linux-kernel - [PATCH] Refuse activation of tpm_tis driver if TPM is not working correctly

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Date:	Mon, 10 Oct 2011 08:16:45 -0400
From:	Stefan Berger <stefanb@...ux.vnet.ibm.com>
To:	"tpmdd-devel@...ts.sourceforge.net" 
	<tpmdd-devel@...ts.sourceforge.net>,
	James Morris <jmorris@...ei.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Rajiv Andrade <srajiv@...ux.vnet.ibm.com>,
	m.selhorst@...rix.com
Cc:	a.miskiewicz@...il.com
Subject: [PATCH] Refuse activation of tpm_tis driver if TPM is not working
 correctly

Refuse activation of tpm_tis driver if the TPM is found not to be
working correctly. This prevents suspend/resume problems for me on
Lenovo W500 and T61p.

Signed-off-by: Stefan Berger <stefanb@...ux.vnet.ibm.com>

---
 drivers/char/tpm/tpm_tis.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
index 3f4051a..7f2761d 100644
--- a/drivers/char/tpm/tpm_tis.c
+++ b/drivers/char/tpm/tpm_tis.c
@@ -549,6 +549,7 @@ static int tpm_tis_init(struct device *dev, resource_size_t start,
 	u32 vendor, intfcaps, intmask;
 	int rc, i, irq_s, irq_e;
 	struct tpm_chip *chip;
+	u8 digest[TPM_DIGEST_SIZE];
 
 	if (!(chip = tpm_register_hardware(dev, &tpm_tis)))
 		return -ENODEV;
@@ -616,6 +617,18 @@ static int tpm_tis_init(struct device *dev, resource_size_t start,
 	/* get the timeouts before testing for irqs */
 	tpm_get_timeouts(chip);
 
+	/* test for correctly working TPM; refuse driver if not working 
+	   to prevent suspend/resume problems */
+	rc = tpm_pcr_read(chip->dev_num, 0, digest);
+	if (rc != 0) {
+		dev_err(dev, "Could not read PCR 0. "
+			"TPM is not working correctly.\n");
+		dev_err(dev, "Was machine previously suspended without TPM "
+			"driver present?\n");
+		rc = -ENODEV;
+		goto out_err;
+	}
+
 	/* INTERRUPT Setup */
 	init_waitqueue_head(&chip->vendor.read_queue);
 	init_waitqueue_head(&chip->vendor.int_queue);
-- 
1.7.6.4


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