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
  27 static 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
  36 static struct hwrng ixp4xx_rng_ops = {
  37         .name           = "ixp4xx",
  38         .data_read      = ixp4xx_rng_data_read,
  39 };
  40
  41 static int ixp4xx_rng_probe(struct platform_device *pdev)
  42 {
  43         void __iomem * rng_base;
  44         struct device *dev = &pdev->dev;
  45
  46         if (!cpu_is_ixp46x()) /* includes IXP455 */
  47                 return -ENOSYS;
  48
  49         rng_base = devm_platform_ioremap_resource(pdev, 0);
  50         if (IS_ERR(rng_base))
  51                 return PTR_ERR(rng_base);
  52
  53         ixp4xx_rng_ops.priv = (unsigned long)rng_base;
  54         return devm_hwrng_register(dev, &ixp4xx_rng_ops);
  55 }
  56
  57 static const struct of_device_id ixp4xx_rng_of_match[] = {
  58         {
  59                 .compatible = "intel,ixp46x-rng",
  60         },
  61         {},
  62 };
  63 MODULE_DEVICE_TABLE(of, ixp4xx_rng_of_match);
  64
  65 static struct platform_driver ixp4xx_rng_driver = {
  66         .driver = {
  67                 .name = "ixp4xx-hwrandom",
  68                 .of_match_table = ixp4xx_rng_of_match,
  69         },
  70         .probe = ixp4xx_rng_probe,
  71 };
  72 module_platform_driver(ixp4xx_rng_driver);
  73
  74 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
  75 MODULE_DESCRIPTION("H/W Pseudo-Random Number Generator (RNG) driver for IXP45x/46x");
  76 MODULE_LICENSE("GPL");