ppi_stub.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <types.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: 1.3 */
                acpigen_write_return_string("1.3");
        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));
}