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* %NULL if a chip is not found.
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* %NULL if the chip is not available.
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*/
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struct tpm_chip *tpm_chip_find_get(struct tpm_chip *chip)
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{
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struct tpm_chip *res = NULL;
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int chip_num = 0;
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int chip_prev;
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mutex_lock(&idr_lock);
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if (!chip) {
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do {
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chip_prev = chip_num;
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chip = idr_get_next(&dev_nums_idr, &chip_num);
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if (chip && !tpm_try_get_ops(chip)) {
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res = chip;
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break;
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}
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} while (chip_prev != chip_num);
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} else {
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if (!tpm_try_get_ops(chip))
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res = chip;
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}
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mutex_unlock(&idr_lock);
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return res;
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}
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/**
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* tpm_dev_release() - free chip memory and the device number
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* @dev: the character device for the TPM chip
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*
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* This is used as the release function for the character device.
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*/
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static void tpm_dev_release(struct device *dev)
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{
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struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
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mutex_lock(&idr_lock);
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idr_remove(&dev_nums_idr, chip->dev_num);
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mutex_unlock(&idr_lock);
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kfree(chip->log.bios_event_log);
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kfree(chip->work_space.context_buf);
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kfree(chip->work_space.session_buf);
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kfree(chip);
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}
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static void tpm_devs_release(struct device *dev)
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{
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struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs);
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/* release the master device reference */
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put_device(&chip->dev);
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}
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/**
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* tpm_class_shutdown() - prepare the TPM device for loss of power.
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* @dev: device to which the chip is associated.
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*
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* Issues a TPM2_Shutdown command prior to loss of power, as required by the
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* TPM 2.0 spec.
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* Then, calls bus- and device- specific shutdown code.
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*
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* XXX: This codepath relies on the fact that sysfs is not enabled for
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* TPM2: sysfs uses an implicit lock on chip->ops, so this could race if TPM2
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* has sysfs support enabled before TPM sysfs's implicit locking is fixed.
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*/
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static int tpm_class_shutdown(struct device *dev)
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{
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struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
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if (chip->flags & TPM_CHIP_FLAG_TPM2) {
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down_write(&chip->ops_sem);
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tpm2_shutdown(chip, TPM2_SU_CLEAR);
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chip->ops = NULL;
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up_write(&chip->ops_sem);
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}
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return 0;
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}
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/**
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* tpm_chip_alloc() - allocate a new struct tpm_chip instance
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* @pdev: device to which the chip is associated
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* At this point pdev mst be initialized, but does not have to
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* be registered
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* @ops: struct tpm_class_ops instance
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*
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* Allocates a new struct tpm_chip instance and assigns a free
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* device number for it. Must be paired with put_device(&chip->dev).
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*/
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struct tpm_chip *tpm_chip_alloc(struct device *pdev,
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const struct tpm_class_ops *ops)
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{
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struct tpm_chip *chip;
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int rc;
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chip = kzalloc(sizeof(*chip), GFP_KERNEL);
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if (chip == NULL)
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return ERR_PTR(-ENOMEM);
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mutex_init(&chip->tpm_mutex);
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init_rwsem(&chip->ops_sem);
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chip->ops = ops;
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mutex_lock(&idr_lock);
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rc = idr_alloc(&dev_nums_idr, NULL, 0, TPM_NUM_DEVICES, GFP_KERNEL);
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mutex_unlock(&idr_lock);
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if (rc < 0) {
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dev_err(pdev, "No available tpm device numbers\n");
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kfree(chip);
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return ERR_PTR(rc);
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}
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chip->dev_num = rc;
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device_initialize(&chip->dev);
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device_initialize(&chip->devs);
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chip->dev.class = tpm_class;
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chip->dev.class->shutdown_pre = tpm_class_shutdown;
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chip->dev.release = tpm_dev_release;
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chip->dev.parent = pdev;
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chip->dev.groups = chip->groups;
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chip->devs.parent = pdev;
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chip->devs.class = tpmrm_class;
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chip->devs.release = tpm_devs_release;
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/* get extra reference on main device to hold on
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* behalf of devs. This holds the chip structure
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* while cdevs is in use. The corresponding put
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* is in the tpm_devs_release (TPM2 only)
