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/*
* Copyright (c) 2011 The Chromium OS Authors.
*
* SPDX-License-Identifier: GPL-2.0+
*/
/*
* The code in this file is based on the article "Writing a TPM Device Driver"
* published on http://ptgmedia.pearsoncmg.com.
*
* One principal difference is that in the simplest config the other than 0
* TPM localities do not get mapped by some devices (for instance, by Infineon
* slb9635), so this driver provides access to locality 0 only.
*/
#include <common.h>
#include <asm/io.h>
#include <tpm.h>
#define PREFIX "lpc_tpm: "
struct tpm_locality {
u32 access;
u8 padding0[4];
u32 int_enable;
u8 vector;
u8 padding1[3];
u32 int_status;
u32 int_capability;
u32 tpm_status;
u8 padding2[8];
u8 data;
u8 padding3[3803];
u32 did_vid;
u8 rid;
u8 padding4[251];
};
/*
* This pointer refers to the TPM chip, 5 of its localities are mapped as an
* array.
*/
#define TPM_TOTAL_LOCALITIES 5
static struct tpm_locality *lpc_tpm_dev =
(struct tpm_locality *)CONFIG_TPM_TIS_BASE_ADDRESS;
/* Some registers' bit field definitions */
#define TIS_STS_VALID (1 << 7) /* 0x80 */
#define TIS_STS_COMMAND_READY (1 << 6) /* 0x40 */
#define TIS_STS_TPM_GO (1 << 5) /* 0x20 */
#define TIS_STS_DATA_AVAILABLE (1 << 4) /* 0x10 */
#define TIS_STS_EXPECT (1 << 3) /* 0x08 */
#define TIS_STS_RESPONSE_RETRY (1 << 1) /* 0x02 */
#define TIS_ACCESS_TPM_REG_VALID_STS (1 << 7) /* 0x80 */
#define TIS_ACCESS_ACTIVE_LOCALITY (1 << 5) /* 0x20 */
#define TIS_ACCESS_BEEN_SEIZED (1 << 4) /* 0x10 */
#define TIS_ACCESS_SEIZE (1 << 3) /* 0x08 */
#define TIS_ACCESS_PENDING_REQUEST (1 << 2) /* 0x04 */
#define TIS_ACCESS_REQUEST_USE (1 << 1) /* 0x02 */
#define TIS_ACCESS_TPM_ESTABLISHMENT (1 << 0) /* 0x01 */
#define TIS_STS_BURST_COUNT_MASK (0xffff)
#define TIS_STS_BURST_COUNT_SHIFT (8)
/*
* Error value returned if a tpm register does not enter the expected state
* after continuous polling. No actual TPM register reading ever returns -1,
* so this value is a safe error indication to be mixed with possible status
* register values.
*/
#define TPM_TIMEOUT_ERR (-1)
/* Error value returned on various TPM driver errors. */
#define TPM_DRIVER_ERR (1)
/* 1 second is plenty for anything TPM does. */
#define MAX_DELAY_US (1000 * 1000)
/* Retrieve burst count value out of the status register contents. */
static u16 burst_count(u32 status)
{
return (status >> TIS_STS_BURST_COUNT_SHIFT) & TIS_STS_BURST_COUNT_MASK;
}
/*
* Structures defined below allow creating descriptions of TPM vendor/device
* ID information for run time discovery. The only device the system knows
* about at this time is Infineon slb9635.
*/
struct device_name {
u16 dev_id;
const char * const dev_name;
};
struct vendor_name {
u16 vendor_id;
const char *vendor_name;
const struct device_name *dev_names;
};
static const struct device_name infineon_devices[] = {
{0xb, "SLB9635 TT 1.2"},
{0}
};
static const struct vendor_name vendor_names[] = {
{0x15d1, "Infineon", infineon_devices},
};
/*
* Cached vendor/device ID pair to indicate that the device has been already
* discovered.
*/
static u32 vendor_dev_id;
/* TPM access wrappers to support tracing */
static u8 tpm_read_byte(const u8 *ptr)
{
u8 ret = readb(ptr);
debug(PREFIX "Read reg 0x%4.4x returns 0x%2.2x\n",
(u32)(uintptr_t)ptr - (u32)(uintptr_t)lpc_tpm_dev, ret);
return ret;
}
static u32 tpm_read_word(const u32 *ptr)
{
u32 ret = readl(ptr);
debug(PREFIX "Read reg 0x%4.4x returns 0x%8.8x\n",
(u32)(uintptr_t)ptr - (u32)(uintptr_t)lpc_tpm_dev, ret);
return ret;
}
static void tpm_write_byte(u8 value, u8 *ptr)
{
debug(PREFIX "Write reg 0x%4.4x with 0x%2.2x\n",
(u32)(uintptr_t)ptr - (u32)(uintptr_t)lpc_tpm_dev, value);
writeb(value, ptr);
}
static void tpm_write_word(u32 value, u32 *ptr)
{
debug(PREFIX "Write reg 0x%4.4x with 0x%8.8x\n",
(u32)(uintptr_t)ptr - (u32)(uintptr_t)lpc_tpm_dev, value);
writel(value, ptr);
}
/*
* tis_wait_reg()
*
* Wait for at least a second for a register to change its state to match the
* expected state. Normally the transition happens within microseconds.
