Patchwork [U-Boot,4/5] tpm: Reorganize the I2C TPM driver

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Submitter Simon Glass
Date April 12, 2013, 9:04 p.m.
Message ID <1365800678-5251-4-git-send-email-sjg@chromium.org>
Download mbox | patch
Permalink /patch/236215/
State Accepted
Delegated to: Tom Rini
Headers show

Comments

Simon Glass - April 12, 2013, 9:04 p.m.
From: Tom Wai-Hong Tam <waihong@chromium.org>

This patch does a similar code reogranzation from
  http://patchwork.ozlabs.org/patch/132179/
which is based on an old version of code (fdt support and bus selection
still not in). It merges this tidy-up on top of the recent code. It does
not make any logical change.

tpm.c implements the interface defined in tpm.h based on underlying
LPC or I2C TPM driver. tpm.c and the underlying driver communicate
throught tpm_private.h.

Note: Merging the LPC driver with tpm.c is left to future patches.

Signed-off-by: Tom Wai-Hong Tam <waihong@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
---
 README                                           |  13 ++
 drivers/tpm/Makefile                             |   7 +-
 drivers/tpm/slb9635_i2c/compatibility.h          |  51 -----
 drivers/tpm/{slb9635_i2c => }/tpm.c              | 280 ++++++++++++++++++-----
 drivers/tpm/{slb9635_i2c/tpm.h => tpm_private.h} |  46 +---
 drivers/tpm/{slb9635_i2c => }/tpm_tis_i2c.c      | 267 +++++++++++----------
 6 files changed, 396 insertions(+), 268 deletions(-)
 delete mode 100644 drivers/tpm/slb9635_i2c/compatibility.h
 rename drivers/tpm/{slb9635_i2c => }/tpm.c (63%)
 rename drivers/tpm/{slb9635_i2c/tpm.h => tpm_private.h} (71%)
 rename drivers/tpm/{slb9635_i2c => }/tpm_tis_i2c.c (73%)

Patch

diff --git a/README b/README
index abc8b55..697962e 100644
--- a/README
+++ b/README
@@ -1212,6 +1212,19 @@  The following options need to be configured:
 		CONFIG_TPM
 		Support TPM devices.
 
+		CONFIG_TPM_TIS_I2C
+		Support for i2c bus TPM devices. Only one device
+		per system is supported at this time.
+
+			CONFIG_TPM_TIS_I2C_BUS_NUMBER
+			Define the the i2c bus number for the TPM device
+
+			CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS
+			Define the TPM's address on the i2c bus
+
+			CONFIG_TPM_TIS_I2C_BURST_LIMITATION
+			Define the burst count bytes upper limit
+
 		CONFIG_TPM_TIS_LPC
 		Support for generic parallel port TPM devices. Only one device
 		per system is supported at this time.
diff --git a/drivers/tpm/Makefile b/drivers/tpm/Makefile
index d1f9bbf..913dd9c 100644
--- a/drivers/tpm/Makefile
+++ b/drivers/tpm/Makefile
@@ -25,9 +25,10 @@  LIB := $(obj)libtpm.o
 
 $(shell mkdir -p $(obj)slb9635_i2c)
 
-COBJS-$(CONFIG_TPM_TIS_LPC) = tpm_tis_lpc.o
-COBJS-$(CONFIG_INFINEON_TPM_I2C) += tis_i2c.o slb9635_i2c/tpm.o
-COBJS-$(CONFIG_INFINEON_TPM_I2C) += slb9635_i2c/tpm_tis_i2c.o
+# TODO: Merge tpm_tis_lpc.c with tpm.c
+COBJS-$(CONFIG_TPM_TIS_I2C) += tpm.o
+COBJS-$(CONFIG_TPM_TIS_I2C) += tpm_tis_i2c.o
+COBJS-$(CONFIG_TPM_TIS_LPC) += tpm_tis_lpc.o
 
