linux-kernel - Re: [PATCH v11 3/4] tpm: Add a driver for Loongson TPM device

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Message-ID: <aFs2RDOeOKvWUN2L@kernel.org>
Date: Wed, 25 Jun 2025 02:35:32 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Qunqin Zhao <zhaoqunqin@...ngson.cn>
Cc: lee@...nel.org, herbert@...dor.apana.org.au,
	linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev,
	davem@...emloft.net, linux-crypto@...r.kernel.org,
	peterhuewe@....de, jgg@...pe.ca, linux-integrity@...r.kernel.org,
	Yinggang Gu <guyinggang@...ngson.cn>,
	Huacai Chen <chenhuacai@...ngson.cn>
Subject: Re: [PATCH v11 3/4] tpm: Add a driver for Loongson TPM device

On Thu, Jun 19, 2025 at 10:51:37AM +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>
> ---
>  drivers/char/tpm/Kconfig        |  9 ++++
>  drivers/char/tpm/Makefile       |  1 +
>  drivers/char/tpm/tpm_loongson.c | 84 +++++++++++++++++++++++++++++++++
>  3 files changed, 94 insertions(+)
>  create mode 100644 drivers/char/tpm/tpm_loongson.c
> 
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index dddd702b2..ba3924eb1 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 9de1b3ea3..5b5cdc0d3 100644
> --- a/drivers/char/tpm/Makefile
> +++ b/drivers/char/tpm/Makefile
> @@ -46,3 +46,4 @@ 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_SVSM) += tpm_svsm.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..5cbdb37f8
> --- /dev/null
> +++ b/drivers/char/tpm/tpm_loongson.c
> @@ -0,0 +1,84 @@
> +// 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;
> +
> +	if (cmd_ret->data_len > count)
> +		return -EIO;
> +
> +	memcpy(buf, tpm_engine->data_buffer, cmd_ret->data_len);
> +
> +	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;
> +
> +	if (count > tpm_engine->buffer_size)
> +		return -E2BIG;
> +
> +	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",

This patch looks otherwise great but I'd prefer here tho use
"tpm_loongson_probe" for the value of the name field.

> +	},
> +};
> +module_platform_driver(tpm_loongson);
> +
> +MODULE_ALIAS("platform:loongson-tpm");
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Loongson TPM driver");
> -- 
> 2.45.2
> 

BR, Jarkko