LXR linux/drivers/char/hw_random/ixp4xx-rng.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * drivers/char/hw_random/ixp4xx-rng.c
   4 *
   5 * RNG driver for Intel IXP4xx family of NPUs
   6 *
   7 * Author: Deepak Saxena <dsaxena@plexity.net>
   8 *
   9 * Copyright 2005 (c) MontaVista Software, Inc.
  10 *
  11 * Fixes by Michael Buesch
  12 */
  13
  14#include <linux/kernel.h>
  15#include <linux/types.h>
  16#include <linux/module.h>
  17#include <linux/moduleparam.h>
  18#include <linux/platform_device.h>
  19#include <linux/init.h>
  20#include <linux/bitops.h>
  21#include <linux/hw_random.h>
  22#include <linux/of.h>
  23#include <linux/soc/ixp4xx/cpu.h>
  24
  25#include <asm/io.h>
  26
  27static int ixp4xx_rng_data_read(struct hwrng *rng, u32 *buffer)
  28{
  29        void __iomem * rng_base = (void __iomem *)rng->priv;
  30
  31        *buffer = __raw_readl(rng_base);
  32
  33        return 4;
  34}
  35
  36static struct hwrng ixp4xx_rng_ops = {
  37        .name           = "ixp4xx",
  38        .data_read      = ixp4xx_rng_data_read,
  39};
  40
  41static int ixp4xx_rng_probe(struct platform_device *pdev)
  42{
  43        void __iomem * rng_base;
  44        struct device *dev = &pdev->dev;
  45        struct resource *res;
  46
  47        if (!cpu_is_ixp46x()) /* includes IXP455 */
  48                return -ENOSYS;
  49
  50        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  51        rng_base = devm_ioremap_resource(dev, res);
  52        if (IS_ERR(rng_base))
  53                return PTR_ERR(rng_base);
  54
  55        ixp4xx_rng_ops.priv = (unsigned long)rng_base;
  56        return devm_hwrng_register(dev, &ixp4xx_rng_ops);
  57}
  58
  59static const struct of_device_id ixp4xx_rng_of_match[] = {
  60        {
  61                .compatible = "intel,ixp46x-rng",
  62        },
  63        {},
  64};
  65MODULE_DEVICE_TABLE(of, ixp4xx_rng_of_match);
  66
  67static struct platform_driver ixp4xx_rng_driver = {
  68        .driver = {
  69                .name = "ixp4xx-hwrandom",
  70                .of_match_table = ixp4xx_rng_of_match,
  71        },
  72        .probe = ixp4xx_rng_probe,
  73};
  74module_platform_driver(ixp4xx_rng_driver);
  75
  76MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
  77MODULE_DESCRIPTION("H/W Pseudo-Random Number Generator (RNG) driver for IXP45x/46x");
  78MODULE_LICENSE("GPL");
  79