drivers/char/hw_random/hisi-trng-v2.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2019 HiSilicon Limited. */
   3
   4 #include <linux/acpi.h>
   5 #include <linux/err.h>
   6 #include <linux/hw_random.h>
   7 #include <linux/io.h>
   8 #include <linux/iopoll.h>
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/random.h>
  13
  14 #define HISI_TRNG_REG           0x00F0
  15 #define HISI_TRNG_BYTES         4
  16 #define HISI_TRNG_QUALITY       512
  17 #define SLEEP_US                10
  18 #define TIMEOUT_US              10000
  19
  20 struct hisi_trng {
  21         void __iomem *base;
  22         struct hwrng rng;
  23 };
  24
  25 static int hisi_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
  26 {
  27         struct hisi_trng *trng;
  28         int currsize = 0;
  29         u32 val = 0;
  30         u32 ret;
  31
  32         trng = container_of(rng, struct hisi_trng, rng);
  33
  34         do {
  35                 ret = readl_poll_timeout(trng->base + HISI_TRNG_REG, val,
  36                                          val, SLEEP_US, TIMEOUT_US);
  37                 if (ret)
  38                         return currsize;
  39
  40                 if (max - currsize >= HISI_TRNG_BYTES) {
  41                         memcpy(buf + currsize, &val, HISI_TRNG_BYTES);
  42                         currsize += HISI_TRNG_BYTES;
  43                         if (currsize == max)
  44                                 return currsize;
  45                         continue;
  46                 }
  47
  48                 /* copy remaining bytes */
  49                 memcpy(buf + currsize, &val, max - currsize);
  50                 currsize = max;
  51         } while (currsize < max);
  52
  53         return currsize;
  54 }
  55
  56 static int hisi_trng_probe(struct platform_device *pdev)
  57 {
  58         struct hisi_trng *trng;
  59         int ret;
  60
  61         trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
  62         if (!trng)
  63                 return -ENOMEM;
  64
  65         trng->base = devm_platform_ioremap_resource(pdev, 0);
  66         if (IS_ERR(trng->base))
  67                 return PTR_ERR(trng->base);
  68
  69         trng->rng.name = pdev->name;
  70         trng->rng.read = hisi_trng_read;
  71         trng->rng.quality = HISI_TRNG_QUALITY;
  72
  73         ret = devm_hwrng_register(&pdev->dev, &trng->rng);
  74         if (ret)
  75                 dev_err(&pdev->dev, "failed to register hwrng!\n");
  76
  77         return ret;
  78 }
  79
  80 static const struct acpi_device_id hisi_trng_acpi_match[] = {
  81         { "HISI02B3", 0 },
  82         { }
  83 };
  84 MODULE_DEVICE_TABLE(acpi, hisi_trng_acpi_match);
  85
  86 static struct platform_driver hisi_trng_driver = {
  87         .probe          = hisi_trng_probe,
  88         .driver         = {
  89                 .name   = "hisi-trng-v2",
  90                 .acpi_match_table = ACPI_PTR(hisi_trng_acpi_match),
  91         },
  92 };
  93
  94 module_platform_driver(hisi_trng_driver);
  95
  96 MODULE_LICENSE("GPL v2");
  97 MODULE_AUTHOR("Weili Qian <qianweili@huawei.com>");
  98 MODULE_AUTHOR("Zaibo Xu <xuzaibo@huawei.com>");
  99 MODULE_DESCRIPTION("HiSilicon true random number generator V2 driver");