// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2012,2013 Infineon Technologies
*
* Authors:
* Peter Huewe <[email protected]>
*
* Device driver for TCG/TCPA TPM (trusted platform module).
* Specifications at www.trustedcomputinggroup.org
*
* This device driver implements the TPM interface as defined in
* the TCG TPM Interface Spec version 1.2, revision 1.0 and the
* Infineon I2C Protocol Stack Specification v0.20.
*
* It is based on the original tpm_tis device driver from Leendert van
* Dorn and Kyleen Hall.
*/
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/wait.h>
#include "tpm.h"
#define TPM_I2C_INFINEON_BUFSIZE 1260
/* max. number of iterations after I2C NAK */
#define MAX_COUNT 3
#define SLEEP_DURATION_LOW 55
#define SLEEP_DURATION_HI 65
/* max. number of iterations after I2C NAK for 'long' commands
* we need this especially for sending TPM_READY, since the cleanup after the
* transtion to the ready state may take some time, but it is unpredictable
* how long it will take.
*/
#define MAX_COUNT_LONG 50
#define SLEEP_DURATION_LONG_LOW 200
#define SLEEP_DURATION_LONG_HI 220
/* After sending TPM_READY to 'reset' the TPM we have to sleep even longer */
#define SLEEP_DURATION_RESET_LOW 2400
#define SLEEP_DURATION_RESET_HI 2600
/* we want to use usleep_range instead of msleep for the 5ms TPM_TIMEOUT */
#define TPM_TIMEOUT_US_LOW (TPM_TIMEOUT * 1000)
#define TPM_TIMEOUT_US_HI (TPM_TIMEOUT_US_LOW + 2000)
/* expected value for DIDVID register */
#define TPM_TIS_I2C_DID_VID_9635 0xd1150b00L
#define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L
enum i2c_chip_type {
SLB9635,
SLB9645,
UNKNOWN,
};
struct tpm_inf_dev {
struct i2c_client *client;
int locality;
/* In addition to the data itself, the buffer must fit the 7-bit I2C
* address and the direction bit.
*/
u8 buf[TPM_I2C_INFINEON_BUFSIZE + 1];
struct tpm_chip *chip;
enum i2c_chip_type chip_type;
unsigned int adapterlimit;
};
static struct tpm_inf_dev tpm_dev;
/*
* iic_tpm_read() - read from TPM register
* @addr: register address to read from
* @buffer: provided by caller
* @len: number of bytes to read
*
* Read len bytes from TPM register and put them into
* buffer (little-endian format, i.e. first byte is put into buffer[0]).
*
* NOTE: TPM is big-endian for multi-byte values. Multi-byte
* values have to be swapped.
*
* NOTE: We can't unfortunately use the combined read/write functions
* provided by the i2c core as the TPM currently does not support the
* repeated start condition and due to it's special requirements.
* The i2c_smbus* functions do not work for this chip.
*
* Return -EIO on error, 0 on success.
*/
static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
{
struct i2c_msg msg1 = {
.addr = tpm_dev.client->addr,
.len = 1,
.buf = &addr
};
struct i2c_msg msg2 = {
.addr = tpm_dev.client->addr,
.flags = I2C_M_RD,
.len = len,
.buf = buffer
};
struct i2c_msg msgs[] = {msg1, msg2};
int rc = 0;
int count;
unsigned int msglen = len;
/* Lock the adapter for the duration of the whole sequence. */
if (!tpm_dev.client->adapter->algo->master_xfer)
return -EOPNOTSUPP;
i2c_lock_bus(tpm_dev.client->adapter, I2C_LOCK_SEGMENT);
if (tpm_dev.chip_type == SLB9645) {
/* use a combined read for newer chips
* unfortunately the smbus functions are not suitable due to
* the 32 byte limit of the smbus.
* retries should usually not be needed, but are kept just to
* be on the safe side.
*/
for (count = 0; count < MAX_COUNT; count++) {
rc = __i2c_transfer(tpm_dev.client->adapter, msgs, 2);
if (rc > 0)
break; /* break here to skip sleep */
usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
}
} else {
/* Expect to send one command message and one data message, but
* support looping over each or both if necessary.
