target/linux/mcs814x/files-3.3/drivers/char/hw_random/mcs814x-rng.c

   1 /*
   2  * RNG driver for Moschip MCS814x SoC
   3  *
   4  * Copyright 2012 (C), Florian Fainelli <florian@openwrt.org>
   5  *
   6  * This file is licensed under  the terms of the GNU General Public
   7  * License version 2. This program is licensed "as is" without any
   8  * warranty of any kind, whether express or implied.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/slab.h>
  13 #include <linux/module.h>
  14 #include <linux/types.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/hw_random.h>
  17 #include <linux/io.h>
  18 #include <linux/of.h>
  19
  20 #define STAT    0x00
  21 #define RND     0x04
  22
  23 struct mcs814x_rng_priv {
  24         void __iomem    *regs;
  25 };
  26
  27 static int mcs814x_rng_data_read(struct hwrng *rng, u32 *buffer)
  28 {
  29         struct mcs814x_rng_priv *priv = (struct mcs814x_rng_priv *)rng->priv;
  30
  31         *buffer = readl_relaxed(priv->regs + RND);
  32
  33         return 4;
  34 }
  35
  36 static int mcs814x_rng_probe(struct platform_device *pdev)
  37 {
  38         struct resource *res;
  39         struct mcs814x_rng_priv *priv;
  40         struct hwrng *rng;
  41         int ret;
  42
  43         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  44         if (!res)
  45                 return -ENODEV;
  46
  47         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  48         if (!priv) {
  49                 ret = -ENOMEM;
  50                 goto out;
  51         }
  52
  53         rng = kzalloc(sizeof(*rng), GFP_KERNEL);
  54         if (!rng) {
  55                 ret = -ENOMEM;
  56                 goto out_priv;
  57         }
  58
  59         platform_set_drvdata(pdev, rng);
  60         rng->priv = (unsigned long)priv;
  61         rng->name = pdev->name;
  62         rng->data_read = mcs814x_rng_data_read;
  63
  64         priv->regs = devm_request_and_ioremap(&pdev->dev, res);
  65         if (!priv->regs) {
  66                 ret = -ENOMEM;
  67                 goto out_rng;
  68         }
  69
  70         ret = hwrng_register(rng);
  71         if (ret) {
  72                 dev_err(&pdev->dev, "failed to register hwrng driver\n");
  73                 goto out;
  74         }
  75
  76         dev_info(&pdev->dev, "registered\n");
  77
  78         return ret;
  79
  80 out_rng:
  81         platform_set_drvdata(pdev, NULL);
  82         kfree(rng);
  83 out_priv:
  84         kfree(priv);
  85 out:
  86         return ret;
  87 }
  88
  89 static int mcs814x_rng_remove(struct platform_device *pdev)
  90 {
  91         struct hwrng *rng = platform_get_drvdata(pdev);
  92         struct mcs814x_rng_priv *priv = (struct mcs814x_rng_priv *)rng->priv;
  93
  94         hwrng_unregister(rng);
  95         kfree(priv);
  96         kfree(rng);
  97         platform_set_drvdata(pdev, NULL);
  98
  99         return 0;
 100 }
 101
 102 static const struct of_device_id mcs814x_rng_ids[] = {
 103         { .compatible = "moschip,mcs814x-rng", },
 104         { /* sentinel */ },
 105 };
 106
 107 static struct platform_driver mcs814x_rng_driver = {
 108         .driver = {
 109                 .name   = "mcs814x-rng",
 110                 .owner  = THIS_MODULE,
 111                 .of_match_table = mcs814x_rng_ids,
 112         },
 113         .probe  = mcs814x_rng_probe,
 114         .remove = __devexit_p(mcs814x_rng_remove),
 115 };
 116
 117 module_platform_driver(mcs814x_rng_driver);
 118
 119 MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
 120 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) for Moschip MCS814x");
 121 MODULE_LICENSE("GPL");