linux-kernel - [PATCH v9 2/4] tpm: of: Make of-tree specific function commonly available

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Message-Id: <20230418134409.177485-3-stefanb@linux.ibm.com>
Date:   Tue, 18 Apr 2023 09:44:07 -0400
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     kexec@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Cc:     nayna@...ux.ibm.com, nasastry@...ibm.com, mpe@...erman.id.au,
        Stefan Berger <stefanb@...ux.ibm.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Nageswara R Sastry <rnsastry@...ux.ibm.com>,
        Coiby Xu <coxu@...hat.com>
Subject: [PATCH v9 2/4] tpm: of: Make of-tree specific function commonly available

Simplify tpm_read_log_of() by moving reusable parts of the code into
an inline function that makes it commonly available so it can be
used also for kexec support. Call the new of_tpm_get_sml_parameters()
function from the TPM Open Firmware driver.

Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
Cc: Jarkko Sakkinen <jarkko@...nel.org>
Cc: Jason Gunthorpe <jgg@...pe.ca>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Frank Rowand <frowand.list@...il.com>
Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
Tested-by: Nageswara R Sastry <rnsastry@...ux.ibm.com>
Tested-by: Coiby Xu <coxu@...hat.com>
Acked-by: Jarkko Sakkinen <jarkko@...nel.org>

---
v9:
 - Rebased on 6.3-rc7; call tpm_read_log_memory_region if -ENODEV returned

v7:
 - Added original comment back into inlined function

v4:
 - converted to inline function
---
 drivers/char/tpm/eventlog/of.c | 30 +++++-----------------------
 include/linux/tpm.h            | 36 ++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
index 930fe43d5daf..41688d9cbd3b 100644
--- a/drivers/char/tpm/eventlog/of.c
+++ b/drivers/char/tpm/eventlog/of.c
@@ -51,11 +51,10 @@ static int tpm_read_log_memory_region(struct tpm_chip *chip)
 int tpm_read_log_of(struct tpm_chip *chip)
 {
 	struct device_node *np;
-	const u32 *sizep;
-	const u64 *basep;
 	struct tpm_bios_log *log;
 	u32 size;
 	u64 base;
+	int ret;
 
 	log = &chip->log;
 	if (chip->dev.parent && chip->dev.parent->of_node)
@@ -66,30 +65,11 @@ int tpm_read_log_of(struct tpm_chip *chip)
 	if (of_property_read_bool(np, "powered-while-suspended"))
 		chip->flags |= TPM_CHIP_FLAG_ALWAYS_POWERED;
 
-	sizep = of_get_property(np, "linux,sml-size", NULL);
-	basep = of_get_property(np, "linux,sml-base", NULL);
-	if (sizep == NULL && basep == NULL)
+	ret = of_tpm_get_sml_parameters(np, &base, &size);
+	if (ret == -ENODEV)
 		return tpm_read_log_memory_region(chip);
-	if (sizep == NULL || basep == NULL)
-		return -EIO;
-
-	/*
-	 * For both vtpm/tpm, firmware has log addr and log size in big
-	 * endian format. But in case of vtpm, there is a method called
-	 * sml-handover which is run during kernel init even before
-	 * device tree is setup. This sml-handover function takes care
-	 * of endianness and writes to sml-base and sml-size in little
-	 * endian format. For this reason, vtpm doesn't need conversion
-	 * but physical tpm needs the conversion.
-	 */
-	if (of_property_match_string(np, "compatible", "IBM,vtpm") < 0 &&
-	    of_property_match_string(np, "compatible", "IBM,vtpm20") < 0) {
-		size = be32_to_cpup((__force __be32 *)sizep);
-		base = be64_to_cpup((__force __be64 *)basep);
-	} else {
-		size = *sizep;
-		base = *basep;
-	}
+	if (ret < 0)
+		return ret;
 
 	if (size == 0) {
 		dev_warn(&chip->dev, "%s: Event log area empty\n", __func__);
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 4dc97b9f65fb..dd9a376a1dbb 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -461,4 +461,40 @@ static inline struct tpm_chip *tpm_default_chip(void)
 	return NULL;
 }
 #endif
+
+#ifdef CONFIG_OF
+static inline int of_tpm_get_sml_parameters(struct device_node *np,
+					    u64 *base, u32 *size)
+{
+	const u32 *sizep;
+	const u64 *basep;
+
+	sizep = of_get_property(np, "linux,sml-size", NULL);
+	basep = of_get_property(np, "linux,sml-base", NULL);
+	if (sizep == NULL && basep == NULL)
+		return -ENODEV;
+	if (sizep == NULL || basep == NULL)
+		return -EIO;
+
+	/*
+	 * For both vtpm/tpm, firmware has log addr and log size in big
+	 * endian format. But in case of vtpm, there is a method called
+	 * sml-handover which is run during kernel init even before
+	 * device tree is setup. This sml-handover function takes care
+	 * of endianness and writes to sml-base and sml-size in little
+	 * endian format. For this reason, vtpm doesn't need conversion
+	 * but physical tpm needs the conversion.
+	 */
+	if (of_property_match_string(np, "compatible", "IBM,vtpm") < 0 &&
+	    of_property_match_string(np, "compatible", "IBM,vtpm20") < 0) {
+		*size = be32_to_cpup((__force __be32 *)sizep);
+		*base = be64_to_cpup((__force __be64 *)basep);
+	} else {
+		*size = *sizep;
+		*base = *basep;
+	}
+	return 0;
+}
+#endif
+
 #endif
-- 
2.38.1