char/hw_random/meson-rng.c

0001 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
0002 /*
0003  * Copyright (c) 2016 BayLibre, SAS.
0004  * Author: Neil Armstrong <narmstrong@baylibre.com>
0005  * Copyright (C) 2014 Amlogic, Inc.
0006  */
0007 #include <linux/err.h>
0008 #include <linux/module.h>
0009 #include <linux/io.h>
0010 #include <linux/platform_device.h>
0011 #include <linux/hw_random.h>
0012 #include <linux/slab.h>
0013 #include <linux/types.h>
0014 #include <linux/of.h>
0015 #include <linux/clk.h>
0016
0017 #define RNG_DATA 0x00
0018
0019 struct meson_rng_data {
0020     void __iomem *base;
0021     struct platform_device *pdev;
0022     struct hwrng rng;
0023     struct clk *core_clk;
0024 };
0025
0026 static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
0027 {
0028     struct meson_rng_data *data =
0029             container_of(rng, struct meson_rng_data, rng);
0030
0031     *(u32 *)buf = readl_relaxed(data->base + RNG_DATA);
0032
0033     return sizeof(u32);
0034 }
0035
0036 static void meson_rng_clk_disable(void *data)
0037 {
0038     clk_disable_unprepare(data);
0039 }
0040
0041 static int meson_rng_probe(struct platform_device *pdev)
0042 {
0043     struct device *dev = &pdev->dev;
0044     struct meson_rng_data *data;
0045     int ret;
0046
0047     data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
0048     if (!data)
0049         return -ENOMEM;
0050
0051     data->pdev = pdev;
0052
0053     data->base = devm_platform_ioremap_resource(pdev, 0);
0054     if (IS_ERR(data->base))
0055         return PTR_ERR(data->base);
0056
0057     data->core_clk = devm_clk_get_optional(dev, "core");
0058     if (IS_ERR(data->core_clk))
0059         return dev_err_probe(dev, PTR_ERR(data->core_clk),
0060                      "Failed to get core clock\n");
0061
0062     if (data->core_clk) {
0063         ret = clk_prepare_enable(data->core_clk);
0064         if (ret)
0065             return ret;
0066         ret = devm_add_action_or_reset(dev, meson_rng_clk_disable,
0067                            data->core_clk);
0068         if (ret)
0069             return ret;
0070     }
0071
0072     data->rng.name = pdev->name;
0073     data->rng.read = meson_rng_read;
0074
0075     platform_set_drvdata(pdev, data);
0076
0077     return devm_hwrng_register(dev, &data->rng);
0078 }
0079
0080 static const struct of_device_id meson_rng_of_match[] = {
0081     { .compatible = "amlogic,meson-rng", },
0082     {},
0083 };
0084 MODULE_DEVICE_TABLE(of, meson_rng_of_match);
0085
0086 static struct platform_driver meson_rng_driver = {
0087     .probe  = meson_rng_probe,
0088     .driver = {
0089         .name = "meson-rng",
0090         .of_match_table = meson_rng_of_match,
0091     },
0092 };
0093
0094 module_platform_driver(meson_rng_driver);
0095
0096 MODULE_DESCRIPTION("Meson H/W Random Number Generator driver");
0097 MODULE_AUTHOR("Lawrence Mok <lawrence.mok@amlogic.com>");
0098 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
0099 MODULE_LICENSE("Dual BSD/GPL");