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/* Copyright 2015 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "ftdi_spi_tpm.h"
static struct mpsse_context *mpsse_;
static unsigned locality_; /* Set at initialization. */
static int ftdi_trace_enabled;
/* Assorted TPM2 registers for interface type FIFO. */
#define TPM_ACCESS_REG 0
#define TPM_STS_REG 0x18
#define TPM_DATA_FIFO_REG 0x24
#define TPM_DID_VID_REG 0xf00
#define TPM_RID_REG 0xf04
static struct swig_string_data empty_string_data = (struct swig_string_data){
.size = 0, .data = NULL
};
/* Locality management bits (in TPM_ACCESS_REG). */
enum TpmAccessBits {
tpmRegValidSts = (1 << 7),
activeLocality = (1 << 5),
requestUse = (1 << 1),
tpmEstablishment = (1 << 0),
};
enum TpmStsBits {
tpmFamilyShift = 26,
tpmFamilyMask = ((1 << 2) - 1), /* 2 bits wide. */
tpmFamilyTPM2 = 1,
resetEstablishmentBit = (1 << 25),
commandCancel = (1 << 24),
burstCountShift = 8,
burstCountMask = ((1 << 16) - 1), /* 16 bits wide. */
stsValid = (1 << 7),
commandReady = (1 << 6),
tpmGo = (1 << 5),
dataAvail = (1 << 4),
Expect = (1 << 3),
selfTestDone = (1 << 2),
responseRetry = (1 << 1),
};
enum {
false = 0,
true = 1
};
/*
* SPI frame header for TPM transactions is 4 bytes in size, it is described
* in section "6.4.6 Spi Bit Protocol" of the TCG issued "TPM Profile (PTP)
* Specification Revision 00.43.
*/
struct SpiFrameHeader {
unsigned char body[4];
};
void FtdiStop(void)
{
if (mpsse_)
Close(mpsse_);
mpsse_ = NULL;
}
static void StartTransaction(int read_write, size_t bytes, unsigned addr)
{
struct SpiFrameHeader header;
int i;
uint8_t flow_c;
char *transfer_data;
/*
* give it 10 ms. TODO(vbendeb): remove this once cr50 SPS TPM driver
* performance is fixed.
*/
usleep(10000);
/*
* The first byte of the frame header encodes the transaction type
* (read or write) and size (set to length - 1).
*/
header.body[0] = (read_write ? 0x80 : 0) | 0x40 | (bytes - 1);
/* The rest of the frame header is the internal address in the TPM. */
for (i = 0; i < 3; i++)
header.body[i + 1] = (addr >> (8 * (2 - i))) & 0xff;
Start(mpsse_);
transfer_data =
Transfer(mpsse_, (char *)header.body, sizeof(header.body));
/*
* The TCG TPM over SPI specification itroduces the notion of SPI flow
* control (Section "6.4.5 Flow Control" of the TCG issued "TPM
* Profile (PTP) Specification Revision 00.43).
*
* The slave (TPM device) expects each transaction to start with a 4
* byte header trasmitted by master. If the slave needs to stall the
* transaction, it sets the MOSI bit to 0 during the last clock of the
* 4 byte header. In this case the master is supposed to start polling
* the line, byte at time, until the last bit in the received byte
* (transferred during the last clock of the byte) is set to 1.
