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path: root/drivers/char/hw_random/hisi-rng.c
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Diffstat (limited to 'drivers/char/hw_random/hisi-rng.c')
-rw-r--r--drivers/char/hw_random/hisi-rng.c126
1 files changed, 126 insertions, 0 deletions
diff --git a/drivers/char/hw_random/hisi-rng.c b/drivers/char/hw_random/hisi-rng.c
new file mode 100644
index 000000000..40d96572c
--- /dev/null
+++ b/drivers/char/hw_random/hisi-rng.c
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2016 HiSilicon Co., Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/hw_random.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/random.h>
+
+#define RNG_SEED 0x0
+#define RNG_CTRL 0x4
+ #define RNG_SEED_SEL BIT(2)
+ #define RNG_RING_EN BIT(1)
+ #define RNG_EN BIT(0)
+#define RNG_RAN_NUM 0x10
+#define RNG_PHY_SEED 0x14
+
+#define to_hisi_rng(p) container_of(p, struct hisi_rng, rng)
+
+static int seed_sel;
+module_param(seed_sel, int, S_IRUGO);
+MODULE_PARM_DESC(seed_sel, "Auto reload seed. 0, use LFSR(default); 1, use ring oscillator.");
+
+struct hisi_rng {
+ void __iomem *base;
+ struct hwrng rng;
+};
+
+static int hisi_rng_init(struct hwrng *rng)
+{
+ struct hisi_rng *hrng = to_hisi_rng(rng);
+ int val = RNG_EN;
+ u32 seed;
+
+ /* get a random number as initial seed */
+ get_random_bytes(&seed, sizeof(seed));
+
+ writel_relaxed(seed, hrng->base + RNG_SEED);
+
+ /**
+ * The seed is reload periodically, there are two choice
+ * of seeds, default seed using the value from LFSR, or
+ * will use seed generated by ring oscillator.
+ */
+ if (seed_sel == 1)
+ val |= RNG_RING_EN | RNG_SEED_SEL;
+
+ writel_relaxed(val, hrng->base + RNG_CTRL);
+ return 0;
+}
+
+static void hisi_rng_cleanup(struct hwrng *rng)
+{
+ struct hisi_rng *hrng = to_hisi_rng(rng);
+
+ writel_relaxed(0, hrng->base + RNG_CTRL);
+}
+
+static int hisi_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
+{
+ struct hisi_rng *hrng = to_hisi_rng(rng);
+ u32 *data = buf;
+
+ *data = readl_relaxed(hrng->base + RNG_RAN_NUM);
+ return 4;
+}
+
+static int hisi_rng_probe(struct platform_device *pdev)
+{
+ struct hisi_rng *rng;
+ struct resource *res;
+ int ret;
+
+ rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
+ if (!rng)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, rng);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ rng->base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(rng->base))
+ return PTR_ERR(rng->base);
+
+ rng->rng.name = pdev->name;
+ rng->rng.init = hisi_rng_init;
+ rng->rng.cleanup = hisi_rng_cleanup;
+ rng->rng.read = hisi_rng_read;
+
+ ret = devm_hwrng_register(&pdev->dev, &rng->rng);
+ if (ret) {
+ dev_err(&pdev->dev, "failed to register hwrng\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static const struct of_device_id hisi_rng_dt_ids[] = {
+ { .compatible = "hisilicon,hip04-rng" },
+ { .compatible = "hisilicon,hip05-rng" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, hisi_rng_dt_ids);
+
+static struct platform_driver hisi_rng_driver = {
+ .probe = hisi_rng_probe,
+ .driver = {
+ .name = "hisi-rng",
+ .of_match_table = of_match_ptr(hisi_rng_dt_ids),
+ },
+};
+
+module_platform_driver(hisi_rng_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Kefeng Wang <wangkefeng.wang@huawei>");
+MODULE_DESCRIPTION("Hisilicon random number generator driver");