tpm/tpm_crb: Enable TPM CRB interface for ARM64

This enables TPM Command Response Buffer interface driver for
ARM64 and implements an ARM specific TPM CRB start method that
invokes a Secure Monitor Call (SMC) to request the TrustZone
Firmware to execute or cancel a TPM 2.0 command.

In ARM, TrustZone security extensions enable a secure software
environment with Secure Monitor mode. A Secure Monitor Call
(SMC) is used to enter the Secure Monitor mode and perform a
Secure Monitor service to communicate with TrustZone firmware
which has control over the TPM hardware.

Signed-off-by: Jiandi An <[e-mail]>
Tested-by: Shanker Donthineni <[e-mail]>
Reviewed-by: Jarkko Sakkinen <[e-mail]>
Tested-by: Jarkko Sakkinen <[e-mail]> (on x86/PTT)
Signed-off-by: Jarkko Sakkinen <[e-mail]>

drivers/char/tpm/Kconfig

···
 
 config TCG_CRB
 	tristate "TPM 2.0 CRB Interface"
-	depends on X86 && ACPI
+	depends on ACPI
 	---help---
 	  If you have a TPM security chip that is compliant with the
 	  TCG CRB 2.0 TPM specification say Yes and it will be accessible

drivers/char/tpm/tpm_crb.c

···
 #include <linux/rculist.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
+#ifdef CONFIG_ARM64
+#include <linux/arm-smccc.h>
+#endif
 #include "tpm.h"
 
 #define ACPI_SIG_TPM2 "TPM2"
···
 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 {
···
 	u8 __iomem *cmd;
 	u8 __iomem *rsp;
 	u32 cmd_size;
+	u32 smc_func_id;
+};
+
+struct tpm2_crb_smc {
+	u32 interrupt;
+	u8 interrupt_flags;
+	u8 op_flags;
+	u16 reserved2;
+	u32 smc_func_id;
 };
 
 /**
···
  */
 static int __maybe_unused crb_go_idle(struct device *dev, struct crb_priv *priv)
 {
-	if (priv->flags & CRB_FL_ACPI_START)
+	if ((priv->flags & CRB_FL_ACPI_START) ||
+	    (priv->flags & CRB_FL_CRB_SMC_START))
 		return 0;
 
 	iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->regs_t->ctrl_req);
···
 static int __maybe_unused crb_cmd_ready(struct device *dev,
 					struct crb_priv *priv)
 {
-	if (priv->flags & CRB_FL_ACPI_START)
+	if ((priv->flags & CRB_FL_ACPI_START) ||
+	    (priv->flags & CRB_FL_CRB_SMC_START))
 		return 0;
 
 	iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->regs_t->ctrl_req);
···
 	return rc;
 }
 
+#ifdef CONFIG_ARM64
+/*
+ * This is a TPM Command Response Buffer start method that invokes a
+ * Secure Monitor Call to requrest the firmware to execute or cancel
+ * a TPM 2.0 command.
+ */
+static int tpm_crb_smc_start(struct device *dev, unsigned long func_id)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_smc(func_id, 0, 0, 0, 0, 0, 0, 0, &res);
+	if (res.a0 != 0) {
+		dev_err(dev,
+			FW_BUG "tpm_crb_smc_start() returns res.a0 = 0x%lx\n",
+			res.a0);
+		return -EIO;
+	}
+
+	return 0;
+}
+#else
+static int tpm_crb_smc_start(struct device *dev, unsigned long func_id)
+{
+	dev_err(dev, FW_BUG "tpm_crb: incorrect start method\n");
+	return -EINVAL;
+}
+#endif
+
 static int crb_send(struct tpm_chip *chip, u8 *buf, size_t len)
 {
 	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
···
 
 	if (priv->flags & CRB_FL_ACPI_START)
 		rc = crb_do_acpi_start(chip);
+
+	if (priv->flags & CRB_FL_CRB_SMC_START) {
+		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
+		rc = tpm_crb_smc_start(&chip->dev, priv->smc_func_id);
+	}
 
 	return rc;
 }
···
 	struct crb_priv *priv;
 	struct tpm_chip *chip;
 	struct device *dev = &device->dev;
+	struct tpm2_crb_smc *crb_smc;
 	acpi_status status;
 	u32 sm;
 	int rc;
···
 	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_SMC) {
+		if (buf->header.length < (sizeof(*buf) + sizeof(*crb_smc))) {
+			dev_err(dev,
+				FW_BUG "TPM2 ACPI table has wrong size %u for start method type %d\n",
+				buf->header.length,
+				ACPI_TPM2_COMMAND_BUFFER_WITH_SMC);
+			return -EINVAL;
+		}
+		crb_smc = ACPI_ADD_PTR(struct tpm2_crb_smc, buf,
+				       ACPI_TPM2_START_METHOD_PARAMETER_OFFSET);
+		priv->smc_func_id = crb_smc->smc_func_id;
+		priv->flags |= CRB_FL_CRB_SMC_START;
+	}
 
 	rc = crb_map_io(device, priv, buf);
 	if (rc)