kernel/drivers/char/hw_random/bcm63xx-rng.c

   1 /*
   2  * Broadcom BCM63xx Random Number Generator support
   3  *
   4  * Copyright (C) 2011, Florian Fainelli <florian@openwrt.org>
   5  * Copyright (C) 2009, Broadcom Corporation
   6  *
   7  */
   8 #include <linux/module.h>
   9 #include <linux/slab.h>
  10 #include <linux/io.h>
  11 #include <linux/err.h>
  12 #include <linux/clk.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/hw_random.h>
  15
  16 #define RNG_CTRL                        0x00
  17 #define RNG_EN                          (1 << 0)
  18
  19 #define RNG_STAT                        0x04
  20 #define RNG_AVAIL_MASK                  (0xff000000)
  21
  22 #define RNG_DATA                        0x08
  23 #define RNG_THRES                       0x0c
  24 #define RNG_MASK                        0x10
  25
  26 struct bcm63xx_rng_priv {
  27         struct hwrng rng;
  28         struct clk *clk;
  29         void __iomem *regs;
  30 };
  31
  32 #define to_rng_priv(rng)        container_of(rng, struct bcm63xx_rng_priv, rng)
  33
  34 static int bcm63xx_rng_init(struct hwrng *rng)
  35 {
  36         struct bcm63xx_rng_priv *priv = to_rng_priv(rng);
  37         u32 val;
  38         int error;
  39
  40         error = clk_prepare_enable(priv->clk);
  41         if (error)
  42                 return error;
  43
  44         val = __raw_readl(priv->regs + RNG_CTRL);
  45         val |= RNG_EN;
  46         __raw_writel(val, priv->regs + RNG_CTRL);
  47
  48         return 0;
  49 }
  50
  51 static void bcm63xx_rng_cleanup(struct hwrng *rng)
  52 {
  53         struct bcm63xx_rng_priv *priv = to_rng_priv(rng);
  54         u32 val;
  55
  56         val = __raw_readl(priv->regs + RNG_CTRL);
  57         val &= ~RNG_EN;
  58         __raw_writel(val, priv->regs + RNG_CTRL);
  59
  60         clk_disable_unprepare(priv->clk);
  61 }
  62
  63 static int bcm63xx_rng_data_present(struct hwrng *rng, int wait)
  64 {
  65         struct bcm63xx_rng_priv *priv = to_rng_priv(rng);
  66
  67         return __raw_readl(priv->regs + RNG_STAT) & RNG_AVAIL_MASK;
  68 }
  69
  70 static int bcm63xx_rng_data_read(struct hwrng *rng, u32 *data)
  71 {
  72         struct bcm63xx_rng_priv *priv = to_rng_priv(rng);
  73
  74         *data = __raw_readl(priv->regs + RNG_DATA);
  75
  76         return 4;
  77 }
  78
  79 static int bcm63xx_rng_probe(struct platform_device *pdev)
  80 {
  81         struct resource *r;
  82         struct clk *clk;
  83         int ret;
  84         struct bcm63xx_rng_priv *priv;
  85         struct hwrng *rng;
  86
  87         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  88         if (!r) {
  89                 dev_err(&pdev->dev, "no iomem resource\n");
  90                 return -ENXIO;
  91         }
  92
  93         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  94         if (!priv)
  95                 return -ENOMEM;
  96
  97         priv->rng.name = pdev->name;
  98         priv->rng.init = bcm63xx_rng_init;
  99         priv->rng.cleanup = bcm63xx_rng_cleanup;
 100         priv->rng.data_present = bcm63xx_rng_data_present;
 101         priv->rng.data_read = bcm63xx_rng_data_read;
 102
 103         priv->clk = devm_clk_get(&pdev->dev, "ipsec");
 104         if (IS_ERR(priv->clk)) {
 105                 ret = PTR_ERR(priv->clk);
 106                 dev_err(&pdev->dev, "no clock for device: %d\n", ret);
 107                 return ret;
 108         }
 109
 110         if (!devm_request_mem_region(&pdev->dev, r->start,
 111                                         resource_size(r), pdev->name)) {
 112                 dev_err(&pdev->dev, "request mem failed");
 113                 return -EBUSY;
 114         }
 115
 116         priv->regs = devm_ioremap_nocache(&pdev->dev, r->start,
 117                                         resource_size(r));
 118         if (!priv->regs) {
 119                 dev_err(&pdev->dev, "ioremap failed");
 120                 return -ENOMEM;
 121         }
 122
 123         ret = devm_hwrng_register(&pdev->dev, &priv->rng);
 124         if (ret) {
 125                 dev_err(&pdev->dev, "failed to register rng device: %d\n",
 126                         ret);
 127                 return ret;
 128         }
 129
 130         dev_info(&pdev->dev, "registered RNG driver\n");
 131
 132         return 0;
 133 }
 134
 135 static struct platform_driver bcm63xx_rng_driver = {
 136         .probe          = bcm63xx_rng_probe,
 137         .driver         = {
 138                 .name   = "bcm63xx-rng",
 139         },
 140 };
 141
 142 module_platform_driver(bcm63xx_rng_driver);
 143
 144 MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
 145 MODULE_DESCRIPTION("Broadcom BCM63xx RNG driver");
 146 MODULE_LICENSE("GPL");