LXR linux/drivers/char/hw_random/powernv-rng.c

   1/*
   2 * Copyright 2013 Michael Ellerman, Guo Chao, IBM Corp.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public License
   6 * as published by the Free Software Foundation; either version
   7 * 2 of the License, or (at your option) any later version.
   8 */
   9
  10#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  11
  12#include <linux/module.h>
  13#include <linux/kernel.h>
  14#include <linux/platform_device.h>
  15#include <linux/random.h>
  16#include <linux/hw_random.h>
  17
  18static int powernv_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
  19{
  20        unsigned long *buf;
  21        int i, len;
  22
  23        /* We rely on rng_buffer_size() being >= sizeof(unsigned long) */
  24        len = max / sizeof(unsigned long);
  25
  26        buf = (unsigned long *)data;
  27
  28        for (i = 0; i < len; i++)
  29                powernv_get_random_long(buf++);
  30
  31        return len * sizeof(unsigned long);
  32}
  33
  34static struct hwrng powernv_hwrng = {
  35        .name = "powernv-rng",
  36        .read = powernv_rng_read,
  37};
  38
  39static int powernv_rng_remove(struct platform_device *pdev)
  40{
  41        hwrng_unregister(&powernv_hwrng);
  42
  43        return 0;
  44}
  45
  46static int powernv_rng_probe(struct platform_device *pdev)
  47{
  48        int rc;
  49
  50        rc = hwrng_register(&powernv_hwrng);
  51        if (rc) {
  52                /* We only register one device, ignore any others */
  53                if (rc == -EEXIST)
  54                        rc = -ENODEV;
  55
  56                return rc;
  57        }
  58
  59        pr_info("Registered powernv hwrng.\n");
  60
  61        return 0;
  62}
  63
  64static const struct of_device_id powernv_rng_match[] = {
  65        { .compatible   = "ibm,power-rng",},
  66        {},
  67};
  68MODULE_DEVICE_TABLE(of, powernv_rng_match);
  69
  70static struct platform_driver powernv_rng_driver = {
  71        .driver = {
  72                .name = "powernv_rng",
  73                .of_match_table = powernv_rng_match,
  74        },
  75        .probe  = powernv_rng_probe,
  76        .remove = powernv_rng_remove,
  77};
  78module_platform_driver(powernv_rng_driver);
  79
  80MODULE_LICENSE("GPL");
  81MODULE_DESCRIPTION("Bare metal HWRNG driver for POWER7+ and above");
  82