linux-kernel - [PATCH] tpm_tis: Add missing start/stop_tpm

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Date:   Sat, 23 Jan 2021 02:42:47 +0100
From:   Lukasz Majczak <lma@...ihalf.com>
To:     Peter Huewe <peterhuewe@....de>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        Radoslaw Biernacki <rad@...ihalf.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Alex Levin <levinale@...gle.com>
Subject: [PATCH] tpm_tis: Add missing start/stop_tpm_chip calls

There is a missing call to start_tpm_chip before the call to
the tpm_get_timeouts() and tpm_tis_probe_irq_single(). As the current
approach maight work for tpm2, it fails for tpm1.x - in that case
call to tpm_get_timeouts() or tpm_tis_probe_irq_single() tries to
transmit TPM commands on a disabled chip what what doesn't succeed
and in turn causes tpm_tis_core_init() to fail.
Tested on Samsung Chromebook Pro (Caroline).

Signed-off-by: Lukasz Majczak <lma@...ihalf.com>
---
 drivers/char/tpm/tpm_tis_core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 92c51c6cfd1b..ff0e5fe46a9d 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -1063,12 +1063,16 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 	init_waitqueue_head(&priv->read_queue);
 	init_waitqueue_head(&priv->int_queue);
 	if (irq != -1) {
+		rc = tpm_chip_start(chip);
+		if (rc)
+			goto out_err;
 		/* Before doing irq testing issue a command to the TPM in polling mode
 		 * to make sure it works. May as well use that command to set the
 		 * proper timeouts for the driver.
 		 */
 		if (tpm_get_timeouts(chip)) {
 			dev_err(dev, "Could not get TPM timeouts and durations\n");
+			tpm_chip_stop(chip);
 			rc = -ENODEV;
 			goto out_err;
 		}
@@ -1085,6 +1089,7 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
 		} else {
 			tpm_tis_probe_irq(chip, intmask);
 		}
+		tpm_chip_stop(chip);
 	}
 
 	rc = tpm_chip_register(chip);
-- 
2.25.1