[U-Boot] [PATCH] Introduce generic TPM support in u-boot
Vadim Bendebury
vbendeb at chromium.org
Mon Oct 10 04:53:26 CEST 2011
TPM (Trusted Platform Module) is an integrated circuit and
software platform that provides computer manufacturers with the
core components of a subsystem used to assure authenticity,
integrity and confidentiality.
This driver supports version 1.2 of the TCG (Trusted Computing
Group) specifications.
The TCG specification defines several so called localities in a
TPM chip, to be controlled by different software layers. When
used on a typical x86 platform during the firmware phase, only
locality 0 can be accessed by the CPU, so this driver even while
supporting the locality concept presumes that only locality zero
is used.
This implementation is loosely based on the article "Writing a
TPM Device Driver" published on http://ptgmedia.pearsoncmg.com
and a submission by Stefan Berger on Qemu-devel mailing list
(http://lists.gnu.org/archive/html/qemu-devel).
Compiling this driver with DEBUG defined will generate trace of
all accesses to TMP registers.
This driver has been tested and is being used in three different
functional ChromeOS machines (Pinetrail and Sandy Bridge Intel
chipsets) all using the same Infineon SLB 9635 TT 1.2 device.
A u-boot cli command allowing access to the TPM was also
implemented and will be submitted separately.
Change-Id: I22a33c3e5b2e20eec9557a7621bd463b30389d73
Signed-off-by: Vadim Bendebury <vbendeb at chromium.org>
CC: Wolfgang Denk <wd at denx.de>
---
Makefile | 3 +
README | 8 +
drivers/tpm/Makefile | 27 ++
drivers/tpm/generic_lpc_tpm.c | 523 +++++++++++++++++++++++++++++++++++++++++
include/tpm.h | 17 ++
5 files changed, 578 insertions(+), 0 deletions(-)
create mode 100644 drivers/tpm/Makefile
create mode 100644 drivers/tpm/generic_lpc_tpm.c
create mode 100644 include/tpm.h
diff --git a/Makefile b/Makefile
index cd6fc8c..996db11 100644
--- a/Makefile
+++ b/Makefile
@@ -268,6 +268,9 @@ LIBS += arch/powerpc/cpu/mpc8xxx/lib8xxx.o
endif
LIBS += drivers/rtc/librtc.o
LIBS += drivers/serial/libserial.o
+ifneq ($(CONFIG_GENERIC_LPC_TPM),)
+LIBS += drivers/tpm/libtpm.o
+endif
LIBS += drivers/twserial/libtws.o
LIBS += drivers/usb/eth/libusb_eth.o
LIBS += drivers/usb/gadget/libusb_gadget.o
diff --git a/README b/README
index 0868531..e831d68 100644
--- a/README
+++ b/README
@@ -1016,6 +1016,14 @@ The following options need to be configured:
CONFIG_SH_ETHER_CACHE_WRITEBACK
If this option is set, the driver enables cache flush.
+- TPM Support:
+ CONFIG_GENERIC_LPC_TPM
+ Support for generic parallel port TPM devices.
+
+ CONFIG_TPM_TIS_BASE_ADDRESS
+ Base address where the generic TPM device is mapped
+ to. Default value is 0xfed40000.
+
- USB Support:
At the moment only the UHCI host controller is
supported (PIP405, MIP405, MPC5200); define
diff --git a/drivers/tpm/Makefile b/drivers/tpm/Makefile
new file mode 100644
index 0000000..abe1180
--- /dev/null
+++ b/drivers/tpm/Makefile
@@ -0,0 +1,27 @@
+# Copyright (c) 2011 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 $(TOPDIR)/config.mk
+
+LIB := $(obj)libtpm.o
+
+COBJS-$(CONFIG_GENERIC_LPC_TPM) = generic_lpc_tpm.o
+
+COBJS := $(COBJS-y)
+SRCS := $(COBJS:.o=.c)
+OBJS := $(addprefix $(obj),$(COBJS))
+
+all: $(LIB)
+
+$(LIB): $(obj).depend $(OBJS)
+ $(AR) $(ARFLAGS) $@ $(OBJS)
+
+#########################################################################
+
+include $(SRCTREE)/rules.mk
+
+sinclude $(obj).depend
+
+#########################################################################
diff --git a/drivers/tpm/generic_lpc_tpm.c b/drivers/tpm/generic_lpc_tpm.c
new file mode 100644
index 0000000..939f715
--- /dev/null
+++ b/drivers/tpm/generic_lpc_tpm.c
@@ -0,0 +1,523 @@
+/* Copyright (c) 2011 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.
