Re: [PATCH 1/3] docs: Add support for TPM devices over I2C bus

[Ninad Palsule <ninad@linux.vnet.ibm.com>]

Hello Cedric,

I tried to use ast2600-evb machine but it is not getting any message on 
I2C bus.

Any suggestions?

# Start the software TPM emulator.
     $ swtpm socket --tpmstate dir=/tmp/mytpm1   --ctrl 
type=unixio,path=/tmp/mytpm1/swtpm-sock   --tpm2   --log level=100

# Start a qemu and point at swtpm. I am using i2c bus 12 and address 0x2e
     $ ~/qemu/build/qemu-system-arm -M ast2600-evb -nographic -kernel 
$IMAGEDIR/zImage -dtb $IMAGEDIR/aspeed-ast2600-evb.dtb -initrd 
$IMAGEDIR/rootfs.cpio -chardev 
socket,id=chrtpm,path=/tmp/mytpm1/swtpm-sock -tpmdev 
emulator,id=tpm0,chardev=chrtpm -device 
tpm-tis-i2c,tpmdev=tpm0,bus=aspeed.i2c.bus.12,address=0x2e

# Inside the ast2600-evb machine. Insantiated the device
     # echo 12 0x2e > /sys/bus/i2c/devices/i2c-12/new_device
     [  158.265321] i2c i2c-12: new_device: Instantiated device 12 at 0x2e

# Tried to instantiate TPM device but nothing happening on I2C bus.
     # echo 12-002e > /sys/bus/i2c/drivers/tpm_tis_i2c/bind
     sh: write error: No such device

Thanks & Regards,

Ninad Palsule

On 3/23/23 2:49 AM, Cédric Le Goater wrote:
> On 3/23/23 04:01, Ninad Palsule wrote:
>> This is a documentation change for I2C TPM device support.
>>
>> Qemu already supports devices attached to ISA and sysbus.
>> This drop adds support for the I2C bus attached TPM devices.
>>
>> Signed-off-by: Ninad Palsule <ninad@linux.ibm.com>
>>
>> ---
>> V2:
>>
>> Incorporated Stephen's review comments
>> - Added example in the document.
>> ---
>>   docs/specs/tpm.rst | 20 +++++++++++++++++++-
>>   1 file changed, 19 insertions(+), 1 deletion(-)
>>
>> diff --git a/docs/specs/tpm.rst b/docs/specs/tpm.rst
>> index 535912a92b..bf7249b09c 100644
>> --- a/docs/specs/tpm.rst
>> +++ b/docs/specs/tpm.rst
>> @@ -21,11 +21,15 @@ QEMU files related to TPM TIS interface:
>>    - ``hw/tpm/tpm_tis_common.c``
>>    - ``hw/tpm/tpm_tis_isa.c``
>>    - ``hw/tpm/tpm_tis_sysbus.c``
>> + - ``hw/tpm/tpm_tis_i2c.c``
>>    - ``hw/tpm/tpm_tis.h``
>>     Both an ISA device and a sysbus device are available. The former is
>>   used with pc/q35 machine while the latter can be instantiated in the
>> -Arm virt machine.
>> +Arm virt machine. An I2C device support is also added which can be
>> +instantiated in the arm based emulation machine. An I2C device is also
>> +supported for the Arm virt machine. This device only supports the
>> +TPM 2 protocol.
>>     CRB interface
>>   -------------
>> @@ -348,6 +352,20 @@ In case an Arm virt machine is emulated, use the 
>> following command line:
>>       -drive if=pflash,format=raw,file=flash0.img,readonly=on \
>>       -drive if=pflash,format=raw,file=flash1.img
>>   +In case a Rainier bmc machine is emulated, use the following 
>> command line:
>> +
>> +.. code-block:: console
>> +
>> +  qemu-system-arm -M rainier-bmc -nographic \
>> +    -kernel ${IMAGEPATH}/fitImage-linux.bin \
>> +    -dtb ${IMAGEPATH}/aspeed-bmc-ibm-rainier.dtb \
>> +    -initrd ${IMAGEPATH}/obmc-phosphor-initramfs.rootfs.cpio.xz \
>> +    -drive 
>> file=${IMAGEPATH}/obmc-phosphor-image.rootfs.wic.qcow2,if=sd,index=2\
>> +    -net nic -net 
>> user,hostfwd=:127.0.0.1:2222-:22,hostfwd=:127.0.0.1:2443-:443\
>> +    -chardev socket,id=chrtpm,path=/tmp/mytpm1/swtpm-sock \
>> +    -tpmdev emulator,id=tpm0,chardev=chrtpm \
>> +    -device tpm-tis-i2c,tpmdev=tpm0,bus=aspeed.i2c.bus.12,address=0x2e
>
>
> The rainier images are not the easiest to find. Could we use an 
> AST2600 EVB
> machine instead and instantiate the device from user space ? see commit
> 3302184f7f or 7a7308eae0.
>
> Thanks,
>
> C.
>
>>   In case SeaBIOS is used as firmware, it should show the TPM menu item
>>   after entering the menu with 'ESC'.
>