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|
/*
* Copyright (C) 2011 Infineon Technologies
*
* Authors:
* Peter Huewe <huewe.external@infineon.com>
*
* Description:
* 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 Linux kernel driver tpm.c from Leendert van
* Dorn, Dave Safford, Reiner Sailer, and Kyleen Hall.
*
* Version: 2.1.1
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, version 2 of the
* License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <stdint.h>
#include <string.h>
#include <types.h>
#include <delay.h>
#include <console/console.h>
#include <device/i2c.h>
#include <endian.h>
#include "tpm.h"
/* Address of the TPM on the I2C bus */
#define TPM_I2C_ADDR 0x20
/* max. number of iterations after I2C NAK */
#define MAX_COUNT 3
#define SLEEP_DURATION 60 /* in usec */
/* 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 210 /* in usec */
/* expected value for DIDVID register */
#define TPM_TIS_I2C_DID_VID_9635 0x000b15d1L
#define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L
enum i2c_chip_type {
SLB9635,
SLB9645,
UNKNOWN,
};
static const char * const chip_name[] = {
[SLB9635] = "slb9635tt",
[SLB9645] = "slb9645tt",
[UNKNOWN] = "unknown/fallback to slb9635",
};
/* Structure to store I2C TPM specific stuff */
struct tpm_inf_dev {
int bus;
unsigned int addr;
uint8_t buf[TPM_BUFSIZE + sizeof(uint8_t)]; // max. buffer size + addr
enum i2c_chip_type chip_type;
};
static struct tpm_inf_dev tpm_dev = {
.bus = -1,
.addr = TPM_I2C_ADDR
};
/*
* 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.
*
* Return -1 on error, 0 on success.
*/
static int iic_tpm_read(uint8_t addr, uint8_t *buffer, size_t len)
{
int rc;
int count;
if (tpm_dev.bus < 0)
return -1;
if ((tpm_dev.chip_type == SLB9635) || (tpm_dev.chip_type == UNKNOWN)) {
/* slb9635 protocol should work in both cases */
for (count = 0; count < MAX_COUNT; count++) {
rc = i2c_write_raw(tpm_dev.bus, tpm_dev.addr, &addr, 1);
if (rc == 0)
break; /* success, break to skip sleep */
udelay(SLEEP_DURATION);
}
if (rc)
return -1;
/* 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++) {
udelay(SLEEP_DURATION);
rc = i2c_read_raw(tpm_dev.bus, tpm_dev.addr,
buffer, len);
if (rc == 0)
break; /* success, break to skip sleep */
}
} else {
/* 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 safe on the safe side.
*/
struct i2c_seg aseg = { .read = 0, .chip = tpm_dev.addr,
.buf = &addr, .len = 1 };
struct i2c_seg dseg = { .read = 1, .chip = tpm_dev.addr,
.buf = buffer, .len = len };
for (count = 0; count < MAX_COUNT; count++) {
rc = i2c_transfer(tpm_dev.bus, &aseg, 1) ||
i2c_transfer(tpm_dev.bus, &dseg, 1);
if (rc == 0)
break; /* break here to skip sleep */
udelay(SLEEP_DURATION);
}
}
/* take care of 'guard time' */
udelay(SLEEP_DURATION);
if (rc)
return -1;
return 0;
}
static int iic_tpm_write_generic(uint8_t addr, uint8_t *buffer, size_t len,
unsigned int sleep_time,
uint8_t max_count)
{
int rc = 0;
int count;
if (len > TPM_BUFSIZE) {
printk(BIOS_DEBUG, "%s: Length %zd is too large\n", __func__, len);
return -1;
}
/* prepare send buffer */
tpm_dev.buf[0] = addr;
memcpy(&(tpm_dev.buf[1]), buffer, len);
if (tpm_dev.bus < 0)
return -1;
for (count = 0; count < max_count; count++) {
rc = i2c_write_raw(tpm_dev.bus, tpm_dev.addr,
tpm_dev.buf, len + 1);
