linux-kernel - Re: [tpmdd-devel] [PATCH v2] tpm: do not suspend/resume if power stays on

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Date:   Fri, 3 Mar 2017 16:46:21 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     Rob Herring <robh+dt@...nel.org>, Peter Huewe <peterhuewe@....de>,
        Mark Rutland <mark.rutland@....com>,
        tpmdd-devel@...ts.sourceforge.net,
        Sonny Rao <sonnyrao@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [tpmdd-devel] [PATCH v2] tpm: do not suspend/resume if power
 stays on

Hi Jarkko,

Thanks for the review

On 03/03/17 16:12, Jarkko Sakkinen wrote:
> On Thu, Mar 02, 2017 at 04:42:57PM +0100, Enric Balletbo i Serra wrote:
>> From: Sonny Rao <sonnyrao@...omium.org>
>>
>> The suspend/resume behavior of the TPM can be controlled by setting
>> "powered-while-suspended" in the DTS. This is useful for the cases
>> when hardware does not power-off the TPM.
>>
>> Signed-off-by: Sonny Rao <sonnyrao@...omium.org>
>> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
>> ---
>>
>> Changes since v1:
>>  Jason Gunthorpe :
>>   - Move the code to handle suspend/resume in the common chip code.
>>
>>  Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt | 6 ++++++
>>  drivers/char/tpm/tpm-interface.c                           | 3 +++
>>  drivers/char/tpm/tpm.h                                     | 3 +++
>>  drivers/char/tpm/tpm_of.c                                  | 3 +++
>>  4 files changed, 15 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt b/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt
>> index 8cb638b..85c8216 100644
>> --- a/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt
>> +++ b/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt
>> @@ -8,6 +8,12 @@ Required properties:
>>                     the firmware event log
>>  - linux,sml-size : size of the memory allocated for the firmware event log
>>  
>> +Optional properties:
>> +
>> +- powered-while-suspended: present when the TPM is left powered on between
>> +                           suspend and resume (makes the suspend/resume
>> +                           callbacks do nothing).
>> +
>>  Example (for OpenPower Systems with Nuvoton TPM 2.0 on I2C)
>>  ----------------------------------------------------------
>>  
>> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
>> index a2688ac..7f60780 100644
>> --- a/drivers/char/tpm/tpm-interface.c
>> +++ b/drivers/char/tpm/tpm-interface.c
>> @@ -944,6 +944,9 @@ int tpm_pm_suspend(struct device *dev)
>>  	if (chip == NULL)
>>  		return -ENODEV;
>>  
>> +	if (chip->powered_while_suspended)
>> +		return 0;
> 
> Why there can't just be TPM_CHIP_FLAG_ALWAYS_POWERED or something similar?
> 

Right this seems a better way for tpm subsystem. I'll send a v3 today.

>> +
>>  	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
>>  		tpm2_shutdown(chip, TPM2_SU_STATE);
>>  		return 0;
>> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
>> index 1ae9768..c8f796c 100644
>> --- a/drivers/char/tpm/tpm.h
>> +++ b/drivers/char/tpm/tpm.h
>> @@ -183,10 +183,13 @@ struct tpm_chip {
>>  	unsigned long duration[3]; /* jiffies */
>>  	bool duration_adjusted;
>>  
>> +	bool powered_while_suspended;
>> +
>>  	struct dentry *bios_dir[TPM_NUM_EVENT_LOG_FILES];
>>  
>>  	const struct attribute_group *groups[3];
>>  	unsigned int groups_cnt;
>> +
> 
> trailing newline
> 
>>  #ifdef CONFIG_ACPI
>>  	acpi_handle acpi_dev_handle;
>>  	char ppi_version[TPM_PPI_VERSION_LEN + 1];
>> diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
>> index 7dee42d7..33eddd4 100644
>> --- a/drivers/char/tpm/tpm_of.c
>> +++ b/drivers/char/tpm/tpm_of.c
>> @@ -34,6 +34,9 @@ int tpm_read_log_of(struct tpm_chip *chip)
>>  	else
>>  		return -ENODEV;
>>  
>> +	chip->powered_while_suspended = of_property_read_bool(np,
>> +						"powered-while-suspended");
>> +
>>  	sizep = of_get_property(np, "linux,sml-size", NULL);
>>  	basep = of_get_property(np, "linux,sml-base", NULL);
>>  	if (sizep == NULL && basep == NULL)
>> -- 
>> 2.9.3
>>
>>
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