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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 #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 <florian@openwrt.org>");
153 MODULE_DESCRIPTION("Broadcom BCM63xx RNG driver");
154 MODULE_LICENSE("GPL");
155 

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