linux-imx

/*

 * Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk>

 *

 * This file is licensed under  the terms of the GNU General Public

 * License version 2. This program is licensed "as is" without any

 * warranty of any kind, whether express or implied.

 */

​

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/mod_devicetable.h>

#include <linux/slab.h>

#include <linux/err.h>

#include <linux/clk.h>

#include <linux/io.h>

#include <linux/hw_random.h>

#include <linux/platform_device.h>

​

#define TRNG_CR     0x00

#define TRNG_ISR    0x1c

#define TRNG_ODATA  0x50

​

#define TRNG_KEY    0x524e4700 /* RNG */

​

struct atmel_trng {

    struct clk *clk;

    void __iomem *base;

    struct hwrng rng;

};

​

static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,

               bool wait)

{

    struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);

    u32 *data = buf;

​

    /* data ready? */

    if (readl(trng->base + TRNG_ISR) & 1) {

        *data = readl(trng->base + TRNG_ODATA);

        /*

          ensure data ready is only set again AFTER the next data

          word is ready in case it got set between checking ISR

          and reading ODATA, so we don't risk re-reading the

          same word

        */

        readl(trng->base + TRNG_ISR);

        return 4;

    } else

        return 0;

}

​

static void atmel_trng_enable(struct atmel_trng *trng)

{

    writel(TRNG_KEY | 1, trng->base + TRNG_CR);

}

​

static void atmel_trng_disable(struct atmel_trng *trng)

{

    writel(TRNG_KEY, trng->base + TRNG_CR);

}

​

static int atmel_trng_probe(struct platform_device *pdev)

{