Re: [PATCH v2 6/7] tpm: Implement state command for Cr50

[Simon Glass <sjg@chromium.org>]

Hi Ilias,

On Tue, 16 Aug 2022 at 06:43, Ilias Apalodimas
<ilias.apalodimas@linaro.org> wrote:
>
> Hi Simon,
>
> I know little of this device and the whole patch seems fine apart from
> the definitions and declarations of the state functions.
>
>
> On Sat, 13 Aug 2022 at 22:56, Simon Glass <sjg@chromium.org> wrote:
> >
>
> >
> >  drivers/tpm/cr50_i2c.c | 117 +++++++++++++++++++++++++++++++++++++++++
> >  include/tpm-v2.h       |  54 +++++++++++++++++++
> >  lib/tpm-v2.c           |  24 +++++++++
>
> [...]
>
> > diff --git a/include/tpm-v2.h b/include/tpm-v2.h
> > index e79c90b9395..8e90a616220 100644
> > --- a/include/tpm-v2.h
> > +++ b/include/tpm-v2.h
> > @@ -419,6 +419,50 @@ enum {
> >         HR_NV_INDEX             = TPM_HT_NV_INDEX << HR_SHIFT,
> >  };
> >
> > +/*
> > + * Operations specific to the Cr50 TPM used on Chromium OS and Android devices
> > + *
> > + * FIXME: below is not enough to differentiate between vendors commands
> > + * of numerous devices. However, the current tpm2 APIs aren't very amenable
> > + * to extending generically because the marshaling code is assuming all
> > + * knowledge of all commands.
> > + */
> > +#define TPM2_CC_VENDOR_BIT_MASK                        0x20000000
> > +
> > +#define TPM2_CR50_VENDOR_COMMAND               (TPM2_CC_VENDOR_BIT_MASK | 0)
> > +#define TPM2_CR50_SUB_CMD_IMMEDIATE_RESET      19
> > +#define TPM2_CR50_SUB_CMD_NVMEM_ENABLE_COMMITS 21
> > +#define TPM2_CR50_SUB_CMD_REPORT_TPM_STATE     23
> > +#define TPM2_CR50_SUB_CMD_TURN_UPDATE_ON       24
> > +#define TPM2_CR50_SUB_CMD_GET_REC_BTN          29
> > +#define TPM2_CR50_SUB_CMD_TPM_MODE             40
> > +#define TPM2_CR50_SUB_CMD_GET_BOOT_MODE                52
> > +#define TPM2_CR50_SUB_CMD_RESET_EC             53
> > +
> > +/* Cr50 vendor-specific error codes. */
> > +#define VENDOR_RC_ERR              0x00000500
> > +enum cr50_vendor_rc {
> > +       VENDOR_RC_INTERNAL_ERROR        = (VENDOR_RC_ERR | 6),
> > +       VENDOR_RC_NO_SUCH_SUBCOMMAND    = (VENDOR_RC_ERR | 8),
> > +       VENDOR_RC_NO_SUCH_COMMAND       = (VENDOR_RC_ERR | 127),
> > +};
> > +
> > +enum cr50_tpm_mode {
> > +       /*
> > +        * Default state: TPM is enabled, and may be set to either
> > +        * TPM_MODE_ENABLED or TPM_MODE_DISABLED.
> > +        */
> > +       TPM_MODE_ENABLED_TENTATIVE = 0,
> > +
> > +       /* TPM is enabled, and mode may not be changed. */
> > +       TPM_MODE_ENABLED = 1,
> > +
> > +       /* TPM is disabled, and mode may not be changed. */
> > +       TPM_MODE_DISABLED = 2,
> > +
> > +       TPM_MODE_INVALID,
> > +};
> > +
> >  /**
> >   * Issue a TPM2_Startup command.
> >   *
> > @@ -658,4 +702,14 @@ u32 tpm2_disable_platform_hierarchy(struct udevice *dev);
> >  u32 tpm2_submit_command(struct udevice *dev, const u8 *sendbuf,
> >                         u8 *recvbuf, size_t *recv_size);
> >
> > +/**
> > + * tpm_cr50_report_state() - Report the Cr50 internal state
> > + *
> > + * @dev:       TPM device
> > + * @recvbuf:   Buffer to save the response to
> > + * @recv_size: Pointer to the size of the response buffer
> > + * Return: result of the operation
> > + */
> > +u32 tpm2_cr50_report_state(struct udevice *dev, u8 *recvbuf, size_t *recv_size);
> > +
>
> I think we should keep the generic include files clean for hardware
> specific details.
>
> >  #endif /* __TPM_V2_H */
> > diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> > index 3e240bb4c67..3de4841974a 100644
> > --- a/lib/tpm-v2.c
> > +++ b/lib/tpm-v2.c
> > @@ -679,3 +679,27 @@ u32 tpm2_submit_command(struct udevice *dev, const u8 *sendbuf,
> >  {
> >         return tpm_sendrecv_command(dev, sendbuf, recvbuf, recv_size);
> >  }
> > +
> > +u32 tpm2_cr50_report_state(struct udevice *dev, u8 *recvbuf, size_t *recv_size)
> > +{
> > +       u8 command_v2[COMMAND_BUFFER_SIZE] = {
> > +               /* header 10 bytes */
> > +               tpm_u16(TPM2_ST_NO_SESSIONS),           /* TAG */
> > +               tpm_u32(10 + 2),                        /* Length */
> > +               tpm_u32(TPM2_CR50_VENDOR_COMMAND),      /* Command code */
> > +
> > +               tpm_u16(TPM2_CR50_SUB_CMD_REPORT_TPM_STATE),
> > +       };
> > +       int ret;
> > +
> > +       ret = tpm_sendrecv_command(dev, command_v2, recvbuf, recv_size);
> > +       log_debug("ret=%s, %x\n", dev->name, ret);
> > +       if (ret)
> > +               return ret;
> > +       if (*recv_size < 12)
> > +               return -ENODATA;
> > +       *recv_size -= 12;
> > +       memcpy(recvbuf, recvbuf + 12, *recv_size);
> > +
> > +       return 0;
> > +}
>
> Same here, this functions seems ok but shouldn't land in the generic TPM API

So shall I create a new tpm_cr50.h header file? What about the C file?

>
> Thanks
> /Ilias
> > --
> > 2.37.1.595.g718a3a8f04-goog
> >

Regards,
Simon