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// 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");
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