231 lines
6.4 KiB
C
231 lines
6.4 KiB
C
/*
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* ATMEL I2C TPM AT97SC3204T
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*
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* Copyright (C) 2012 V Lab Technologies
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* Teddy Reed <teddy@prosauce.org>
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* Copyright (C) 2013, Obsidian Research Corp.
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* Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
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* Device driver for ATMEL I2C TPMs.
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*
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* Teddy Reed determined the basic I2C command flow, unlike other I2C TPM
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* devices the raw TCG formatted TPM command data is written via I2C and then
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* raw TCG formatted TPM command data is returned via I2C.
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*
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* TGC status/locality/etc functions seen in the LPC implementation do not
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* seem to be present.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see http://www.gnu.org/licenses/>.
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include "tpm.h"
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#define I2C_DRIVER_NAME "tpm_i2c_atmel"
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#define TPM_I2C_SHORT_TIMEOUT 750 /* ms */
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#define TPM_I2C_LONG_TIMEOUT 2000 /* 2 sec */
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#define ATMEL_STS_OK 1
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struct priv_data {
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size_t len;
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/* This is the amount we read on the first try. 25 was chosen to fit a
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* fair number of read responses in the buffer so a 2nd retry can be
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* avoided in small message cases. */
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u8 buffer[sizeof(struct tpm_output_header) + 25];
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};
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static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t len)
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{
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struct priv_data *priv = chip->vendor.priv;
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struct i2c_client *client = to_i2c_client(chip->pdev);
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s32 status;
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priv->len = 0;
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if (len <= 2)
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return -EIO;
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status = i2c_master_send(client, buf, len);
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dev_dbg(chip->pdev,
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"%s(buf=%*ph len=%0zx) -> sts=%d\n", __func__,
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(int)min_t(size_t, 64, len), buf, len, status);
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return status;
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}
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static int i2c_atmel_recv(struct tpm_chip *chip, u8 *buf, size_t count)
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{
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struct priv_data *priv = chip->vendor.priv;
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struct i2c_client *client = to_i2c_client(chip->pdev);
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struct tpm_output_header *hdr =
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(struct tpm_output_header *)priv->buffer;
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u32 expected_len;
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int rc;
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if (priv->len == 0)
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return -EIO;
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/* Get the message size from the message header, if we didn't get the
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* whole message in read_status then we need to re-read the
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* message. */
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expected_len = be32_to_cpu(hdr->length);
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if (expected_len > count)
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return -ENOMEM;
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if (priv->len >= expected_len) {
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dev_dbg(chip->pdev,
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"%s early(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
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(int)min_t(size_t, 64, expected_len), buf, count,
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expected_len);
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memcpy(buf, priv->buffer, expected_len);
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return expected_len;
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}
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rc = i2c_master_recv(client, buf, expected_len);
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dev_dbg(chip->pdev,
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"%s reread(buf=%*ph count=%0zx) -> ret=%d\n", __func__,
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(int)min_t(size_t, 64, expected_len), buf, count,
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expected_len);
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return rc;
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}
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static void i2c_atmel_cancel(struct tpm_chip *chip)
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{
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dev_err(chip->pdev, "TPM operation cancellation was requested, but is not supported");
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}
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static u8 i2c_atmel_read_status(struct tpm_chip *chip)
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{
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struct priv_data *priv = chip->vendor.priv;
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struct i2c_client *client = to_i2c_client(chip->pdev);
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int rc;
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/* The TPM fails the I2C read until it is ready, so we do the entire
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* transfer here and buffer it locally. This way the common code can
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* properly handle the timeouts. */
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priv->len = 0;
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memset(priv->buffer, 0, sizeof(priv->buffer));
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/* Once the TPM has completed the command the command remains readable
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* until another command is issued. */
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rc = i2c_master_recv(client, priv->buffer, sizeof(priv->buffer));
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dev_dbg(chip->pdev,
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"%s: sts=%d", __func__, rc);
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if (rc <= 0)
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return 0;
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priv->len = rc;
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return ATMEL_STS_OK;
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}
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static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status)
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{
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return false;
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}
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static const struct tpm_class_ops i2c_atmel = {
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.status = i2c_atmel_read_status,
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.recv = i2c_atmel_recv,
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.send = i2c_atmel_send,
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.cancel = i2c_atmel_cancel,
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.req_complete_mask = ATMEL_STS_OK,
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.req_complete_val = ATMEL_STS_OK,
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.req_canceled = i2c_atmel_req_canceled,
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};
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static int i2c_atmel_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct tpm_chip *chip;
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struct device *dev = &client->dev;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
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return -ENODEV;
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chip = tpmm_chip_alloc(dev, &i2c_atmel);
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if (IS_ERR(chip))
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return PTR_ERR(chip);
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chip->vendor.priv = devm_kzalloc(dev, sizeof(struct priv_data),
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GFP_KERNEL);
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if (!chip->vendor.priv)
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return -ENOMEM;
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/* Default timeouts */
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chip->vendor.timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
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chip->vendor.timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT);
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chip->vendor.timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
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chip->vendor.timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT);
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chip->vendor.irq = 0;
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/* There is no known way to probe for this device, and all version
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* information seems to be read via TPM commands. Thus we rely on the
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* TPM startup process in the common code to detect the device. */
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if (tpm_get_timeouts(chip))
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return -ENODEV;
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if (tpm_do_selftest(chip))
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return -ENODEV;
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return tpm_chip_register(chip);
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}
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static int i2c_atmel_remove(struct i2c_client *client)
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{
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struct device *dev = &(client->dev);
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struct tpm_chip *chip = dev_get_drvdata(dev);
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tpm_chip_unregister(chip);
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return 0;
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}
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static const struct i2c_device_id i2c_atmel_id[] = {
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{I2C_DRIVER_NAME, 0},
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{}
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};
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MODULE_DEVICE_TABLE(i2c, i2c_atmel_id);
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#ifdef CONFIG_OF
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static const struct of_device_id i2c_atmel_of_match[] = {
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{.compatible = "atmel,at97sc3204t"},
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{},
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};
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MODULE_DEVICE_TABLE(of, i2c_atmel_of_match);
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#endif
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static SIMPLE_DEV_PM_OPS(i2c_atmel_pm_ops, tpm_pm_suspend, tpm_pm_resume);
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static struct i2c_driver i2c_atmel_driver = {
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.id_table = i2c_atmel_id,
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.probe = i2c_atmel_probe,
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.remove = i2c_atmel_remove,
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.driver = {
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.name = I2C_DRIVER_NAME,
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.owner = THIS_MODULE,
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.pm = &i2c_atmel_pm_ops,
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.of_match_table = of_match_ptr(i2c_atmel_of_match),
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},
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};
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module_i2c_driver(i2c_atmel_driver);
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MODULE_AUTHOR("Jason Gunthorpe <jgunthorpe@obsidianresearch.com>");
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MODULE_DESCRIPTION("Atmel TPM I2C Driver");
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MODULE_LICENSE("GPL");
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