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

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Ingenic Random Number Generator driver
   4 * Copyright (c) 2017 PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
   5 * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
   6 */
   7
   8#include <linux/err.h>
   9#include <linux/kernel.h>
  10#include <linux/hw_random.h>
  11#include <linux/io.h>
  12#include <linux/iopoll.h>
  13#include <linux/module.h>
  14#include <linux/of_device.h>
  15#include <linux/platform_device.h>
  16#include <linux/slab.h>
  17
  18/* RNG register offsets */
  19#define RNG_REG_ERNG_OFFSET             0x0
  20#define RNG_REG_RNG_OFFSET              0x4
  21
  22/* bits within the ERND register */
  23#define ERNG_READY                              BIT(31)
  24#define ERNG_ENABLE                             BIT(0)
  25
  26enum ingenic_rng_version {
  27        ID_JZ4780,
  28        ID_X1000,
  29};
  30
  31/* Device associated memory */
  32struct ingenic_rng {
  33        enum ingenic_rng_version version;
  34
  35        void __iomem *base;
  36        struct hwrng rng;
  37};
  38
  39static int ingenic_rng_init(struct hwrng *rng)
  40{
  41        struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
  42
  43        writel(ERNG_ENABLE, priv->base + RNG_REG_ERNG_OFFSET);
  44
  45        return 0;
  46}
  47
  48static void ingenic_rng_cleanup(struct hwrng *rng)
  49{
  50        struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
  51
  52        writel(0, priv->base + RNG_REG_ERNG_OFFSET);
  53}
  54
  55static int ingenic_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
  56{
  57        struct ingenic_rng *priv = container_of(rng, struct ingenic_rng, rng);
  58        u32 *data = buf;
  59        u32 status;
  60        int ret;
  61
  62        if (priv->version >= ID_X1000) {
  63                ret = readl_poll_timeout(priv->base + RNG_REG_ERNG_OFFSET, status,
  64                                         status & ERNG_READY, 10, 1000);
  65                if (ret == -ETIMEDOUT) {
  66                        pr_err("%s: Wait for RNG data ready timeout\n", __func__);
  67                        return ret;
  68                }
  69        } else {
  70                /*
  71                 * A delay is required so that the current RNG data is not bit shifted
  72                 * version of previous RNG data which could happen if random data is
  73                 * read continuously from this device.
  74                 */
  75                udelay(20);
  76        }
  77
  78        *data = readl(priv->base + RNG_REG_RNG_OFFSET);
  79
  80        return 4;
  81}
  82
  83static int ingenic_rng_probe(struct platform_device *pdev)
  84{
  85        struct ingenic_rng *priv;
  86        int ret;
  87
  88        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  89        if (!priv)
  90                return -ENOMEM;
  91
  92        priv->base = devm_platform_ioremap_resource(pdev, 0);
  93        if (IS_ERR(priv->base)) {
  94                pr_err("%s: Failed to map RNG registers\n", __func__);
  95                return PTR_ERR(priv->base);
  96        }
  97
  98        priv->version = (enum ingenic_rng_version)of_device_get_match_data(&pdev->dev);
  99
 100        priv->rng.name = pdev->name;
 101        priv->rng.init = ingenic_rng_init;
 102        priv->rng.cleanup = ingenic_rng_cleanup;
 103        priv->rng.read = ingenic_rng_read;
 104
 105        ret = hwrng_register(&priv->rng);
 106        if (ret) {
 107                dev_err(&pdev->dev, "Failed to register hwrng\n");
 108                return ret;
 109        }
 110
 111        platform_set_drvdata(pdev, priv);
 112
 113        dev_info(&pdev->dev, "Ingenic RNG driver registered\n");
 114        return 0;
 115}
 116
 117static int ingenic_rng_remove(struct platform_device *pdev)
 118{
 119        struct ingenic_rng *priv = platform_get_drvdata(pdev);
 120
 121        hwrng_unregister(&priv->rng);
 122
 123        writel(0, priv->base + RNG_REG_ERNG_OFFSET);
 124
 125        return 0;
 126}
 127
 128static const struct of_device_id ingenic_rng_of_match[] = {
 129        { .compatible = "ingenic,jz4780-rng", .data = (void *) ID_JZ4780 },
 130        { .compatible = "ingenic,x1000-rng", .data = (void *) ID_X1000 },
 131        { /* sentinel */ }
 132};
 133MODULE_DEVICE_TABLE(of, ingenic_rng_of_match);
 134
 135static struct platform_driver ingenic_rng_driver = {
 136        .probe          = ingenic_rng_probe,
 137        .remove         = ingenic_rng_remove,
 138        .driver         = {
 139                .name   = "ingenic-rng",
 140                .of_match_table = ingenic_rng_of_match,
 141        },
 142};
 143
 144module_platform_driver(ingenic_rng_driver);
 145
 146MODULE_LICENSE("GPL");
 147MODULE_AUTHOR("PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>");
 148MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
 149MODULE_DESCRIPTION("Ingenic Random Number Generator driver");
 150