drivers/char/hw_random/bcm63xx-rng.c

   1 /*
   2  * Broadcom BCM63xx Random Number Generator support
   3  *
   4  * Copyright (C) 2011, Florian Fainelli <[email protected]>
   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 #include <linux/of.h>
  16
  17 #define RNG_CTRL                        0x00
  18 #define RNG_EN                          (1 << 0)
  19
  20 #define RNG_STAT                        0x04
  21 #define RNG_AVAIL_MASK                  (0xff000000)
  22
  23 #define RNG_DATA                        0x08
  24 #define RNG_THRES                       0x0c
  25 #define RNG_MASK                        0x10
  26
  27 struct bcm63xx_rng_priv {
  28         struct hwrng rng;
  29         struct clk *clk;
  30         void __iomem *regs;
  31 };
  32
  33 #define to_rng_priv(rng)        container_of(rng, struct bcm63xx_rng_priv, rng)
  34
  35 static int bcm63xx_rng_init(struct hwrng *rng)
  36 {
  37         struct bcm63xx_rng_priv *priv = to_rng_priv(rng);
  38         u32 val;
  39         int error;
  40
  41         error = clk_prepare_enable(priv->clk);
  42         if (error)
  43                 return error;
  44
  45         val = __raw_readl(priv->regs + RNG_CTRL);
  46         val |= RNG_EN;
  47         __raw_writel(val, priv->regs + RNG_CTRL);
  48
  49         return 0;
  50 }
  51
  52 static void bcm63xx_rng_cleanup(struct hwrng *rng)
  53 {
  54         struct bcm63xx_rng_priv *priv = to_rng_priv(rng);
  55         u32 val;
  56
  57         val = __raw_readl(priv->regs + RNG_CTRL);
  58         val &= ~RNG_EN;
  59         __raw_writel(val, priv->regs + RNG_CTRL);
  60
  61         clk_disable_unprepare(priv->clk);
  62 }
  63
  64 static int bcm63xx_rng_data_present(struct hwrng *rng, int wait)
  65 {
  66         struct bcm63xx_rng_priv *priv = to_rng_priv(rng);
  67
  68         return __raw_readl(priv->regs + RNG_STAT) & RNG_AVAIL_MASK;
  69 }
  70
  71 static int bcm63xx_rng_data_read(struct hwrng *rng, u32 *data)
  72 {
  73         struct bcm63xx_rng_priv *priv = to_rng_priv(rng);
  74
  75         *data = __raw_readl(priv->regs + RNG_DATA);
  76
  77         return 4;
  78 }
  79
  80 static int bcm63xx_rng_probe(struct platform_device *pdev)
  81 {
  82         struct resource *r;
  83         int ret;
  84         struct bcm63xx_rng_priv *priv;
  85
  86         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  87         if (!r) {
  88                 dev_err(&pdev->dev, "no iomem resource\n");
  89                 return -ENXIO;
  90         }
  91
  92         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  93         if (!priv)
  94                 return -ENOMEM;
  95
  96         priv->rng.name = pdev->name;
  97         priv->rng.init = bcm63xx_rng_init;
  98         priv->rng.cleanup = bcm63xx_rng_cleanup;
  99         priv->rng.data_present = bcm63xx_rng_data_present;
 100         priv->rng.data_read = bcm63xx_rng_data_read;
 101
 102         priv->clk = devm_clk_get(&pdev->dev, "ipsec");
 103         if (IS_ERR(priv->clk)) {
 104                 ret = PTR_ERR(priv->clk);
 105                 dev_err(&pdev->dev, "no clock for device: %d\n", ret);
 106                 return ret;
 107         }
 108
 109         if (!devm_request_mem_region(&pdev->dev, r->start,
 110                                         resource_size(r), pdev->name)) {
 111                 dev_err(&pdev->dev, "request mem failed");
 112                 return -EBUSY;
 113         }
 114
 115         priv->regs = devm_ioremap_nocache(&pdev->dev, r->start,
 116                                         resource_size(r));
 117         if (!priv->regs) {
 118                 dev_err(&pdev->dev, "ioremap failed");
 119                 return -ENOMEM;
 120         }
 121
 122         ret = devm_hwrng_register(&pdev->dev, &priv->rng);
 123         if (ret) {
 124                 dev_err(&pdev->dev, "failed to register rng device: %d\n",
 125                         ret);
 126                 return ret;
 127         }
 128
 129         dev_info(&pdev->dev, "registered RNG driver\n");
 130
 131         return 0;
 132 }
 133
 134 #ifdef CONFIG_OF
 135 static const struct of_device_id bcm63xx_rng_of_match[] = {
 136         { .compatible = "brcm,bcm6368-rng", },
 137         {},
 138 };
 139 MODULE_DEVICE_TABLE(of, bcm63xx_rng_of_match);
 140 #endif
 141
 142 static struct platform_driver bcm63xx_rng_driver = {
 143         .probe          = bcm63xx_rng_probe,
 144         .driver         = {
 145                 .name   = "bcm63xx-rng",
 146                 .of_match_table = of_match_ptr(bcm63xx_rng_of_match),
 147         },
 148 };
 149
 150 module_platform_driver(bcm63xx_rng_driver);
 151
 152 MODULE_AUTHOR("Florian Fainelli <[email protected]>");
 153 MODULE_DESCRIPTION("Broadcom BCM63xx RNG driver");
 154 MODULE_LICENSE("GPL");