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