Implements the minimal functionality necessary to talk to an I2C TPM
according to the TCG TPM I2C Interface Specification.
Limitations:
* No IRQ support
* No support for updating GUARD_TIME (uses always the default of 250µs)
* No support for Data Checksum register (optional feature only for I2C)
Signed-off-by: Alexander Steffen <Alexander.Steffen@xxxxxxxxxxxx>
---
drivers/char/tpm/Kconfig | 11 ++
drivers/char/tpm/Makefile | 1 +
drivers/char/tpm/tpm_tis_i2c.c | 233 +++++++++++++++++++++++++++++++++
3 files changed, 245 insertions(+)
create mode 100644 drivers/char/tpm/tpm_tis_i2c.c
diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index 17bfbf9f572f..383371d30931 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -67,6 +67,17 @@ config TCG_TIS_SPI
within Linux. To compile this driver as a module, choose M here;
the module will be called tpm_tis_spi.
+config TCG_TIS_I2C
+ tristate "TPM I2C Interface Specification"
+ depends on I2C
+ 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 c354cdff9c62..c969e4250a1d 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -22,6 +22,7 @@ tpm-$(CONFIG_OF) += eventlog/of.o
obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
obj-$(CONFIG_TCG_TIS) += tpm_tis.o
obj-$(CONFIG_TCG_TIS_SPI) += tpm_tis_spi.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 000000000000..d6eea9e2af5b
--- /dev/null
+++ b/drivers/char/tpm/tpm_tis_i2c.c
@@ -0,0 +1,233 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 Infineon Technologies AG
+ *
+ * Authors:
+ * Alexander Steffen <alexander.steffen@xxxxxxxxxxxx>
+ *
+ * Maintained by: <tpmdd-devel@xxxxxxxxxxxxxxxxxxxxx>
+ *
+ * Device driver for TCG/TCPA TPM (trusted platform module).
+ * Specifications at www.trustedcomputinggroup.org
+ *
+ * This device driver implements the TPM interface as defined in
+ * the TCG TPM I2C Interface Specification Familiy 2.0, Revision 1.00.
+ *
+ * It is based on the tpm_tis_spi device driver.
+ */
+
+#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/i2c.h>
+#include <linux/tpm.h>
+#include "tpm.h"
+#include "tpm_tis_core.h"
+
+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_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;
+
+ u8 locality[] = {
+ 0, // TPM_LOC_SEL
+ addr >> 12, // locality
+ };
+ u8 reg = address_to_register(addr);
+ struct i2c_msg msgs[] = {
+ {
+ .addr = phy->i2c_client->addr,
+ .len = sizeof(locality),
+ .buf = locality,
+ },
+ {
+ .addr = phy->i2c_client->addr,
+ .len = sizeof(reg),
+ .buf = ®,
+ },
+ {
+ .addr = phy->i2c_client->addr,
+ .len = len,
+ .buf = result,
+ .flags = I2C_M_RD,
+ },
+ };
+
+ ret = i2c_transfer(phy->i2c_client->adapter, msgs, ARRAY_SIZE(msgs));
+
+ if (ret < 0)
+ return ret;
+
+ usleep_range(250, 300); // wait default GUARD_TIME of 250µs
+
+ 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;
+
+ u8 locality[] = {
+ 0, // TPM_LOC_SEL
+ addr >> 12, // locality
+ };
+
+ 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 = sizeof(locality),
+ .buf = locality,
+ },
+ {
+ .addr = phy->i2c_client->addr,
+ .len = len + 1,
+ .buf = phy->iobuf,
+ },
+ };
+
+ ret = i2c_transfer(phy->i2c_client->adapter, msgs,
+ ARRAY_SIZE(msgs));
+ }
+ } else {
+ u8 reg = address_to_register(addr);
+
+ struct i2c_msg msgs[] = {
+ {
+ .addr = phy->i2c_client->addr,
+ .len = sizeof(locality),
+ .buf = locality,
+ },
+ {
+ .addr = phy->i2c_client->addr,
+ .len = sizeof(reg),
+ .buf = ®,
+ },
+ {
+ .addr = phy->i2c_client->addr,
+ .len = len,
+ .buf = (u8*)value,
+ .flags = I2C_M_NOSTART,
+ },
+ };
+
+ ret = i2c_transfer(phy->i2c_client->adapter, msgs,
+ ARRAY_SIZE(msgs));
+ }
+
+ if (ret < 0)
+ return ret;
+
+ usleep_range(250, 300); // wait default GUARD_TIME of 250µs
+
+ return 0;
+}
+
+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;
+
+ 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;
+ }
+
+ return tpm_tis_core_init(&dev->dev, &phy->priv, -1, &tpm_i2c_phy_ops,
+ NULL);
+}
+
+static SIMPLE_DEV_PM_OPS(tpm_tis_pm, tpm_pm_suspend, tpm_tis_resume);
+
+static int tpm_tis_i2c_remove(struct i2c_client *dev)
+{
+ struct tpm_chip *chip = i2c_get_clientdata(dev);
+
+ tpm_chip_unregister(chip);
+ tpm_tis_remove(chip);
+ return 0;
+}
+
+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 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,
+ .remove = tpm_tis_i2c_remove,
+ .id_table = tpm_tis_i2c_id,
+};
+module_i2c_driver(tpm_tis_i2c_driver);
+
+MODULE_DESCRIPTION("TPM Driver for native I2C access");
+MODULE_LICENSE("GPL");
--
2.17.1
