Message-ID: <2nuadbg5awe6gvagxg7t5ewvxsbmiq4qrcrycvnrmt2etzq2ke@6oyzavctwrma>
Date: Tue, 6 May 2025 16:13:04 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Qunqin Zhao <zhaoqunqin@...ngson.cn>
Cc: lee@...nel.org, herbert@...dor.apana.org.au, davem@...emloft.net, 
	peterhuewe@....de, jarkko@...nel.org, linux-kernel@...r.kernel.org, 
	loongarch@...ts.linux.dev, linux-crypto@...r.kernel.org, jgg@...pe.ca, 
	linux-integrity@...r.kernel.org, pmenzel@...gen.mpg.de, Yinggang Gu <guyinggang@...ngson.cn>, 
	Huacai Chen <chenhuacai@...ngson.cn>
Subject: Re: [PATCH v9 4/5] tpm: Add a driver for Loongson TPM device

On Tue, May 06, 2025 at 11:19:46AM +0800, Qunqin Zhao wrote:
>Loongson Security Engine supports random number generation, hash,
>symmetric encryption and asymmetric encryption. Based on these
>encryption functions, TPM2 have been implemented in the Loongson
>Security Engine firmware. This driver is responsible for copying data
>into the memory visible to the firmware and receiving data from the
>firmware.
>
>Co-developed-by: Yinggang Gu <guyinggang@...ngson.cn>
>Signed-off-by: Yinggang Gu <guyinggang@...ngson.cn>
>Signed-off-by: Qunqin Zhao <zhaoqunqin@...ngson.cn>
>Reviewed-by: Huacai Chen <chenhuacai@...ngson.cn>
>Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
>---
>v9: "tpm_loongson_driver" --> "tpm_loongson"
>    "depends on CRYPTO_DEV_LOONGSON_SE" --> "depends on MFD_LOONGSON_SE"
>
>v8: In the send callback, it will wait until the TPM2 command is
>    completed. So do not need to wait in the recv callback.
>    Removed Jarkko's tag cause there are some changes in v8
>
>v7: Moved Kconfig entry between TCG_IBMVTPM and TCG_XEN.
>    Added Jarkko's tag(a little change, should be fine).
>
>v6: Replace all "ls6000se" with "loongson"
>    Prefix all with tpm_loongson instead of tpm_lsse.
>    Removed Jarkko's tag cause there are some changes in v6
>
>v5: None
>v4: Prefix all with tpm_lsse instead of tpm.
>    Removed MODULE_AUTHOR fields.
>
>v3: Added reminder about Loongson security engine to git log.
>
> drivers/char/tpm/Kconfig        |  9 ++++
> drivers/char/tpm/Makefile       |  1 +
> drivers/char/tpm/tpm_loongson.c | 78 +++++++++++++++++++++++++++++++++
> 3 files changed, 88 insertions(+)
> create mode 100644 drivers/char/tpm/tpm_loongson.c
>
>diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
>index fe4f3a609..13f0682c6 100644
>--- a/drivers/char/tpm/Kconfig
>+++ b/drivers/char/tpm/Kconfig
>@@ -189,6 +189,15 @@ config TCG_IBMVTPM
> 	  will be accessible from within Linux.  To compile this driver
> 	  as a module, choose M here; the module will be called tpm_ibmvtpm.
>
>+config TCG_LOONGSON
>+	tristate "Loongson TPM Interface"
>+	depends on MFD_LOONGSON_SE
>+	help
>+	  If you want to make Loongson TPM support available, 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_loongson.
>+
> config TCG_XEN
> 	tristate "XEN TPM Interface"
> 	depends on TCG_TPM && XEN
>diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
>index 2b004df8c..cb534b235 100644
>--- a/drivers/char/tpm/Makefile
>+++ b/drivers/char/tpm/Makefile
>@@ -45,3 +45,4 @@ obj-$(CONFIG_TCG_CRB) += tpm_crb.o
> obj-$(CONFIG_TCG_ARM_CRB_FFA) += tpm_crb_ffa.o
> obj-$(CONFIG_TCG_VTPM_PROXY) += tpm_vtpm_proxy.o
> obj-$(CONFIG_TCG_FTPM_TEE) += tpm_ftpm_tee.o
>+obj-$(CONFIG_TCG_LOONGSON) += tpm_loongson.o
>diff --git a/drivers/char/tpm/tpm_loongson.c b/drivers/char/tpm/tpm_loongson.c
>new file mode 100644
>index 000000000..cbbd9c22a
>--- /dev/null
>+++ b/drivers/char/tpm/tpm_loongson.c
>@@ -0,0 +1,78 @@
>+// SPDX-License-Identifier: GPL-2.0
>+/* Copyright (c) 2025 Loongson Technology Corporation Limited. */
>+
>+#include <linux/device.h>
>+#include <linux/mfd/loongson-se.h>
>+#include <linux/platform_device.h>
>+#include <linux/wait.h>
>+
>+#include "tpm.h"
>+
>+struct tpm_loongson_cmd {
>+	u32 cmd_id;
>+	u32 data_off;
>+	u32 data_len;
>+	u32 pad[5];
>+};
>+
>+static int tpm_loongson_recv(struct tpm_chip *chip, u8 *buf, size_t count)
>+{
>+	struct loongson_se_engine *tpm_engine = dev_get_drvdata(&chip->dev);
>+	struct tpm_loongson_cmd *cmd_ret = tpm_engine->command_ret;
>+
>+	memcpy(buf, tpm_engine->data_buffer, cmd_ret->data_len);