*/
while (len > 0) {
/* slb9635 protocol should work in all cases */
for (count = 0; count < MAX_COUNT; count++) {
rc = __i2c_transfer(tpm_dev.client->adapter,
&msg1, 1);
if (rc > 0)
break; /* break here to skip sleep */
usleep_range(SLEEP_DURATION_LOW,
SLEEP_DURATION_HI);
}
if (rc <= 0)
goto out;
/* After the TPM has successfully received the register
* address it needs some time, thus we're sleeping here
* again, before retrieving the data
*/
for (count = 0; count < MAX_COUNT; count++) {
if (tpm_dev.adapterlimit) {
msglen = min_t(unsigned int,
tpm_dev.adapterlimit,
len);
msg2.len = msglen;
}
usleep_range(SLEEP_DURATION_LOW,
SLEEP_DURATION_HI);
rc = __i2c_transfer(tpm_dev.client->adapter,
&msg2, 1);
if (rc > 0) {
/* Since len is unsigned, make doubly
* sure we do not underflow it.
*/
if (msglen > len)
len = 0;
else
len -= msglen;
msg2.buf += msglen;
break;
}
/* If the I2C adapter rejected the request (e.g
* when the quirk read_max_len < len) fall back
* to a sane minimum value and try again.
*/
if (rc == -EOPNOTSUPP)
tpm_dev.adapterlimit =
I2C_SMBUS_BLOCK_MAX;
}
if (rc <= 0)
goto out;
}
}
out:
i2c_unlock_bus(tpm_dev.client->adapter, I2C_LOCK_SEGMENT);
/* take care of 'guard time' */
usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
/* __i2c_transfer returns the number of successfully transferred
* messages.
* So rc should be greater than 0 here otherwise we have an error.
*/
if (rc <= 0)
return -EIO;
return 0;
}
static int iic_tpm_write_generic(u8 addr, u8 *buffer, size_t len,
unsigned int sleep_low,
unsigned int sleep_hi, u8 max_count)
{
int rc = -EIO;
int count;
struct i2c_msg msg1 = {
.addr = tpm_dev.client->addr,
.len = len + 1,
.buf = tpm_dev.buf
};
if (len > TPM_I2C_INFINEON_BUFSIZE)
return -EINVAL;
if (!tpm_dev.client->adapter->algo->master_xfer)
return -EOPNOTSUPP;
i2c_lock_bus(tpm_dev.client->adapter, I2C_LOCK_SEGMENT);
/* prepend the 'register address' to the buffer */
tpm_dev.buf[0] = addr;
memcpy(&(tpm_dev.buf[1]), buffer, len);
/*
* NOTE: We have to use these special mechanisms here and unfortunately
* cannot rely on the standard behavior of i2c_transfer.
* Even for newer chips the smbus functions are not
* suitable due to the 32 byte limit of the smbus.
*/
for (count = 0; count < max_count; count++) {
rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1);
if (rc > 0)
break;
usleep_range(sleep_low, sleep_hi);
}
i2c_unlock_bus(tpm_dev.client->adapter, I2C_LOCK_SEGMENT);
/* take care of 'guard time' */
usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
/* __i2c_transfer returns the number of successfully transferred
* messages.
* So rc should be greater than 0 here otherwise we have an error.
*/
if (rc <= 0)
return -EIO;
return 0;
}
/*
* iic_tpm_write() - write to TPM register
* @addr: register address to write to
* @buffer: containing data to be written
* @len: number of bytes to write
*
* Write len bytes from provided buffer to TPM register (little
* endian format, i.e. buffer[0] is written as first byte).
*
* NOTE: TPM is big-endian for multi-byte values. Multi-byte
* values have to be swapped.
*
* NOTE: use this function instead of the iic_tpm_write_generic function.