*/
flow_c = transfer_data[3];
free(transfer_data);
while (!(flow_c & 1)) {
transfer_data = Read(mpsse_, 1);
flow_c = transfer_data[0];
free(transfer_data);
}
}
static void trace_dump(const char *prefix, unsigned reg, size_t bytes,
const uint8_t *buffer)
{
if (!ftdi_trace_enabled)
return;
printf("%s %2.2x:", prefix, reg);
if (bytes == 4) {
printf(" %8.8x\n", *(const uint32_t *)buffer);
} else {
int i;
for (i = 0; i < bytes; i++)
printf(" %2.2x", buffer[i]);
printf("\n");
}
}
static int FtdiWriteReg(unsigned reg_number, size_t bytes, void *buffer)
{
if (!mpsse_)
return false;
trace_dump("W", reg_number, bytes, buffer);
StartTransaction(false, bytes, reg_number + locality_ * 0x10000);
Write(mpsse_, buffer, bytes);
Stop(mpsse_);
return true;
}
static int FtdiReadReg(unsigned reg_number, size_t bytes, void *buffer)
{
void *data;
if (!mpsse_)
return false;
StartTransaction(true, bytes, reg_number + locality_ * 0x10000);
data = Read(mpsse_, bytes);
if (data)
memcpy(buffer, data, bytes);
free(data);
Stop(mpsse_);
trace_dump("R", reg_number, bytes, buffer);
return true;
}
static int ReadTpmSts(uint32_t *status)
{
return FtdiReadReg(TPM_STS_REG, sizeof(*status), status);
}
static int WriteTpmSts(uint32_t status)
{
return FtdiWriteReg(TPM_STS_REG, sizeof(status), &status);
}
static uint32_t GetBurstCount(void)
{
uint32_t status;
ReadTpmSts(&status);
return (status >> burstCountShift) & burstCountMask;
}
int FtdiSpiInit(uint32_t freq, int enable_debug)
{
uint32_t did_vid, status;
uint8_t cmd;
uint16_t vid;
if (mpsse_)
return true;
ftdi_trace_enabled = enable_debug;
/* round frequency down to the closest 100KHz */
freq = (freq / (100 * 1000)) * 100 * 1000;
printf("Starting MPSSE at %d kHz\n", freq / 1000);
mpsse_ = MPSSE(freq, MSB, NULL);
if (!mpsse_)
return false;
/* Reset the TPM using GPIOL0, issue a 100 ms long pulse. */
PinLow(mpsse_, GPIOL0);
usleep(100000);
PinHigh(mpsse_, GPIOL0);
FtdiReadReg(TPM_DID_VID_REG, sizeof(did_vid), &did_vid);
vid = did_vid & 0xffff;
if ((vid != 0x15d1) && (vid != 0x1ae0)) {
fprintf(stderr, "unknown did_vid: %#x\n", did_vid);
return false;
}
/* Try claiming locality zero. */
FtdiReadReg(TPM_ACCESS_REG, sizeof(cmd), &cmd);
if ((cmd & (activeLocality & tpmRegValidSts)) ==
(activeLocality & tpmRegValidSts)) {
/*
* Locality active - maybe reset line is not connected?
* Release the locality and try again
*/
cmd = activeLocality;
FtdiWriteReg(TPM_ACCESS_REG, sizeof(cmd), &cmd);
FtdiReadReg(TPM_ACCESS_REG, sizeof(cmd), &cmd);
}
/* tpmEstablishment can be either set or not. */
if ((cmd & ~tpmEstablishment) != tpmRegValidSts) {
fprintf(stderr, "invalid reset status: %#x\n", cmd);
return false;
}
cmd = requestUse;
FtdiWriteReg(TPM_ACCESS_REG, sizeof(cmd), &cmd);
FtdiReadReg(TPM_ACCESS_REG, sizeof(cmd), &cmd);
if ((cmd & ~tpmEstablishment) != (tpmRegValidSts | activeLocality)) {
fprintf(stderr, "failed to claim locality, status: %#x\n", cmd);
return false;
}
ReadTpmSts(&status);
if (((status >> tpmFamilyShift) & tpmFamilyMask) != tpmFamilyTPM2) {
fprintf(stderr, "unexpected TPM family value, status: %#x\n",
status);
return false;
}
FtdiReadReg(TPM_RID_REG, sizeof(cmd), &cmd);
printf("Connected to device vid:did:rid of %4.4x:%4.4x:%2.2x\n",
did_vid & 0xffff, did_vid >> 16, cmd);
return true;
}
/* This is in seconds. */
#define MAX_STATUS_TIMEOUT 120
static int WaitForStatus(uint32_t statusMask, uint32_t statusExpected)
{
uint32_t status;
time_t target_time;
static unsigned max_timeout;
target_time = time(NULL) + MAX_STATUS_TIMEOUT;
do {
usleep(10000);
if (time(NULL) >= target_time) {
fprintf(stderr, "failed to get expected status %x\n",
statusExpected);
return false;
}
ReadTpmSts(&status);
} while ((status & statusMask) != statusExpected);
/* Calculate time spent waiting */
target_time = MAX_STATUS_TIMEOUT - target_time + time(NULL);
if (max_timeout < (unsigned)target_time) {
max_timeout = target_time;
printf("New max timeout: %d s\n", max_timeout);
}
return true;
}
static void SpinSpinner(void)
{
