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 <anjiandi@codeaurora.org>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> (on x86/PTT)
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

2 files changed, 66 insertions, 3 deletions

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index d520ac51c11c..a30352202f1f 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -136,7 +136,7 @@ config TCG_XEN
 
 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
diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index d91e47dc2d79..72b03c328198 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -20,6 +20,9 @@
 #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"
@@ -93,6 +96,7 @@ enum crb_status {
 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 {
@@ -103,6 +107,15 @@ 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;
 };
 
 /**
@@ -122,7 +135,8 @@ struct crb_priv {
  */
 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);
@@ -167,7 +181,8 @@ static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32 value,
 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);
@@ -262,6 +277,34 @@ static int crb_do_acpi_start(struct tpm_chip *chip)
         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);
@@ -289,6 +332,11 @@ static int crb_send(struct tpm_chip *chip, u8 *buf, size_t len)
         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;
 }
 
@@ -483,6 +531,7 @@ static int crb_acpi_add(struct acpi_device *device)
         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;
@@ -515,6 +564,20 @@ static int crb_acpi_add(struct acpi_device *device)
             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)
                 return rc;