drivers/char/tpm/tpm_i2c_atmel.c - linux - Git at Google

 /*
  * ATMEL I2C TPM AT97SC3204T
  *
  * Copyright (C) 2012 V Lab Technologies
  *  Teddy Reed <teddy@prosauce.org>
  * Copyright (C) 2013, Obsidian Research Corp.
  *  Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
  * Device driver for ATMEL I2C TPMs.
  *
  * Teddy Reed determined the basic I2C command flow, unlike other I2C TPM
  * devices the raw TCG formatted TPM command data is written via I2C and then
  * raw TCG formatted TPM command data is returned via I2C.
  *
  * TGC status/locality/etc functions seen in the LPC implementation do not
  * seem to be present.
  *
  * 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, see http://www.gnu.org/licenses/>.
  */
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include "tpm.h"

 #define I2C_DRIVER_NAME "tpm_i2c_atmel"

 #define TPM_I2C_SHORT_TIMEOUT  750     /* ms */
 #define TPM_I2C_LONG_TIMEOUT   2000    /* 2 sec */

 #define ATMEL_STS_OK 1

 struct priv_data {
 	size_t len;
 	/* This is the amount we read on the first try. 25 was chosen to fit a
 	 * fair number of read responses in the buffer so a 2nd retry can be
 	 * avoided in small message cases. */
 	u8 buffer[sizeof(struct tpm_header) + 25];
 };

 static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t len)
 {
 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
 	struct i2c_client *client = to_i2c_client(chip->dev.parent);
 	s32 status;

 	priv->len = 0;

 	if (len <= 2)
 		return -EIO;

 	status = i2c_master_send(client, buf, len);

 	dev_dbg(&chip->dev,
 		"%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__,
 		(int)min_t(size_t, 64, len), buf, len, status);

 	if (status < 0)
 		return status;

 	/* The upper layer does not support incomplete sends. */
 	if (status != len)
 		return -E2BIG;

 	return 0;
 }

 static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
 	struct i2c_client *client = to_i2c_client(chip->dev.parent);
 	struct tpm_header *hdr = (struct tpm_header *)priv->buffer;
 	u32 expected_len;
 	int rc;

 	if (priv->len == 0)
 		return -EIO;

 	/* Get the message size from the message header, if we didn't get the
 	 * whole message in read_status then we need to re-read the
 	 * message. */
 	expected_len = be32_to_cpu(hdr->length);
 	if (expected_len > count)
 		return -ENOMEM;

 	if (priv->len >= expected_len) {
 		dev_dbg(&chip->dev,
 			"%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
 			(int)min_t(size_t, 64, expected_len), buf, count,
 			expected_len);
 		memcpy(buf, priv->buffer, expected_len);
 		return expected_len;
 	}

 	rc = i2c_master_recv(client, buf, expected_len);
 	dev_dbg(&chip->dev,
 		"%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
 		(int)min_t(size_t, 64, expected_len), buf, count,
 		expected_len);
 	return rc;
 }

 static void i2c_atmel_cancel(struct tpm_chip *chip)
 {
 	dev_err(&chip->dev, "TPM operation cancellation was requested, but is not supported");
 }

 static u8 i2c_atmel_read_status(struct tpm_chip *chip)
 {
 	struct priv_data *priv = dev_get_drvdata(&chip->dev);
 	struct i2c_client *client = to_i2c_client(chip->dev.parent);
 	int rc;

 	/* The TPM fails the I2C read until it is ready, so we do the entire
 	 * transfer here and buffer it locally. This way the common code can
 	 * properly handle the timeouts. */
 	priv->len = 0;
 	memset(priv->buffer, 0, sizeof(priv->buffer));


 	/* Once the TPM has completed the command the command remains readable
 	 * until another command is issued. */
 	rc = i2c_master_recv(client, priv->buffer, sizeof(priv->buffer));
 	dev_dbg(&chip->dev,
 		"%s: sts=%d", __func__, rc);
 	if (rc <= 0)
 		return 0;

 	priv->len = rc;

 	return ATMEL_STS_OK;
 }

 static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status)
 {
 	return false;
 }

 static const struct tpm_class_ops i2c_atmel = {
 	.flags = TPM_OPS_AUTO_STARTUP,
 	.status = i2c_atmel_read_status,
 	.recv = i2c_atmel_recv,
 	.send = i2c_atmel_send,
 	.cancel = i2c_atmel_cancel,
 	.req_complete_mask = ATMEL_STS_OK,
 	.req_complete_val = ATMEL_STS_OK,
 	.req_canceled = i2c_atmel_req_canceled,
 };

 static int i2c_atmel_probe(struct i2c_client *client,
 			   const struct i2c_device_id *id)
 {
 	struct tpm_chip *chip;
 	struct device *dev = &client->dev;
 	struct priv_data *priv;