*
* Return -EIO on error, 0 on success
*/
static int iic_tpm_write(u8 addr, u8 *buffer, size_t len)
{
return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION_LOW,
SLEEP_DURATION_HI, MAX_COUNT);
}
/*
* This function is needed especially for the cleanup situation after
* sending TPM_READY
* */
static int iic_tpm_write_long(u8 addr, u8 *buffer, size_t len)
{
return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION_LONG_LOW,
SLEEP_DURATION_LONG_HI, MAX_COUNT_LONG);
}
enum tis_access {
TPM_ACCESS_VALID = 0x80,
TPM_ACCESS_ACTIVE_LOCALITY = 0x20,
TPM_ACCESS_REQUEST_PENDING = 0x04,
TPM_ACCESS_REQUEST_USE = 0x02,
};
enum tis_status {
TPM_STS_VALID = 0x80,
TPM_STS_COMMAND_READY = 0x40,
TPM_STS_GO = 0x20,
TPM_STS_DATA_AVAIL = 0x10,
TPM_STS_DATA_EXPECT = 0x08,
};
enum tis_defaults {
TIS_SHORT_TIMEOUT = 750, /* ms */
TIS_LONG_TIMEOUT = 2000, /* 2 sec */
};
#define TPM_ACCESS(l) (0x0000 | ((l) << 4))
#define TPM_STS(l) (0x0001 | ((l) << 4))
#define TPM_DATA_FIFO(l) (0x0005 | ((l) << 4))
#define TPM_DID_VID(l) (0x0006 | ((l) << 4))
static bool check_locality(struct tpm_chip *chip, int loc)
{
u8 buf;
int rc;
rc = iic_tpm_read(TPM_ACCESS(loc), &buf, 1);
if (rc < 0)
return false;
if ((buf & (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) ==
(TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) {
tpm_dev.locality = loc;
return true;
}
return false;
}
/* implementation similar to tpm_tis */
static void release_locality(struct tpm_chip *chip, int loc, int force)
{
u8 buf;
if (iic_tpm_read(TPM_ACCESS(loc), &buf, 1) < 0)
return;
if (force || (buf & (TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID)) ==
(TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID)) {
buf = TPM_ACCESS_ACTIVE_LOCALITY;
iic_tpm_write(TPM_ACCESS(loc), &buf, 1);
}
}
static int request_locality(struct tpm_chip *chip, int loc)
{
unsigned long stop;
u8 buf = TPM_ACCESS_REQUEST_USE;
if (check_locality(chip, loc))
return loc;
iic_tpm_write(TPM_ACCESS(loc), &buf, 1);
/* wait for burstcount */
stop = jiffies + chip->timeout_a;
do {
if (check_locality(chip, loc))
return loc;
usleep_range(TPM_TIMEOUT_US_LOW, TPM_TIMEOUT_US_HI);
} while (time_before(jiffies, stop));
return -ETIME;
}
static u8 tpm_tis_i2c_status(struct tpm_chip *chip)
{
/* NOTE: since I2C read may fail, return 0 in this case --> time-out */
u8 buf = 0xFF;
u8 i = 0;
do {
if (iic_tpm_read(TPM_STS(tpm_dev.locality), &buf, 1) < 0)
return 0;
i++;
/* if locallity is set STS should not be 0xFF */
} while ((buf == 0xFF) && i < 10);
return buf;
}
static void tpm_tis_i2c_ready(struct tpm_chip *chip)
{
/* this causes the current command to be aborted */
u8 buf = TPM_STS_COMMAND_READY;
iic_tpm_write_long(TPM_STS(tpm_dev.locality), &buf, 1);
}
static ssize_t get_burstcount(struct tpm_chip *chip)
{
unsigned long stop;
ssize_t burstcnt;
u8 buf[3];
/* wait for burstcount */
/* which timeout value, spec has 2 answers (c & d) */
stop = jiffies + chip->timeout_d;
do {
/* Note: STS is little endian */
if (iic_tpm_read(TPM_STS(tpm_dev.locality)+1, buf, 3) < 0)
burstcnt = 0;
else
burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0];
if (burstcnt)
return burstcnt;
usleep_range(TPM_TIMEOUT_US_LOW, TPM_TIMEOUT_US_HI);
} while (time_before(jiffies, stop));
return -EBUSY;
}
static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
int *status)
{
unsigned long stop;
/* check current status */
*status = tpm_tis_i2c_status(chip);
if ((*status != 0xFF) && (*status & mask) == mask)
