Re: [PATCH v4 4/5] tpm_crb: add support for the Arm FF-A start method

[Jarkko Sakkinen]

On Mon, 2025-02-17 at 16:49 -0600, Stuart Yoder wrote:
> The TCG ACPI spec v1.4 defines a start method for the
> TPMs implemented with the Arm CRB over FF-A ABI.
> 
> Add support for the FF-A start method, and use interfaces
> provided by the ffa_crb driver to interact with the
> FF-A based TPM.
> 
> Signed-off-by: Stuart Yoder <stuart.yoder@xxxxxxx>
> ---
>  drivers/char/tpm/tpm_crb.c | 71 +++++++++++++++++++++++++++++++++++-
> --
>  1 file changed, 66 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index 31db879f1324..2a57650ba9b4 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -19,6 +19,7 @@
>  #ifdef CONFIG_ARM64
>  #include <linux/arm-smccc.h>
>  #endif
> +#include "tpm_crb_ffa.h"
>  #include "tpm.h"
>  
>  #define ACPI_SIG_TPM2 "TPM2"
> @@ -100,6 +101,8 @@ struct crb_priv {
>  	u32 smc_func_id;
>  	u32 __iomem *pluton_start_addr;
>  	u32 __iomem *pluton_reply_addr;
> +	u8 ffa_flags;
> +	u8 ffa_attributes;
>  };
>  
>  struct tpm2_crb_smc {
> @@ -110,6 +113,14 @@ struct tpm2_crb_smc {
>  	u32 smc_func_id;
>  };
>  
> +/* CRB over FFA start method parameters in TCG2 ACPI table */
> +struct tpm2_crb_ffa {
> +	u8 flags;
> +	u8 attributes;
> +	u16 partition_id;
> +	u8 reserved[8];
> +};
> +
>  struct tpm2_crb_pluton {
>  	u64 start_addr;
>  	u64 reply_addr;
> @@ -122,7 +133,8 @@ static inline bool tpm_crb_has_idle(u32
> start_method)
>  {
>  	return start_method == ACPI_TPM2_START_METHOD ||
>  	       start_method ==
> ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD ||
> -	       start_method ==
> ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC;
> +	       start_method == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC
> ||
> +	       start_method == ACPI_TPM2_CRB_WITH_ARM_FFA;
>  }
>  
>  static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32
> value,
> @@ -261,13 +273,20 @@ static int crb_cmd_ready(struct tpm_chip *chip)
>  static int __crb_request_locality(struct device *dev,
>  				  struct crb_priv *priv, int loc)
>  {
> -	u32 value = CRB_LOC_STATE_LOC_ASSIGNED |
> -		    CRB_LOC_STATE_TPM_REG_VALID_STS;
> +	u32 value = CRB_LOC_STATE_LOC_ASSIGNED |
> CRB_LOC_STATE_TPM_REG_VALID_STS;
> +	int rc;
>  
>  	if (!priv->regs_h)
>  		return 0;
>  
>  	iowrite32(CRB_LOC_CTRL_REQUEST_ACCESS, &priv->regs_h-
> >loc_ctrl);
> +
> +	if (priv->sm == ACPI_TPM2_CRB_WITH_ARM_FFA) {
> +		rc =
> tpm_crb_ffa_start(CRB_FFA_START_TYPE_LOCALITY_REQUEST, loc);
> +		if (rc)
> +			return rc;
> +	}
> +
>  	if (!crb_wait_for_reg_32(&priv->regs_h->loc_state, value,
> value,
>  				 TPM2_TIMEOUT_C)) {
>  		dev_warn(dev, "TPM_LOC_STATE_x.requestAccess timed
> out\n");
> @@ -287,14 +306,21 @@ static int crb_request_locality(struct tpm_chip
> *chip, int loc)
>  static int __crb_relinquish_locality(struct device *dev,
>  				     struct crb_priv *priv, int loc)
>  {
> -	u32 mask = CRB_LOC_STATE_LOC_ASSIGNED |
> -		   CRB_LOC_STATE_TPM_REG_VALID_STS;
> +	u32 mask = CRB_LOC_STATE_LOC_ASSIGNED |
> CRB_LOC_STATE_TPM_REG_VALID_STS;
>  	u32 value = CRB_LOC_STATE_TPM_REG_VALID_STS;
> +	int rc;
>  
>  	if (!priv->regs_h)
>  		return 0;
>  
