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

[Stefan Berger <stefanb@linux.ibm.com>]

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@linux.ibm.com>
>> Cc: Jarkko Sakkinen <jarkko@kernel.org>
>> Cc: Jason Gunthorpe <jgg@ziepe.ca>
>> Cc: Rob Herring <robh+dt@kernel.org>
>> Cc: Frank Rowand <frowand.list@gmail.com>
>> ---
>>   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
>>
>>