[PATCH v14 6/7] tpm: tpm_tis: add tpm_tis_i2c driver

From: amirmizi6
Date: Mon Sep 13 2021 - 10:52:48 EST

From: Amir Mizinski <amirmizi6@xxxxxxxxx>

I2C support for TPM devices on the TIS interface is currently available
only as a proprietary driver implementation for each TPM vendor.
This patch implements the infrastructure for a TCG-compliant TPM TIS I2C
driver with the functionality required to communicate with a TPM device
over I2C according to the "TCG PC Client PTP Interface Specification"
and "Device Driver Design Principles for TPM 2.0"

References:
[1] "TCG PC Client Platform TPM Profile(PTP) Interface Specification for
TPM 2.0" Version 01.03 Revision 22 at:
https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/
[2] "TCG PC Client Device Driver Design Principles for TPM 2.0"
Version 1.0 Revision 27 at:
https://trustedcomputinggroup.org/resource/tcg-pc-client-device-driver-design-principles-for-tpm-2-0/

Signed-off-by: Amir Mizinski <amirmizi6@xxxxxxxxx>
Tested-by: Eddie James <eajames@xxxxxxxxxxxxx>
Tested-by: Joel Stanley <joel@xxxxxxxxx>
---
drivers/char/tpm/Kconfig | 12 +++
drivers/char/tpm/Makefile | 1 +
drivers/char/tpm/tpm_tis_i2c.c | 227 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 240 insertions(+)
create mode 100644 drivers/char/tpm/tpm_tis_i2c.c

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index 4308f9c..1395968 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -86,6 +86,18 @@ config TCG_TIS_SYNQUACER
To compile this driver as a module, choose M here;
the module will be called tpm_tis_synquacer.

+config TCG_TIS_I2C
+ tristate "TPM I2C Interface Specification"
+ depends on I2C
+ select CRC_CCITT
+ select TCG_TIS_CORE
+ help
+ If you have a TPM security chip, compliant with the TCG TPM PTP
+ (I2C interface) specification and connected to an I2C bus master,
+ 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_CR50
tristate "TPM Interface Specification 2.0 Interface (I2C - CR50)"
depends on I2C
diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index 66d39ea..0222b1d 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -29,6 +29,7 @@ tpm_tis_spi-$(CONFIG_TCG_TIS_SPI_CR50) += tpm_tis_spi_cr50.o

obj-$(CONFIG_TCG_TIS_I2C_CR50) += tpm_tis_i2c_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..b57c485
--- /dev/null
+++ b/drivers/char/tpm/tpm_tis_i2c.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2014-2021 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
+ * version 01.05 r14" and "TCG PC Client Device Driver Design Principles
+ * version 1.0 r27" for TPM 2.0 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/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_I2C_DID_VID 0x48
+#define TPM_I2C_RID 0x4C
+
+struct tpm_tis_i2c_phy {
+ struct tpm_tis_data priv;
+ struct i2c_client *i2c_client;
+ 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 SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_resume);
+
+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,
+};
+
+static int tpm_tis_i2c_probe(struct i2c_client *dev,
+ const struct i2c_device_id *id)
+{
+ struct tpm_tis_i2c_phy *phy;
+ int rc;
+ const u8 loc_init = 0;
+
+ 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;
+
+ 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 = "nuvoton,npct75x", },
+ { .compatible = "tcg,tpm-tis-i2c", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, of_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),
+ },
+ .probe = tpm_tis_i2c_probe,
+ .id_table = tpm_tis_i2c_id,
+};
+
+module_i2c_driver(tpm_tis_i2c_driver);
+
+MODULE_DESCRIPTION("TPM Driver");
+MODULE_LICENSE("GPL");
--
2.7.4