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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2010 Michael Neuling IBM Corporation
*
* Driver for the pseries hardware RNG for POWER7+ and above
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/hw_random.h>
#include <asm/vio.h>
static int pseries_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
{
u64 buffer[PLPAR_HCALL_BUFSIZE];
int rc;
rc = plpar_hcall(H_RANDOM, (unsigned long *)buffer);
if (rc != H_SUCCESS) {
pr_err_ratelimited("H_RANDOM call failed %d\n", rc);
return -EIO;
}
memcpy(data, buffer, 8);
/* The hypervisor interface returns 64 bits */
return 8;
}
/**
* pseries_rng_get_desired_dma - Return desired DMA allocate for CMO operations
*
* This is a required function for a driver to operate in a CMO environment
* but this device does not make use of DMA allocations, return 0.
*
* Return value:
* Number of bytes of IO data the driver will need to perform well -> 0
*/
static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev)
{
return 0;
};
static struct hwrng pseries_rng = {
.name = KBUILD_MODNAME,
.read = pseries_rng_read,
};
static int pseries_rng_probe(struct vio_dev *dev,
const struct vio_device_id *id)
{
return hwrng_register(&pseries_rng);
}
static int pseries_rng_remove(struct vio_dev *dev)
{
hwrng_unregister(&pseries_rng);
return 0;
}
static const struct vio_device_id pseries_rng_driver_ids[] = {
{ "ibm,random-v1", "ibm,random"},
{ "", "" }
};
MODULE_DEVICE_TABLE(vio, pseries_rng_driver_ids);
static struct vio_driver pseries_rng_driver = {
.name = KBUILD_MODNAME,
.probe = pseries_rng_probe,
.remove = pseries_rng_remove,
.get_desired_dma = pseries_rng_get_desired_dma,
.id_table = pseries_rng_driver_ids
};
static int __init rng_init(void)
{
pr_info("Registering IBM pSeries RNG driver\n");
return vio_register_driver(&pseries_rng_driver);
}
module_init(rng_init);
static void __exit rng_exit(void)
{
vio_unregister_driver(&pseries_rng_driver);
}
module_exit(rng_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michael Neuling <mikey@neuling.org>");
MODULE_DESCRIPTION("H/W RNG driver for IBM pSeries processors");
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