+ *
+ * The code in this file has been heavily based on the article "Writing a TPM
+ * Device Driver" published on http://ptgmedia.pearsoncmg.com and the
+ * submission by Stefan Berger on Qemu-devel mailing list.
+ *
+ * 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.
+ */
+
+/* #define DEBUG */
+#include <common.h>
+#include <asm/io.h>
+#include <tpm.h>
+
+#ifdef DEBUG
+#define TPM_DEBUG_ON 1
+#else
+#define TPM_DEBUG_ON 0
+#endif
+
+#define PREFIX "lpc_tpm: "
+#define TPM_DEBUG(fmt, args...) \
+ if (TPM_DEBUG_ON) { \
+ printf(PREFIX); \
+ printf(fmt , ##args); \
+ }
+
+#ifndef CONFIG_TPM_TIS_BASE_ADDRESS
+/* Base TPM address standard for x86 systems */
+#define CONFIG_TPM_TIS_BASE_ADDRESS 0xfed40000
+#endif
+
+/* the macro accepts the locality value, but only locality 0 is operational */
+#define TIS_REG(LOCALITY, REG) \
+ (void *)(CONFIG_TPM_TIS_BASE_ADDRESS + (LOCALITY << 12) + REG)
+
+/* hardware registers' offsets */
+#define TIS_REG_ACCESS 0x0
+#define TIS_REG_INT_ENABLE 0x8
+#define TIS_REG_INT_VECTOR 0xc
+#define TIS_REG_INT_STATUS 0x10
+#define TIS_REG_INTF_CAPABILITY 0x14
+#define TIS_REG_STS 0x18
+#define TIS_REG_DATA_FIFO 0x24
+#define TIS_REG_DID_VID 0xf00
+#define TIS_REG_RID 0xf04
+
+/* 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 ~0,
+ * so this value is a safe error indication to be mixed with possible status
+ * register values.
+ */
+#define TPM_TIMEOUT_ERR (~0)
+
+/* Error value returned on various TPM driver errors */
+#define TPM_DRIVER_ERR (~0)
+
+ /* 1 second is plenty for anything TPM does.*/
+#define MAX_DELAY_US (1000 * 1000)
+
+/* Retrieve burst count value out of the status register contents. */
+#define BURST_COUNT(status) ((u16)(((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;
+ struct device_name *dev_names;
+};
+
+static 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;
+
+static int is_byte_reg(u32 reg)
+{
+ /*
+ * These TPM registers are 8 bits wide and as such require byte access
+ * on writes and truncated value on reads.
+ */
+ return ((reg == TIS_REG_ACCESS) ||
+ (reg == TIS_REG_INT_VECTOR) ||
+ (reg == TIS_REG_DATA_FIFO));
+}
+
+/* TPM access functions are carved out to make tracing easier. */
+static u32 tpm_read(int locality, u32 reg)
+{
+ u32 value;
+ /*
+ * Data FIFO register must be read and written in byte access mode,
+ * otherwise the FIFO values are returned 4 bytes at a time.
+ */
+ if (is_byte_reg(reg))
+ value = readb(TIS_REG(locality, reg));
+ else
+ value = readl(TIS_REG(locality, reg));
+
+ TPM_DEBUG("Read reg 0x%x returns 0x%x\n", reg, value);
+ return value;
+}
+
+static void tpm_write(u32 value, int locality, u32 reg)
+{
+ TPM_DEBUG("Write reg 0x%x with 0x%x\n", reg, value);
+
+ if (is_byte_reg(reg))
+ writeb(value & 0xff, TIS_REG(locality, reg));
+ else
+ writel(value, TIS_REG(locality, reg));
+}
+
+/*
+ * 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 - the TPM register offset
+ * @locality - locality
+ * @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(u8 reg, u8 locality, u8 mask, u8 expected)
+{
+ u32 time_us = MAX_DELAY_US;
+ while (time_us > 0) {
+ u32 value = tpm_read(locality, 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.
+ */
+static u32 tis_probe(void)
+{
+ u32 didvid = tpm_read(0, TIS_REG_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;
+ }
+ /* this will have to be converted into debug printout */
+ TPM_DEBUG("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(TIS_REG_STS, locality, 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(locality, TIS_REG_STS));
+ }
+
+ 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(burst, len - offset - 1);
+ while (count--)
+ tpm_write(data[offset++], locality, TIS_REG_DATA_FIFO);
+
+ value = tis_wait_reg(TIS_REG_STS, locality,
+ 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(data[offset++], locality, TIS_REG_DATA_FIFO);
+
+ /*
+ * Verify that TPM does not expect any more data as part of this
+ * command.