return 0;
stop = jiffies + timeout;
do {
/* since we just checked the status, give the TPM some time */
usleep_range(TPM_TIMEOUT_US_LOW, TPM_TIMEOUT_US_HI);
*status = tpm_tis_i2c_status(chip);
if ((*status & mask) == mask)
return 0;
} while (time_before(jiffies, stop));
return -ETIME;
}
static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
{
size_t size = 0;
ssize_t burstcnt;
u8 retries = 0;
int rc;
while (size < count) {
burstcnt = get_burstcount(chip);
/* burstcnt < 0 = TPM is busy */
if (burstcnt < 0)
return burstcnt;
/* limit received data to max. left */
if (burstcnt > (count - size))
burstcnt = count - size;
rc = iic_tpm_read(TPM_DATA_FIFO(tpm_dev.locality),
&(buf[size]), burstcnt);
if (rc == 0)
size += burstcnt;
else if (rc < 0)
retries++;
/* avoid endless loop in case of broken HW */
if (retries > MAX_COUNT_LONG)
return -EIO;
}
return size;
}
static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
int size = 0;
int status;
u32 expected;
if (count < TPM_HEADER_SIZE) {
size = -EIO;
goto out;
}
/* read first 10 bytes, including tag, paramsize, and result */
size = recv_data(chip, buf, TPM_HEADER_SIZE);
if (size < TPM_HEADER_SIZE) {
dev_err(&chip->dev, "Unable to read header\n");
goto out;
}
expected = be32_to_cpu(*(__be32 *)(buf + 2));
if (((size_t) expected > count) || (expected < TPM_HEADER_SIZE)) {
size = -EIO;
goto out;
}
size += recv_data(chip, &buf[TPM_HEADER_SIZE],
expected - TPM_HEADER_SIZE);
if (size < expected) {
dev_err(&chip->dev, "Unable to read remainder of result\n");
size = -ETIME;
goto out;
}
wait_for_stat(chip, TPM_STS_VALID, chip->timeout_c, &status);
if (status & TPM_STS_DATA_AVAIL) { /* retry? */
dev_err(&chip->dev, "Error left over data\n");
size = -EIO;
goto out;
}
out:
tpm_tis_i2c_ready(chip);
/* The TPM needs some time to clean up here,
* so we sleep rather than keeping the bus busy
*/
usleep_range(SLEEP_DURATION_RESET_LOW, SLEEP_DURATION_RESET_HI);
release_locality(chip, tpm_dev.locality, 0);
return size;
}
static int tpm_tis_i2c_send(struct tpm_chip *chip, u8 *buf, size_t len)
{
int rc, status;
ssize_t burstcnt;
size_t count = 0;
u8 retries = 0;
u8 sts = TPM_STS_GO;
if (len > TPM_I2C_INFINEON_BUFSIZE)
return -E2BIG;
if (request_locality(chip, 0) < 0)
return -EBUSY;
status = tpm_tis_i2c_status(chip);
if ((status & TPM_STS_COMMAND_READY) == 0) {
tpm_tis_i2c_ready(chip);
if (wait_for_stat
(chip, TPM_STS_COMMAND_READY,
chip->timeout_b, &status) < 0) {
rc = -ETIME;
goto out_err;
}
}
while (count < len - 1) {
burstcnt = get_burstcount(chip);
/* burstcnt < 0 = TPM is busy */
if (burstcnt < 0)
return burstcnt;
if (burstcnt > (len - 1 - count))
burstcnt = len - 1 - count;
rc = iic_tpm_write(TPM_DATA_FIFO(tpm_dev.locality),
&(buf[count]), burstcnt);
if (rc == 0)
count += burstcnt;
else if (rc < 0)
retries++;
/* avoid endless loop in case of broken HW */
if (retries > MAX_COUNT_LONG) {
rc = -EIO;
goto out_err;
}
wait_for_stat(chip, TPM_STS_VALID,
chip->timeout_c, &status);
if ((status & TPM_STS_DATA_EXPECT) == 0) {
rc = -EIO;
goto out_err;
}
}
/* write last byte */
iic_tpm_write(TPM_DATA_FIFO(tpm_dev.locality), &(buf[count]), 1);
wait_for_stat(chip, TPM_STS_VALID, chip->timeout_c, &status);
if ((status & TPM_STS_DATA_EXPECT) != 0) {
rc = -EIO;
goto out_err;
}
/* go and do it */
iic_tpm_write(TPM_STS(tpm_dev.locality), &sts, 1);
return 0;
out_err:
tpm_tis_i2c_ready(chip);
/* The TPM needs some time to clean up here,
* so we sleep rather than keeping the bus busy
*/
