Re: [PATCH v3 7/7] char: tpm: add tpm_tis_i2c driver

[Eddie James <eajames@linux.ibm.com>]

On 2/10/20 10:28 AM, amirmizi6@gmail.com wrote:
> From: Amir Mizinski <amirmizi6@gmail.com>
>
> Implements the functionality needed to communicate with an I2C TPM
> according to the TCG TPM I2C Interface Specification.


Hi,

I tested this driver (and really the whole series) on a system running 
the NPCT75X connected over I2C. Worked just fine. Thanks!


Tested-by: Eddie James <eajames@linux.ibm.com>


>
> Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>
> ---
>   drivers/char/tpm/Kconfig       |  12 ++
>   drivers/char/tpm/Makefile      |   1 +
>   drivers/char/tpm/tpm_tis_i2c.c | 292 +++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 305 insertions(+)
>   create mode 100644 drivers/char/tpm/tpm_tis_i2c.c
>
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index aacdeed..b482bbf 100644
> --- a/drivers/char/tpm/Kconfig
> +++ b/drivers/char/tpm/Kconfig
> @@ -74,6 +74,18 @@ config TCG_TIS_SPI_CR50
>   	  If you have a H1 secure module running Cr50 firmware on SPI bus,
>   	  say Yes and it will be accessible from within Linux.
>   
> +config TCG_TIS_I2C
> +	tristate "TPM I2C Interface Specification"
> +	depends on I2C
> +	 depends on CRC_CCITT
> +	select TCG_TIS_CORE
> +	---help---
> +	  If you have a TPM security chip which is connected to a regular
> +	  I2C master (i.e. most embedded platforms) that is compliant with the
> +	  TCG TPM I2C Interface Specification 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.
> +
>   config TCG_TIS_I2C_ATMEL
>   	tristate "TPM Interface Specification 1.2 Interface (I2C - Atmel)"
>   	depends on I2C
> diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> index 5a0d99d..5c9a31d 100644
> --- a/drivers/char/tpm/Makefile
> +++ b/drivers/char/tpm/Makefile
> @@ -24,6 +24,7 @@ obj-$(CONFIG_TCG_TIS) += tpm_tis.o
>   obj-$(CONFIG_TCG_TIS_SPI) += tpm_tis_spi_mod.o
>   tpm_tis_spi_mod-y := tpm_tis_spi.o
>   tpm_tis_spi_mod-$(CONFIG_TCG_TIS_SPI_CR50) += tpm_tis_spi_cr50.o
> +obj-$(CONFIG_TCG_TIS_I2C) += tpm_tis_i2c.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
> diff --git a/drivers/char/tpm/tpm_tis_i2c.c b/drivers/char/tpm/tpm_tis_i2c.c
> new file mode 100644
> index 0000000..c10ec7e
> --- /dev/null
> +++ b/drivers/char/tpm/tpm_tis_i2c.c
> @@ -0,0 +1,292 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2014-2019 Nuvoton Technology corporation
> + *
> + * TPM TIS I2C
> + *
> + * TPM TIS I2C Device Driver Interface for devices that implement the TPM I2C
> + * Interface defined by TCG PC Client Platform TPM Profile (PTP) Specification
> + * Revision 01.03 v22 at www.trustedcomputinggroup.org
> + */
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/slab.h>
> +#include <linux/interrupt.h>
> +#include <linux/wait.h>
> +#include <linux/acpi.h>
> +#include <linux/freezer.h>
> +#include <linux/crc-ccitt.h>
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/gpio.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_gpio.h>
> +#include <linux/tpm.h>
> +#include "tpm.h"
> +#include "tpm_tis_core.h"
> +
> +#define TPM_LOC_SEL                    0x04
> +#define TPM_I2C_INTERFACE_CAPABILITY   0x30
