linux-kernel - [PATCH 3/3] tpm: Drop CONFIG_HW_RANDOM

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Date:   Wed, 2 Aug 2023 20:50:15 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     <jarkko@...nel.org>, <peterhuewe@....de>
CC:     <linux-kernel@...r.kernel.org>, <linux-integrity@...r.kernel.org>,
        <Jason@...c4.com>, <dragonn@...pl>,
        Mario Limonciello <mario.limonciello@....com>
Subject: [PATCH 3/3] tpm: Drop CONFIG_HW_RANDOM_TPM

As the behavior of whether a TPM is registered for hwrng can be controlled
by command line, drop the kernel configuration option.

Cc: Mateusz Schyboll <dragonn@...pl>
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
 drivers/char/tpm/Kconfig    | 11 -----------
 drivers/char/tpm/tpm-chip.c |  6 +++---
 2 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index 927088b2c3d3f..69aaa730dc208 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -27,17 +27,6 @@ menuconfig TCG_TPM
 
 if TCG_TPM
 
-config HW_RANDOM_TPM
-	bool "TPM HW Random Number Generator support"
-	depends on TCG_TPM && HW_RANDOM && !(TCG_TPM=y && HW_RANDOM=m)
-	default y
-	help
-	  This setting exposes the TPM's Random Number Generator as a hwrng
-	  device. This allows the kernel to collect randomness from the TPM at
-	  boot, and provides the TPM randomines in /dev/hwrng.
-
-	  If unsure, say Y.
-
 config TCG_TIS_CORE
 	tristate
 	help
diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 8fb42232bd7a5..0d69335743469 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -533,7 +533,7 @@ static int tpm_add_hwrng(struct tpm_chip *chip)
 	if (!trust_tpm)
 		chip->flags |= TPM_CHIP_FLAG_HWRNG_DISABLED;
 
-	if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM) || tpm_is_firmware_upgrade(chip) ||
+	if (tpm_is_firmware_upgrade(chip) ||
 	    chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED)
 		return 0;
 
@@ -639,7 +639,7 @@ int tpm_chip_register(struct tpm_chip *chip)
 	return 0;
 
 out_hwrng:
-	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip) &&
+	if (!tpm_is_firmware_upgrade(chip) &&
 	    !(chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED))
 		hwrng_unregister(&chip->hwrng);
 out_ppi:
@@ -665,7 +665,7 @@ EXPORT_SYMBOL_GPL(tpm_chip_register);
 void tpm_chip_unregister(struct tpm_chip *chip)
 {
 	tpm_del_legacy_sysfs(chip);
-	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM) && !tpm_is_firmware_upgrade(chip) &&
+	if (!tpm_is_firmware_upgrade(chip) &&
 	    !(chip->flags & TPM_CHIP_FLAG_HWRNG_DISABLED))
 		hwrng_unregister(&chip->hwrng);
 	tpm_bios_log_teardown(chip);
-- 
2.34.1