The TPM device has a builtin random number generator(RNG)
functionality. Expose the RNG functions of the TPM device to the
driver model so that they can be used by the EFI_RNG_PROTOCOL if the
protocol is installed.
Also change the function arguments and return type of the random
number functions to comply with the driver model api.
Signed-off-by: Sughosh Ganu <sughosh.g...@linaro.org>
---
Changes since V5:
* Use the dev_get_parent() interface for getting the TPM device when
calling the tpm_get_random() function
drivers/rng/Kconfig | 11 +++++++++++
drivers/rng/Makefile | 1 +
drivers/rng/tpm_rng.c | 23 +++++++++++++++++++++++
lib/Kconfig | 1 +
lib/tpm-v1.c | 13 +++++++------
lib/tpm-v2.c | 6 +++---
lib/tpm_api.c | 6 +++---
7 files changed, 49 insertions(+), 12 deletions(-)
create mode 100644 drivers/rng/tpm_rng.c
diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
index c10f7d345b..67c65311c7 100644
--- a/drivers/rng/Kconfig
+++ b/drivers/rng/Kconfig
@@ -58,4 +58,15 @@ config RNG_IPROC200
depends on DM_RNG
help
Enable random number generator for RPI4.
+
+config TPM_RNG
+ bool "Enable random number generator on TPM device"
+ depends on TPM
+ default y
+ help
+ The TPM device has an inbuilt random number generator
+ functionality. Enable random number generator on TPM
+ devices.
+
+
endif
diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile
index 435b3b965a..e4ca9c4149 100644
--- a/drivers/rng/Makefile
+++ b/drivers/rng/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_RNG_OPTEE) += optee_rng.o
obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o
obj-$(CONFIG_RNG_ROCKCHIP) += rockchip_rng.o
obj-$(CONFIG_RNG_IPROC200) += iproc_rng200.o
+obj-$(CONFIG_TPM_RNG) += tpm_rng.o
diff --git a/drivers/rng/tpm_rng.c b/drivers/rng/tpm_rng.c
new file mode 100644
index 0000000000..1a5e9e2e4b
--- /dev/null
+++ b/drivers/rng/tpm_rng.c
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2022, Linaro Limited
+ */
+
+#include <dm.h>
+#include <rng.h>
+#include <tpm_api.h>
+
+static int rng_tpm_random_read(struct udevice *dev, void *data, size_t count)
+{
+ return tpm_get_random(dev_get_parent(dev), data, count);
+}
+
+static const struct dm_rng_ops tpm_rng_ops = {
+ .read = rng_tpm_random_read,
+};
+
+U_BOOT_DRIVER(tpm_rng) = {
+ .name = "tpm-rng",
+ .id = UCLASS_RNG,
+ .ops = &tpm_rng_ops,
+};
diff --git a/lib/Kconfig b/lib/Kconfig
index acc0ac081a..17efaa4c80 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -358,6 +358,7 @@ source lib/crypt/Kconfig
config TPM
bool "Trusted Platform Module (TPM) Support"
depends on DM
+ imply DM_RNG
help
This enables support for TPMs which can be used to provide security
features for your board. The TPM can be connected via LPC or I2C
diff --git a/lib/tpm-v1.c b/lib/tpm-v1.c
index 22a769c587..f7091e5bc7 100644
--- a/lib/tpm-v1.c
+++ b/lib/tpm-v1.c
@@ -9,12 +9,13 @@
#include <common.h>
#include <dm.h>
#include <log.h>
-#include <asm/unaligned.h>
-#include <u-boot/sha1.h>
#include <tpm-common.h>
#include <tpm-v1.h>
#include "tpm-utils.h"
+#include <asm/unaligned.h>
+#include <u-boot/sha1.h>
+
#ifdef CONFIG_TPM_AUTH_SESSIONS
#ifndef CONFIG_SHA1
@@ -892,19 +893,19 @@ u32 tpm1_get_random(struct udevice *dev, void *data, u32
count)
if (pack_byte_string(buf, sizeof(buf), "sd",
0, command, sizeof(command),
length_offset, this_bytes))
- return TPM_LIB_ERROR;
+ return -EIO;
err = tpm_sendrecv_command(dev, buf, response,
&response_length);
if (err)
return err;
if (unpack_byte_string(response, response_length, "d",
data_size_offset, &data_size))
- return TPM_LIB_ERROR;
+ return -EIO;
if (data_size > count)
- return TPM_LIB_ERROR;
+ return -EIO;
if (unpack_byte_string(response, response_length, "s",
data_offset, out, data_size))
- return TPM_LIB_ERROR;
+ return -EIO;
count -= data_size;
out += data_size;
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index 1bf627853a..abca9a14b0 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -585,19 +585,19 @@ u32 tpm2_get_random(struct udevice *dev, void *data, u32
count)
if (pack_byte_string(buf, sizeof(buf), "sw",
0, command_v2, sizeof(command_v2),
sizeof(command_v2), this_bytes))
- return TPM_LIB_ERROR;
+ return -EIO;
err = tpm_sendrecv_command(dev, buf, response,
&response_length);
if (err)
return err;
if (unpack_byte_string(response, response_length, "w",
data_size_offset, &data_size))
- return TPM_LIB_ERROR;
+ return -EIO;
if (data_size > this_bytes)
return TPM_LIB_ERROR;
if (unpack_byte_string(response, response_length, "s",
data_offset, out, data_size))
- return TPM_LIB_ERROR;
+ return -EIO;
count -= data_size;
out += data_size;
diff --git a/lib/tpm_api.c b/lib/tpm_api.c
index 4ac4612c81..032f383ca0 100644
--- a/lib/tpm_api.c
+++ b/lib/tpm_api.c
@@ -269,7 +269,7 @@ u32 tpm_get_random(struct udevice *dev, void *data, u32
count)
if (tpm_is_v1(dev))
return tpm1_get_random(dev, data, count);
else if (tpm_is_v2(dev))
- return -ENOSYS; /* not implemented yet */
- else
- return -ENOSYS;
+ return tpm2_get_random(dev, data, count);
+
+ return -ENOSYS;
}
--
2.25.1