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 		return -ENODEV;

 	chip = tpmm_chip_alloc(dev, &i2c_atmel);
 	if (IS_ERR(chip))
 		return PTR_ERR(chip);

 	priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

 	/* Default timeouts */
 	chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
 	chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
 	chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
 	chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);

 	dev_set_drvdata(&chip->dev, priv);

 	/* There is no known way to probe for this device, and all version
 	 * information seems to be read via TPM commands. Thus we rely on the
 	 * TPM startup process in the common code to detect the device. */

 	return tpm_chip_register(chip);
 }

 static int i2c_atmel_remove(struct i2c_client *client)
 {
 	struct device *dev = &(client->dev);
 	struct tpm_chip *chip = dev_get_drvdata(dev);
 	tpm_chip_unregister(chip);
 	return 0;
 }

 static const struct i2c_device_id i2c_atmel_id[] = {
 	{I2C_DRIVER_NAME, 0},
 	{}
 };
 MODULE_DEVICE_TABLE(i2c, i2c_atmel_id);

 #ifdef CONFIG_OF
 static const struct of_device_id i2c_atmel_of_match[] = {
 	{.compatible = "atmel,at97sc3204t"},
 	{},
 };
 MODULE_DEVICE_TABLE(of, i2c_atmel_of_match);
 #endif

 static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume);

 static struct i2c_driver i2c_atmel_driver = {
 	.id_table = i2c_atmel_id,
 	.probe = i2c_atmel_probe,
 	.remove = i2c_atmel_remove,
 	.driver = {
 		.name = I2C_DRIVER_NAME,
 		.pm = &i2c_atmel_pm_ops,
 		.of_match_table = of_match_ptr(i2c_atmel_of_match),
 	},
 };

 module_i2c_driver(i2c_atmel_driver);

 MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>");
 MODULE_DESCRIPTION("Atmel TPM I2C Driver");
 MODULE_LICENSE("GPL");
	/*
	* ATMEL I2C TPM AT97SC3204T
	*
	* Copyright (C) 2012 V Lab Technologies
	* Teddy Reed <teddy@prosauce.org>
	* Copyright (C) 2013, Obsidian Research Corp.
	* Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
	* Device driver for ATMEL I2C TPMs.
	*
	* Teddy Reed determined the basic I2C command flow, unlike other I2C TPM
	* devices the raw TCG formatted TPM command data is written via I2C and then
	* raw TCG formatted TPM command data is returned via I2C.
	*
	* TGC status/locality/etc functions seen in the LPC implementation do not
	* seem to be present.
	*
	* 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, see http://www.gnu.org/licenses/>.
	*/
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/slab.h>
	#include <linux/i2c.h>
	#include "tpm.h"

	#define I2C_DRIVER_NAME "tpm_i2c_atmel"

	#define TPM_I2C_SHORT_TIMEOUT 750 /* ms */
	#define TPM_I2C_LONG_TIMEOUT 2000 /* 2 sec */

	#define ATMEL_STS_OK 1

	struct priv_data {
	size_t len;
	/* This is the amount we read on the first try. 25 was chosen to fit a
	* fair number of read responses in the buffer so a 2nd retry can be
	* avoided in small message cases. */
	u8 buffer[sizeof(struct tpm_header) + 25];
	};

	static int i2c_atmel_send(struct tpm_chip chip, u8 buf, size_t len)
	{
	struct priv_data *priv = dev_get_drvdata(&chip->dev);
	struct i2c_client *client = to_i2c_client(chip->dev.parent);
	s32 status;

	priv->len = 0;

	if (len <= 2)
	return -EIO;

	status = i2c_master_send(client, buf, len);

	dev_dbg(&chip->dev,
	"%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__,
	(int)min_t(size_t, 64, len), buf, len, status);

	if (status < 0)
	return status;

	/* The upper layer does not support incomplete sends. */
	if (status != len)
	return -E2BIG;

	return 0;
	}

	static int i2c_atmel_recv(struct tpm_chip chip, u8 buf, size_t count)
	{
	struct priv_data *priv = dev_get_drvdata(&chip->dev);
	struct i2c_client *client = to_i2c_client(chip->dev.parent);
	struct tpm_header hdr = (struct tpm_header )priv->buffer;
	u32 expected_len;
	int rc;

	if (priv->len == 0)
	return -EIO;

