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Linux/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");
147 

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