>  	iowrite32(CRB_LOC_CTRL_RELINQUISH, &priv->regs_h->loc_ctrl);
> +
> +	if (priv->sm == ACPI_TPM2_CRB_WITH_ARM_FFA) {
> +		rc =
> tpm_crb_ffa_start(CRB_FFA_START_TYPE_LOCALITY_REQUEST, loc);
> +		if (rc)
> +			return rc;
> +	}
> +
>  	if (!crb_wait_for_reg_32(&priv->regs_h->loc_state, mask,
> value,
>  				 TPM2_TIMEOUT_C)) {
>  		dev_warn(dev, "TPM_LOC_STATE_x.Relinquish timed
> out\n");
> @@ -443,6 +469,11 @@ static int crb_send(struct tpm_chip *chip, u8
> *buf, size_t len)
>  		rc = tpm_crb_smc_start(&chip->dev, priv-
> >smc_func_id);
>  	}
>  
> +	if (priv->sm == ACPI_TPM2_CRB_WITH_ARM_FFA) {
> +		iowrite32(CRB_START_INVOKE, &priv->regs_t-
> >ctrl_start);
> +		rc = tpm_crb_ffa_start(CRB_FFA_START_TYPE_COMMAND,
> chip->locality);
> +	}
> +
>  	if (rc)
>  		return rc;
>  
> @@ -452,6 +483,7 @@ static int crb_send(struct tpm_chip *chip, u8
> *buf, size_t len)
>  static void crb_cancel(struct tpm_chip *chip)
>  {
>  	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
> +	int rc;
>  
>  	iowrite32(CRB_CANCEL_INVOKE, &priv->regs_t->ctrl_cancel);
>  
> @@ -459,6 +491,12 @@ static void crb_cancel(struct tpm_chip *chip)
>  	     priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
> &&
>  	     crb_do_acpi_start(chip))
>  		dev_err(&chip->dev, "ACPI Start failed\n");
> +
> +	if (priv->sm == ACPI_TPM2_CRB_WITH_ARM_FFA) {
> +		rc = tpm_crb_ffa_start(CRB_FFA_START_TYPE_COMMAND,
> chip->locality);
> +		if (rc)
> +			dev_err(&chip->dev, "FF-A Start failed\n");
> +	}
>  }
>  
>  static bool crb_req_canceled(struct tpm_chip *chip, u8 status)
> @@ -616,6 +654,7 @@ static int crb_map_io(struct acpi_device *device,
> struct crb_priv *priv,
>  	 * stuff that puts the control area outside the ACPI IO
> region.
>  	 */
>  	if (priv->sm == ACPI_TPM2_COMMAND_BUFFER ||
> +	    priv->sm == ACPI_TPM2_CRB_WITH_ARM_FFA ||
>  	    priv->sm == ACPI_TPM2_MEMORY_MAPPED) {
>  		if (iores &&
>  		    buf->control_address == iores->start +
> @@ -737,6 +776,7 @@ static int crb_acpi_add(struct acpi_device
> *device)
>  	struct tpm_chip *chip;
>  	struct device *dev = &device->dev;
>  	struct tpm2_crb_smc *crb_smc;
> +	struct tpm2_crb_ffa *crb_ffa;
>  	struct tpm2_crb_pluton *crb_pluton;
>  	acpi_status status;
>  	u32 sm;
> @@ -775,6 +815,27 @@ static int crb_acpi_add(struct acpi_device
> *device)
>  		priv->smc_func_id = crb_smc->smc_func_id;
>  	}
>  
> +	if (sm == ACPI_TPM2_CRB_WITH_ARM_FFA) {
> +		if (buf->header.length < (sizeof(*buf) +
> sizeof(*crb_ffa))) {
> +			dev_err(dev,
> +				FW_BUG "TPM2 ACPI table has wrong
> size %u for start method type %d\n",
> +				buf->header.length,
> +				ACPI_TPM2_CRB_WITH_ARM_FFA);
> +			rc = -EINVAL;
> +			goto out;
> +		}
> +		crb_ffa = ACPI_ADD_PTR(struct tpm2_crb_ffa, buf,
> sizeof(*buf));
> +		priv->ffa_flags = crb_ffa->flags;
> +		priv->ffa_attributes = crb_ffa->attributes;
> +		rc = tpm_crb_ffa_init();
> +		if (rc) {
> +			if (rc == -ENOENT) {  // FF-A driver is not
> available yet
> +				rc = -EPROBE_DEFER;
> +			}
> +			goto out;
> +		}
> +	}
> +
>  	if (sm == ACPI_TPM2_COMMAND_BUFFER_WITH_PLUTON) {
>  		if (buf->header.length < (sizeof(*buf) +
> sizeof(*crb_pluton))) {
>  			dev_err(dev,

Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>

BR, Jarkko