1 files changed, 103 insertions, 0 deletions
diff --git a/drivers/char/hw_random/mpfs-rng.c b/drivers/char/hw_random/mpfs-rng.c
new file mode 100644
index 0000000000..c6972734ae
--- /dev/null
+++ b/drivers/char/hw_random/mpfs-rng.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Microchip PolarFire SoC (MPFS) hardware random driver
+ *
+ * Copyright (c) 2020-2022 Microchip Corporation. All rights reserved.
+ *
+ * Author: Conor Dooley <conor.dooley@microchip.com>
+ */
+
+#include <linux/module.h>
+#include <linux/hw_random.h>
+#include <linux/platform_device.h>
+#include <soc/microchip/mpfs.h>
+
+#define CMD_OPCODE	0x21
+#define CMD_DATA_SIZE	0U
+#define CMD_DATA	NULL
+#define MBOX_OFFSET	0U
+#define RESP_OFFSET	0U
+#define RNG_RESP_BYTES	32U
+
+struct mpfs_rng {
+	struct mpfs_sys_controller *sys_controller;
+	struct hwrng rng;
+};
+
+static int mpfs_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+	struct mpfs_rng *rng_priv = container_of(rng, struct mpfs_rng, rng);
+	u32 response_msg[RNG_RESP_BYTES / sizeof(u32)];
+	unsigned int count = 0, copy_size_bytes;
+	int ret;
+
+	struct mpfs_mss_response response = {
+		.resp_status = 0U,
+		.resp_msg = (u32 *)response_msg,
+		.resp_size = RNG_RESP_BYTES
+	};
+	struct mpfs_mss_msg msg = {
+		.cmd_opcode = CMD_OPCODE,
+		.cmd_data_size = CMD_DATA_SIZE,
+		.response = &response,
+		.cmd_data = CMD_DATA,
+		.mbox_offset = MBOX_OFFSET,
+		.resp_offset = RESP_OFFSET
+	};
+
+	while (count < max) {
+		ret = mpfs_blocking_transaction(rng_priv->sys_controller, &msg);
+		if (ret)
+			return ret;
+
+		copy_size_bytes = max - count > RNG_RESP_BYTES ? RNG_RESP_BYTES : max - count;
+		memcpy(buf + count, response_msg, copy_size_bytes);
+
+		count += copy_size_bytes;
+		if (!wait)
+			break;
+	}
+
+	return count;
+}
+
+static int mpfs_rng_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mpfs_rng *rng_priv;
+	int ret;
+
+	rng_priv = devm_kzalloc(dev, sizeof(*rng_priv), GFP_KERNEL);
+	if (!rng_priv)
+		return -ENOMEM;
+
+	rng_priv->sys_controller =  mpfs_sys_controller_get(&pdev->dev);
+	if (IS_ERR(rng_priv->sys_controller))
+		return dev_err_probe(dev, PTR_ERR(rng_priv->sys_controller),
+				     "Failed to register system controller hwrng sub device\n");
+
+	rng_priv->rng.read = mpfs_rng_read;
+	rng_priv->rng.name = pdev->name;
+
+	platform_set_drvdata(pdev, rng_priv);
+
+	ret = devm_hwrng_register(&pdev->dev, &rng_priv->rng);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret, "Failed to register MPFS hwrng\n");
+
+	dev_info(&pdev->dev, "Registered MPFS hwrng\n");
+
+	return 0;
+}
+
+static struct platform_driver mpfs_rng_driver = {
+	.driver = {
+		.name = "mpfs-rng",
+	},
+	.probe = mpfs_rng_probe,
+};
+module_platform_driver(mpfs_rng_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
+MODULE_DESCRIPTION("PolarFire SoC (MPFS) hardware random driver");