usleep_range(SLEEP_DURATION_RESET_LOW, SLEEP_DURATION_RESET_HI);
release_locality(chip, tpm_dev.locality, 0);
return rc;
}
static bool tpm_tis_i2c_req_canceled(struct tpm_chip *chip, u8 status)
{
return (status == TPM_STS_COMMAND_READY);
}
static const struct tpm_class_ops tpm_tis_i2c = {
.flags = TPM_OPS_AUTO_STARTUP,
.status = tpm_tis_i2c_status,
.recv = tpm_tis_i2c_recv,
.send = tpm_tis_i2c_send,
.cancel = tpm_tis_i2c_ready,
.req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
.req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
.req_canceled = tpm_tis_i2c_req_canceled,
};
static int tpm_tis_i2c_init(struct device *dev)
{
u32 vendor;
int rc = 0;
struct tpm_chip *chip;
chip = tpmm_chip_alloc(dev, &tpm_tis_i2c);
if (IS_ERR(chip))
return PTR_ERR(chip);
/* Default timeouts */
chip->timeout_a = msecs_to_jiffies(TIS_SHORT_TIMEOUT);
chip->timeout_b = msecs_to_jiffies(TIS_LONG_TIMEOUT);
chip->timeout_c = msecs_to_jiffies(TIS_SHORT_TIMEOUT);
chip->timeout_d = msecs_to_jiffies(TIS_SHORT_TIMEOUT);
if (request_locality(chip, 0) != 0) {
dev_err(dev, "could not request locality\n");
rc = -ENODEV;
goto out_err;
}
/* read four bytes from DID_VID register */
if (iic_tpm_read(TPM_DID_VID(0), (u8 *)&vendor, 4) < 0) {
dev_err(dev, "could not read vendor id\n");
rc = -EIO;
goto out_release;
}
if (vendor == TPM_TIS_I2C_DID_VID_9645) {
tpm_dev.chip_type = SLB9645;
} else if (vendor == TPM_TIS_I2C_DID_VID_9635) {
tpm_dev.chip_type = SLB9635;
} else {
dev_err(dev, "vendor id did not match! ID was %08x\n", vendor);
rc = -ENODEV;
goto out_release;
}
dev_info(dev, "1.2 TPM (device-id 0x%X)\n", vendor >> 16);
tpm_dev.chip = chip;
return tpm_chip_register(chip);
out_release:
release_locality(chip, tpm_dev.locality, 1);
tpm_dev.client = NULL;
out_err:
return rc;
}
static const struct i2c_device_id tpm_tis_i2c_table[] = {
{"tpm_i2c_infineon"},
{"slb9635tt"},
{"slb9645tt"},
{},
};
MODULE_DEVICE_TABLE(i2c, tpm_tis_i2c_table);
#ifdef CONFIG_OF
static const struct of_device_id tpm_tis_i2c_of_match[] = {
{.compatible = "infineon,tpm_i2c_infineon"},
{.compatible = "infineon,slb9635tt"},
{.compatible = "infineon,slb9645tt"},
{},
};
MODULE_DEVICE_TABLE(of, tpm_tis_i2c_of_match);
#endif
static SIMPLE_DEV_PM_OPS(tpm_tis_i2c_ops, tpm_pm_suspend, tpm_pm_resume);
static int tpm_tis_i2c_probe(struct i2c_client *client)
{
int rc;
struct device *dev = &(client->dev);
if (tpm_dev.client != NULL) {
dev_err(dev, "This driver only supports one client at a time\n");
return -EBUSY; /* We only support one client */
}
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
dev_err(dev, "no algorithms associated to the i2c bus\n");
return -ENODEV;
}
tpm_dev.client = client;
rc = tpm_tis_i2c_init(&client->dev);
if (rc != 0) {
tpm_dev.client = NULL;
rc = -ENODEV;
}
return rc;
}
static void tpm_tis_i2c_remove(struct i2c_client *client)
{
struct tpm_chip *chip = tpm_dev.chip;
tpm_chip_unregister(chip);
release_locality(chip, tpm_dev.locality, 1);
tpm_dev.client = NULL;
}
static struct i2c_driver tpm_tis_i2c_driver = {
.id_table = tpm_tis_i2c_table,
.probe = tpm_tis_i2c_probe,
.remove = tpm_tis_i2c_remove,
.driver = {
.name = "tpm_i2c_infineon",
.pm = &tpm_tis_i2c_ops,
.of_match_table = of_match_ptr(tpm_tis_i2c_of_match),
},
};
module_i2c_driver(tpm_tis_i2c_driver);
MODULE_AUTHOR("Peter Huewe <[email protected]>");
MODULE_DESCRIPTION("TPM TIS I2C Infineon Driver");
MODULE_VERSION("2.2.0");
MODULE_LICENSE("GPL");
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