 COBJS	:= $(COBJS-y)
 SRCS	:= $(COBJS:.o=.c)
diff --git a/drivers/tpm/slb9635_i2c/compatibility.h b/drivers/tpm/slb9635_i2c/compatibility.h
deleted file mode 100644
index 62dc9fa..0000000
--- a/drivers/tpm/slb9635_i2c/compatibility.h
+++ /dev/null
@@ -1,51 +0,0 @@ 
-/*
- * Copyright (C) 2011 Infineon Technologies
- *
- * Authors:
- * Peter Huewe <huewe.external@infineon.com>
- *
- * 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; either version 2 of
- * the License, or (at your option) any later version.
- *
- * 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
- */
-
-#ifndef _COMPATIBILITY_H_
-#define _COMPATIBILITY_H_
-
-/* all includes from U-Boot */
-#include <linux/types.h>
-#include <linux/unaligned/be_byteshift.h>
-#include <asm-generic/errno.h>
-#include <compiler.h>
-#include <common.h>
-
-/* extended error numbers from linux (see errno.h) */
-#define	ECANCELED	125	/* Operation Canceled */
-
-#define msleep(t) udelay((t)*1000)
-
-/* Timer frequency. Corresponds to msec timer resolution*/
-#define HZ             1000
-
-#define dev_dbg(dev, format, arg...) debug(format, ##arg)
-#define dev_err(dev, format, arg...) printf(format, ##arg)
-#define dev_info(dev, format, arg...) debug(format, ##arg)
-#define dbg_printf debug
-
-#endif
diff --git a/drivers/tpm/slb9635_i2c/tpm.c b/drivers/tpm/tpm.c
similarity index 63%
rename from drivers/tpm/slb9635_i2c/tpm.c
rename to drivers/tpm/tpm.c
index 496c48e..b657334 100644
--- a/drivers/tpm/slb9635_i2c/tpm.c
+++ b/drivers/tpm/tpm.c
@@ -32,11 +32,30 @@ 
  * MA 02111-1307 USA
  */
 
-#include <malloc.h>
-#include "tpm.h"
+#include <config.h>
+#include <common.h>
+#include <compiler.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <tpm.h>
+#include <asm-generic/errno.h>
+#include <linux/types.h>
+#include <linux/unaligned/be_byteshift.h>
 
-/* global structure for tpm chip data */
-struct tpm_chip g_chip;
+#include "tpm_private.h"
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/* TPM configuration */
+struct tpm {
+	int i2c_bus;
+	int slave_addr;
+	char inited;
+	int old_bus;
+} tpm;
+
+/* Global structure for tpm chip data */
+static struct tpm_chip g_chip;
 
 enum tpm_duration {
 	TPM_SHORT = 0,
@@ -45,9 +64,18 @@  enum tpm_duration {
 	TPM_UNDEFINED,
 };
 
-#define TPM_MAX_ORDINAL 243
-#define TPM_MAX_PROTECTED_ORDINAL 12
-#define TPM_PROTECTED_ORDINAL_MASK 0xFF
+/* Extended error numbers from linux (see errno.h) */
+#define ECANCELED	125	/* Operation Canceled */
+
+/* Timer frequency. Corresponds to msec timer resolution*/
+#define HZ		1000
+
+#define TPM_MAX_ORDINAL			243
+#define TPM_MAX_PROTECTED_ORDINAL	12
+#define TPM_PROTECTED_ORDINAL_MASK	0xFF
+
+#define TPM_CMD_COUNT_BYTE	2
+#define TPM_CMD_ORDINAL_BYTE	6
 
 /*
  * Array with one entry per ordinal defining the maximum amount
@@ -318,34 +346,31 @@  static const u8 tpm_ordinal_duration[TPM_MAX_ORDINAL] = {
 	TPM_MEDIUM,
 };
 
-/*
- * Returns max number of milliseconds to wait
- */
-unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
+/* Returns max number of milliseconds to wait */
+static unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip,
+		u32 ordinal)
 {
 	int duration_idx = TPM_UNDEFINED;
 	int duration = 0;
 
-	if (ordinal < TPM_MAX_ORDINAL)
+	if (ordinal < TPM_MAX_ORDINAL) {
 		duration_idx = tpm_ordinal_duration[ordinal];
-	else if ((ordinal & TPM_PROTECTED_ORDINAL_MASK) <
-		 TPM_MAX_PROTECTED_ORDINAL)
-		duration_idx =
-		    tpm_protected_ordinal_duration[ordinal &
-						   TPM_PROTECTED_ORDINAL_MASK];
+	} else if ((ordinal & TPM_PROTECTED_ORDINAL_MASK) <
+			TPM_MAX_PROTECTED_ORDINAL) {
+		duration_idx = tpm_protected_ordinal_duration[
+				ordinal & TPM_PROTECTED_ORDINAL_MASK];
+	}
 
 	if (duration_idx != TPM_UNDEFINED)
 		duration = chip->vendor.duration[duration_idx];
+
 	if (duration <= 0)
-		return 2 * 60 * HZ; /*two minutes timeout*/
+		return 2 * 60 * HZ; /* Two minutes timeout */
 	else
 		return duration;
 }
 
-#define TPM_CMD_COUNT_BYTE 2
-#define TPM_CMD_ORDINAL_BYTE 6
-
-ssize_t tpm_transmit(const unsigned char *buf, size_t bufsiz)
+static ssize_t tpm_transmit(const unsigned char *buf, size_t bufsiz)
 {
 	ssize_t rc;
 	u32 count, ordinal;
@@ -358,18 +383,17 @@  ssize_t tpm_transmit(const unsigned char *buf, size_t bufsiz)
 	ordinal = get_unaligned_be32(buf + TPM_CMD_ORDINAL_BYTE);
 
 	if (count == 0) {
-		dev_err(chip->dev, "no data\n");
+		error("no data\n");
 		return -ENODATA;
 	}
 	if (count > bufsiz) {
-		dev_err(chip->dev,
-			"invalid count value %x %zx\n", count, bufsiz);
+		error("invalid count value %x %zx\n", count, bufsiz);
 		return -E2BIG;
 	}
 
 	rc = chip->vendor.send(chip, (u8 *)buf, count);
 	if (rc < 0) {
-		dev_err(chip->dev, "tpm_transmit: tpm_send: error %zd\n", rc);
+		error("tpm_transmit: tpm_send: error %zd\n", rc);
 		goto out;
 	}
 
