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

/*
 * Copyright (C) 2010 Michael Neuling IBM Corporation
 *
 * Driver for the pseries hardware RNG for POWER7+ and above
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#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];
	size_t size = max < 8 ? max : 8;
	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, size);

	/* The hypervisor interface returns 64 bits */
	return size;
}

/**
 * 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 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
649e9ea0 KY	1	/*
	2	* Copyright (C) 2010 Michael Neuling IBM Corporation
	3	*
	4	* Driver for the pseries hardware RNG for POWER7+ and above
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*
	15	* You should have received a copy of the GNU General Public License
	16	* along with this program; if not, write to the Free Software
	17	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	18	*/
	19
d319fe2a ME	20	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	21
	22	#include <linux/kernel.h>
649e9ea0 KY	23	#include <linux/module.h>
	24	#include <linux/hw_random.h>
	25	#include <asm/vio.h>
	26
649e9ea0	27
24c65bc7	28	static int pseries_rng_read(struct hwrng rng, void data, size_t max, bool wait)
649e9ea0	29	{
24c65bc7 GK	30	u64 buffer[PLPAR_HCALL_BUFSIZE];
24c65bc7 GK	31	size_t size = max < 8 ? max : 8;
d319fe2a ME	32	int rc;
d319fe2a ME	33
24c65bc7	34	rc = plpar_hcall(H_RANDOM, (unsigned long *)buffer);
d319fe2a ME	35	if (rc != H_SUCCESS) {
	36	pr_err_ratelimited("H_RANDOM call failed %d\n", rc);
	37	return -EIO;
649e9ea0	38	}
24c65bc7	39	memcpy(data, buffer, size);
d319fe2a ME	40
d319fe2a ME	41	/* The hypervisor interface returns 64 bits */
24c65bc7	42	return size;
649e9ea0 KY	43	}
	44
	45	/**
	46	* pseries_rng_get_desired_dma - Return desired DMA allocate for CMO operations
	47	*
	48	* This is a required function for a driver to operate in a CMO environment
	49	* but this device does not make use of DMA allocations, return 0.
	50	*
	51	* Return value:
	52	* Number of bytes of IO data the driver will need to perform well -> 0
	53	*/
	54	static unsigned long pseries_rng_get_desired_dma(struct vio_dev *vdev)
	55	{
	56	return 0;
	57	};
	58
	59	static struct hwrng pseries_rng = {
49cca7e0	60	.name = KBUILD_MODNAME,
24c65bc7	61	.read = pseries_rng_read,
649e9ea0 KY	62	};
649e9ea0 KY	63
257bedd4	64	static int pseries_rng_probe(struct vio_dev *dev,
649e9ea0 KY	65	const struct vio_device_id *id)
	66	{
	67	return hwrng_register(&pseries_rng);
	68	}
	69
257bedd4	70	static int pseries_rng_remove(struct vio_dev *dev)
649e9ea0 KY	71	{
	72	hwrng_unregister(&pseries_rng);
	73	return 0;
	74	}
	75
	76	static struct vio_device_id pseries_rng_driver_ids[] = {
	77	{ "ibm,random-v1", "ibm,random"},
	78	{ "", "" }
	79	};
	80	MODULE_DEVICE_TABLE(vio, pseries_rng_driver_ids);
	81
	82	static struct vio_driver pseries_rng_driver = {
49cca7e0	83	.name = KBUILD_MODNAME,
649e9ea0 KY	84	.probe = pseries_rng_probe,
	85	.remove = pseries_rng_remove,
	86	.get_desired_dma = pseries_rng_get_desired_dma,
	87	.id_table = pseries_rng_driver_ids
	88	};
	89
	90	static int __init rng_init(void)
	91	{
7a1ae9c0	92	pr_info("Registering IBM pSeries RNG driver\n");
649e9ea0 KY	93	return vio_register_driver(&pseries_rng_driver);
	94	}
	95
	96	module_init(rng_init);
	97
	98	static void __exit rng_exit(void)
	99	{
	100	vio_unregister_driver(&pseries_rng_driver);
	101	}
	102	module_exit(rng_exit);
	103
	104	MODULE_LICENSE("GPL");
	105	MODULE_AUTHOR("Michael Neuling <mikey@neuling.org>");
	106	MODULE_DESCRIPTION("H/W RNG driver for IBM pSeries processors");