[deliverable/linux.git] / drivers / char / tpm / tpm_i2c_atmel.c

/*
 * 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_output_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);
	return status;
}

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_output_header *hdr =
		(struct tpm_output_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");
Commit	Line	Data
a2871c62 JG	1	/*
	2	* ATMEL I2C TPM AT97SC3204T
	3	*
	4	* Copyright (C) 2012 V Lab Technologies
	5	* Teddy Reed <teddy@prosauce.org>
	6	* Copyright (C) 2013, Obsidian Research Corp.
	7	* Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
	8	* Device driver for ATMEL I2C TPMs.
	9	*
	10	* Teddy Reed determined the basic I2C command flow, unlike other I2C TPM
	11	* devices the raw TCG formatted TPM command data is written via I2C and then
	12	* raw TCG formatted TPM command data is returned via I2C.
	13	*
	14	* TGC status/locality/etc functions seen in the LPC implementation do not
	15	* seem to be present.
	16	*
	17	* This program is free software: you can redistribute it and/or modify
	18	* it under the terms of the GNU General Public License as published by
	19	* the Free Software Foundation, either version 2 of the License, or
	20	* (at your option) any later version.
	21	*
	22	* This program is distributed in the hope that it will be useful,
	23	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	24	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	25	* GNU General Public License for more details.
	26	*
	27	* You should have received a copy of the GNU General Public License
	28	* along with this program. If not, see http://www.gnu.org/licenses/>.
	29	*/
	30	#include <linux/init.h>
	31	#include <linux/module.h>
	32	#include <linux/moduleparam.h>
	33	#include <linux/slab.h>
	34	#include <linux/i2c.h>
	35	#include "tpm.h"
	36
	37	#define I2C_DRIVER_NAME "tpm_i2c_atmel"
	38
	39	#define TPM_I2C_SHORT_TIMEOUT 750 /* ms */
	40	#define TPM_I2C_LONG_TIMEOUT 2000 /* 2 sec */
	41
	42	#define ATMEL_STS_OK 1
	43
	44	struct priv_data {
	45	size_t len;
	46	/* This is the amount we read on the first try. 25 was chosen to fit a
	47	* fair number of read responses in the buffer so a 2nd retry can be
	48	* avoided in small message cases. */
	49	u8 buffer[sizeof(struct tpm_output_header) + 25];
	50	};
	51
	52	static int i2c_atmel_send(struct tpm_chip chip, u8 buf, size_t len)
	53	{
9e0d39d8	54	struct priv_data *priv = dev_get_drvdata(&chip->dev);
8cfffc9d	55	struct i2c_client *client = to_i2c_client(chip->dev.parent);
a2871c62 JG	56	s32 status;
	57
	58	priv->len = 0;
	59
	60	if (len <= 2)
	61	return -EIO;
	62
	63	status = i2c_master_send(client, buf, len);
	64
8cfffc9d	65	dev_dbg(&chip->dev,
a2871c62 JG	66	"%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__,
	67	(int)min_t(size_t, 64, len), buf, len, status);
	68	return status;
	69	}
	70
	71	static int i2c_atmel_recv(struct tpm_chip chip, u8 buf, size_t count)
	72	{
9e0d39d8	73	struct priv_data *priv = dev_get_drvdata(&chip->dev);
8cfffc9d	74	struct i2c_client *client = to_i2c_client(chip->dev.parent);
a2871c62 JG	75	struct tpm_output_header *hdr =
	76	(struct tpm_output_header *)priv->buffer;
	77	u32 expected_len;
	78	int rc;
	79
	80	if (priv->len == 0)
	81	return -EIO;
	82
	83	/* Get the message size from the message header, if we didn't get the
	84	* whole message in read_status then we need to re-read the
	85	* message. */
	86	expected_len = be32_to_cpu(hdr->length);
	87	if (expected_len > count)
	88	return -ENOMEM;
	89
	90	if (priv->len >= expected_len) {
8cfffc9d	91	dev_dbg(&chip->dev,
a2871c62 JG	92	"%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
	93	(int)min_t(size_t, 64, expected_len), buf, count,
	94	expected_len);
	95	memcpy(buf, priv->buffer, expected_len);
	96	return expected_len;
	97	}
	98
	99	rc = i2c_master_recv(client, buf, expected_len);
8cfffc9d	100	dev_dbg(&chip->dev,
a2871c62 JG	101	"%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
	102	(int)min_t(size_t, 64, expected_len), buf, count,
	103	expected_len);
	104	return rc;
	105	}
	106
