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

[Ilias Apalodimas]

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 at 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

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