if (rc == 0)
break; /* success, break to skip sleep */
udelay(sleep_time);
}
/* take care of 'guard time' */
udelay(SLEEP_DURATION);
if (rc)
return -1;
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(uint8_t addr, uint8_t *buffer, size_t len)
{
return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION,
MAX_COUNT);
}
/*
* This function is needed especially for the cleanup situation after
* sending TPM_READY
* */
static int iic_tpm_write_long(uint8_t addr, uint8_t *buffer, size_t len)
{
return iic_tpm_write_generic(addr, buffer, len, SLEEP_DURATION_LONG,
MAX_COUNT_LONG);
}
#define TPM_HEADER_SIZE 10
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,
};
#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 int check_locality(struct tpm_chip *chip, int loc)
{
uint8_t buf;
if (iic_tpm_read(TPM_ACCESS(loc), &buf, 1) < 0)
return -1;
if ((buf & (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) ==
(TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) {
chip->vendor.locality = loc;
return loc;
}
return -1;
}
static void release_locality(struct tpm_chip *chip, int loc, int force)
{
uint8_t 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)
{
uint8_t buf = TPM_ACCESS_REQUEST_USE;
if (check_locality(chip, loc) >= 0)
return loc; /* we already have the locality */
iic_tpm_write(TPM_ACCESS(loc), &buf, 1);
/* wait for burstcount */
int timeout = 2 * 1000; /* 2s timeout */
while (timeout) {
if (check_locality(chip, loc) >= 0)
return loc;
mdelay(TPM_TIMEOUT);
timeout--;
}
return -1;
}
static uint8_t tpm_tis_i2c_status(struct tpm_chip *chip)
{
/* NOTE: Since I2C read may fail, return 0 in this case --> time-out */
uint8_t buf;
if (iic_tpm_read(TPM_STS(chip->vendor.locality), &buf, 1) < 0)
return 0;
else
return buf;
}
static void tpm_tis_i2c_ready(struct tpm_chip *chip)
{
/* this causes the current command to be aborted */
uint8_t buf = TPM_STS_COMMAND_READY;
iic_tpm_write_long(TPM_STS(chip->vendor.locality), &buf, 1);
}
static ssize_t get_burstcount(struct tpm_chip *chip)
{
ssize_t burstcnt;
uint8_t buf[3];
/* wait for burstcount */
int timeout = 2 * 1000; /* 2s timeout */
while (timeout) {
/* Note: STS is little endian */
if (iic_tpm_read(TPM_STS(chip->vendor.locality) + 1, buf, 3) < 0)
burstcnt = 0;
else
burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0];
if (burstcnt)
return burstcnt;
mdelay(TPM_TIMEOUT);
timeout--;
}
return -1;
}
static int wait_for_stat(struct tpm_chip *chip, uint8_t mask, int *status)
{
unsigned long timeout = 2 * 1024;
while (timeout) {
*status = tpm_tis_i2c_status(chip);
if ((*status & mask) == mask)
return 0;
mdelay(TPM_TIMEOUT);
timeout--;
}
return -1;
}
static int recv_data(struct tpm_chip *chip, uint8_t *buf, size_t count)
{
size_t size = 0;
while (size < count) {
ssize_t burstcnt = get_burstcount(chip);
int rc;
/* burstcount < 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(chip->vendor.locality),
&(buf[size]),
burstcnt);
if (rc == 0)
size += burstcnt;
}
return size;
}
static int tpm_tis_i2c_recv(struct tpm_chip *chip, uint8_t *buf, size_t count)
{
int size = 0;
uint32_t expected;
int status;
if (count < TPM_HEADER_SIZE) {
size = -1;
goto out;
}
/* read first 10 bytes, including tag, paramsize, and result */
size = recv_data(chip, buf, TPM_HEADER_SIZE);
if (size < TPM_HEADER_SIZE) {