	107	static void i2c_atmel_cancel(struct tpm_chip *chip)
	108	{
8cfffc9d	109	dev_err(&chip->dev, "TPM operation cancellation was requested, but is not supported");
a2871c62 JG	110	}
	111
	112	static u8 i2c_atmel_read_status(struct tpm_chip *chip)
	113	{
9e0d39d8	114	struct priv_data *priv = dev_get_drvdata(&chip->dev);
8cfffc9d	115	struct i2c_client *client = to_i2c_client(chip->dev.parent);
a2871c62 JG	116	int rc;
	117
	118	/* The TPM fails the I2C read until it is ready, so we do the entire
	119	* transfer here and buffer it locally. This way the common code can
	120	* properly handle the timeouts. */
	121	priv->len = 0;
	122	memset(priv->buffer, 0, sizeof(priv->buffer));
	123
	124
	125	/* Once the TPM has completed the command the command remains readable
	126	* until another command is issued. */
	127	rc = i2c_master_recv(client, priv->buffer, sizeof(priv->buffer));
8cfffc9d	128	dev_dbg(&chip->dev,
a2871c62 JG	129	"%s: sts=%d", __func__, rc);
	130	if (rc <= 0)
	131	return 0;
	132
	133	priv->len = rc;
	134
	135	return ATMEL_STS_OK;
	136	}
	137
a2871c62 JG	138	static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status)
a2871c62 JG	139	{
ba6a09d7	140	return false;
a2871c62 JG	141	}
a2871c62 JG	142
01ad1fa7	143	static const struct tpm_class_ops i2c_atmel = {
cae8b441	144	.flags = TPM_OPS_AUTO_STARTUP,
a2871c62 JG	145	.status = i2c_atmel_read_status,
	146	.recv = i2c_atmel_recv,
	147	.send = i2c_atmel_send,
	148	.cancel = i2c_atmel_cancel,
	149	.req_complete_mask = ATMEL_STS_OK,
	150	.req_complete_val = ATMEL_STS_OK,
	151	.req_canceled = i2c_atmel_req_canceled,
a2871c62 JG	152	};
	153
	154	static int i2c_atmel_probe(struct i2c_client *client,
	155	const struct i2c_device_id *id)
	156	{
a2871c62 JG	157	struct tpm_chip *chip;
a2871c62 JG	158	struct device *dev = &client->dev;
9e0d39d8	159	struct priv_data *priv;
a2871c62 JG	160
	161	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	162	return -ENODEV;
	163
afb5abc2 JS	164	chip = tpmm_chip_alloc(dev, &i2c_atmel);
	165	if (IS_ERR(chip))
	166	return PTR_ERR(chip);
a2871c62	167
9e0d39d8 CR	168	priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL);
9e0d39d8 CR	169	if (!priv)
afb5abc2	170	return -ENOMEM;
a2871c62 JG	171
a2871c62 JG	172	/* Default timeouts */
af782f33 CR	173	chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
	174	chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
	175	chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
	176	chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
a2871c62	177
9e0d39d8 CR	178	dev_set_drvdata(&chip->dev, priv);
9e0d39d8 CR	179
a2871c62 JG	180	/* There is no known way to probe for this device, and all version
	181	* information seems to be read via TPM commands. Thus we rely on the
	182	* TPM startup process in the common code to detect the device. */
a2871c62	183
afb5abc2	184	return tpm_chip_register(chip);
a2871c62 JG	185	}
	186
	187	static int i2c_atmel_remove(struct i2c_client *client)
	188	{
	189	struct device *dev = &(client->dev);
	190	struct tpm_chip *chip = dev_get_drvdata(dev);
afb5abc2	191	tpm_chip_unregister(chip);
a2871c62 JG	192	return 0;
	193	}
	194
	195	static const struct i2c_device_id i2c_atmel_id[] = {
	196	{I2C_DRIVER_NAME, 0},
	197	{}
	198	};
	199	MODULE_DEVICE_TABLE(i2c, i2c_atmel_id);
	200
	201	#ifdef CONFIG_OF
	202	static const struct of_device_id i2c_atmel_of_match[] = {
	203	{.compatible = "atmel,at97sc3204t"},
	204	{},
	205	};
	206	MODULE_DEVICE_TABLE(of, i2c_atmel_of_match);
	207	#endif
	208
	209	static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume);
	210
	211	static struct i2c_driver i2c_atmel_driver = {
	212	.id_table = i2c_atmel_id,
	213	.probe = i2c_atmel_probe,
	214	.remove = i2c_atmel_remove,
	215	.driver = {
	216	.name = I2C_DRIVER_NAME,
a2871c62 JG	217	.pm = &i2c_atmel_pm_ops,
	218	.of_match_table = of_match_ptr(i2c_atmel_of_match),
	219	},
	220	};
	221
	222	module_i2c_driver(i2c_atmel_driver);
	223
	224	MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>");
	225	MODULE_DESCRIPTION("Atmel TPM I2C Driver");
	226	MODULE_LICENSE("GPL");