Re: [PATCH v2 1/3] tpm: of: Move of-tree specific code from tpm driver into of driver

Stefan Berger <stefanb@xxxxxxxxxxxxx> · Tue, 28 Jun 2022 09:29:48 -0400

On 6/27/22 18:43, Rob Herring wrote:
On Thu, Jun 16, 2022 at 11:41:28AM -0400, Stefan Berger wrote:
Simplify tpm_read_log_of() by moving Openfirmware-specific code into
the Openfirmware driver to make the code reusable. Call the new

There is no such 'Openfirmware driver'.

of_tpm_get_sml_parameters() function from the TPM Openfirmware driver.

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/tpm/eventlog/of.c | 31 +++++--------------------------
  drivers/of/Makefile            |  2 +-
  drivers/of/device_node.c       | 27 +++++++++++++++++++++++++++

Humm, definitely the wrong direction. Generally, code for specific
bindings does not go in drivers/of/. There used to be some, but we've
moved it to the appropriate subsystems. kexec was an exception to not
have 2 copies of the same code in arch/.

The function I am moving here is called by the TPM subsystem and also 
now by of/kexec.c. The latter is compiled under the following conditions:

ifdef CONFIG_KEXEC_FILE
ifdef CONFIG_OF_FLATTREE
obj-y	+= kexec.o
endif
endif

The code that current calls it is compiled under the following conditions:

tpm-$(CONFIG_OF) += eventlog/of.o

To make it available to both I could keep it in the TPM subsystem like this:

obj-$(CONFIG_OF) = tpm_of.o


Jarrko, if you read this, any comment?


   Stefan



  include/linux/of_device_node.h |  9 +++++++++

of_tpm.h would be the right name assuming we kept this structure which
we shouldn't. Probably linux/tpm.h? Just a guess, I'm not familar with
the TPM code really.


  4 files changed, 42 insertions(+), 27 deletions(-)
  create mode 100644 drivers/of/device_node.c
  create mode 100644 include/linux/of_device_node.h

diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c
index a9ce66d09a75..5b18f4333ad1 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/of_device_node.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/of/Makefile b/drivers/of/Makefile
index e0360a44306e..1c9feac450ad 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -1,5 +1,5 @@
  # SPDX-License-Identifier: GPL-2.0
-obj-y = base.o device.o platform.o property.o
+obj-y = base.o device.o platform.o property.o device_node.o
  obj-$(CONFIG_OF_KOBJ) += kobj.o
  obj-$(CONFIG_OF_DYNAMIC) += dynamic.o
  obj-$(CONFIG_OF_FLATTREE) += fdt.o
diff --git a/drivers/of/device_node.c b/drivers/of/device_node.c
new file mode 100644
index 000000000000..71a19bc1bac2
--- /dev/null
+++ b/drivers/of/device_node.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/export.h>
+#include <linux/of_device_node.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/of_device_node.h b/include/linux/of_device_node.h
new file mode 100644
index 000000000000..ae3faf023aab
--- /dev/null
+++ b/include/linux/of_device_node.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_OF_DEVICE_NODE_H
+#define _LINUX_OF_DEVICE_NODE_H
+
+#include <linux/of.h>
+
+int of_tpm_get_sml_parameters(struct device_node *np, u64 *base, u32 *size);
+
+#endif /* _LINUX_OF_DEVICE_NODE_H */
--
2.35.1








