[linux-2.6-block.git] / drivers / char / tpm / tpm_i2c_atmel.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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.
 */
#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");
Commit	Line	Data
1ccea77e	1	// SPDX-License-Identifier: GPL-2.0-or-later
a2871c62 JG	2	/*
	3	* ATMEL I2C TPM AT97SC3204T
	4	*
	5	* Copyright (C) 2012 V Lab Technologies
	6	* Teddy Reed <teddy@prosauce.org>
	7	* Copyright (C) 2013, Obsidian Research Corp.
	8	* Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
	9	* Device driver for ATMEL I2C TPMs.
	10	*
	11	* Teddy Reed determined the basic I2C command flow, unlike other I2C TPM
	12	* devices the raw TCG formatted TPM command data is written via I2C and then
	13	* raw TCG formatted TPM command data is returned via I2C.
	14	*
	15	* TGC status/locality/etc functions seen in the LPC implementation do not
	16	* seem to be present.
a2871c62 JG	17	*/
	18	#include <linux/init.h>
	19	#include <linux/module.h>
	20	#include <linux/moduleparam.h>
	21	#include <linux/slab.h>
	22	#include <linux/i2c.h>
	23	#include "tpm.h"
	24
	25	#define I2C_DRIVER_NAME "tpm_i2c_atmel"
	26
	27	#define TPM_I2C_SHORT_TIMEOUT 750 /* ms */
	28	#define TPM_I2C_LONG_TIMEOUT 2000 /* 2 sec */
	29
	30	#define ATMEL_STS_OK 1
	31
	32	struct priv_data {
	33	size_t len;
	34	/* This is the amount we read on the first try. 25 was chosen to fit a
	35	* fair number of read responses in the buffer so a 2nd retry can be
	36	* avoided in small message cases. */
b34b77a9	37	u8 buffer[sizeof(struct tpm_header) + 25];
a2871c62 JG	38	};
	39
	40	static int i2c_atmel_send(struct tpm_chip chip, u8 buf, size_t len)
	41	{
9e0d39d8	42	struct priv_data *priv = dev_get_drvdata(&chip->dev);
8cfffc9d	43	struct i2c_client *client = to_i2c_client(chip->dev.parent);
a2871c62 JG	44	s32 status;
	45
	46	priv->len = 0;
	47
	48	if (len <= 2)
	49	return -EIO;
	50
	51	status = i2c_master_send(client, buf, len);
	52
8cfffc9d	53	dev_dbg(&chip->dev,
a2871c62 JG	54	"%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__,
a2871c62 JG	55	(int)min_t(size_t, 64, len), buf, len, status);
f5595f5b JS	56
	57	if (status < 0)
	58	return status;
	59
442601e8 JS	60	/* The upper layer does not support incomplete sends. */
	61	if (status != len)
	62	return -E2BIG;
	63
f5595f5b	64	return 0;
a2871c62 JG	65	}
	66
	67	static int i2c_atmel_recv(struct tpm_chip chip, u8 buf, size_t count)
	68	{
9e0d39d8	69	struct priv_data *priv = dev_get_drvdata(&chip->dev);
8cfffc9d	70	struct i2c_client *client = to_i2c_client(chip->dev.parent);
b34b77a9	71	struct tpm_header hdr = (struct tpm_header )priv->buffer;
a2871c62 JG	72	u32 expected_len;
	73	int rc;
	74
	75	if (priv->len == 0)
	76	return -EIO;
	77
	78	/* Get the message size from the message header, if we didn't get the
	79	* whole message in read_status then we need to re-read the
	80	* message. */
	81	expected_len = be32_to_cpu(hdr->length);
	82	if (expected_len > count)
	83	return -ENOMEM;
	84
	85	if (priv->len >= expected_len) {
8cfffc9d	86	dev_dbg(&chip->dev,
a2871c62 JG	87	"%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
	88	(int)min_t(size_t, 64, expected_len), buf, count,
	89	expected_len);
	90	memcpy(buf, priv->buffer, expected_len);
	91	return expected_len;
	92	}
	93
	94	rc = i2c_master_recv(client, buf, expected_len);
8cfffc9d	95	dev_dbg(&chip->dev,
a2871c62 JG	96	"%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
	97	(int)min_t(size_t, 64, expected_len), buf, count,
	98	expected_len);
	99	return rc;
	100	}
	101
	102	static void i2c_atmel_cancel(struct tpm_chip *chip)
	103	{
8cfffc9d	104	dev_err(&chip->dev, "TPM operation cancellation was requested, but is not supported");
a2871c62 JG	105	}
	106
	107	static u8 i2c_atmel_read_status(struct tpm_chip *chip)
	108	{