*
* @reg - pointer to the TPM register
* @mask - bitmask for the bitfield(s) to watch
* @expected - value the field(s) are supposed to be set to
*
* Returns the register contents in case the expected value was found in the
* appropriate register bits, or TPM_TIMEOUT_ERR on timeout.
*/
static u32 tis_wait_reg(u32 *reg, u8 mask, u8 expected)
{
u32 time_us = MAX_DELAY_US;
while (time_us > 0) {
u32 value = tpm_read_word(reg);
if ((value & mask) == expected)
return value;
udelay(1); /* 1 us */
time_us--;
}
return TPM_TIMEOUT_ERR;
}
/*
* Probe the TPM device and try determining its manufacturer/device name.
*
* Returns 0 on success (the device is found or was found during an earlier
* invocation) or TPM_DRIVER_ERR if the device is not found.
*/
int tis_init(void)
{
u32 didvid = tpm_read_word(&lpc_tpm_dev[0].did_vid);
int i;
const char *device_name = "unknown";
const char *vendor_name = device_name;
u16 vid, did;
if (vendor_dev_id)
return 0; /* Already probed. */
if (!didvid || (didvid == 0xffffffff)) {
printf("%s: No TPM device found\n", __func__);
return TPM_DRIVER_ERR;
}
vendor_dev_id = didvid;
vid = didvid & 0xffff;
did = (didvid >> 16) & 0xffff;
for (i = 0; i < ARRAY_SIZE(vendor_names); i++) {
int j = 0;
u16 known_did;
if (vid == vendor_names[i].vendor_id)
vendor_name = vendor_names[i].vendor_name;
while ((known_did = vendor_names[i].dev_names[j].dev_id) != 0) {
if (known_did == did) {
device_name =
vendor_names[i].dev_names[j].dev_name;
break;
}
j++;
}
break;
}
printf("Found TPM %s by %s\n", device_name, vendor_name);
return 0;
}
/*
* tis_senddata()
*
* send the passed in data to the TPM device.
*
* @data - address of the data to send, byte by byte
* @len - length of the data to send
*
* Returns 0 on success, TPM_DRIVER_ERR on error (in case the device does
* not accept the entire command).
*/
static u32 tis_senddata(const u8 * const data, u32 len)
{
u32 offset = 0;
u16 burst = 0;
u32 max_cycles = 0;
u8 locality = 0;
u32 value;
value = tis_wait_reg(&lpc_tpm_dev[locality].tpm_status,
TIS_STS_COMMAND_READY, TIS_STS_COMMAND_READY);
if (value == TPM_TIMEOUT_ERR) {
printf("%s:%d - failed to get 'command_ready' status\n",
__FILE__, __LINE__);
return TPM_DRIVER_ERR;
}
burst = burst_count(value);
while (1) {
unsigned count;
/* Wait till the device is ready to accept more data. */
while (!burst) {
if (max_cycles++ == MAX_DELAY_US) {
printf("%s:%d failed to feed %d bytes of %d\n",
__FILE__, __LINE__, len - offset, len);
return TPM_DRIVER_ERR;
}
udelay(1);
burst = burst_count(tpm_read_word(&lpc_tpm_dev
[locality].tpm_status));
}
max_cycles = 0;
/*
* Calculate number of bytes the TPM is ready to accept in one
* shot.
*
* We want to send the last byte outside of the loop (hence
* the -1 below) to make sure that the 'expected' status bit
* changes to zero exactly after the last byte is fed into the
* FIFO.
*/
count = min((u32)burst, len - offset - 1);
while (count--)
tpm_write_byte(data[offset++],
&lpc_tpm_dev[locality].data);
value = tis_wait_reg(&lpc_tpm_dev[locality].tpm_status,
TIS_STS_VALID, TIS_STS_VALID);
if ((value == TPM_TIMEOUT_ERR) || !(value & TIS_STS_EXPECT)) {
printf("%s:%d TPM command feed overflow\n",
__FILE__, __LINE__);
return TPM_DRIVER_ERR;
}
burst = burst_count(value);
if ((offset == (len - 1)) && burst) {
/*
* We need to be able to send the last byte to the
* device, so burst size must be nonzero before we
* break out.
*/
break;
}
}
/* Send the last byte. */
tpm_write_byte(data[offset++], &lpc_tpm_dev[locality].data);
/*
* Verify that TPM does not expect any more data as part of this
* command.
*/
value = tis_wait_reg(&lpc_tpm_dev[locality].tpm_status,
TIS_STS_VALID, TIS_STS_VALID);
if ((value == TPM_TIMEOUT_ERR) || (value & TIS_STS_EXPECT)) {
printf("%s:%d unexpected TPM status 0x%x\n",
__FILE__, __LINE__, value);
return TPM_DRIVER_ERR;
}
/* OK, sitting pretty, let's start the command execution. */
tpm_write_word(TIS_STS_TPM_GO, &lpc_tpm_dev[locality].tpm_status);
return 0;
}
/*
* tis_readresponse()
*
* read the TPM device response after a command was issued.