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*/
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if (chip->flags & TPM_CHIP_FLAG_TPM2)
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get_device(&chip->dev);
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if (chip->dev_num == 0)
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chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR);
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else
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chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num);
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chip->devs.devt =
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MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES);
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rc = dev_set_name(&chip->dev, "tpm%d", chip->dev_num);
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if (rc)
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goto out;
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rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
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if (rc)
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goto out;
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if (!pdev)
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chip->flags |= TPM_CHIP_FLAG_VIRTUAL;
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cdev_init(&chip->cdev, &tpm_fops);
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cdev_init(&chip->cdevs, &tpmrm_fops);
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chip->cdev.owner = THIS_MODULE;
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chip->cdevs.owner = THIS_MODULE;
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chip->work_space.context_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
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if (!chip->work_space.context_buf) {
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rc = -ENOMEM;
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goto out;
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}
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chip->work_space.session_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
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if (!chip->work_space.session_buf) {
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rc = -ENOMEM;
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goto out;
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}
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chip->locality = -1;
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return chip;
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out:
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put_device(&chip->devs);
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put_device(&chip->dev);
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return ERR_PTR(rc);
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}
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EXPORT_SYMBOL_GPL(tpm_chip_alloc);
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/**
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* tpmm_chip_alloc() - allocate a new struct tpm_chip instance
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* @pdev: parent device to which the chip is associated
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* @ops: struct tpm_class_ops instance
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*
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* Same as tpm_chip_alloc except devm is used to do the put_device
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*/
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struct tpm_chip *tpmm_chip_alloc(struct device *pdev,
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const struct tpm_class_ops *ops)
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{
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struct tpm_chip *chip;
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int rc;
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chip = tpm_chip_alloc(pdev, ops);
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if (IS_ERR(chip))
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return chip;
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rc = devm_add_action_or_reset(pdev,
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(void (*)(void *)) put_device,
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&chip->dev);
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if (rc)
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return ERR_PTR(rc);
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dev_set_drvdata(pdev, chip);
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return chip;
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}
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EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
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static int tpm_add_char_device(struct tpm_chip *chip)
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{
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int rc;
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rc = cdev_device_add(&chip->cdev, &chip->dev);
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if (rc) {
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dev_err(&chip->dev,
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"unable to cdev_device_add() %s, major %d, minor %d, err=%d\n",
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dev_name(&chip->dev), MAJOR(chip->dev.devt),
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MINOR(chip->dev.devt), rc);
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return rc;
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}
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if (chip->flags & TPM_CHIP_FLAG_TPM2) {
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rc = cdev_device_add(&chip->cdevs, &chip->devs);
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if (rc) {
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dev_err(&chip->devs,
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"unable to cdev_device_add() %s, major %d, minor %d, err=%d\n",
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dev_name(&chip->devs), MAJOR(chip->devs.devt),
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MINOR(chip->devs.devt), rc);
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return rc;
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}
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}
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/* Make the chip available. */
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mutex_lock(&idr_lock);
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idr_replace(&dev_nums_idr, chip, chip->dev_num);
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mutex_unlock(&idr_lock);
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return rc;
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}
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static void tpm_del_char_device(struct tpm_chip *chip)
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{
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cdev_device_del(&chip->cdev, &chip->dev);
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/* Make the chip unavailable. */
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mutex_lock(&idr_lock);
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idr_replace(&dev_nums_idr, NULL, chip->dev_num);
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mutex_unlock(&idr_lock);
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/* Make the driver uncallable. */
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down_write(&chip->ops_sem);
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if (chip->flags & TPM_CHIP_FLAG_TPM2)
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tpm2_shutdown(chip, TPM2_SU_CLEAR);
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chip->ops = NULL;
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up_write(&chip->ops_sem);
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}
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static void tpm_del_legacy_sysfs(struct tpm_chip *chip)
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{
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struct attribute **i;
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if (chip->flags & (TPM_CHIP_FLAG_TPM2 | TPM_CHIP_FLAG_VIRTUAL))
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return;
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sysfs_remove_link(&chip->dev.parent->kobj, "ppi");
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for (i = chip->groups[0]->attrs; *i != NULL; ++i)
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sysfs_remove_link(&chip->dev.parent->kobj, (*i)->name);
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}
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/* For compatibility with legacy sysfs paths we provide symlinks from the
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* parent dev directory to selected names within the tpm chip directory. Old
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* kernel versions created these files directly under the parent.