9e0d39d8	109	struct priv_data *priv = dev_get_drvdata(&chip->dev);
8cfffc9d	110	struct i2c_client *client = to_i2c_client(chip->dev.parent);
a2871c62 JG	111	int rc;
	112
	113	/* The TPM fails the I2C read until it is ready, so we do the entire
	114	* transfer here and buffer it locally. This way the common code can
	115	* properly handle the timeouts. */
	116	priv->len = 0;
	117	memset(priv->buffer, 0, sizeof(priv->buffer));
	118
	119
	120	/* Once the TPM has completed the command the command remains readable
	121	* until another command is issued. */
	122	rc = i2c_master_recv(client, priv->buffer, sizeof(priv->buffer));
8cfffc9d	123	dev_dbg(&chip->dev,
a2871c62 JG	124	"%s: sts=%d", __func__, rc);
	125	if (rc <= 0)
	126	return 0;
	127
	128	priv->len = rc;
	129
	130	return ATMEL_STS_OK;
	131	}
	132
a2871c62 JG	133	static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status)
a2871c62 JG	134	{
ba6a09d7	135	return false;
a2871c62 JG	136	}
a2871c62 JG	137
01ad1fa7	138	static const struct tpm_class_ops i2c_atmel = {
cae8b441	139	.flags = TPM_OPS_AUTO_STARTUP,
a2871c62 JG	140	.status = i2c_atmel_read_status,
	141	.recv = i2c_atmel_recv,
	142	.send = i2c_atmel_send,
	143	.cancel = i2c_atmel_cancel,
	144	.req_complete_mask = ATMEL_STS_OK,
	145	.req_complete_val = ATMEL_STS_OK,
	146	.req_canceled = i2c_atmel_req_canceled,
a2871c62 JG	147	};
	148
	149	static int i2c_atmel_probe(struct i2c_client *client,
	150	const struct i2c_device_id *id)
	151	{
a2871c62 JG	152	struct tpm_chip *chip;
a2871c62 JG	153	struct device *dev = &client->dev;
9e0d39d8	154	struct priv_data *priv;
a2871c62 JG	155
	156	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	157	return -ENODEV;
	158
afb5abc2 JS	159	chip = tpmm_chip_alloc(dev, &i2c_atmel);
	160	if (IS_ERR(chip))
	161	return PTR_ERR(chip);
a2871c62	162
9e0d39d8 CR	163	priv = devm_kzalloc(dev, sizeof(struct priv_data), GFP_KERNEL);
9e0d39d8 CR	164	if (!priv)
afb5abc2	165	return -ENOMEM;
a2871c62 JG	166
a2871c62 JG	167	/* Default timeouts */
af782f33 CR	168	chip->timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
	169	chip->timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
	170	chip->timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
	171	chip->timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
a2871c62	172
9e0d39d8 CR	173	dev_set_drvdata(&chip->dev, priv);
9e0d39d8 CR	174
a2871c62 JG	175	/* There is no known way to probe for this device, and all version
	176	* information seems to be read via TPM commands. Thus we rely on the
	177	* TPM startup process in the common code to detect the device. */
a2871c62	178
afb5abc2	179	return tpm_chip_register(chip);
a2871c62 JG	180	}
	181
	182	static int i2c_atmel_remove(struct i2c_client *client)
	183	{
	184	struct device *dev = &(client->dev);
	185	struct tpm_chip *chip = dev_get_drvdata(dev);
afb5abc2	186	tpm_chip_unregister(chip);
a2871c62 JG	187	return 0;
	188	}
	189
	190	static const struct i2c_device_id i2c_atmel_id[] = {
	191	{I2C_DRIVER_NAME, 0},
	192	{}
	193	};
	194	MODULE_DEVICE_TABLE(i2c, i2c_atmel_id);
	195
	196	#ifdef CONFIG_OF
	197	static const struct of_device_id i2c_atmel_of_match[] = {
	198	{.compatible = "atmel,at97sc3204t"},
	199	{},
	200	};
	201	MODULE_DEVICE_TABLE(of, i2c_atmel_of_match);
	202	#endif
	203
	204	static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume);
	205
	206	static struct i2c_driver i2c_atmel_driver = {
	207	.id_table = i2c_atmel_id,
	208	.probe = i2c_atmel_probe,
	209	.remove = i2c_atmel_remove,
	210	.driver = {
	211	.name = I2C_DRIVER_NAME,
a2871c62 JG	212	.pm = &i2c_atmel_pm_ops,
	213	.of_match_table = of_match_ptr(i2c_atmel_of_match),
	214	},
	215	};
	216
	217	module_i2c_driver(i2c_atmel_driver);
	218
	219	MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>");
	220	MODULE_DESCRIPTION("Atmel TPM I2C Driver");
	221	MODULE_LICENSE("GPL");