@@ -379,47 +403,126 @@  ssize_t tpm_transmit(const unsigned char *buf, size_t bufsiz)
 	start = get_timer(0);
 	stop = tpm_calc_ordinal_duration(chip, ordinal);
 	do {
-		dbg_printf("waiting for status...\n");
+		debug("waiting for status...\n");
 		u8 status = chip->vendor.status(chip);
 		if ((status & chip->vendor.req_complete_mask) ==
 		    chip->vendor.req_complete_val) {
-			dbg_printf("...got it;\n");
+			debug("...got it;\n");
 			goto out_recv;
 		}
 
 		if ((status == chip->vendor.req_canceled)) {
-			dev_err(chip->dev, "Operation Canceled\n");
+			error("Operation Canceled\n");
 			rc = -ECANCELED;
 			goto out;
 		}
-		msleep(TPM_TIMEOUT);
+		udelay(TPM_TIMEOUT * 1000);
 	} while (get_timer(start) < stop);
 
 	chip->vendor.cancel(chip);
-	dev_err(chip->dev, "Operation Timed out\n");
+	error("Operation Timed out\n");
 	rc = -ETIME;
 	goto out;
 
 out_recv:
-
-	dbg_printf("out_recv: reading response...\n");
+	debug("out_recv: reading response...\n");
 	rc = chip->vendor.recv(chip, (u8 *)buf, TPM_BUFSIZE);
 	if (rc < 0)
-		dev_err(chip->dev, "tpm_transmit: tpm_recv: error %zd\n", rc);
+		error("tpm_transmit: tpm_recv: error %zd\n", rc);
+
 out:
 	return rc;
 }
 
-#define TPM_ERROR_SIZE 10
+static int tpm_open(uint32_t dev_addr)
+{
+	int rc;
+	if (g_chip.is_open)
+		return -EBUSY;
+	rc = tpm_vendor_init(dev_addr);
+	if (rc < 0)
+		g_chip.is_open = 0;
+	return rc;
+}
 
-enum tpm_capabilities {
-	TPM_CAP_PROP = cpu_to_be32(5),
-};
+static void tpm_close(void)
+{
+	if (g_chip.is_open) {
+		tpm_vendor_cleanup(&g_chip);
+		g_chip.is_open = 0;
+	}
+}
 
-enum tpm_sub_capabilities {
-	TPM_CAP_PROP_TIS_TIMEOUT = cpu_to_be32(0x115),
-	TPM_CAP_PROP_TIS_DURATION = cpu_to_be32(0x120),
-};
+static int tpm_select(void)
+{
+	int ret;
+
+	tpm.old_bus = i2c_get_bus_num();
+	if (tpm.old_bus != tpm.i2c_bus) {
+		ret = i2c_set_bus_num(tpm.i2c_bus);
+		if (ret) {
+			debug("%s: Fail to set i2c bus %d\n", __func__,
+			      tpm.i2c_bus);
+			return -1;
+		}
+	}
+	return 0;
+}
+
+static int tpm_deselect(void)
+{
+	int ret;
+
+	if (tpm.old_bus != i2c_get_bus_num()) {
+		ret = i2c_set_bus_num(tpm.old_bus);
+		if (ret) {
+			debug("%s: Fail to restore i2c bus %d\n",
+			      __func__, tpm.old_bus);
+			return -1;
+		}
+	}
+	tpm.old_bus = -1;
+	return 0;
+}
+
+/**
+ * Decode TPM configuration.
+ *
+ * @param dev	Returns a configuration of TPM device
+ * @return 0 if ok, -1 on error
+ */
+static int tpm_decode_config(struct tpm *dev)
+{
+#ifdef CONFIG_OF_CONTROL
+	const void *blob = gd->fdt_blob;
+	int node, parent;
+	int i2c_bus;
+
+	node = fdtdec_next_compatible(blob, 0, COMPAT_INFINEON_SLB9635_TPM);
+	if (node < 0) {
+		node = fdtdec_next_compatible(blob, 0,
+				COMPAT_INFINEON_SLB9645_TPM);
+	}
+	if (node < 0) {
+		debug("%s: Node not found\n", __func__);
+		return -1;
+	}
+	parent = fdt_parent_offset(blob, node);
+	if (parent < 0) {
+		debug("%s: Cannot find node parent\n", __func__);
+		return -1;
+	}
+	i2c_bus = i2c_get_bus_num_fdt(parent);
+	if (i2c_bus < 0)
+		return -1;
+	dev->i2c_bus = i2c_bus;
+	dev->slave_addr = fdtdec_get_addr(blob, node, "reg");
+#else
+	dev->i2c_bus = CONFIG_TPM_TIS_I2C_BUS_NUMBER;
+	dev->slave_addr = CONFIG_TPM_TIS_I2C_SLAVE_ADDRESS;
+#endif
+	return 0;
+}
 
