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         if (!devm_request_mem_region(&pdev->dev,
  65                                 res->start, resource_size(res),
  66                                 pdev->name)) {
  67                 ret = -EBUSY;
  68                 goto out_rng;
  69         }
  70
  71         priv->regs = devm_ioremap(&pdev->dev, res->start, resource_size(res));
  72         if (!priv->regs) {
  73                 ret = -ENOMEM;
  74                 goto out_rng;
  75         }
  76
  77         ret = hwrng_register(rng);
  78         if (ret) {
  79                 dev_err(&pdev->dev, "failed to register hwrng driver\n");
  80                 goto out;
  81         }
  82
  83         dev_info(&pdev->dev, "registered\n");
  84
  85         return ret;
  86
  87 out_rng:
  88         platform_set_drvdata(pdev, NULL);
  89         kfree(rng);
  90 out_priv:
  91         kfree(priv);
  92 out:
  93         return ret;
  94 }
  95
  96 static int mcs814x_rng_remove(struct platform_device *pdev)
  97 {
  98         struct hwrng *rng = platform_get_drvdata(pdev);
  99         struct mcs814x_rng_priv *priv = (struct mcs814x_rng_priv *)rng->priv;
 100
 101         hwrng_unregister(rng);
 102         kfree(priv);
 103         kfree(rng);
 104         platform_set_drvdata(pdev, NULL);
 105
 106         return 0;
 107 }
 108
 109 static const struct of_device_id mcs814x_rng_ids[] = {
 110         { .compatible = "moschip,mcs814x-rng", },
 111         { /* sentinel */ },
 112 };
 113
 114 static struct platform_driver mcs814x_rng_driver = {
 115         .driver = {
 116                 .name   = "mcs814x-rng",
 117                 .owner  = THIS_MODULE,
 118                 .of_match_table = mcs814x_rng_ids,
 119         },
 120         .probe  = mcs814x_rng_probe,
 121         .remove = __devexit_p(mcs814x_rng_remove),
 122 };
 123
 124 module_platform_driver(mcs814x_rng_driver);
 125
 126 MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
 127 MODULE_DESCRIPTION("H/W Random Number Generator (RNG) for Moschip MCS814x");
 128 MODULE_LICENSE("GPL");