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// 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");
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