src/drivers/tpm/ppi_stub.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #include <types.h>
   4 #include <acpi/acpigen.h>
   5 #include <acpi/acpi_device.h>
   6
   7 #include "tpm_ppi.h"
   8
   9 static void tpm_ppi_func0_cb(void *arg)
  10 {
  11         /* Functions 1-8. */
  12         u8 buf[] = {0xff, 0x01};
  13         acpigen_write_return_byte_buffer(buf, sizeof(buf));
  14 }
  15
  16 static void tpm_ppi_func1_cb(void *arg)
  17 {
  18         if (CONFIG(TPM2))
  19                 /* Interface version: 1.3 */
  20                 acpigen_write_return_string("1.3");
  21         else
  22                 /* Interface version: 1.2 */
  23                 acpigen_write_return_string("1.2");
  24 }
  25
  26 static void tpm_ppi_func2_cb(void *arg)
  27 {
  28         /* Submit operations: drop on the floor and return success. */
  29         acpigen_write_return_byte(PPI2_RET_SUCCESS);
  30 }
  31
  32 static void tpm_ppi_func3_cb(void *arg)
  33 {
  34         /* Pending operation: none. */
  35         acpigen_emit_byte(RETURN_OP);
  36         acpigen_write_package(2);
  37         acpigen_write_byte(0);
  38         acpigen_write_byte(0);
  39         acpigen_pop_len();
  40 }
  41
  42 static void tpm_ppi_func4_cb(void *arg)
  43 {
  44         /* Pre-OS transition method: reboot. */
  45         acpigen_write_return_byte(2);
  46 }
  47
  48 static void tpm_ppi_func5_cb(void *arg)
  49 {
  50         /* Operation response: no operation executed. */
  51         acpigen_emit_byte(RETURN_OP);
  52         acpigen_write_package(3);
  53         acpigen_write_byte(0);
  54         acpigen_write_byte(0);
  55         acpigen_write_byte(0);
  56         acpigen_pop_len();
  57 }
  58
  59 static void tpm_ppi_func6_cb(void *arg)
  60 {
  61         /*
  62          * Set preferred user language: deprecated and must return 3 AKA
  63          * "not implemented".
  64          */
  65         acpigen_write_return_byte(PPI6_RET_NOT_IMPLEMENTED);
  66 }
  67
  68 static void tpm_ppi_func7_cb(void *arg)
  69 {
  70         /* Submit operations: deny. */
  71         acpigen_write_return_byte(PPI7_RET_BLOCKED_BY_FIRMWARE);
  72 }
  73
  74 static void tpm_ppi_func8_cb(void *arg)
  75 {
  76         /* All actions are forbidden. */
  77         acpigen_write_return_byte(PPI8_RET_FIRMWARE_ONLY);
  78 }
  79
  80 static void (*tpm_ppi_callbacks[])(void *) = {
  81         tpm_ppi_func0_cb,
  82         tpm_ppi_func1_cb,
  83         tpm_ppi_func2_cb,
  84         tpm_ppi_func3_cb,
  85         tpm_ppi_func4_cb,
  86         tpm_ppi_func5_cb,
  87         tpm_ppi_func6_cb,
  88         tpm_ppi_func7_cb,
  89         tpm_ppi_func8_cb,
  90 };
  91
  92 static void tpm_mci_func0_cb(void *arg)
  93 {
  94         /* Function 1. */
  95         acpigen_write_return_singleton_buffer(0x3);
  96 }
  97 static void tpm_mci_func1_cb(void *arg)
  98 {
  99         /* Just return success. */
 100         acpigen_write_return_byte(0);
 101 }
 102
 103 static void (*tpm_mci_callbacks[])(void *) = {
 104         tpm_mci_func0_cb,
 105         tpm_mci_func1_cb,
 106 };
 107
 108 void tpm_ppi_acpi_fill_ssdt(const struct device *dev)
 109 {
 110         /*
 111          * _DSM method
 112          */
 113         struct dsm_uuid ids[] = {
 114                 /* Physical presence interface.
 115                  * This is used to submit commands like "Clear TPM" to
 116                  * be run at next reboot provided that user confirms
 117                  * them. Spec allows user to cancel all commands and/or
 118                  * configure BIOS to reject commands. So we pretend that
 119                  * user did just this: cancelled everything. If user
 120                  * really wants to clear TPM the only option now is to
 121                  * do it manually in payload.
 122                  */
 123                 DSM_UUID(TPM_PPI_UUID, tpm_ppi_callbacks,
 124                         ARRAY_SIZE(tpm_ppi_callbacks), NULL),
 125                 /* Memory clearing on boot: just a dummy. */
 126                 DSM_UUID(TPM_MCI_UUID, tpm_mci_callbacks,
 127                         ARRAY_SIZE(tpm_mci_callbacks), NULL),
 128         };
 129
 130         acpigen_write_dsm_uuid_arr(ids, ARRAY_SIZE(ids));
 131 }