 struct tpm_chip *tpm_register_hardware(const struct tpm_vendor_specific *entry)
 {
@@ -433,21 +536,94 @@  struct tpm_chip *tpm_register_hardware(const struct tpm_vendor_specific *entry)
 	return chip;
 }
 
-int tpm_open(uint32_t dev_addr)
+int tis_init(void)
+{
+	if (tpm.inited)
+		return 0;
+
+	if (tpm_decode_config(&tpm))
+		return -1;
+
+	if (tpm_select())
+		return -1;
+
+	/*
+	 * Probe TPM twice; the first probing might fail because TPM is asleep,
+	 * and the probing can wake up TPM.
+	 */
+	if (i2c_probe(tpm.slave_addr) && i2c_probe(tpm.slave_addr)) {
+		debug("%s: fail to probe i2c addr 0x%x\n", __func__,
+		      tpm.slave_addr);
+		return -1;
+	}
+
+	tpm_deselect();
+
+	tpm.inited = 1;
+
+	return 0;
+}
+
+int tis_open(void)
 {
 	int rc;
-	if (g_chip.is_open)
-		return -EBUSY;
-	rc = tpm_vendor_init(dev_addr);
-	if (rc < 0)
-		g_chip.is_open = 0;
+
+	if (!tpm.inited)
+		return -1;
+
+	if (tpm_select())
+		return -1;
+
+	rc = tpm_open(tpm.slave_addr);
+
+	tpm_deselect();
+
 	return rc;
 }
 
-void tpm_close(void)
+int tis_close(void)
 {
-	if (g_chip.is_open) {
-		tpm_vendor_cleanup(&g_chip);
-		g_chip.is_open = 0;
+	if (!tpm.inited)
+		return -1;
+
+	if (tpm_select())
+		return -1;
+
+	tpm_close();
+
+	tpm_deselect();
+
+	return 0;
+}
+
+int tis_sendrecv(const uint8_t *sendbuf, size_t sbuf_size,
+		uint8_t *recvbuf, size_t *rbuf_len)
+{
+	int len;
+	uint8_t buf[4096];
+
+	if (!tpm.inited)
+		return -1;
+
+	if (sizeof(buf) < sbuf_size)
+		return -1;
+
+	memcpy(buf, sendbuf, sbuf_size);
+
+	if (tpm_select())
+		return -1;
+
+	len = tpm_transmit(buf, sbuf_size);
+
+	tpm_deselect();
+
+	if (len < 10) {
+		*rbuf_len = 0;
+		return -1;
 	}
+
+	memcpy(recvbuf, buf, len);
+	*rbuf_len = len;
+
+	return 0;
 }
diff --git a/drivers/tpm/slb9635_i2c/tpm.h b/drivers/tpm/tpm_private.h
similarity index 71%
rename from drivers/tpm/slb9635_i2c/tpm.h
rename to drivers/tpm/tpm_private.h
index 9ddee86..888a074 100644
--- a/drivers/tpm/slb9635_i2c/tpm.h
+++ b/drivers/tpm/tpm_private.h
@@ -33,12 +33,11 @@ 
  * MA 02111-1307 USA
  */
 
-#ifndef _TPM_H_
-#define _TPM_H_
+#ifndef _TPM_PRIVATE_H_
+#define _TPM_PRIVATE_H_
 
 #include <linux/compiler.h>
-
-#include "compatibility.h"
+#include <linux/types.h>
 
 enum tpm_timeout {
 	TPM_TIMEOUT = 5,	/* msecs */
@@ -47,13 +46,9 @@  enum tpm_timeout {
 /* Size of external transmit buffer (used in tpm_transmit)*/
 #define TPM_BUFSIZE 4096
 
-/* Index of fields in TPM command buffer */
-#define TPM_CMD_SIZE_BYTE 2
-#define TPM_CMD_ORDINAL_BYTE 6
-
 /* Index of Count field in TPM response buffer */
-#define TPM_RSP_SIZE_BYTE 2
-#define TPM_RSP_RC_BYTE 6
+#define TPM_RSP_SIZE_BYTE	2
+#define TPM_RSP_RC_BYTE		6
 
 struct tpm_chip;
 
