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