tpm: Add support for new Infineon I2C TPM (SLB 9645 TT 1.2 I2C)

This driver adds support for Infineon's new SLB 9645 TT 1.2 I2C TPMs,
which supports clockstretching, combined reads and a bus speed of
up to 400khz. The device also has a new device id.

The driver works now also fine with device trees, so you can
instantiate your device by adding:
 +       tpm {
 +               compatible = "infineon,slb9645tt";
 +               reg = <0x20>;
 +       };
 for SLB 9645 devices or

 +       tpm {
 +               compatible = "infineon,slb9635tt";
 +               reg = <0x20>;
 +       };
 for SLB 9635 devices

to your device tree.
tpm_i2c_infineon is also retained as a compatible id as a fallback to
slb9635 protocol.

The driver was tested on Beaglebone.

Signed-off-by: Peter Huewe <peter.huewe@infineon.com>
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>

1 files changed, 97 insertions, 40 deletions

diff --git a/drivers/char/tpm/tpm_i2c_infineon.c b/drivers/char/tpm/tpm_i2c_infineon.c
index 8e47e2b99ef..bd9a2958dc3 100644
--- a/drivers/char/tpm/tpm_i2c_infineon.c
+++ b/drivers/char/tpm/tpm_i2c_infineon.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Infineon Technologies
+ * Copyright (C) 2012,2013 Infineon Technologies
  *
  * Authors:
  * Peter Huewe <peter.huewe@infineon.com>
@@ -56,13 +56,21 @@
 #define TPM_TIMEOUT_US_HI  (TPM_TIMEOUT_US_LOW + 2000)
 
 /* expected value for DIDVID register */
-#define TPM_TIS_I2C_DID_VID 0x000b15d1L
+#define TPM_TIS_I2C_DID_VID_9635 0xd1150b00L
+#define TPM_TIS_I2C_DID_VID_9645 0x001a15d1L
+
+enum i2c_chip_type {
+	SLB9635,
+	SLB9645,
+	UNKNOWN,
+};
 
 /* Structure to store I2C TPM specific stuff */
 struct tpm_inf_dev {
 	struct i2c_client *client;
 	u8 buf[TPM_BUFSIZE + sizeof(u8)]; /* max. buffer size + addr */
 	struct tpm_chip *chip;
+	enum i2c_chip_type chip_type;
 };
 
 static struct tpm_inf_dev tpm_dev;
@@ -101,8 +109,9 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
 		.len = len,
 		.buf = buffer
 	};
+	struct i2c_msg msgs[] = {msg1, msg2};
 
-	int rc;
+	int rc = 0;
 	int count;
 
 	/* Lock the adapter for the duration of the whole sequence. */
@@ -110,30 +119,49 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
 		return -EOPNOTSUPP;
 	i2c_lock_adapter(tpm_dev.client->adapter);
 
-	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++) {
-		usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
-		rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);
-		if (rc > 0)
-			break;
+	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 {
+		/* 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++) {
+			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
+			rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);
+			if (rc > 0)
+				break;
+		}
 	}
 
 out:
 	i2c_unlock_adapter(tpm_dev.client->adapter);
+	/* take care of 'guard time' */
+	usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
+
 	if (rc <= 0)
 		return -EIO;
 
@@ -167,16 +195,19 @@ static int iic_tpm_write_generic(u8 addr, u8 *buffer, size_t 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_adapter(tpm_dev.client->adapter);
+	/* take care of 'guard time' */
+	usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
 	if (rc <= 0)
 		return -EIO;
 
@@ -296,11 +327,18 @@ 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 */
-	u8 buf;
-	if (iic_tpm_read(TPM_STS(chip->vendor.locality), &buf, 1) < 0)
-		return 0;
-	else
-		return buf;
+	u8 buf = 0xFF;
+	u8 i = 0;
+
+	do {
+		if (iic_tpm_read(TPM_STS(chip->vendor.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)
@@ -341,7 +379,7 @@ static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
 
 	/* check current status */
 	*status = tpm_tis_i2c_status(chip);
-	if ((*status & mask) == mask)
+	if ((*status != 0xFF) && (*status & mask) == mask)
 		return 0;
 
 	stop = jiffies + timeout;
@@ -385,7 +423,6 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 		/* avoid endless loop in case of broken HW */
 		if (retries > MAX_COUNT_LONG)
 			return -EIO;
-
 	}
 	return size;
 }
@@ -493,7 +530,6 @@ static int tpm_tis_i2c_send(struct tpm_chip *chip, u8 *buf, size_t len)
 			rc = -EIO;
 			goto out_err;
 		}
-
 	}
 
 	/* write last byte */
@@ -581,6 +617,7 @@ static int tpm_tis_i2c_init(struct device *dev)
 
 	chip = tpm_register_hardware(dev, &tpm_tis_i2c);
 	if (!chip) {
+		dev_err(dev, "could not register hardware\n");
 		rc = -ENODEV;
 		goto out_err;
 	}
@@ -595,20 +632,24 @@ static int tpm_tis_i2c_init(struct device *dev)
 	chip->vendor.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_vendor;
 	}
 
 	/* 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;
 	}
 
-	/* create DID_VID register value, after swapping to little-endian */
-	vendor = be32_to_cpu((__be32) vendor);
-
-	if (vendor != TPM_TIS_I2C_DID_VID) {
+	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;
 	}
@@ -644,22 +685,38 @@ out_err:
 
 static const struct i2c_device_id tpm_tis_i2c_table[] = {
 	{"tpm_i2c_infineon", 0},
+	{"slb9635tt", 0},
+	{"slb9645tt", 1},
 	{},
 };
 
 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", .data = (void *)0 },
+	{ .compatible = "infineon,slb9635tt", .data = (void *)0 },
+	{ .compatible = "infineon,slb9645tt", .data = (void *)1 },
+	{},
+};
+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,
 			     const struct i2c_device_id *id)
 {
 	int rc;
-	if (tpm_dev.client != NULL)
+	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(&client->dev,
-			"no algorithms associated to the i2c bus\n");
+		dev_err(dev, "no algorithms associated to the i2c bus\n");
 		return -ENODEV;
 	}
 
@@ -695,7 +752,6 @@ static int tpm_tis_i2c_remove(struct i2c_client *client)
 }
 
 static struct i2c_driver tpm_tis_i2c_driver = {
-
 	.id_table = tpm_tis_i2c_table,
 	.probe = tpm_tis_i2c_probe,
 	.remove = tpm_tis_i2c_remove,
@@ -703,11 +759,12 @@ static struct i2c_driver tpm_tis_i2c_driver = {
 		   .name = "tpm_i2c_infineon",
 		   .owner = THIS_MODULE,
 		   .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 <peter.huewe@infineon.com>");
 MODULE_DESCRIPTION("TPM TIS I2C Infineon Driver");
-MODULE_VERSION("2.1.5");
+MODULE_VERSION("2.2.0");
 MODULE_LICENSE("GPL");