@@ -65,10 +60,10 @@  struct tpm_vendor_specific {
 	int (*recv) (struct tpm_chip *, u8 *, size_t);
 	int (*send) (struct tpm_chip *, u8 *, size_t);
 	void (*cancel) (struct tpm_chip *);
-	 u8(*status) (struct tpm_chip *);
+	u8(*status) (struct tpm_chip *);
 	int locality;
-	unsigned long timeout_a, timeout_b, timeout_c, timeout_d; /* msec */
-	unsigned long duration[3];	/* msec */
+	unsigned long timeout_a, timeout_b, timeout_c, timeout_d;  /* msec */
+	unsigned long duration[3];  /* msec */
 };
 
 struct tpm_chip {
@@ -132,30 +127,11 @@  struct tpm_cmd_t {
 	union tpm_cmd_params params;
 } __packed;
 
+struct tpm_chip *tpm_register_hardware(const struct tpm_vendor_specific *);
 
-/* ---------- Interface for TPM vendor ------------ */
-
-extern struct tpm_chip *tpm_register_hardware(
-	const struct tpm_vendor_specific *);
+int tpm_vendor_init(uint32_t dev_addr);
 
-extern int tpm_vendor_init(uint32_t dev_addr);
+void tpm_vendor_cleanup(struct tpm_chip *chip);
 
-extern void tpm_vendor_cleanup(struct tpm_chip *chip);
-
-/* ---------- Interface for TDDL ------------------- */
-
-/*
- * if dev_addr != 0 - redefines TPM device address
- * Returns < 0 on error, 0 on success.
- */
-extern int tpm_open(uint32_t dev_addr);
-
-extern void tpm_close(void);
-
-/*
- * Transmit bufsiz bytes out of buf to TPM and get results back in buf, too.
- * Returns < 0 on error, 0 on success.
- */
-extern ssize_t tpm_transmit(const unsigned char *buf, size_t bufsiz);
 
 #endif
diff --git a/drivers/tpm/slb9635_i2c/tpm_tis_i2c.c b/drivers/tpm/tpm_tis_i2c.c
similarity index 73%
rename from drivers/tpm/slb9635_i2c/tpm_tis_i2c.c
rename to drivers/tpm/tpm_tis_i2c.c
index c2e1041..2dd8501 100644
--- a/drivers/tpm/slb9635_i2c/tpm_tis_i2c.c
+++ b/drivers/tpm/tpm_tis_i2c.c
@@ -38,34 +38,66 @@ 
 
 #include <common.h>
 #include <fdtdec.h>
+#include <compiler.h>
 #include <i2c.h>
+#include <tpm.h>
+#include <asm-generic/errno.h>
 #include <linux/types.h>
+#include <linux/unaligned/be_byteshift.h>
 
-#include "compatibility.h"
-#include "tpm.h"
+#include "tpm_private.h"
 
 DECLARE_GLOBAL_DATA_PTR;
 
-/* max. buffer size supported by our tpm */
-#ifdef TPM_BUFSIZE
-#undef TPM_BUFSIZE
-#endif
-#define TPM_BUFSIZE 1260
 /* 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 TPM_I2C_ADDR		0x20
+
+/* Max buffer size supported by our tpm */
+#define TPM_DEV_BUFSIZE		1260
 
-#define SLEEP_DURATION 60 /*in usec*/
+/* Max number of iterations after i2c NAK */
+#define MAX_COUNT		3
 
-/* max. number of iterations after i2c NAK for 'long' commands
- * we need this especially for sending TPM_READY, since the cleanup after the
+/*
+ * 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 MAX_COUNT_LONG		50
+
+#define SLEEP_DURATION		60	/* in usec */
+#define SLEEP_DURATION_LONG	210	/* in usec */
+
+#define TPM_HEADER_SIZE		10
+
+/*
+ * Expected value for DIDVID register
+ *
+ * The only device the system knows about at this moment is Infineon slb9635.
+ */
+#define TPM_TIS_I2C_DID_VID	0x000b15d1L
+
+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 SLEEP_DURATION_LONG 210 /* in usec */
+enum tis_defaults {
+	TIS_SHORT_TIMEOUT		= 750,	/* ms */
+	TIS_LONG_TIMEOUT		= 2000,	/* ms */
+};
 
 /* expected value for DIDVID register */
 #define TPM_TIS_I2C_DID_VID_9635 0x000b15d1L
@@ -83,17 +115,24 @@  static const char * const chip_name[] = {
 	[UNKNOWN] = "unknown/fallback to slb9635",
 };
 
+#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))
+
 /* Structure to store I2C TPM specific stuff */
-struct tpm_inf_dev {
+struct tpm_dev {
 	uint addr;
-	u8 buf[TPM_BUFSIZE + sizeof(u8)];	/* max. buffer size + addr */
+	u8 buf[TPM_DEV_BUFSIZE + sizeof(u8)];  /* Max buffer size + addr */
 	enum i2c_chip_type chip_type;
 };
 
