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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: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
This commit is contained in:
Stefan Berger 2018-06-26 15:09:30 -04:00 committed by Jarkko Sakkinen
parent fc1d52b745
commit aaae815363
2 changed files with 32 additions and 0 deletions
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27
drivers/char/tpm/tpm-chip.c
View File

@ -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

5
include/linux/tpm.h
View File

@ -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