LXR linux/drivers/char/hw_random/meson-rng.c

   1// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
   2/*
   3 * Copyright (c) 2016 BayLibre, SAS.
   4 * Author: Neil Armstrong <narmstrong@baylibre.com>
   5 * Copyright (C) 2014 Amlogic, Inc.
   6 */
   7#include <linux/err.h>
   8#include <linux/module.h>
   9#include <linux/io.h>
  10#include <linux/platform_device.h>
  11#include <linux/hw_random.h>
  12#include <linux/slab.h>
  13#include <linux/types.h>
  14#include <linux/of.h>
  15#include <linux/clk.h>
  16
  17#define RNG_DATA 0x00
  18
  19struct meson_rng_data {
  20        void __iomem *base;
  21        struct platform_device *pdev;
  22        struct hwrng rng;
  23        struct clk *core_clk;
  24};
  25
  26static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
  27{
  28        struct meson_rng_data *data =
  29                        container_of(rng, struct meson_rng_data, rng);
  30
  31        *(u32 *)buf = readl_relaxed(data->base + RNG_DATA);
  32
  33        return sizeof(u32);
  34}
  35
  36static void meson_rng_clk_disable(void *data)
  37{
  38        clk_disable_unprepare(data);
  39}
  40
  41static int meson_rng_probe(struct platform_device *pdev)
  42{
  43        struct device *dev = &pdev->dev;
  44        struct meson_rng_data *data;
  45        int ret;
  46
  47        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
  48        if (!data)
  49                return -ENOMEM;
  50
  51        data->pdev = pdev;
  52
  53        data->base = devm_platform_ioremap_resource(pdev, 0);
  54        if (IS_ERR(data->base))
  55                return PTR_ERR(data->base);
  56
  57        data->core_clk = devm_clk_get(dev, "core");
  58        if (IS_ERR(data->core_clk))
  59                data->core_clk = NULL;
  60
  61        if (data->core_clk) {
  62                ret = clk_prepare_enable(data->core_clk);
  63                if (ret)
  64                        return ret;
  65                ret = devm_add_action_or_reset(dev, meson_rng_clk_disable,
  66                                               data->core_clk);
  67                if (ret)
  68                        return ret;
  69        }
  70
  71        data->rng.name = pdev->name;
  72        data->rng.read = meson_rng_read;
  73
  74        platform_set_drvdata(pdev, data);
  75
  76        return devm_hwrng_register(dev, &data->rng);
  77}
  78
  79static const struct of_device_id meson_rng_of_match[] = {
  80        { .compatible = "amlogic,meson-rng", },
  81        {},
  82};
  83MODULE_DEVICE_TABLE(of, meson_rng_of_match);
  84
  85static struct platform_driver meson_rng_driver = {
  86        .probe  = meson_rng_probe,
  87        .driver = {
  88                .name = "meson-rng",
  89                .of_match_table = meson_rng_of_match,
  90        },
  91};
  92
  93module_platform_driver(meson_rng_driver);
  94
  95MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
  96MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
  97MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
  98MODULE_LICENSE("Dual BSD/GPL");
  99