-static struct tpm_inf_dev tpm_dev = {
+static struct tpm_dev tpm_dev = {
 	.addr = TPM_I2C_ADDR
 };
 
+static struct tpm_dev tpm_dev;
+
 /*
  * iic_tpm_read() - read from TPM register
  * @addr: register address to read from
@@ -108,24 +147,21 @@  static struct tpm_inf_dev tpm_dev = {
  *
  * Return -EIO on error, 0 on success.
  */
-int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
+static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
 {
 	int rc;
 	int count;
-	uint myaddr = addr;
-	/* we have to use uint here, uchar hangs the board */
+	uint32_t addrbuf = addr;
 
 	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(tpm_dev.addr, 0, 0,
-				       (uchar *)&myaddr, 1);
+				       (uchar *)&addrbuf, 1);
 			if (rc == 0)
-				break;  /* success, break to skip sleep */
-
+				break;  /* Success, break to skip sleep */
 			udelay(SLEEP_DURATION);
 		}
-
 		if (rc)
 			return -rc;
 
@@ -140,10 +176,11 @@  int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
 				break;  /* success, break to skip sleep */
 		}
 	} else {
-		/* use a combined read for newer chips
-		 * unfortunately the smbus functions are not suitable due to
+		/*
+		 * 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
+		 * Retries should usually not be needed, but are kept just to
 		 * be safe on the safe side.
 		 */
 		for (count = 0; count < MAX_COUNT; count++) {
@@ -154,7 +191,7 @@  int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
 		}
 	}
 
-	/* take care of 'guard time' */
+	/* Take care of 'guard time' */
 	udelay(SLEEP_DURATION);
 	if (rc)
 		return -rc;
@@ -163,21 +200,19 @@  int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
 }
 
 static int iic_tpm_write_generic(u8 addr, u8 *buffer, size_t len,
-				unsigned int sleep_time,
-				u8 max_count)
+		unsigned int sleep_time, u8 max_count)
 {
 	int rc = 0;
 	int count;
 
-	/* prepare send buffer */
+	/* Prepare send buffer */
 	tpm_dev.buf[0] = addr;
 	memcpy(&(tpm_dev.buf[1]), buffer, len);
 
 	for (count = 0; count < max_count; count++) {
 		rc = i2c_write(tpm_dev.addr, 0, 0, tpm_dev.buf, len + 1);
 		if (rc == 0)
-			break;  /* success, break to skip sleep */
-
+			break;  /* Success, break to skip sleep */
 		udelay(sleep_time);
 	}
 
@@ -214,42 +249,16 @@  static int iic_tpm_write(u8 addr, u8 *buffer, size_t len)
 /*
  * 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,
 			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,
-};
-
-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 int check_locality(struct tpm_chip *chip, int loc)
 {
+	const u8 mask = TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID;
 	u8 buf;
 	int rc;
 
@@ -257,8 +266,7 @@  static int check_locality(struct tpm_chip *chip, int loc)
 	if (rc < 0)
 		return rc;
 
-	if ((buf & (TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) ==
-		(TPM_ACCESS_ACTIVE_LOCALITY | TPM_ACCESS_VALID)) {
+	if ((buf & mask) == mask) {
 		chip->vendor.locality = loc;
 		return loc;
 	}
@@ -268,12 +276,13 @@  static int check_locality(struct tpm_chip *chip, int loc)
 
 static void release_locality(struct tpm_chip *chip, int loc, int force)
 {
+	const u8 mask = TPM_ACCESS_REQUEST_PENDING | TPM_ACCESS_VALID;
 	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)) {
+	if (force || (buf & mask) == mask) {
 		buf = TPM_ACCESS_ACTIVE_LOCALITY;
 		iic_tpm_write(TPM_ACCESS(loc), &buf, 1);
 	}
@@ -285,17 +294,17 @@  static int request_locality(struct tpm_chip *chip, int loc)
 	u8 buf = TPM_ACCESS_REQUEST_USE;
 
 	if (check_locality(chip, loc) >= 0)
-		return loc; /* we already have the locality */
+		return loc;  /* We already have the locality */
 
 	iic_tpm_write(TPM_ACCESS(loc), &buf, 1);
 
