crypto: loongson - add Loongson RNG driver support

Loongson's Random Number Generator is found inside Loongson Security
Engine chip.

Co-developed-by: Yinggang Gu <guyinggang@loongson.cn>
Signed-off-by: Yinggang Gu <guyinggang@loongson.cn>
Signed-off-by: Qunqin Zhao <zhaoqunqin@loongson.cn>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Link: https://lore.kernel.org/r/20250705072045.1067-3-zhaoqunqin@loongson.cn
Signed-off-by: Lee Jones <lee@kernel.org>

drivers/crypto/Kconfig

@@ -840,6 +840,7 @@ config CRYPTO_DEV_CCREE
 	  If unsure say Y.
 
 source "drivers/crypto/hisilicon/Kconfig"
+source "drivers/crypto/loongson/Kconfig"
 
 source "drivers/crypto/amlogic/Kconfig"
 

drivers/crypto/Makefile

@@ -44,6 +44,7 @@ obj-y += inside-secure/
 obj-$(CONFIG_CRYPTO_DEV_ARTPEC6) += axis/
 obj-y += xilinx/
 obj-y += hisilicon/
+obj-y += loongson/
 obj-$(CONFIG_CRYPTO_DEV_AMLOGIC_GXL) += amlogic/
 obj-y += intel/
 obj-y += starfive/

drivers/crypto/loongson/Kconfig

@@ -0,0 +1,5 @@
+config CRYPTO_DEV_LOONGSON_RNG
+	tristate "Support for Loongson RNG Driver"
+	depends on MFD_LOONGSON_SE
+	help
+	  Support for Loongson RNG Driver.

