1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Microchip PolarFire SoC (MPFS) hardware random driver
4 *
5 * Copyright (c) 2020-2022 Microchip Corporation. All rights reserved.
6 *
7 * Author: Conor Dooley <conor.dooley@microchip.com>
8 */
9
10 #include <linux/module.h>
11 #include <linux/hw_random.h>
12 #include <linux/platform_device.h>
13 #include <soc/microchip/mpfs.h>
14
15 #define CMD_OPCODE 0x21
16 #define CMD_DATA_SIZE 0U
17 #define CMD_DATA NULL
18 #define MBOX_OFFSET 0U
19 #define RESP_OFFSET 0U
20 #define RNG_RESP_BYTES 32U
21
22 struct mpfs_rng {
23 struct mpfs_sys_controller *sys_controller;
24 struct hwrng rng;
25 };
26
mpfs_rng_read(struct hwrng * rng,void * buf,size_t max,bool wait)27 static int mpfs_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
28 {
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;
32 int ret;
33
34 struct mpfs_mss_response response = {
35 .resp_status = 0U,
36 .resp_msg = (u32 *)response_msg,
37 .resp_size = RNG_RESP_BYTES
38 };
39 struct mpfs_mss_msg msg = {
40 .cmd_opcode = CMD_OPCODE,
41 .cmd_data_size = CMD_DATA_SIZE,
42 .response = &response,
43 .cmd_data = CMD_DATA,
44 .mbox_offset = MBOX_OFFSET,
45 .resp_offset = RESP_OFFSET
46 };
47
48 while (count < max) {
49 ret = mpfs_blocking_transaction(rng_priv->sys_controller, &msg);
50 if (ret)
51 return ret;
52
53 copy_size_bytes = max - count > RNG_RESP_BYTES ? RNG_RESP_BYTES : max - count;
54 memcpy(buf + count, response_msg, copy_size_bytes);
55
56 count += copy_size_bytes;
57 if (!wait)
58 break;
59 }
60
61 return count;
62 }
63
mpfs_rng_probe(struct platform_device * pdev)64 static int mpfs_rng_probe(struct platform_device *pdev)
65 {
66 struct device *dev = &pdev->dev;
67 struct mpfs_rng *rng_priv;
68 int ret;
69
70 rng_priv = devm_kzalloc(dev, sizeof(*rng_priv), GFP_KERNEL);
71 if (!rng_priv)
72 return -ENOMEM;
73
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");
78
79 rng_priv->rng.read = mpfs_rng_read;
80 rng_priv->rng.name = pdev->name;
81
82 platform_set_drvdata(pdev, rng_priv);
83
84 ret = devm_hwrng_register(&pdev->dev, &rng_priv->rng);
85 if (ret)
86 return dev_err_probe(&pdev->dev, ret, "Failed to register MPFS hwrng\n");
87
88 dev_info(&pdev->dev, "Registered MPFS hwrng\n");
89
90 return 0;
91 }
92
93 static struct platform_driver mpfs_rng_driver = {
94 .driver = {
95 .name = "mpfs-rng",
96 },
97 .probe = mpfs_rng_probe,
98 };
99 module_platform_driver(mpfs_rng_driver);
100
101 MODULE_LICENSE("GPL");
102 MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
103 MODULE_DESCRIPTION("PolarFire SoC (MPFS) hardware random driver");
104
