drivers/char/hw_random/ingenic-trng.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Ingenic True Random Number Generator driver
   4  * Copyright (c) 2019 漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>
   5  * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
   6  */
   7
   8 #include <linux/clk.h>
   9 #include <linux/err.h>
  10 #include <linux/kernel.h>
  11 #include <linux/hw_random.h>
  12 #include <linux/io.h>
  13 #include <linux/iopoll.h>
  14 #include <linux/module.h>
  15 #include <linux/of_device.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/slab.h>
  18
  19 /* DTRNG register offsets */
  20 #define TRNG_REG_CFG_OFFSET                     0x00
  21 #define TRNG_REG_RANDOMNUM_OFFSET       0x04
  22 #define TRNG_REG_STATUS_OFFSET          0x08
  23
  24 /* bits within the CFG register */
  25 #define CFG_RDY_CLR                                     BIT(12)
  26 #define CFG_INT_MASK                            BIT(11)
  27 #define CFG_GEN_EN                                      BIT(0)
  28
  29 /* bits within the STATUS register */
  30 #define STATUS_RANDOM_RDY                       BIT(0)
  31
  32 struct ingenic_trng {
  33         void __iomem *base;
  34         struct clk *clk;
  35         struct hwrng rng;
  36 };
  37
  38 static int ingenic_trng_init(struct hwrng *rng)
  39 {
  40         struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
  41         unsigned int ctrl;
  42
  43         ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
  44         ctrl |= CFG_GEN_EN;
  45         writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
  46
  47         return 0;
  48 }
  49
  50 static void ingenic_trng_cleanup(struct hwrng *rng)
  51 {
  52         struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
  53         unsigned int ctrl;
  54
  55         ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
  56         ctrl &= ~CFG_GEN_EN;
  57         writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
  58 }
  59
  60 static int ingenic_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
  61 {
  62         struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
  63         u32 *data = buf;
  64         u32 status;
  65         int ret;
  66
  67         ret = readl_poll_timeout(trng->base + TRNG_REG_STATUS_OFFSET, status,
  68                                  status & STATUS_RANDOM_RDY, 10, 1000);
  69         if (ret == -ETIMEDOUT) {
  70                 pr_err("%s: Wait for DTRNG data ready timeout\n", __func__);
  71                 return ret;
  72         }
  73
  74         *data = readl(trng->base + TRNG_REG_RANDOMNUM_OFFSET);
  75
  76         return 4;
  77 }
  78
  79 static int ingenic_trng_probe(struct platform_device *pdev)
  80 {
  81         struct ingenic_trng *trng;
  82         int ret;
  83
  84         trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
  85         if (!trng)
  86                 return -ENOMEM;
  87
  88         trng->base = devm_platform_ioremap_resource(pdev, 0);
  89         if (IS_ERR(trng->base)) {
  90                 pr_err("%s: Failed to map DTRNG registers\n", __func__);
  91                 ret = PTR_ERR(trng->base);
  92                 return PTR_ERR(trng->base);
  93         }
  94
  95         trng->clk = devm_clk_get(&pdev->dev, NULL);
  96         if (IS_ERR(trng->clk)) {
  97                 ret = PTR_ERR(trng->clk);
  98                 pr_crit("%s: Cannot get DTRNG clock\n", __func__);
  99                 return PTR_ERR(trng->clk);
 100         }
 101
 102         ret = clk_prepare_enable(trng->clk);
 103         if (ret) {
 104                 pr_crit("%s: Unable to enable DTRNG clock\n", __func__);
 105                 return ret;
 106         }
 107
 108         trng->rng.name = pdev->name;
 109         trng->rng.init = ingenic_trng_init;
 110         trng->rng.cleanup = ingenic_trng_cleanup;
 111         trng->rng.read = ingenic_trng_read;
 112
 113         ret = hwrng_register(&trng->rng);
 114         if (ret) {
 115                 dev_err(&pdev->dev, "Failed to register hwrng\n");
 116                 return ret;
 117         }
 118
 119         platform_set_drvdata(pdev, trng);
 120
 121         dev_info(&pdev->dev, "Ingenic DTRNG driver registered\n");
 122         return 0;
 123 }
 124
 125 static int ingenic_trng_remove(struct platform_device *pdev)
 126 {
 127         struct ingenic_trng *trng = platform_get_drvdata(pdev);
 128         unsigned int ctrl;
 129
 130         hwrng_unregister(&trng->rng);
 131
 132         ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
 133         ctrl &= ~CFG_GEN_EN;
 134         writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
 135
 136         clk_disable_unprepare(trng->clk);
 137
 138         return 0;
 139 }
 140
 141 static const struct of_device_id ingenic_trng_of_match[] = {
 142         { .compatible = "ingenic,x1830-dtrng" },
 143         { /* sentinel */ }
 144 };
 145 MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
 146
 147 static struct platform_driver ingenic_trng_driver = {
 148         .probe          = ingenic_trng_probe,
 149         .remove         = ingenic_trng_remove,
 150         .driver         = {
 151                 .name   = "ingenic-trng",
 152                 .of_match_table = ingenic_trng_of_match,
 153         },
 154 };
 155
 156 module_platform_driver(ingenic_trng_driver);
 157
 158 MODULE_LICENSE("GPL");
 159 MODULE_AUTHOR("漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>");
 160 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
 161 MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");