tpm/tpm_crb: Use start method value from ACPI table directly

This patch gets rid of dealing with intermediate flag for start method
and use start method value from ACPI table directly.

For ARM64, the locality is handled by Trust Zone in FW. The layout
does not have crb_regs_head. It is hitting the following line.
dev_warn(dev, FW_BUG "Bad ACPI memory layout");

Current code excludes CRB_FL_ACPI_START for this check. Now since
ARM64 support for TPM CRB is added, CRB_FL_CRB_SMC_START should also be
excluded from this check.

For goIdle and cmdReady where code was excluding CRB_FL_ACPI_START only
(do nothing for ACPI start method), CRB_FL_CRB_SMC_START was also
excluded as ARM64 SMC start method does not have TPM_CRB_CTRL_REQ.

However with special PPT workaround requiring CRB_FL_CRB_START to be
set in addition to CRB_FL_ACPI_START and the addition flag of SMC
start method CRB_FL_CRB_SMC_START, the code has become difficult to
maintain and undrestand. It is better to make code deal with start
method value from ACPI table directly.

Signed-off-by: Jiandi An <[e-mail]>
Reviewed-by: Jarkko Sakkinen <[e-mail]>
Tested-by: Jarkko Sakkinen <[e-mail]>
Signed-off-by: Jarkko Sakkinen <[e-mail]>

drivers/char/tpm/tpm_crb.c

···
 	CRB_DRV_STS_COMPLETE	= BIT(0),
 };
 
-enum crb_flags {
-	CRB_FL_ACPI_START	= BIT(0),
-	CRB_FL_CRB_START	= BIT(1),
-	CRB_FL_CRB_SMC_START	= BIT(2),
-};
-
 struct crb_priv {
-	unsigned int flags;
+	u32 sm;
+	const char *hid;
 	void __iomem *iobase;
 	struct crb_regs_head __iomem *regs_h;
 	struct crb_regs_tail __iomem *regs_t;
···
  * Anyhow, we do not wait here as a consequent CMD_READY request
  * will be handled correctly even if idle was not completed.
  *
- * The function does nothing for devices with ACPI-start method.
+ * The function does nothing for devices with ACPI-start method
+ * or SMC-start method.
  *
  * Return: 0 always
  */
 static int __maybe_unused crb_go_idle(struct device *dev, struct crb_priv *priv)
 {
-	if ((priv->flags & CRB_FL_ACPI_START) ||
-	    (priv->flags & CRB_FL_CRB_SMC_START))
+	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC))
 		return 0;
 
 	iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->regs_t->ctrl_req);
···
  * The device should respond within TIMEOUT_C.
  *
  * The function does nothing for devices with ACPI-start method
+ * or SMC-start method.
  *
  * Return: 0 on success -ETIME on timeout;
  */
 static int __maybe_unused crb_cmd_ready(struct device *dev,
 					struct crb_priv *priv)
 {
-	if ((priv->flags & CRB_FL_ACPI_START) ||
-	    (priv->flags & CRB_FL_CRB_SMC_START))
+	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC))
 		return 0;
 
 	iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->regs_t->ctrl_req);
···
 	/* Make sure that cmd is populated before issuing start. */
 	wmb();
 
-	if (priv->flags & CRB_FL_CRB_START)
+	/* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
+	 * report only ACPI start but in practice seems to require both
+	 * CRB start, hence invoking CRB start method if hid == MSFT0101.
+	 */
+	if ((priv->sm == ACPI_TPM2_COMMAND_BUFFER) ||
+	    (priv->sm == ACPI_TPM2_MEMORY_MAPPED) ||
+	    (!strcmp(priv->hid, "MSFT0101")))
 		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
 
-	if (priv->flags & CRB_FL_ACPI_START)
+	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD))
 		rc = crb_do_acpi_start(chip);
 
-	if (priv->flags & CRB_FL_CRB_SMC_START) {
+	if (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC) {
 		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
 		rc = tpm_crb_smc_start(&chip->dev, priv->smc_func_id);
 	}
···
 
 	iowrite32(CRB_CANCEL_INVOKE, &priv->regs_t->ctrl_cancel);
 
-	if ((priv->flags & CRB_FL_ACPI_START) && crb_do_acpi_start(chip))
+	if (((priv->sm == ACPI_TPM2_START_METHOD) ||
+	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)) &&
+	     crb_do_acpi_start(chip))
 		dev_err(&chip->dev, "ACPI Start failed\n");
 }
 
···
 	 * the control area, as one nice sane region except for some older
 	 * stuff that puts the control area outside the ACPI IO region.
 	 */
-	if (!(priv->flags & CRB_FL_ACPI_START)) {
+	if ((priv->sm == ACPI_TPM2_COMMAND_BUFFER) ||
+	    (priv->sm == ACPI_TPM2_MEMORY_MAPPED)) {
 		if (buf->control_address == io_res.start +
 		    sizeof(*priv->regs_h))
 			priv->regs_h = priv->iobase;
···
 	if (!priv)
 		return -ENOMEM;
 
-	/* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
-	 * report only ACPI start but in practice seems to require both
-	 * ACPI start and CRB start.
-	 */
-	if (sm == ACPI_TPM2_COMMAND_BUFFER || sm == ACPI_TPM2_MEMORY_MAPPED ||
-	    !strcmp(acpi_device_hid(device), "MSFT0101"))
-		priv->flags |= CRB_FL_CRB_START;
-
-	if (sm == ACPI_TPM2_START_METHOD ||
-	    sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
-		priv->flags |= CRB_FL_ACPI_START;
-
 	if (sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC) {
 		if (buf->header.length < (sizeof(*buf) + sizeof(*crb_smc))) {
 			dev_err(dev,
···
 		}
 		crb_smc = ACPI_ADD_PTR(struct tpm2_crb_smc, buf, sizeof(*buf));
 		priv->smc_func_id = crb_smc->smc_func_id;
-		priv->flags |= CRB_FL_CRB_SMC_START;
 	}
+
+	priv->sm = sm;
+	priv->hid = acpi_device_hid(device);
 
 	rc = crb_map_io(device, priv, buf);
 	if (rc)