*
* @buffer - address where to read the response, byte by byte.
* @len - pointer to the size of buffer
*
* On success stores the number of received bytes to len and returns 0. On
* errors (misformatted TPM data or synchronization problems) returns
* TPM_DRIVER_ERR.
*/
static u32 tis_readresponse(u8 *buffer, u32 *len)
{
u16 burst;
u32 value;
u32 offset = 0;
u8 locality = 0;
const u32 has_data = TIS_STS_DATA_AVAILABLE | TIS_STS_VALID;
u32 expected_count = *len;
int max_cycles = 0;
/* Wait for the TPM to process the command. */
value = tis_wait_reg(&lpc_tpm_dev[locality].tpm_status,
has_data, has_data);
if (value == TPM_TIMEOUT_ERR) {
printf("%s:%d failed processing command\n",
__FILE__, __LINE__);
return TPM_DRIVER_ERR;
}
do {
while ((burst = burst_count(value)) == 0) {
if (max_cycles++ == MAX_DELAY_US) {
printf("%s:%d TPM stuck on read\n",
__FILE__, __LINE__);
return TPM_DRIVER_ERR;
}
udelay(1);
value = tpm_read_word(&lpc_tpm_dev
[locality].tpm_status);
}
max_cycles = 0;
while (burst-- && (offset < expected_count)) {
buffer[offset++] = tpm_read_byte(&lpc_tpm_dev
[locality].data);
if (offset == 6) {
/*
* We got the first six bytes of the reply,
* let's figure out how many bytes to expect
* total - it is stored as a 4 byte number in
* network order, starting with offset 2 into
* the body of the reply.
*/
u32 real_length;
memcpy(&real_length,
buffer + 2,
sizeof(real_length));
expected_count = be32_to_cpu(real_length);
if ((expected_count < offset) ||
(expected_count > *len)) {
printf("%s:%d bad response size %d\n",
__FILE__, __LINE__,
expected_count);
return TPM_DRIVER_ERR;
}
}
}
/* Wait for the next portion. */
value = tis_wait_reg(&lpc_tpm_dev[locality].tpm_status,
TIS_STS_VALID, TIS_STS_VALID);
if (value == TPM_TIMEOUT_ERR) {
printf("%s:%d failed to read response\n",
__FILE__, __LINE__);
return TPM_DRIVER_ERR;
}
if (offset == expected_count)
break; /* We got all we needed. */
} while ((value & has_data) == has_data);
/*
* Make sure we indeed read all there was. The TIS_STS_VALID bit is
* known to be set.
*/
if (value & TIS_STS_DATA_AVAILABLE) {
printf("%s:%d wrong receive status %x\n",
__FILE__, __LINE__, value);
return TPM_DRIVER_ERR;
}
/* Tell the TPM that we are done. */
tpm_write_word(TIS_STS_COMMAND_READY, &lpc_tpm_dev
[locality].tpm_status);
*len = offset;
return 0;
}
int tis_open(void)
{
u8 locality = 0; /* we use locality zero for everything. */
if (tis_close())
return TPM_DRIVER_ERR;
/* now request access to locality. */
tpm_write_word(TIS_ACCESS_REQUEST_USE, &lpc_tpm_dev[locality].access);
/* did we get a lock? */
if (tis_wait_reg(&lpc_tpm_dev[locality].access,
TIS_ACCESS_ACTIVE_LOCALITY,
TIS_ACCESS_ACTIVE_LOCALITY) == TPM_TIMEOUT_ERR) {
printf("%s:%d - failed to lock locality %d\n",
__FILE__, __LINE__, locality);
return TPM_DRIVER_ERR;
}
tpm_write_word(TIS_STS_COMMAND_READY,
&lpc_tpm_dev[locality].tpm_status);
return 0;
}
int tis_close(void)
{
u8 locality = 0;
if (tpm_read_word(&lpc_tpm_dev[locality].access) &
TIS_ACCESS_ACTIVE_LOCALITY) {
tpm_write_word(TIS_ACCESS_ACTIVE_LOCALITY,
&lpc_tpm_dev[locality].access);
if (tis_wait_reg(&lpc_tpm_dev[locality].access,
TIS_ACCESS_ACTIVE_LOCALITY, 0) ==
TPM_TIMEOUT_ERR) {
printf("%s:%d - failed to release locality %d\n",
__FILE__, __LINE__, locality);
return TPM_DRIVER_ERR;
}
}
return 0;
}
int tis_sendrecv(const u8 *sendbuf, size_t send_size,
u8 *recvbuf, size_t *recv_len)
{
if (tis_senddata(sendbuf, send_size)) {
printf("%s:%d failed sending data to TPM\n",
__FILE__, __LINE__);
return TPM_DRIVER_ERR;
}
return tis_readresponse(recvbuf, (u32 *)recv_len);
}