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>

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index d520ac5..a303522 100644 (file)
--- 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 d91e47d..72b03c3 100644 (file)
--- 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;