1 // SPDX-License-Identifier: GPL-2.0
3 * Microchip PolarFire SoC (MPFS) hardware random driver
5 * Copyright (c) 2020-2022 Microchip Corporation. All rights reserved.
7 * Author: Conor Dooley <conor.dooley@microchip.com>
10 #include <linux/module.h>
11 #include <linux/hw_random.h>
12 #include <linux/platform_device.h>
13 #include <soc/microchip/mpfs.h>
15 #define CMD_OPCODE 0x21
16 #define CMD_DATA_SIZE 0U
18 #define MBOX_OFFSET 0U
19 #define RESP_OFFSET 0U
20 #define RNG_RESP_BYTES 32U
23 struct mpfs_sys_controller *sys_controller;
27 static int mpfs_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
29 struct mpfs_rng *rng_priv = container_of(rng, struct mpfs_rng, rng);
30 u32 response_msg[RNG_RESP_BYTES / sizeof(u32)];
31 unsigned int count = 0, copy_size_bytes;
34 struct mpfs_mss_response response = {
36 .resp_msg = (u32 *)response_msg,
37 .resp_size = RNG_RESP_BYTES
39 struct mpfs_mss_msg msg = {
40 .cmd_opcode = CMD_OPCODE,
41 .cmd_data_size = CMD_DATA_SIZE,
42 .response = &response,
44 .mbox_offset = MBOX_OFFSET,
45 .resp_offset = RESP_OFFSET
49 ret = mpfs_blocking_transaction(rng_priv->sys_controller, &msg);
53 copy_size_bytes = max - count > RNG_RESP_BYTES ? RNG_RESP_BYTES : max - count;
54 memcpy(buf + count, response_msg, copy_size_bytes);
56 count += copy_size_bytes;
64 static int mpfs_rng_probe(struct platform_device *pdev)
66 struct device *dev = &pdev->dev;
67 struct mpfs_rng *rng_priv;
70 rng_priv = devm_kzalloc(dev, sizeof(*rng_priv), GFP_KERNEL);
74 rng_priv->sys_controller = mpfs_sys_controller_get(&pdev->dev);
75 if (IS_ERR(rng_priv->sys_controller))
76 return dev_err_probe(dev, PTR_ERR(rng_priv->sys_controller),
77 "Failed to register system controller hwrng sub device\n");
79 rng_priv->rng.read = mpfs_rng_read;
80 rng_priv->rng.name = pdev->name;
81 rng_priv->rng.quality = 1024;
83 platform_set_drvdata(pdev, rng_priv);
85 ret = devm_hwrng_register(&pdev->dev, &rng_priv->rng);
87 return dev_err_probe(&pdev->dev, ret, "Failed to register MPFS hwrng\n");
89 dev_info(&pdev->dev, "Registered MPFS hwrng\n");
94 static struct platform_driver mpfs_rng_driver = {
98 .probe = mpfs_rng_probe,
100 module_platform_driver(mpfs_rng_driver);
102 MODULE_LICENSE("GPL");
103 MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
104 MODULE_DESCRIPTION("PolarFire SoC (MPFS) hardware random driver");