	/* Get the message size from the message header, if we didn't get the
	* whole message in read_status then we need to re-read the
	* message. */
	expected_len = be32_to_cpu(hdr->length);
	if (expected_len > count)
	return -ENOMEM;

	if (priv->len >= expected_len) {
	dev_dbg(&chip->dev,
	"%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
	(int)min_t(size_t, 64, expected_len), buf, count,
	expected_len);
	memcpy(buf, priv->buffer, expected_len);
	return expected_len;
	}

	rc = i2c_master_recv(client, buf, expected_len);
	dev_dbg(&chip->dev,
	"%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
	(int)min_t(size_t, 64, expected_len), buf, count,
	expected_len);
	return rc;
	}

	static void i2c_atmel_cancel(struct tpm_chip *chip)
	{
	dev_err(&chip->dev, "TPM operation cancellation was requested, but is not supported");
	}

	static u8 i2c_atmel_read_status(struct tpm_chip *chip)
	{
	struct priv_data *priv = dev_get_drvdata(&chip->dev);
	struct i2c_client *client = to_i2c_client(chip->dev.parent);
	int rc;

	/* The TPM fails the I2C read until it is ready, so we do the entire
	* transfer here and buffer it locally. This way the common code can
	* properly handle the timeouts. */
	priv->len = 0;
	memset(priv->buffer, 0, sizeof(priv->buffer));


	/* Once the TPM has completed the command the command remains readable
	* until another command is issued. */
	rc = i2c_master_recv(client, priv->buffer, sizeof(priv->buffer));
	dev_dbg(&chip->dev,
	"%s: sts=%d", __func__, rc);
	if (rc <= 0)
	return 0;

	priv->len = rc;

	return ATMEL_STS_OK;
	}

	static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status)
	{
	return false;
	}

	static const struct tpm_class_ops i2c_atmel = {
	.flags = TPM_OPS_AUTO_STARTUP,
	.status = i2c_atmel_read_status,
	.recv = i2c_atmel_recv,
	.send = i2c_atmel_send,
	.cancel = i2c_atmel_cancel,
	.req_complete_mask = ATMEL_STS_OK,
	.req_complete_val = ATMEL_STS_OK,
	.req_canceled = i2c_atmel_req_canceled,
	};

	static int i2c_atmel_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct tpm_chip *chip;
	struct device *dev = &client->dev;
	struct priv_data *priv;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	return -ENODEV;

	chip = tpmm_chip_alloc(dev, &i2c_atmel);
	if (IS_ERR(chip))
	return PTR_ERR(chip);

	priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL);
	if (!priv)
	return -ENOMEM;

	/* Default timeouts */
	chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
	chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
	chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
	chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);

	dev_set_drvdata(&chip->dev, priv);

	/* There is no known way to probe for this device, and all version
	* information seems to be read via TPM commands. Thus we rely on the
	* TPM startup process in the common code to detect the device. */

	return tpm_chip_register(chip);
	}

	static int i2c_atmel_remove(struct i2c_client *client)
	{
	struct device *dev = &(client->dev);
	struct tpm_chip *chip = dev_get_drvdata(dev);
	tpm_chip_unregister(chip);
	return 0;
	}

	static const struct i2c_device_id i2c_atmel_id[] = {
	{I2C_DRIVER_NAME, 0},
	{}
	};
	MODULE_DEVICE_TABLE(i2c, i2c_atmel_id);

	#ifdef CONFIG_OF
	static const struct of_device_id i2c_atmel_of_match[] = {
	{.compatible = "atmel,at97sc3204t"},
	{},
	};
	MODULE_DEVICE_TABLE(of, i2c_atmel_of_match);
	#endif

	static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume);

	static struct i2c_driver i2c_atmel_driver = {
	.id_table = i2c_atmel_id,
	.probe = i2c_atmel_probe,
	.remove = i2c_atmel_remove,
	.driver = {
	.name = I2C_DRIVER_NAME,
	.pm = &i2c_atmel_pm_ops,
	.of_match_table = of_match_ptr(i2c_atmel_of_match),
	},
	};

	module_i2c_driver(i2c_atmel_driver);

	MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>");
	MODULE_DESCRIPTION("Atmel TPM I2C Driver");
	MODULE_LICENSE("GPL");