1 files changed, 133 insertions, 0 deletions
diff --git a/src/drivers/tpm/ppi_stub.c b/src/drivers/tpm/ppi_stub.c
new file mode 100644
index 0000000000..11bd07e10a
--- /dev/null
+++ b/src/drivers/tpm/ppi_stub.c
@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <types.h>
+#include <stddef.h>
+#include <acpi/acpi.h>
+#include <acpi/acpigen.h>
+#include <acpi/acpi_device.h>
+
+#include "tpm_ppi.h"
+
+static void tpm_ppi_func0_cb(void *arg)
+{
+	/* Functions 1-8. */
+	u8 buf[] = {0xff, 0x01};
+	acpigen_write_return_byte_buffer(buf, sizeof(buf));
+}
+
+static void tpm_ppi_func1_cb(void *arg)
+{
+	if (CONFIG(TPM2))
+		/* Interface version: 2.0 */
+		acpigen_write_return_string("2.0");
+	else
+		/* Interface version: 1.2 */
+		acpigen_write_return_string("1.2");
+}
+
+static void tpm_ppi_func2_cb(void *arg)
+{
+	/* Submit operations: drop on the floor and return success. */
+	acpigen_write_return_byte(PPI2_RET_SUCCESS);
+}
+
+static void tpm_ppi_func3_cb(void *arg)
+{
+	/* Pending operation: none. */
+	acpigen_emit_byte(RETURN_OP);
+	acpigen_write_package(2);
+	acpigen_write_byte(0);
+	acpigen_write_byte(0);
+	acpigen_pop_len();
+}
+
+static void tpm_ppi_func4_cb(void *arg)
+{
+	/* Pre-OS transition method: reboot. */
+	acpigen_write_return_byte(2);
+}
+
+static void tpm_ppi_func5_cb(void *arg)
+{
+	/* Operation response: no operation executed. */
+	acpigen_emit_byte(RETURN_OP);
+	acpigen_write_package(3);
+	acpigen_write_byte(0);
+	acpigen_write_byte(0);
+	acpigen_write_byte(0);
+	acpigen_pop_len();
+}
+
+static void tpm_ppi_func6_cb(void *arg)
+{
+	/*
+	 * Set preferred user language: deprecated and must return 3 AKA
+	 * "not implemented".
+	 */
+	acpigen_write_return_byte(PPI6_RET_NOT_IMPLEMENTED);
+}
+
+static void tpm_ppi_func7_cb(void *arg)
+{
+	/* Submit operations: deny. */
+	acpigen_write_return_byte(PPI7_RET_BLOCKED_BY_FIRMWARE);
+}
+
+static void tpm_ppi_func8_cb(void *arg)
+{
+	/* All actions are forbidden. */
+	acpigen_write_return_byte(PPI8_RET_FIRMWARE_ONLY);
+}
+
+static void (*tpm_ppi_callbacks[])(void *) = {
+	tpm_ppi_func0_cb,
+	tpm_ppi_func1_cb,
+	tpm_ppi_func2_cb,
+	tpm_ppi_func3_cb,
+	tpm_ppi_func4_cb,
+	tpm_ppi_func5_cb,
+	tpm_ppi_func6_cb,
+	tpm_ppi_func7_cb,
+	tpm_ppi_func8_cb,
+};
+
+static void tpm_mci_func0_cb(void *arg)
+{
+	/* Function 1. */
+	acpigen_write_return_singleton_buffer(0x3);
+}
+static void tpm_mci_func1_cb(void *arg)
+{
+	/* Just return success. */
+	acpigen_write_return_byte(0);
+}
+
+static void (*tpm_mci_callbacks[])(void *) = {
+	tpm_mci_func0_cb,
+	tpm_mci_func1_cb,
+};
+
+void tpm_ppi_acpi_fill_ssdt(const struct device *dev)
+{
+	/*
+	 * _DSM method
+	 */
+	struct dsm_uuid ids[] = {
+		/* Physical presence interface.
+		 * This is used to submit commands like "Clear TPM" to
+		 * be run at next reboot provided that user confirms
+		 * them. Spec allows user to cancel all commands and/or
+		 * configure BIOS to reject commands. So we pretend that
+		 * user did just this: cancelled everything. If user
+		 * really wants to clear TPM the only option now is to
+		 * do it manually in payload.
+		 */
+		DSM_UUID(TPM_PPI_UUID, tpm_ppi_callbacks,
+			ARRAY_SIZE(tpm_ppi_callbacks), NULL),
+		/* Memory clearing on boot: just a dummy. */
+		DSM_UUID(TPM_MCI_UUID, tpm_mci_callbacks,
+			ARRAY_SIZE(tpm_mci_callbacks), NULL),
+	};
+
+	acpigen_write_dsm_uuid_arr(ids, ARRAY_SIZE(ids));
+}