-	/* wait for burstcount */
+	/* Wait for burstcount */
 	start = get_timer(0);
 	stop = chip->vendor.timeout_a;
 	do {
 		if (check_locality(chip, loc) >= 0)
 			return loc;
-		msleep(TPM_TIMEOUT);
+		udelay(TPM_TIMEOUT * 1000);
 	} while (get_timer(start) < stop);
 
 	return -1;
@@ -303,8 +312,9 @@  static int request_locality(struct tpm_chip *chip, int loc)
 
 static u8 tpm_tis_i2c_status(struct tpm_chip *chip)
 {
-	/* NOTE: since i2c read may fail, return 0 in this case --> time-out */
+	/* NOTE: Since i2c read may fail, return 0 in this case --> time-out */
 	u8 buf;
+
 	if (iic_tpm_read(TPM_STS(chip->vendor.locality), &buf, 1) < 0)
 		return 0;
 	else
@@ -313,8 +323,9 @@  static u8 tpm_tis_i2c_status(struct tpm_chip *chip)
 
 static void tpm_tis_i2c_ready(struct tpm_chip *chip)
 {
-	/* this causes the current command to be aborted */
+	/* This causes the current command to be aborted */
 	u8 buf = TPM_STS_COMMAND_READY;
+
 	iic_tpm_write_long(TPM_STS(chip->vendor.locality), &buf, 1);
 }
 
@@ -322,34 +333,34 @@  static ssize_t get_burstcount(struct tpm_chip *chip)
 {
 	unsigned long start, stop;
 	ssize_t burstcnt;
-	u8 buf[3];
+	u8 addr, buf[3];
 
-	/* wait for burstcount */
-	/* which timeout value, spec has 2 answers (c & d) */
+	/* Wait for burstcount */
+	/* XXX: Which timeout value? Spec has 2 answers (c & d) */
 	start = get_timer(0);
 	stop = chip->vendor.timeout_d;
 	do {
 		/* Note: STS is little endian */
-		if (iic_tpm_read(TPM_STS(chip->vendor.locality) + 1, buf, 3)
-				< 0)
+		addr = TPM_STS(chip->vendor.locality) + 1;
+		if (iic_tpm_read(addr, buf, 3) < 0)
 			burstcnt = 0;
 		else
 			burstcnt = (buf[2] << 16) + (buf[1] << 8) + buf[0];
 
 		if (burstcnt)
 			return burstcnt;
-		msleep(TPM_TIMEOUT);
+		udelay(TPM_TIMEOUT * 1000);
 	} while (get_timer(start) < stop);
 
 	return -EBUSY;
 }
 
 static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
-			int *status)
+		int *status)
 {
 	unsigned long start, stop;
 
-	/* check current status */
+	/* Check current status */
 	*status = tpm_tis_i2c_status(chip);
 	if ((*status & mask) == mask)
 		return 0;
@@ -357,11 +368,10 @@  static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
 	start = get_timer(0);
 	stop = timeout;
 	do {
-		msleep(TPM_TIMEOUT);
+		udelay(TPM_TIMEOUT * 1000);
 		*status = tpm_tis_i2c_status(chip);
 		if ((*status & mask) == mask)
 			return 0;
-
 	} while (get_timer(start) < stop);
 
 	return -ETIME;
@@ -376,17 +386,16 @@  static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 	while (size < count) {
 		burstcnt = get_burstcount(chip);
 
-		/* burstcount < 0 = tpm is busy */
+		/* burstcount < 0 -> tpm is busy */
 		if (burstcnt < 0)
 			return burstcnt;
 
-		/* limit received data to max. left */
+		/* 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);
+				&(buf[size]), burstcnt);
 		if (rc == 0)
 			size += burstcnt;
 	}
@@ -404,10 +413,10 @@  static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 		goto out;
 	}
 
-	/* read first 10 bytes, including tag, paramsize, and result */
+	/* 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");
+		error("Unable to read header\n");
 		goto out;
 	}
 
@@ -418,23 +427,24 @@  static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 	}
 
 	size += recv_data(chip, &buf[TPM_HEADER_SIZE],
-				expected - TPM_HEADER_SIZE);
+			expected - TPM_HEADER_SIZE);
 	if (size < expected) {
-		dev_err(chip->dev, "Unable to read remainder of result\n");
+		error("Unable to read remainder of result\n");
 		size = -ETIME;
 		goto out;
 	}
 
 	wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status);
-	if (status & TPM_STS_DATA_AVAIL) {	/* retry? */
-		dev_err(chip->dev, "Error left over data\n");
+	if (status & TPM_STS_DATA_AVAIL) {  /* Retry? */
+		error("Error left over data\n");
 		size = -EIO;
 		goto out;
 	}
 
 out:
 	tpm_tis_i2c_ready(chip);
-	/* The TPM needs some time to clean up here,
+	/*
+	 * The TPM needs some time to clean up here,
 	 * so we sleep rather than keeping the bus busy
 	 */
 	udelay(2000);
@@ -448,10 +458,11 @@  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;
+	int retry = 0;
 	u8 sts = TPM_STS_GO;
 
-	if (len > TPM_BUFSIZE)
-		return -E2BIG; /* command is too long for our tpm, sorry */
+	if (len > TPM_DEV_BUFSIZE)
+		return -E2BIG;  /* Command is too long for our tpm, sorry */
 
 	if (request_locality(chip, 0) < 0)
 		return -EBUSY;
@@ -459,44 +470,45 @@  static int tpm_tis_i2c_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	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->vendor.timeout_b, &status) < 0) {
+		if (wait_for_stat(chip, TPM_STS_COMMAND_READY,
+				  chip->vendor.timeout_b, &status) < 0) {
 			rc = -ETIME;
 			goto out_err;
 		}
 	}
 