Should we limit the memcpy to `count`?

I mean, can happen that `count` is less than `cmd_ret->data_len`?

Thanks,
Stefano

>+
>+	return cmd_ret->data_len;
>+}
>+
>+static int tpm_loongson_send(struct tpm_chip *chip, u8 *buf, size_t count)
>+{
>+	struct loongson_se_engine *tpm_engine = dev_get_drvdata(&chip->dev);
>+	struct tpm_loongson_cmd *cmd = tpm_engine->command;
>+
>+	cmd->data_len = count;
>+	memcpy(tpm_engine->data_buffer, buf, count);
>+
>+	return loongson_se_send_engine_cmd(tpm_engine);
>+}
>+
>+static const struct tpm_class_ops tpm_loongson_ops = {
>+	.flags = TPM_OPS_AUTO_STARTUP,
>+	.recv = tpm_loongson_recv,
>+	.send = tpm_loongson_send,
>+};
>+
>+static int tpm_loongson_probe(struct platform_device *pdev)
>+{
>+	struct loongson_se_engine *tpm_engine;
>+	struct device *dev = &pdev->dev;
>+	struct tpm_loongson_cmd *cmd;
>+	struct tpm_chip *chip;
>+
>+	tpm_engine = loongson_se_init_engine(dev->parent, SE_ENGINE_TPM);
>+	if (!tpm_engine)
>+		return -ENODEV;
>+	cmd = tpm_engine->command;
>+	cmd->cmd_id = SE_CMD_TPM;
>+	cmd->data_off = tpm_engine->buffer_off;
>+
>+	chip = tpmm_chip_alloc(dev, &tpm_loongson_ops);
>+	if (IS_ERR(chip))
>+		return PTR_ERR(chip);
>+	chip->flags = TPM_CHIP_FLAG_TPM2 | TPM_CHIP_FLAG_IRQ;
>+	dev_set_drvdata(&chip->dev, tpm_engine);
>+
>+	return tpm_chip_register(chip);
>+}
>+
>+static struct platform_driver tpm_loongson = {
>+	.probe   = tpm_loongson_probe,
>+	.driver  = {
>+		.name  = "loongson-tpm",
>+	},
>+};
>+module_platform_driver(tpm_loongson);
>+
>+MODULE_ALIAS("platform:loongson-tpm");
>+MODULE_LICENSE("GPL");
>+MODULE_DESCRIPTION("Loongson TPM driver");
>-- 
>2.45.2
>
>

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