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) <[email protected]>
   5  * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <[email protected]>
   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/mod_devicetable.h>
  15 #include <linux/module.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_GEN_EN                                      BIT(0)
  26
  27 /* bits within the STATUS register */
  28 #define STATUS_RANDOM_RDY                       BIT(0)
  29
  30 struct ingenic_trng {
  31         void __iomem *base;
  32         struct hwrng rng;
  33 };
  34
  35 static int ingenic_trng_init(struct hwrng *rng)
  36 {
  37         struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
  38         unsigned int ctrl;
  39
  40         ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
  41         ctrl |= CFG_GEN_EN;
  42         writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
  43
  44         return 0;
  45 }
  46
  47 static void ingenic_trng_cleanup(struct hwrng *rng)
  48 {
  49         struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
  50         unsigned int ctrl;
  51
  52         ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
  53         ctrl &= ~CFG_GEN_EN;
  54         writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
  55 }
  56
  57 static int ingenic_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
  58 {
  59         struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
  60         u32 *data = buf;
  61         u32 status;
  62         int ret;
  63
  64         ret = readl_poll_timeout(trng->base + TRNG_REG_STATUS_OFFSET, status,
  65                                  status & STATUS_RANDOM_RDY, 10, 1000);
  66         if (ret == -ETIMEDOUT) {
  67                 pr_err("%s: Wait for DTRNG data ready timeout\n", __func__);
  68                 return ret;
  69         }
  70
  71         *data = readl(trng->base + TRNG_REG_RANDOMNUM_OFFSET);
  72
  73         return 4;
  74 }
  75
  76 static int ingenic_trng_probe(struct platform_device *pdev)
  77 {
  78         struct ingenic_trng *trng;
  79         struct clk *clk;
  80         int ret;
  81
  82         trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
  83         if (!trng)
  84                 return -ENOMEM;
  85
  86         trng->base = devm_platform_ioremap_resource(pdev, 0);
  87         if (IS_ERR(trng->base))
  88                 return dev_err_probe(&pdev->dev, PTR_ERR(trng->base),
  89                                      "%s: Failed to map DTRNG registers\n", __func__);
  90
  91         clk = devm_clk_get_enabled(&pdev->dev, NULL);
  92         if (IS_ERR(clk))
  93                 return dev_err_probe(&pdev->dev, PTR_ERR(clk),
  94                                      "%s: Cannot get and enable DTRNG clock\n", __func__);
  95
  96         trng->rng.name = pdev->name;
  97         trng->rng.init = ingenic_trng_init;
  98         trng->rng.cleanup = ingenic_trng_cleanup;
  99         trng->rng.read = ingenic_trng_read;
 100
 101         ret = devm_hwrng_register(&pdev->dev, &trng->rng);
 102         if (ret)
 103                 return dev_err_probe(&pdev->dev, ret, "Failed to register hwrng\n");
 104
 105         platform_set_drvdata(pdev, trng);
 106
 107         dev_info(&pdev->dev, "Ingenic DTRNG driver registered\n");
 108         return 0;
 109 }
 110
 111 static const struct of_device_id ingenic_trng_of_match[] = {
 112         { .compatible = "ingenic,x1830-dtrng" },
 113         { /* sentinel */ }
 114 };
 115 MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
 116
 117 static struct platform_driver ingenic_trng_driver = {
 118         .probe          = ingenic_trng_probe,
 119         .driver         = {
 120                 .name   = "ingenic-trng",
 121                 .of_match_table = ingenic_trng_of_match,
 122         },
 123 };
 124
 125 module_platform_driver(ingenic_trng_driver);
 126
 127 MODULE_LICENSE("GPL");
 128 MODULE_AUTHOR("漆鹏振 (Qi Pengzhen) <[email protected]>");
 129 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <[email protected]>");
 130 MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");