[PATCH v3 1/3] tpm: of: Make of-tree specific function commonly available

[Stefan Berger]

Simplify tpm_read_log_of() by moving reusable parts of the code into
its own file to make the code 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.

Compile the new file when CONFIG_OF is enabled so that
of_tpm_get_sml_parameters() can be called from kexec even if the TPM
subsystem is not enabled.

Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Frank Rowand <frowand.list@xxxxxxxxx>
---
 drivers/char/Makefile              |  1 +
 drivers/char/tpm/Makefile          |  1 +
 drivers/char/tpm/eventlog/of.c     | 31 +++++-------------------------
 drivers/char/tpm/eventlog/tpm_of.c | 27 ++++++++++++++++++++++++++
 include/linux/tpm.h                |  5 +++++
 5 files changed, 39 insertions(+), 26 deletions(-)
 create mode 100644 drivers/char/tpm/eventlog/tpm_of.c

diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 264eb398fdd4..af9edafb944e 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_PCMCIA)		+= pcmcia/
 
 obj-$(CONFIG_HANGCHECK_TIMER)	+= hangcheck-timer.o
 obj-$(CONFIG_TCG_TPM)		+= tpm/
+obj-$(CONFIG_OF)		+= tpm/
 
 obj-$(CONFIG_PS3_FLASH)		+= ps3flash.o
 
diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index 66d39ea6bd10..3c0eaac81f5c 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -19,6 +19,7 @@ tpm-y += eventlog/tpm2.o
 tpm-$(CONFIG_ACPI) += tpm_ppi.o eventlog/acpi.o
 tpm-$(CONFIG_EFI) += eventlog/efi.o
 tpm-$(CONFIG_OF) += eventlog/of.o
+obj-$(CONFIG_OF) += eventlog/tpm_of.o
 obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
 obj-$(CONFIG_TCG_TIS) += tpm_tis.o
 obj-$(CONFIG_TCG_TIS_SYNQUACER) += tpm_tis_synquacer.o
diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
index a9ce66d09a75..f9462d19632e 100644
--- a/drivers/char/tpm/eventlog/of.c
+++ b/drivers/char/tpm/eventlog/of.c
@@ -12,6 +12,7 @@
 
 #include <linux/slab.h>
 #include <linux/of.h>
+#include <linux/tpm.h>
 #include <linux/tpm_eventlog.h>
 
 #include "../tpm.h"
@@ -20,11 +21,10 @@
 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)
@@ -35,30 +35,9 @@ 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)
-		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;
-	}
+	ret = of_tpm_get_sml_parameters(np, &base, &size);
+	if (ret < 0)
+		return ret;
 
 	if (size == 0) {
 		dev_warn(&chip->dev, "%s: Event log area empty\n", __func__);
diff --git a/drivers/char/tpm/eventlog/tpm_of.c b/drivers/char/tpm/eventlog/tpm_of.c
new file mode 100644
index 000000000000..2e6cfcc87035
--- /dev/null
+++ b/drivers/char/tpm/eventlog/tpm_of.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/export.h>
+#include <linux/tpm.h>
+
+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;
+
+	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;
+}
+EXPORT_SYMBOL_GPL(of_tpm_get_sml_parameters);
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index dfeb25a0362d..429bf045db80 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -460,4 +460,9 @@ static inline struct tpm_chip *tpm_default_chip(void)
 	return NULL;
 }
 #endif
+
+#ifdef CONFIG_OF
+int of_tpm_get_sml_parameters(struct device_node *np, u64 *base, u32 *size);
+#endif
+
 #endif
-- 
2.35.1