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1// SPDX-License-Identifier: GPL-2.02/*3 * Microchip PolarFire SoC (MPFS) hardware random driver4 *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 0x2116#define CMD_DATA_SIZE 0U17#define CMD_DATA NULL18#define MBOX_OFFSET 0U19#define RESP_OFFSET 0U20#define RNG_RESP_BYTES 32U21 22struct mpfs_rng {23 struct mpfs_sys_controller *sys_controller;24 struct hwrng rng;25};26 27static 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_BYTES38 };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_OFFSET46 };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 64static 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 ret = devm_hwrng_register(&pdev->dev, &rng_priv->rng);83 if (ret)84 return dev_err_probe(&pdev->dev, ret, "Failed to register MPFS hwrng\n");85 86 dev_info(&pdev->dev, "Registered MPFS hwrng\n");87 88 return 0;89}90 91static struct platform_driver mpfs_rng_driver = {92 .driver = {93 .name = "mpfs-rng",94 },95 .probe = mpfs_rng_probe,96};97module_platform_driver(mpfs_rng_driver);98 99MODULE_LICENSE("GPL");100MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");101MODULE_DESCRIPTION("PolarFire SoC (MPFS) hardware random driver");102