Commit aaae8153 authored by Stefan Berger's avatar Stefan Berger Committed by Jarkko Sakkinen
Browse files

tpm: Implement tpm_default_chip() to find a TPM chip 



Implement tpm_default_chip() to find the first TPM chip and return it to
the caller while increasing the reference count on its device. This
function can be used by other subsystems, such as IMA, to find the system's
default TPM chip and use it for all subsequent TPM operations.

Signed-off-by: default avatarStefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
parent fc1d52b7

drivers/char/tpm/tpm-chip.c

+27 −0
Original line number Diff line number Diff line
@@ -80,6 +80,33 @@ void tpm_put_ops(struct tpm_chip *chip) 
}

EXPORT_SYMBOL_GPL(tpm_put_ops);



/**

 * tpm_default_chip() - find a TPM chip and get a reference to it

 */

struct tpm_chip *tpm_default_chip(void)

{

	struct tpm_chip *chip, *res = NULL;

	int chip_num = 0;

	int chip_prev;



	mutex_lock(&idr_lock);



	do {

		chip_prev = chip_num;

		chip = idr_get_next(&dev_nums_idr, &chip_num);

		if (chip) {

			get_device(&chip->dev);

			res = chip;

			break;

		}

	} while (chip_prev != chip_num);



	mutex_unlock(&idr_lock);



	return res;

}

EXPORT_SYMBOL_GPL(tpm_default_chip);



/**

 * tpm_find_get_ops() - find and reserve a TPM chip

 * @chip:	a &struct tpm_chip instance, %NULL for the default chip

include/linux/tpm.h

+5 −0
Original line number Diff line number Diff line
@@ -63,6 +63,7 @@ extern int tpm_seal_trusted(struct tpm_chip *chip, 
extern int tpm_unseal_trusted(struct tpm_chip *chip,

			      struct trusted_key_payload *payload,

			      struct trusted_key_options *options);

extern struct tpm_chip *tpm_default_chip(void);

#else

static inline int tpm_is_tpm2(struct tpm_chip *chip)

{
@@ -98,5 +99,9 @@ static inline int tpm_unseal_trusted(struct tpm_chip *chip, 
{

	return -ENODEV;

}

static inline struct tpm_chip *tpm_default_chip(void)

{

	return NULL;

}

#endif

#endif

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