static const char *spinner = "\\|/-";
static int index;
if (index > strlen(spinner))
index = 0;
fprintf(stdout, "%c[1D%c", 0x1b, spinner[index++]);
fflush(stdout);
}
#define MAX_RESPONSE_SIZE 4096
#define HEADER_SIZE 6
/* tpm_command points at a buffer 4096 bytes in size */
struct swig_string_data FtdiSendCommandAndWait(char *tpm_command,
int command_size)
{
uint32_t status;
uint32_t expected_status_bits;
size_t handled_so_far;
uint32_t payload_size;
char message[100];
int offset = 0;
uint8_t *response;
if (!mpsse_) {
fprintf(stderr, "attempt to use an uninitialized FTDI TPM!\n");
return empty_string_data;
}
response = malloc(MAX_RESPONSE_SIZE);
if (!response) {
fprintf(stderr, "attempt to use an uninitialized FTDI TPM!\n");
return empty_string_data;
}
handled_so_far = 0;
WriteTpmSts(commandReady);
memcpy(&payload_size, tpm_command + 2, sizeof(payload_size));
payload_size = be32toh(payload_size);
offset +=
snprintf(message, sizeof(message), "Message size %d", payload_size);
/*
* No need to wait for the sts.Expect bit to be set, at least with the
* 15d1:001b and 1ae0:0028 devices. Let's just write the command into
* FIFO, make sure not to exceed the burst count.
*/
do {
uint32_t transaction_size;
uint32_t burst_count = GetBurstCount();
if (burst_count > 64)
burst_count = 64;
transaction_size = command_size - handled_so_far;
if (transaction_size > burst_count)
transaction_size = burst_count;
if (transaction_size) {
FtdiWriteReg(TPM_DATA_FIFO_REG, transaction_size,
tpm_command + handled_so_far);
handled_so_far += transaction_size;
}
} while (handled_so_far != command_size);
/* And tell the device it can start processing it. */
WriteTpmSts(tpmGo);
expected_status_bits = stsValid | dataAvail;
if (!WaitForStatus(expected_status_bits, expected_status_bits)) {
size_t i;
printf("Failed processing. %s:", message);
for (i = 0; i < command_size; i++) {
if (!(i % 16))
printf("\n");
printf(" %2.2x", (uint8_t)tpm_command[i]);
}
printf("\n");
return empty_string_data;
}
/*
* The tpm_command is ready, let's read it.
*
* First we read the FIFO payload header, to see how much data to
* expect. The header size is fixed to six bytes, the total payload
* size is stored in network order in the last four bytes of the
* header.
*/
FtdiReadReg(TPM_DATA_FIFO_REG, HEADER_SIZE, response);
handled_so_far = HEADER_SIZE;
/* Figure out the total payload size. */
memcpy(&payload_size, response + 2, sizeof(payload_size));
payload_size = be32toh(payload_size);
if (ftdi_trace_enabled)
printf("%s response size %d\n\n", message, payload_size);
else
SpinSpinner();
if (payload_size > MAX_RESPONSE_SIZE)
return empty_string_data;
/*
* Let's read all but the last byte in the FIFO to make sure the
* status register is showing correct flow control bits: 'more data'
* until the last byte and then 'no more data' once the last byte is
* read.
*/
payload_size = payload_size - 1;
do {
uint32_t transaction_size;
uint32_t burst_count = GetBurstCount();
if (burst_count > 64)
burst_count = 64;
transaction_size = payload_size - handled_so_far;
if (transaction_size > burst_count)
transaction_size = burst_count;
if (transaction_size) {
FtdiReadReg(TPM_DATA_FIFO_REG, transaction_size,
response + handled_so_far);
handled_so_far += transaction_size;
}
} while (handled_so_far != payload_size);
/* Verify that there is still data to come. */
ReadTpmSts(&status);
if ((status & expected_status_bits) != expected_status_bits) {
fprintf(stderr, "unexpected status %#x\n", status);
return empty_string_data;
}
FtdiReadReg(TPM_DATA_FIFO_REG, 1, response + handled_so_far);
/* Verify that 'data available' is not asseretd any more. */
ReadTpmSts(&status);
if ((status & expected_status_bits) != stsValid) {
fprintf(stderr, "unexpected status %#x\n", status);
return empty_string_data;
}
/* Move the TPM back to idle state. */
WriteTpmSts(commandReady);
handled_so_far++;
return (struct swig_string_data) {
.size = handled_so_far, .data = response};
}
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