+ */
+ value = tis_wait_reg(TIS_REG_STS, locality,
+ 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(TIS_STS_TPM_GO, locality, TIS_REG_STS);
+
+ 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_count;
+ u32 status;
+ 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 */
+ status = tis_wait_reg(TIS_REG_STS, locality, has_data, has_data);
+ if (status == TPM_TIMEOUT_ERR) {
+ printf("%s:%d failed processing command\n",
+ __FILE__, __LINE__);
+ return TPM_DRIVER_ERR;
+ }
+
+ do {
+ while ((burst_count = BURST_COUNT(status)) == 0) {
+ if (max_cycles++ == MAX_DELAY_US) {
+ printf("%s:%d TPM stuck on read\n",
+ __FILE__, __LINE__);
+ return TPM_DRIVER_ERR;
+ }
+ udelay(1);
+ status = tpm_read(locality, TIS_REG_STS);
+ }
+
+ max_cycles = 0;
+
+ while (burst_count-- && (offset < expected_count)) {
+ buffer[offset++] = (u8) tpm_read(locality,
+ TIS_REG_DATA_FIFO);
+ 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 */
+ status = tis_wait_reg(TIS_REG_STS, locality,
+ TIS_STS_VALID, TIS_STS_VALID);
+ if (status == 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 need */
+
+ } while ((status & has_data) == has_data);
+
+ /*
+ * Make sure we indeed read all there was. The TIS_STS_VALID bit is
+ * known to be set.
+ */
+ if (status & TIS_STS_DATA_AVAILABLE) {
+ printf("%s:%d wrong receive status %x\n",
+ __FILE__, __LINE__, status);
+ return TPM_DRIVER_ERR;
+ }
+
+ /* Tell the TPM that we are done. */
+ tpm_write(TIS_STS_COMMAND_READY, locality, TIS_REG_STS);
+
+ *len = offset;
+ return 0;
+}
+
+/*
+ * tis_init()
+ *
+ * Initialize the TPM device. Returns 0 on success or TPM_DRIVER_ERR on
+ * failure (in case device probing did not succeed).
+ */
+int tis_init(void)
+{
+ if (tis_probe())
+ return TPM_DRIVER_ERR;
+ return 0;
+}
+
+/*
+ * tis_open()
+ *
+ * Requests access to locality 0 for the caller. After all commands have been
+ * completed the caller is supposed to call tis_close().
+ *
+ * Returns 0 on success, TPM_DRIVER_ERR on failure.
+ */
+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(TIS_ACCESS_REQUEST_USE, locality, TIS_REG_ACCESS);
+
+ /* did we get a lock? */
+ if (tis_wait_reg(TIS_REG_ACCESS, locality,
+ 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(TIS_STS_COMMAND_READY, locality, TIS_REG_STS);
+
+ return 0;
+}
+
+/*
+ * tis_close()
+ *
+ * terminate the currect session with the TPM by releasing the locked
+ * locality. Returns 0 on success of TPM_DRIVER_ERR on failure (in case lock
+ * removal did not succeed).
+ */
+int tis_close(void)
+{
+ u8 locality = 0;
+ if (tpm_read(locality, TIS_REG_ACCESS) &
+ TIS_ACCESS_ACTIVE_LOCALITY) {
+ tpm_write(TIS_ACCESS_ACTIVE_LOCALITY, locality, TIS_REG_ACCESS);
+
+ if (tis_wait_reg(TIS_REG_ACCESS, locality,
+ 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;
+}
+
+/*
+ * tis_sendrecv()
+ *
+ * Send the requested data to the TPM and then try to get its response
+ *
+ * @sendbuf - buffer of the data to send
+ * @send_size size of the data to send
+ * @recvbuf - memory to save the response to
+ * @recv_len - pointer to the size of the response buffer
+ *
+ * Returns 0 on success (and places the number of response bytes at recv_len)
+ * or TPM_DRIVER_ERR on failure.
+ */
+int tis_sendrecv(const uint8_t *sendbuf, size_t send_size,
+ uint8_t *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, recv_len);
+}
diff --git a/include/tpm.h b/include/tpm.h
new file mode 100644
index 0000000..7b0d415
--- /dev/null
+++ b/include/tpm.h
@@ -0,0 +1,17 @@
+/* Copyright (c) 2011 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.
+ */
+
+#ifndef TPM_H_
+#define TPM_H_
+
+#include <common.h>
+
+int tis_init(void);
+int tis_open(void);
+int tis_close(void);
+int tis_sendrecv(const uint8_t *sendbuf, size_t send_size, uint8_t *recvbuf,
+ size_t *recv_len);
+
+#endif /* TPM_H_ */
--
1.7.3.1
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