[linux-block.git] / drivers / char / hw_random / pseries-rng.c

// 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");
Commit	Line	Data
45051539	1	// SPDX-License-Identifier: GPL-2.0-only
649e9ea0 KY	2	/*
	3	* Copyright (C) 2010 Michael Neuling IBM Corporation
	4	*
	5	* Driver for the pseries hardware RNG for POWER7+ and above
649e9ea0 KY	6	*/
649e9ea0 KY	7
d319fe2a ME	8	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	9
	10	#include <linux/kernel.h>
649e9ea0 KY	11	#include <linux/module.h>
	12	#include <linux/hw_random.h>
	13	#include <asm/vio.h>
	14
649e9ea0	15
24c65bc7	16	static int pseries_rng_read(struct hwrng rng, void data, size_t max, bool wait)
649e9ea0	17	{
24c65bc7	18	u64 buffer[PLPAR_HCALL_BUFSIZE];
d319fe2a ME	19	int rc;
d319fe2a ME	20
24c65bc7	21	rc = plpar_hcall(H_RANDOM, (unsigned long *)buffer);
d319fe2a ME	22	if (rc != H_SUCCESS) {
	23	pr_err_ratelimited("H_RANDOM call failed %d\n", rc);
	24	return -EIO;
649e9ea0	25	}
ed424bb3	26	memcpy(data, buffer, 8);
d319fe2a ME	27
d319fe2a ME	28	/* The hypervisor interface returns 64 bits */
ed424bb3	29	return 8;
649e9ea0 KY	30	}
	31
	32	/**
	33	* pseries_rng_get_desired_dma - Return desired DMA allocate for CMO operations
	34	*
	35	* This is a required function for a driver to operate in a CMO environment
	36	* but this device does not make use of DMA allocations, return 0.
	37	*
	38	* Return value:
	39	* Number of bytes of IO data the driver will need to perform well -> 0
	40	*/
	41	static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev)
	42	{
	43	return 0;
	44	};
	45
	46	static struct hwrng pseries_rng = {
49cca7e0	47	.name = KBUILD_MODNAME,
24c65bc7	48	.read = pseries_rng_read,
649e9ea0 KY	49	};
649e9ea0 KY	50
257bedd4	51	static int pseries_rng_probe(struct vio_dev *dev,
649e9ea0 KY	52	const struct vio_device_id *id)
	53	{
	54	return hwrng_register(&pseries_rng);
	55	}
	56
257bedd4	57	static int pseries_rng_remove(struct vio_dev *dev)
649e9ea0 KY	58	{
	59	hwrng_unregister(&pseries_rng);
	60	return 0;
	61	}
	62
677c4f4c	63	static const struct vio_device_id pseries_rng_driver_ids[] = {
649e9ea0 KY	64	{ "ibm,random-v1", "ibm,random"},
	65	{ "", "" }
	66	};
	67	MODULE_DEVICE_TABLE(vio, pseries_rng_driver_ids);
	68
	69	static struct vio_driver pseries_rng_driver = {
49cca7e0	70	.name = KBUILD_MODNAME,
649e9ea0 KY	71	.probe = pseries_rng_probe,
	72	.remove = pseries_rng_remove,
	73	.get_desired_dma = pseries_rng_get_desired_dma,
	74	.id_table = pseries_rng_driver_ids
	75	};
	76
	77	static int __init rng_init(void)
	78	{
7a1ae9c0	79	pr_info("Registering IBM pSeries RNG driver\n");
649e9ea0 KY	80	return vio_register_driver(&pseries_rng_driver);
	81	}
	82
	83	module_init(rng_init);
	84
	85	static void __exit rng_exit(void)
	86	{
	87	vio_unregister_driver(&pseries_rng_driver);
	88	}
	89	module_exit(rng_exit);
	90
	91	MODULE_LICENSE("GPL");
	92	MODULE_AUTHOR("Michael Neuling <mikey@neuling.org>");
	93	MODULE_DESCRIPTION("H/W RNG driver for IBM pSeries processors");