drivers/crypto/loongson/Makefile

@@ -0,0 +1 @@
+obj-$(CONFIG_CRYPTO_DEV_LOONGSON_RNG)  += loongson-rng.o

drivers/crypto/loongson/loongson-rng.c

@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 HiSilicon Limited. */
+/* Copyright (c) 2025 Loongson Technology Corporation Limited. */
+
+#include <linux/crypto.h>
+#include <linux/err.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/mfd/loongson-se.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/random.h>
+#include <crypto/internal/rng.h>
+
+#define SE_SEED_SIZE 32
+
+struct loongson_rng_list {
+	struct mutex lock;
+	struct list_head list;
+	int registered;
+};
+
+struct loongson_rng {
+	u32 used;
+	struct loongson_se_engine *engine;
+	struct list_head list;
+	struct mutex lock;
+};
+
+struct loongson_rng_ctx {
+	struct loongson_rng *rng;
+};
+
+struct loongson_rng_cmd {
+	u32 cmd_id;
+	union {
+		u32 len;
+		u32 ret;
+	} u;
+	u32 seed_off;
+	u32 out_off;
+	u32 pad[4];
+};
+
+static struct loongson_rng_list rng_devices = {
+	.lock = __MUTEX_INITIALIZER(rng_devices.lock),
+	.list = LIST_HEAD_INIT(rng_devices.list),
+};
+
+static int loongson_rng_generate(struct crypto_rng *tfm, const u8 *src,
+			  unsigned int slen, u8 *dstn, unsigned int dlen)
+{
+	struct loongson_rng_ctx *ctx = crypto_rng_ctx(tfm);
+	struct loongson_rng *rng = ctx->rng;
+	struct loongson_rng_cmd *cmd = rng->engine->command;
+	int err, len;
+
+	mutex_lock(&rng->lock);
+	cmd->seed_off = 0;
+	do {
+		len = min(dlen, rng->engine->buffer_size);
+		cmd = rng->engine->command;
+		cmd->u.len = len;
+		err = loongson_se_send_engine_cmd(rng->engine);
+		if (err)
+			break;
+
+		cmd = rng->engine->command_ret;
+		if (cmd->u.ret) {
+			err = -EIO;
+			break;
+		}
+
+		memcpy(dstn, rng->engine->data_buffer, len);
+		dlen -= len;
+		dstn += len;
+	} while (dlen > 0);
+	mutex_unlock(&rng->lock);
+
+	return err;
+}
+
+static int loongson_rng_init(struct crypto_tfm *tfm)
+{
+	struct loongson_rng_ctx *ctx = crypto_tfm_ctx(tfm);
+	struct loongson_rng *rng;
+	u32 min_used = U32_MAX;
+
+	mutex_lock(&rng_devices.lock);
+	list_for_each_entry(rng, &rng_devices.list, list) {
+		if (rng->used < min_used) {
+			ctx->rng = rng;
+			min_used = rng->used;
+		}
+	}
+	ctx->rng->used++;
+	mutex_unlock(&rng_devices.lock);
+
+	return 0;
+}
+
+static void loongson_rng_exit(struct crypto_tfm *tfm)
+{
+	struct loongson_rng_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	mutex_lock(&rng_devices.lock);
+	ctx->rng->used--;
+	mutex_unlock(&rng_devices.lock);
+}
+
+static int loongson_rng_seed(struct crypto_rng *tfm, const u8 *seed,
+			     unsigned int slen)
+{
+	struct loongson_rng_ctx *ctx = crypto_rng_ctx(tfm);
+	struct loongson_rng *rng = ctx->rng;
+	struct loongson_rng_cmd *cmd;
+	int err;
+
+	if (slen < SE_SEED_SIZE)
+		return -EINVAL;
+
+	slen = min(slen, rng->engine->buffer_size);
+
+	mutex_lock(&rng->lock);
+	cmd = rng->engine->command;
+	cmd->u.len = slen;
+	cmd->seed_off = rng->engine->buffer_off;
+	memcpy(rng->engine->data_buffer, seed, slen);
+	err = loongson_se_send_engine_cmd(rng->engine);
+	if (err)
+		goto out;
+
+	cmd = rng->engine->command_ret;
+	if (cmd->u.ret)
+		err = -EIO;
+out:
+	mutex_unlock(&rng->lock);
+
+	return err;
+}
+
+static struct rng_alg loongson_rng_alg = {
+	.generate = loongson_rng_generate,
+	.seed =	loongson_rng_seed,
+	.seedsize = SE_SEED_SIZE,
+	.base = {
+		.cra_name = "stdrng",
+		.cra_driver_name = "loongson_stdrng",
+		.cra_priority = 300,
+		.cra_ctxsize = sizeof(struct loongson_rng_ctx),
+		.cra_module = THIS_MODULE,
+		.cra_init = loongson_rng_init,
+		.cra_exit = loongson_rng_exit,
+	},
+};
+
+static int loongson_rng_probe(struct platform_device *pdev)
+{
+	struct loongson_rng_cmd *cmd;
+	struct loongson_rng *rng;
+	int ret = 0;
+
+	rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
+	if (!rng)
+		return -ENOMEM;
+
+	rng->engine = loongson_se_init_engine(pdev->dev.parent, SE_ENGINE_RNG);
+	if (!rng->engine)
+		return -ENODEV;
+	cmd = rng->engine->command;
+	cmd->cmd_id = SE_CMD_RNG;
+	cmd->out_off = rng->engine->buffer_off;
+	mutex_init(&rng->lock);
+
+	mutex_lock(&rng_devices.lock);
+
+	if (!rng_devices.registered) {
+		ret = crypto_register_rng(&loongson_rng_alg);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to register crypto(%d)\n", ret);
+			goto out;
+		}
+		rng_devices.registered = 1;
+	}
+
+	list_add_tail(&rng->list, &rng_devices.list);
+out:
+	mutex_unlock(&rng_devices.lock);
+
+	return ret;
+}
+
+static struct platform_driver loongson_rng_driver = {
+	.probe		= loongson_rng_probe,
+	.driver		= {
+		.name	= "loongson-rng",
+	},
+};
+module_platform_driver(loongson_rng_driver);
+
+MODULE_ALIAS("platform:loongson-rng");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Yinggang Gu <guyinggang@loongson.cn>");
+MODULE_AUTHOR("Qunqin Zhao <zhaoqunqin@loongson.cn>");
+MODULE_DESCRIPTION("Loongson Random Number Generator driver");