> +#define TPM_I2C_DEVICE_ADDRESS         0x38
> +#define TPM_DATA_CSUM_ENABLE           0x40
> +#define TPM_DATA_CSUM                  0x44
> +#define TPM_I2C_DID_VID                        0x48
> +#define TPM_I2C_RID                    0x4C
> +
> +//#define I2C_IS_TPM2 1
> +
> +struct tpm_tis_i2c_phy {
> +	struct tpm_tis_data priv;
> +	struct i2c_client *i2c_client;
> +	bool data_csum;
> +	u8 *iobuf;
> +};
> +
> +static inline struct tpm_tis_i2c_phy *to_tpm_tis_i2c_phy(struct tpm_tis_data *data)
> +{
> +	return container_of(data, struct tpm_tis_i2c_phy, priv);
> +}
> +
> +static u8 address_to_register(u32 addr)
> +{
> +	addr &= 0xFFF;
> +
> +	switch (addr) {
> +		// adapt register addresses that have changed compared to
> +		// older TIS versions
> +	case TPM_ACCESS(0):
> +		return 0x04;
> +	case TPM_LOC_SEL:
> +		return 0x00;
> +	case TPM_DID_VID(0):
> +		return 0x48;
> +	case TPM_RID(0):
> +		return 0x4C;
> +	default:
> +		return addr;
> +	}
> +}
> +
> +static int tpm_tis_i2c_read_bytes(struct tpm_tis_data *data, u32 addr,
> +				  u16 len, u8 *result)
> +{
> +	struct tpm_tis_i2c_phy *phy = to_tpm_tis_i2c_phy(data);
> +	int ret = 0;
> +	int i = 0;
> +	u8 reg = address_to_register(addr);
> +	struct i2c_msg msgs[] = {
> +		{
> +			.addr = phy->i2c_client->addr,
> +			.len = sizeof(reg),
> +			.buf = &reg,
> +		},
> +		{
> +			.addr = phy->i2c_client->addr,
> +			.len = len,
> +			.buf = result,
> +			.flags = I2C_M_RD,
> +		},
> +	};
> +
> +	do {
> +		ret = i2c_transfer(phy->i2c_client->adapter, msgs,
> +				   ARRAY_SIZE(msgs));
> +		usleep_range(250, 300); // wait default GUARD_TIME of 250µs
> +
> +	} while (ret < 0 && i++ < TPM_RETRY);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +
> +	return 0;
> +}
> +
> +static int tpm_tis_i2c_write_bytes(struct tpm_tis_data *data, u32 addr,
> +				   u16 len, const u8 *value)
> +{
> +	struct tpm_tis_i2c_phy *phy = to_tpm_tis_i2c_phy(data);
> +	int ret = 0;
> +	int i = 0;
> +
> +	if (phy->iobuf) {
> +		if (len > TPM_BUFSIZE - 1)
> +			return -EIO;
> +
> +		phy->iobuf[0] = address_to_register(addr);
> +		memcpy(phy->iobuf + 1, value, len);
> +
> +		{
> +			struct i2c_msg msgs[] = {
> +				{
> +					.addr = phy->i2c_client->addr,
> +					.len = len + 1,
> +					.buf = phy->iobuf,
> +				},
> +			};
> +
> +			do {
> +				ret = i2c_transfer(phy->i2c_client->adapter,
> +						   msgs, ARRAY_SIZE(msgs));
> +				// wait default GUARD_TIME of 250µs
> +				usleep_range(250, 300);
> +			} while (ret < 0 && i++ < TPM_RETRY);
> +		}
> +	} else {
> +		u8 reg = address_to_register(addr);
> +
> +		struct i2c_msg msgs[] = {
> +			{
> +				.addr = phy->i2c_client->addr,
> +				.len = sizeof(reg),
> +				.buf = &reg,
> +			},
> +			{
> +				.addr = phy->i2c_client->addr,
> +				.len = len,
> +				.buf = (u8 *)value,
> +				.flags = I2C_M_NOSTART,
> +			},
> +		};
> +		do {
> +			ret = i2c_transfer(phy->i2c_client->adapter, msgs,
> +					   ARRAY_SIZE(msgs));
> +			// wait default GUARD_TIME of 250µs
> +			usleep_range(250, 300);
> +		} while (ret < 0 && i++ < TPM_RETRY);
> +	}
> +
> +	if (ret < 0)
> +		return ret;
> +
> +
> +	return 0;
> +}
> +
> +static bool tpm_tis_i2c_check_data(struct tpm_tis_data *data,
> +				   const u8 *buf, size_t len)
