Re: [PATCH v7 1/3] docs: Add support for TPM devices over I2C bus

[Joel Stanley <joel@jms.id.au>]

On Sun, 26 Mar 2023 at 22:44, Ninad Palsule <ninad@linux.ibm.com> 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.
>
> ---
> V4:
> Incorporate Cedric & Stefan's comments
>
> - Added example for ast2600-evb
> - Corrected statement about arm virtual machine.
>
> ---
> V6:
> Incorporated review comments from Stefan.
> ---
>  docs/specs/tpm.rst | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
>
> diff --git a/docs/specs/tpm.rst b/docs/specs/tpm.rst
> index 535912a92b..590e670a9a 100644
> --- a/docs/specs/tpm.rst
> +++ b/docs/specs/tpm.rst
> @@ -21,12 +21,16 @@ 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.
>
> +An I2C device support is also provided which can be instantiated in the Arm
> +based emulation machines. This device only supports the TPM 2 protocol.
> +
>  CRB interface
>  -------------
>
> @@ -348,6 +352,34 @@ 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 ast2600-evb bmc machine is emulated and want to use TPM device
> +attached to I2C bus, use the following command line:
> +
> +.. code-block:: console
> +
> +  qemu-system-arm -M ast2600-evb -nographic \
> +    -kernel arch/arm/boot/zImage \
> +    -dtb arch/arm/boot/dts/aspeed-ast2600-evb.dtb \
> +    -initrd 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

For testing, use this command to load the driver to the correct address:

echo tpm_tis_i2c 0x2e > /sys/bus/i2c/devices/i2c-12/new_device

(I don't know how specific we want to make the instructions, but
adding a line like above would help others from having to re-discover
the command).

> +
> +In case a Rainier bmc machine is emulated and want to use TPM device
> +attached to I2C bus, 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
> +

I'd drop this example, the above one is enough.

>  In case SeaBIOS is used as firmware, it should show the TPM menu item
>  after entering the menu with 'ESC'.
>
> --
> 2.37.2
>