printk(BIOS_DEBUG, "tpm_tis_i2c_recv: Unable to read header\n");
goto out;
}
memcpy(&expected, buf + TPM_RSP_SIZE_BYTE, sizeof(expected));
expected = be32_to_cpu(expected);
if ((size_t)expected > count) {
size = -1;
goto out;
}
size += recv_data(chip, &buf[TPM_HEADER_SIZE],
expected - TPM_HEADER_SIZE);
if (size < expected) {
printk(BIOS_DEBUG, "tpm_tis_i2c_recv: Unable to "
"read remainder of result\n");
size = -1;
goto out;
}
wait_for_stat(chip, TPM_STS_VALID, &status);
if (status & TPM_STS_DATA_AVAIL) { /* retry? */
printk(BIOS_DEBUG, "tpm_tis_i2c_recv: Error left over data\n");
size = -1;
goto out;
}
out:
tpm_tis_i2c_ready(chip);
return size;
}
static int tpm_tis_i2c_send(struct tpm_chip *chip, uint8_t *buf, size_t len)
{
int status;
size_t count = 0;
uint8_t sts = TPM_STS_GO;
if (len > TPM_BUFSIZE)
return -1; /* command is too long for our TPM, sorry */
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, &status) < 0)
goto out_err;
}
while (count < len - 1) {
ssize_t burstcnt = get_burstcount(chip);
/* burstcount < 0 = TPM is busy */
if (burstcnt < 0)
return burstcnt;
if (burstcnt > (len-1-count))
burstcnt = len-1-count;
#ifdef CONFIG_TPM_I2C_BURST_LIMITATION
if (burstcnt > CONFIG_TPM_I2C_BURST_LIMITATION)
burstcnt = CONFIG_TPM_I2C_BURST_LIMITATION;
#endif /* CONFIG_TPM_I2C_BURST_LIMITATION */
if (iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality),
&(buf[count]), burstcnt) == 0)
count += burstcnt;
wait_for_stat(chip, TPM_STS_VALID, &status);
if ((status & TPM_STS_DATA_EXPECT) == 0)
goto out_err;
}
/* write last byte */
iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality), &(buf[count]), 1);
wait_for_stat(chip, TPM_STS_VALID, &status);
if ((status & TPM_STS_DATA_EXPECT) != 0)
goto out_err;
/* go and do it */
iic_tpm_write(TPM_STS(chip->vendor.locality), &sts, 1);
return len;
out_err:
tpm_tis_i2c_ready(chip);
return -1;
}
static struct tpm_vendor_specific tpm_tis_i2c = {
.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_STS_COMMAND_READY,
};
/* Initialization of I2C TPM */
int tpm_vendor_init(unsigned bus, uint32_t dev_addr)
{
uint32_t vendor;
unsigned int old_addr;
struct tpm_chip *chip;
extern struct tpm_chip g_chip;
old_addr = tpm_dev.addr;
if (dev_addr != 0)
tpm_dev.addr = dev_addr;
tpm_dev.bus = bus;
chip = &g_chip;
memcpy(&chip->vendor, &tpm_tis_i2c, sizeof(struct tpm_vendor_specific));
chip->is_open = 1;
/* Disable interrupts (not supported) */
chip->vendor.irq = 0;
if (request_locality(chip, 0) != 0)
goto out_err;
/* Read four bytes from DID_VID register */
if (iic_tpm_read(TPM_DID_VID(0), (uint8_t *)&vendor, 4) < 0)
goto out_release;
if (vendor == TPM_TIS_I2C_DID_VID_9645) {
tpm_dev.chip_type = SLB9645;
} else if (be32_to_cpu(vendor) == TPM_TIS_I2C_DID_VID_9635) {
tpm_dev.chip_type = SLB9635;
} else {
printk(BIOS_DEBUG, "Vendor ID 0x%08x not recognized.\n", vendor);
goto out_release;
}
printk(BIOS_DEBUG, "1.2 TPM (chip type %s device-id 0x%X)\n",
chip_name[tpm_dev.chip_type], vendor >> 16);
/*
* A timeout query to TPM can be placed here.
* Standard timeout values are used so far
*/
return 0;
out_release:
release_locality(chip, 0, 1);
out_err:
tpm_dev.addr = old_addr;
return -1;
}
void tpm_vendor_cleanup(struct tpm_chip *chip)
{
release_locality(chip, chip->vendor.locality, 1);
}
|