From a2871c62e1865c45f87a9343de76f727fb7a0ffd Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Sun, 6 Oct 2013 12:43:36 -0600 Subject: tpm: Add support for Atmel I2C TPMs This is based on the work of Teddy Reed published on GitHub: https://github.com/theopolis/tpm-i2c-atmel.git 34894b988b67e0ae55088d6388e77b0dbf10c07d That driver was never merged, I have taken it as a starting port, forward ported, tested and revised the driver: - Make it broadly textually similar to the Infineon and Nuvoton I2C driver - Place everything in a format suitable for mainline inclusion - Use high level I2C functions i2c_master_send and i2c_master_recv for data xfer - Use the timeout system from the core code, by faking out a status register - Only I2C transfer the number of bytes in the reply, not a fixed message size. - checkpatch cleanups - Testing on ARM Kirkwood, with this device tree, using a AT97SC3204T-X1A180 tpm@29 { compatible = "atmel,at97sc3204t"; reg = <0x29>; }; Signed-off-by: Teddy Reed [jgg: revised and tested] Signed-off-by: Jason Gunthorpe [phuewe: minor whitespace changes] Signed-off-by: Peter Huewe --- drivers/char/tpm/Kconfig | 9 ++ drivers/char/tpm/Makefile | 1 + drivers/char/tpm/tpm_i2c_atmel.c | 284 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 294 insertions(+) create mode 100644 drivers/char/tpm/tpm_i2c_atmel.c (limited to 'drivers/char') diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig index ade71c134a1a..f9085860b716 100644 --- a/drivers/char/tpm/Kconfig +++ b/drivers/char/tpm/Kconfig @@ -33,6 +33,15 @@ config TCG_TIS from within Linux. To compile this driver as a module, choose M here; the module will be called tpm_tis. +config TCG_TIS_I2C_ATMEL + tristate "TPM Interface Specification 1.2 Interface (I2C - Atmel)" + depends on I2C + ---help--- + If you have an Atmel I2C TPM security chip say Yes and it will be + accessible from within Linux. + To compile this driver as a module, choose M here; the module will + be called tpm_tis_i2c_atmel. + config TCG_TIS_I2C_INFINEON tristate "TPM Interface Specification 1.2 Interface (I2C - Infineon)" depends on I2C diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile index 07ee67cf3341..b80a4000daee 100644 --- a/drivers/char/tpm/Makefile +++ b/drivers/char/tpm/Makefile @@ -13,6 +13,7 @@ ifdef CONFIG_TCG_IBMVTPM endif endif obj-$(CONFIG_TCG_TIS) += tpm_tis.o +obj-$(CONFIG_TCG_TIS_I2C_ATMEL) += tpm_i2c_atmel.o obj-$(CONFIG_TCG_TIS_I2C_INFINEON) += tpm_i2c_infineon.o obj-$(CONFIG_TCG_TIS_I2C_NUVOTON) += tpm_i2c_nuvoton.o obj-$(CONFIG_TCG_NSC) += tpm_nsc.o diff --git a/drivers/char/tpm/tpm_i2c_atmel.c b/drivers/char/tpm/tpm_i2c_atmel.c new file mode 100644 index 000000000000..c3cd7fe481a1 --- /dev/null +++ b/drivers/char/tpm/tpm_i2c_atmel.c @@ -0,0 +1,284 @@ +/* + * ATMEL I2C TPM AT97SC3204T + * + * Copyright (C) 2012 V Lab Technologies + * Teddy Reed + * Copyright (C) 2013, Obsidian Research Corp. + * Jason Gunthorpe + * 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 +#include +#include +#include +#include +#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 = chip->vendor.priv; + struct i2c_client *client = to_i2c_client(chip->dev); + 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 = chip->vendor.priv; + struct i2c_client *client = to_i2c_client(chip->dev); + 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 = chip->vendor.priv; + struct i2c_client *client = to_i2c_client(chip->dev); + 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 const struct file_operations i2c_atmel_ops = { + .owner = THIS_MODULE, + .llseek = no_llseek, + .open = tpm_open, + .read = tpm_read, + .write = tpm_write, + .release = tpm_release, +}; + +static DEVICE_ATTR(pubek, S_IRUGO, tpm_show_pubek, NULL); +static DEVICE_ATTR(pcrs, S_IRUGO, tpm_show_pcrs, NULL); +static DEVICE_ATTR(enabled, S_IRUGO, tpm_show_enabled, NULL); +static DEVICE_ATTR(active, S_IRUGO, tpm_show_active, NULL); +static DEVICE_ATTR(owned, S_IRUGO, tpm_show_owned, NULL); +static DEVICE_ATTR(temp_deactivated, S_IRUGO, tpm_show_temp_deactivated, NULL); +static DEVICE_ATTR(caps, S_IRUGO, tpm_show_caps, NULL); +static DEVICE_ATTR(cancel, S_IWUSR | S_IWGRP, NULL, tpm_store_cancel); +static DEVICE_ATTR(durations, S_IRUGO, tpm_show_durations, NULL); +static DEVICE_ATTR(timeouts, S_IRUGO, tpm_show_timeouts, NULL); + +static struct attribute *i2c_atmel_attrs[] = { + &dev_attr_pubek.attr, + &dev_attr_pcrs.attr, + &dev_attr_enabled.attr, + &dev_attr_active.attr, + &dev_attr_owned.attr, + &dev_attr_temp_deactivated.attr, + &dev_attr_caps.attr, + &dev_attr_cancel.attr, + &dev_attr_durations.attr, + &dev_attr_timeouts.attr, + NULL, +}; + +static struct attribute_group i2c_atmel_attr_grp = { + .attrs = i2c_atmel_attrs +}; + +static bool i2c_atmel_req_canceled(struct tpm_chip *chip, u8 status) +{ + return 0; +} + +static const struct tpm_vendor_specific i2c_atmel = { + .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, + .attr_group = &i2c_atmel_attr_grp, + .miscdev.fops = &i2c_atmel_ops, +}; + +static int i2c_atmel_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + int rc; + struct tpm_chip *chip; + struct device *dev = &client->dev; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + chip = tpm_register_hardware(dev, &i2c_atmel); + if (!chip) { + dev_err(dev, "%s() error in tpm_register_hardware\n", __func__); + return -ENODEV; + } + + chip->vendor.priv = devm_kzalloc(dev, sizeof(struct priv_data), + GFP_KERNEL); + + /* Default timeouts */ + chip->vendor.timeout_a = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); + chip->vendor.timeout_b = msecs_to_jiffies(TPM_I2C_LONG_TIMEOUT); + chip->vendor.timeout_c = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); + chip->vendor.timeout_d = msecs_to_jiffies(TPM_I2C_SHORT_TIMEOUT); + chip->vendor.irq = 0; + + /* 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. */ + if (tpm_get_timeouts(chip)) { + rc = -ENODEV; + goto out_err; + } + + if (tpm_do_selftest(chip)) { + rc = -ENODEV; + goto out_err; + } + + return 0; + +out_err: + tpm_dev_vendor_release(chip); + tpm_remove_hardware(chip->dev); + return rc; +} + +static int i2c_atmel_remove(struct i2c_client *client) +{ + struct device *dev = &(client->dev); + struct tpm_chip *chip = dev_get_drvdata(dev); + + if (chip) + tpm_dev_vendor_release(chip); + tpm_remove_hardware(dev); + kfree(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, + .owner = THIS_MODULE, + .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 "); +MODULE_DESCRIPTION("Atmel TPM I2C Driver"); +MODULE_LICENSE("GPL"); -- cgit v1.2.3