| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
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| 2 | /* |
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| 3 | * Copyright 2013 Michael Ellerman, Guo Chao, IBM Corp. |
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| 4 | */ |
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| 5 | |
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| 6 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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| 7 | |
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| 8 | #include <linux/module.h> |
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| 9 | #include <linux/mod_devicetable.h> |
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| 10 | #include <linux/kernel.h> |
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| 11 | #include <linux/platform_device.h> |
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| 12 | #include <linux/random.h> |
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| 13 | #include <linux/hw_random.h> |
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| 14 | #include <asm/archrandom.h> |
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| 15 | |
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| 16 | static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) |
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| 17 | { |
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| 18 | unsigned long *buf; |
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| 19 | int i, len; |
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| 20 | |
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| 21 | /* We rely on rng_buffer_size() being >= sizeof(unsigned long) */ |
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| 22 | len = max / sizeof(unsigned long); |
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| 23 | |
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| 24 | buf = (unsigned long *)data; |
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| 25 | |
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| 26 | for (i = 0; i < len; i++) |
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| 27 | pnv_get_random_long(buf++); |
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| 28 | |
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| 29 | return len * sizeof(unsigned long); |
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| 30 | } |
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| 31 | |
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| 32 | static struct hwrng powernv_hwrng = { |
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| 33 | .name = "powernv-rng" , |
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| 34 | .read = powernv_rng_read, |
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| 35 | }; |
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| 36 | |
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| 37 | static int powernv_rng_probe(struct platform_device *pdev) |
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| 38 | { |
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| 39 | int rc; |
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| 40 | |
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| 41 | rc = devm_hwrng_register(dev: &pdev->dev, rng: &powernv_hwrng); |
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| 42 | if (rc) { |
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| 43 | /* We only register one device, ignore any others */ |
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| 44 | if (rc == -EEXIST) |
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| 45 | rc = -ENODEV; |
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| 46 | |
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| 47 | return rc; |
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| 48 | } |
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| 49 | |
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| 50 | pr_info("Registered powernv hwrng.\n" ); |
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| 51 | |
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| 52 | return 0; |
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| 53 | } |
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| 54 | |
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| 55 | static const struct of_device_id powernv_rng_match[] = { |
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| 56 | { .compatible = "ibm,power-rng" ,}, |
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| 57 | {}, |
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| 58 | }; |
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| 59 | MODULE_DEVICE_TABLE(of, powernv_rng_match); |
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| 60 | |
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| 61 | static struct platform_driver powernv_rng_driver = { |
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| 62 | .driver = { |
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| 63 | .name = "powernv_rng" , |
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| 64 | .of_match_table = powernv_rng_match, |
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| 65 | }, |
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| 66 | .probe = powernv_rng_probe, |
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| 67 | }; |
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| 68 | module_platform_driver(powernv_rng_driver); |
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| 69 | |
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| 70 | MODULE_LICENSE("GPL" ); |
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| 71 | MODULE_DESCRIPTION("Bare metal HWRNG driver for POWER7+ and above" ); |
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| 72 | |
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