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authorStefan Berger <stefanb@linux.vnet.ibm.com>2018-06-26 15:09:30 -0400
committerJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>2018-07-28 17:03:11 +0300
commitaaae81536351f831fe6719e5b4e6afbadc5e5f85 (patch)
tree3d4c41248a9da034233b08aa88eb76cd88cc067f /drivers/char/tpm/tpm-chip.c
parentfc1d52b745bae6108102096d85e743ac33b446f2 (diff)
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>
Diffstat (limited to 'drivers/char/tpm/tpm-chip.c')
-rw-r--r--drivers/char/tpm/tpm-chip.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 242b716aed5e..f551061262c9 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -81,6 +81,33 @@ 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
*

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