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 <[email protected]>
   5  * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <[email protected]>
   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.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
  26 enum ingenic_rng_version {
  27         ID_JZ4780,
  28         ID_X1000,
  29 };
  30
  31 /* Device associated memory */
  32 struct ingenic_rng {
  33         enum ingenic_rng_version version;
  34
  35         void __iomem *base;
  36         struct hwrng rng;
  37 };
  38
  39 static 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
  48 static 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
  55 static 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
  83 static 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)(uintptr_t)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
 117 static void 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
 126 static const struct of_device_id ingenic_rng_of_match[] = {
 127         { .compatible = "ingenic,jz4780-rng", .data = (void *) ID_JZ4780 },
 128         { .compatible = "ingenic,x1000-rng", .data = (void *) ID_X1000 },
 129         { /* sentinel */ }
 130 };
 131 MODULE_DEVICE_TABLE(of, ingenic_rng_of_match);
 132
 133 static struct platform_driver ingenic_rng_driver = {
 134         .probe          = ingenic_rng_probe,
 135         .remove         = ingenic_rng_remove,
 136         .driver         = {
 137                 .name   = "ingenic-rng",
 138                 .of_match_table = ingenic_rng_of_match,
 139         },
 140 };
 141
 142 module_platform_driver(ingenic_rng_driver);
 143
 144 MODULE_LICENSE("GPL");
 145 MODULE_AUTHOR("PrasannaKumar Muralidharan <[email protected]>");
 146 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <[email protected]>");
 147 MODULE_DESCRIPTION("Ingenic Random Number Generator driver");