> +{
> +	struct tpm_tis_i2c_phy *phy = to_tpm_tis_i2c_phy(data);
> +	u16 crc, crc_tpm;
> +	int rc;
> +
> +	if (phy->data_csum) {
> +		crc = crc_ccitt(0x0000, buf, len);
> +		rc = tpm_tis_read16(data, TPM_DATA_CSUM, &crc_tpm);
> +		if (rc < 0)
> +			return false;
> +
> +		crc_tpm = be16_to_cpu(crc_tpm);
> +		return crc == crc_tpm;
> +	}
> +
> +	return true;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_resume);
> +
> +static int csum_state_store(struct tpm_tis_data *data, u8 new_state)
> +{
> +	struct tpm_tis_i2c_phy *phy = to_tpm_tis_i2c_phy(data);
> +	u8 cur_state;
> +	int rc;
> +
> +	rc = tpm_tis_i2c_write_bytes(&phy->priv, TPM_DATA_CSUM_ENABLE,
> +				     1, &new_state);
> +	if (rc < 0)
> +		return rc;
> +
> +	rc = tpm_tis_i2c_read_bytes(&phy->priv, TPM_DATA_CSUM_ENABLE,
> +				    1, &cur_state);
> +	if (rc < 0)
> +		return rc;
> +
> +	if (new_state == cur_state)
> +		phy->data_csum = (bool)new_state;
> +
> +	return rc;
> +}
> +
> +static const struct tpm_tis_phy_ops tpm_i2c_phy_ops = {
> +	.read_bytes = tpm_tis_i2c_read_bytes,
> +	.write_bytes = tpm_tis_i2c_write_bytes,
> +	.check_data = tpm_tis_i2c_check_data,
> +};
> +
> +static int tpm_tis_i2c_probe(struct i2c_client *dev,
> +			     const struct i2c_device_id *id)
> +{
> +	struct tpm_tis_i2c_phy *phy;
> +	int rc;
> +	int CRC_Checksum = 0;
> +	const u8 loc_init = 0;
> +	struct device_node *np;
> +
> +	phy = devm_kzalloc(&dev->dev, sizeof(struct tpm_tis_i2c_phy),
> +			   GFP_KERNEL);
> +	if (!phy)
> +		return -ENOMEM;
> +
> +	phy->i2c_client = dev;
> +
> +	if (!i2c_check_functionality(dev->adapter, I2C_FUNC_NOSTART)) {
> +		phy->iobuf = devm_kmalloc(&dev->dev, TPM_BUFSIZE, GFP_KERNEL);
> +		if (!phy->iobuf)
> +			return -ENOMEM;
> +	}
> +
> +	// select locality 0 (the driver will access only via locality 0)
> +	rc = tpm_tis_i2c_write_bytes(&phy->priv, TPM_LOC_SEL, 1, &loc_init);
> +	if (rc < 0)
> +		return rc;
> +
> +	// set CRC checksum calculation enable
> +	np = dev->dev.of_node;
> +	if (of_property_read_bool(np, "crc-checksum"))
> +		CRC_Checksum = 1;
> +
> +	rc = csum_state_store(&phy->priv, CRC_Checksum);
> +	if (rc < 0)
> +		return rc;
> +
> +	return tpm_tis_core_init(&dev->dev, &phy->priv, -1, &tpm_i2c_phy_ops,
> +					NULL);
> +}
> +
> +static const struct i2c_device_id tpm_tis_i2c_id[] = {
> +	{"tpm_tis_i2c", 0},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, tpm_tis_i2c_id);
> +
> +static const struct of_device_id of_tis_i2c_match[] = {
> +	{ .compatible = "tcg,tpm-tis-i2c", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, of_tis_i2c_match);
> +
> +static const struct acpi_device_id acpi_tis_i2c_match[] = {
> +	{"SMO0768", 0},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(acpi, acpi_tis_i2c_match);
> +
> +static struct i2c_driver tpm_tis_i2c_driver = {
> +	.driver = {
> +		.owner = THIS_MODULE,
> +		.name = "tpm_tis_i2c",
> +		.pm = &tpm_tis_pm,
> +		.of_match_table = of_match_ptr(of_tis_i2c_match),
> +		.acpi_match_table = ACPI_PTR(acpi_tis_i2c_match),
> +	},
> +	.probe = tpm_tis_i2c_probe,
> +	.id_table = tpm_tis_i2c_id,
> +};
> +
> +module_i2c_driver(tpm_tis_i2c_driver);
> +
> +MODULE_DESCRIPTION("TPM Driver for native I2C access");
> +MODULE_LICENSE("GPL");