[PATCH v6 5/6] tpm: Add a driver for Loongson TPM device

[Qunqin Zhao]

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@xxxxxxxxxxx>
Signed-off-by: Yinggang Gu <guyinggang@xxxxxxxxxxx>
Signed-off-by: Qunqin Zhao <zhaoqunqin@xxxxxxxxxxx>
---
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 | 103 ++++++++++++++++++++++++++++++++
 3 files changed, 113 insertions(+)
 create mode 100644 drivers/char/tpm/tpm_loongson.c

diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
index 0fc9a510e..5d0e7a1f8 100644
--- a/drivers/char/tpm/Kconfig
+++ b/drivers/char/tpm/Kconfig
@@ -225,5 +225,14 @@ config TCG_FTPM_TEE
 	help
 	  This driver proxies for firmware TPM running in TEE.
 
+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.
+
 source "drivers/char/tpm/st33zp24/Kconfig"
 endif # TCG_TPM
diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index 9bb142c75..e84a2f7a9 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -44,3 +44,4 @@ obj-$(CONFIG_TCG_XEN) += xen-tpmfront.o
 obj-$(CONFIG_TCG_CRB) += tpm_crb.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..91e0390c8
--- /dev/null
+++ b/drivers/char/tpm/tpm_loongson.c
@@ -0,0 +1,103 @@
+// 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_msg {
+	u32 cmd;
+	u32 data_off;
+	u32 data_len;
+	u32 info[5];
+};
+
+struct tpm_loongson_dev {
+	struct lsse_ch *se_ch;
+	struct completion tpm_loongson_completion;
+};
+
+static void tpm_loongson_complete(struct lsse_ch *ch)
+{
+	struct tpm_loongson_dev *td = ch->priv;
+
+	complete(&td->tpm_loongson_completion);
+}
+
+static int tpm_loongson_recv(struct tpm_chip *chip, u8 *buf, size_t count)
+{
+	struct tpm_loongson_dev *td = dev_get_drvdata(&chip->dev);
+	struct tpm_loongson_msg *rmsg;
+	int sig;
+
+	sig = wait_for_completion_interruptible(&td->tpm_loongson_completion);
+	if (sig)
+		return sig;
+
+	rmsg = td->se_ch->rmsg;
+	memcpy(buf, td->se_ch->data_buffer, rmsg->data_len);
+
+	return rmsg->data_len;
+}
+
+static int tpm_loongson_send(struct tpm_chip *chip, u8 *buf, size_t count)
+{
+	struct tpm_loongson_dev *td = dev_get_drvdata(&chip->dev);
+	struct tpm_loongson_msg *smsg = td->se_ch->smsg;
+
+	memcpy(td->se_ch->data_buffer, buf, count);
+	smsg->data_len = count;
+
+	return se_send_ch_requeset(td->se_ch);
+}
+
+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 device *dev = &pdev->dev;
+	struct tpm_loongson_msg *smsg;
+	struct tpm_loongson_dev *td;
+	struct tpm_chip *chip;
+
+	td = devm_kzalloc(dev, sizeof(struct tpm_loongson_dev), GFP_KERNEL);
+	if (!td)
+		return -ENOMEM;
+
+	init_completion(&td->tpm_loongson_completion);
+	td->se_ch = se_init_ch(dev->parent, SE_CH_TPM, PAGE_SIZE,
+			       2 * sizeof(struct tpm_loongson_msg), td,
+			       tpm_loongson_complete);
+	if (!td->se_ch)
+		return -ENODEV;
+	smsg = td->se_ch->smsg;
+	smsg->cmd = SE_CMD_TPM;
+	smsg->data_off = td->se_ch->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, td);
+
+	return tpm_chip_register(chip);
+}
+
+static struct platform_driver tpm_loongson_driver = {
+	.probe   = tpm_loongson_probe,
+	.driver  = {
+		.name  = "loongson-tpm",
+	},
+};
+module_platform_driver(tpm_loongson_driver);
+
+MODULE_ALIAS("platform:loongson-tpm");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Loongson TPM driver");
-- 
2.45.2