linux-imx

// SPDX-License-Identifier: GPL-2.0

// Copyright (c) 2017-18 Linaro Limited

//

// Based on msm-rng.c and downstream driver

​

#include <crypto/internal/rng.h>

#include <linux/acpi.h>

#include <linux/clk.h>

#include <linux/crypto.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/platform_device.h>

​

/* Device specific register offsets */

#define PRNG_DATA_OUT       0x0000

#define PRNG_STATUS     0x0004

#define PRNG_LFSR_CFG       0x0100

#define PRNG_CONFIG     0x0104

​

/* Device specific register masks and config values */

#define PRNG_LFSR_CFG_MASK  0x0000ffff

#define PRNG_LFSR_CFG_CLOCKS    0x0000dddd

#define PRNG_CONFIG_HW_ENABLE   BIT(1)

#define PRNG_STATUS_DATA_AVAIL  BIT(0)

​

#define WORD_SZ         4

​

struct qcom_rng {

    struct mutex lock;

    void __iomem *base;

    struct clk *clk;

    unsigned int skip_init;

};

​

struct qcom_rng_ctx {

    struct qcom_rng *rng;

};

​

static struct qcom_rng *qcom_rng_dev;

​

static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)

{

    unsigned int currsize = 0;

    u32 val;

​

    /* read random data from hardware */

    do {

        val = readl_relaxed(rng->base + PRNG_STATUS);

        if (!(val & PRNG_STATUS_DATA_AVAIL))

            break;

​

        val = readl_relaxed(rng->base + PRNG_DATA_OUT);

        if (!val)

            break;

​

        if ((max - currsize) >= WORD_SZ) {

            memcpy(data, &val, WORD_SZ);

            data += WORD_SZ;

            currsize += WORD_SZ;

        } else {

            /* copy only remaining bytes */

            memcpy(data, &val, max - currsize);

            break;