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*/
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static int tpm_add_legacy_sysfs(struct tpm_chip *chip)
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{
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struct attribute **i;
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int rc;
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if (chip->flags & (TPM_CHIP_FLAG_TPM2 | TPM_CHIP_FLAG_VIRTUAL))
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return 0;
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rc = __compat_only_sysfs_link_entry_to_kobj(
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&chip->dev.parent->kobj, &chip->dev.kobj, "ppi");
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if (rc && rc != -ENOENT)
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return rc;
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/* All the names from tpm-sysfs */
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for (i = chip->groups[0]->attrs; *i != NULL; ++i) {
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rc = __compat_only_sysfs_link_entry_to_kobj(
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&chip->dev.parent->kobj, &chip->dev.kobj, (*i)->name);
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if (rc) {
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tpm_del_legacy_sysfs(chip);
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return rc;
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}
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}
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return 0;
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}
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static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
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{
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struct tpm_chip *chip = container_of(rng, struct tpm_chip, hwrng);
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return tpm_get_random(chip, data, max);
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}
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static int tpm_add_hwrng(struct tpm_chip *chip)
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{
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if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM))
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return 0;
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snprintf(chip->hwrng_name, sizeof(chip->hwrng_name),
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"tpm-rng-%d", chip->dev_num);
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chip->hwrng.name = chip->hwrng_name;
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chip->hwrng.read = tpm_hwrng_read;
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return hwrng_register(&chip->hwrng);
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}
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/*
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* tpm_chip_register() - create a character device for the TPM chip
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* @chip: TPM chip to use.
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*
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* Creates a character device for the TPM chip and adds sysfs attributes for
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* the device. As the last step this function adds the chip to the list of TPM
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* chips available for in-kernel use.
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*
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* This function should be only called after the chip initialization is
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* complete.
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*/
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int tpm_chip_register(struct tpm_chip *chip)
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{
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int rc;
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if (chip->ops->flags & TPM_OPS_AUTO_STARTUP) {
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if (chip->flags & TPM_CHIP_FLAG_TPM2)
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rc = tpm2_auto_startup(chip);
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else
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rc = tpm1_auto_startup(chip);
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if (rc)
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return rc;
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}
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tpm_sysfs_add_device(chip);
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rc = tpm_bios_log_setup(chip);
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if (rc != 0 && rc != -ENODEV)
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return rc;
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tpm_add_ppi(chip);
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rc = tpm_add_hwrng(chip);
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if (rc)
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goto out_ppi;
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rc = tpm_add_char_device(chip);
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if (rc)
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goto out_hwrng;
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rc = tpm_add_legacy_sysfs(chip);
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if (rc) {
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tpm_chip_unregister(chip);
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return rc;
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}
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return 0;
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out_hwrng:
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if (IS_ENABLED(CONFIG_HW_RANDOM_TPM))
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hwrng_unregister(&chip->hwrng);
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out_ppi:
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tpm_bios_log_teardown(chip);
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return rc;
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}
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EXPORT_SYMBOL_GPL(tpm_chip_register);
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/*
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* tpm_chip_unregister() - release the TPM driver
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* @chip: TPM chip to use.
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*
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* Takes the chip first away from the list of available TPM chips and then
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* cleans up all the resources reserved by tpm_chip_register().
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*
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* Once this function returns the driver call backs in 'op's will not be
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* running and will no longer start.
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*
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* NOTE: This function should be only called before deinitializing chip
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* resources.
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*/
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void tpm_chip_unregister(struct tpm_chip *chip)
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{
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tpm_del_legacy_sysfs(chip);
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if (IS_ENABLED(CONFIG_HW_RANDOM_TPM))
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hwrng_unregister(&chip->hwrng);
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tpm_bios_log_teardown(chip);
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if (chip->flags & TPM_CHIP_FLAG_TPM2)
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cdev_device_del(&chip->cdevs, &chip->devs);
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tpm_del_char_device(chip);
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}
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EXPORT_SYMBOL_GPL(tpm_chip_unregister);
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