-	while (count < len - 1) {
-		burstcnt = get_burstcount(chip);
+	burstcnt = get_burstcount(chip);
 
-		/* burstcount < 0 = tpm is busy */
-		if (burstcnt < 0)
-			return burstcnt;
+	/* burstcount < 0 -> tpm is busy */
+	if (burstcnt < 0)
+		return burstcnt;
 
-		if (burstcnt > (len-1-count))
-			burstcnt = len-1-count;
+	while (count < len - 1) {
+		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 */
+#ifdef CONFIG_TPM_TIS_I2C_BURST_LIMITATION
+		if (retry && burstcnt > CONFIG_TPM_TIS_I2C_BURST_LIMITATION)
+			burstcnt = CONFIG_TPM_TIS_I2C_BURST_LIMITATION;
+#endif /* CONFIG_TPM_TIS_I2C_BURST_LIMITATION */
 
 		rc = iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality),
-				   &(buf[count]), burstcnt);
+				&(buf[count]), burstcnt);
 		if (rc == 0)
 			count += burstcnt;
-
-		wait_for_stat(chip, TPM_STS_VALID,
-			      chip->vendor.timeout_c, &status);
-
-		if ((status & TPM_STS_DATA_EXPECT) == 0) {
-			rc = -EIO;
-			goto out_err;
+		else {
+			retry++;
+			wait_for_stat(chip, TPM_STS_VALID,
+				      chip->vendor.timeout_c, &status);
+
+			if ((status & TPM_STS_DATA_EXPECT) == 0) {
+				rc = -EIO;
+				goto out_err;
+			}
 		}
 	}
 
-	/* write last byte */
+	/* Write last byte */
 	iic_tpm_write(TPM_DATA_FIFO(chip->vendor.locality), &(buf[count]), 1);
 	wait_for_stat(chip, TPM_STS_VALID, chip->vendor.timeout_c, &status);
 	if ((status & TPM_STS_DATA_EXPECT) != 0) {
@@ -504,13 +516,15 @@  static int tpm_tis_i2c_send(struct tpm_chip *chip, u8 *buf, size_t len)
 		goto out_err;
 	}
 
-	/* go and do it */
+	/* Go and do it */
 	iic_tpm_write(TPM_STS(chip->vendor.locality), &sts, 1);
 
 	return len;
+
 out_err:
 	tpm_tis_i2c_ready(chip);
-	/* The TPM needs some time to clean up here,
+	/*
+	 * The TPM needs some time to clean up here,
 	 * so we sleep rather than keeping the bus busy
 	 */
 	udelay(2000);
@@ -529,6 +543,7 @@  static struct tpm_vendor_specific tpm_tis_i2c = {
 	.req_canceled = TPM_STS_COMMAND_READY,
 };
 
+
 static enum i2c_chip_type tpm_vendor_chip_type(void)
 {
 #ifdef CONFIG_OF_CONTROL
@@ -543,9 +558,7 @@  static enum i2c_chip_type tpm_vendor_chip_type(void)
 	return UNKNOWN;
 }
 
-/* initialisation of i2c tpm */
-
-
+/* Initialisation of i2c tpm */
 int tpm_vendor_init(uint32_t dev_addr)
 {
 	u32 vendor;
@@ -575,12 +588,12 @@  int tpm_vendor_init(uint32_t dev_addr)
 	chip->vendor.timeout_c = TIS_SHORT_TIMEOUT;
 	chip->vendor.timeout_d = TIS_SHORT_TIMEOUT;
 
-	if (request_locality(chip, 0) != 0) {
+	if (request_locality(chip, 0) < 0) {
 		rc = -ENODEV;
 		goto out_err;
 	}
 
-	/* read four bytes from DID_VID register */
+	/* Read four bytes from DID_VID register */
 	if (iic_tpm_read(TPM_DID_VID(0), (uchar *)&vendor, 4) < 0) {
 		rc = -EIO;
 		goto out_release;
@@ -595,13 +608,13 @@  int tpm_vendor_init(uint32_t dev_addr)
 	}
 
 	if (tpm_dev.chip_type != UNKNOWN && vendor != expected_did_vid) {
-		dev_err(dev, "vendor id did not match! ID was %08x\n", vendor);
+		error("Vendor id did not match! ID was %08x\n", vendor);
 		rc = -ENODEV;
 		goto out_release;
 	}
 
-	dev_info(dev, "1.2 TPM (chip type %s device-id 0x%X)\n",
-		 chip_name[tpm_dev.chip_type], vendor >> 16);
+	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.