| /* |
| * Driver for Mediatek Hardware Random Number Generator |
| * |
| * Copyright (C) 2017 Sean Wang <sean.wang@mediatek.com> |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License as |
| * published by the Free Software Foundation; either version 2 of |
| * the License, or (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| */ |
| #define MTK_RNG_DEV KBUILD_MODNAME |
| |
| #include <linux/clk.h> |
| #include <linux/delay.h> |
| #include <linux/err.h> |
| #include <linux/hw_random.h> |
| #include <linux/io.h> |
| #include <linux/iopoll.h> |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/of.h> |
| #include <linux/platform_device.h> |
| |
| #define USEC_POLL 2 |
| #define TIMEOUT_POLL 20 |
| |
| #define RNG_CTRL 0x00 |
| #define RNG_EN BIT(0) |
| #define RNG_READY BIT(31) |
| |
| #define RNG_DATA 0x08 |
| |
| #define to_mtk_rng(p) container_of(p, struct mtk_rng, rng) |
| |
| struct mtk_rng { |
| void __iomem *base; |
| struct clk *clk; |
| struct hwrng rng; |
| }; |
| |
| static int mtk_rng_init(struct hwrng *rng) |
| { |
| struct mtk_rng *priv = to_mtk_rng(rng); |
| u32 val; |
| int err; |
| |
| err = clk_prepare_enable(priv->clk); |
| if (err) |
| return err; |
| |
| val = readl(priv->base + RNG_CTRL); |
| val |= RNG_EN; |
| writel(val, priv->base + RNG_CTRL); |
| |
| return 0; |
| } |
| |
| static void mtk_rng_cleanup(struct hwrng *rng) |
| { |
| struct mtk_rng *priv = to_mtk_rng(rng); |
| u32 val; |
| |
| val = readl(priv->base + RNG_CTRL); |
| val &= ~RNG_EN; |
| writel(val, priv->base + RNG_CTRL); |
| |
| clk_disable_unprepare(priv->clk); |
| } |
| |
| static bool mtk_rng_wait_ready(struct hwrng *rng, bool wait) |
| { |
| struct mtk_rng *priv = to_mtk_rng(rng); |
| int ready; |
| |
| ready = readl(priv->base + RNG_CTRL) & RNG_READY; |
| if (!ready && wait) |
| readl_poll_timeout_atomic(priv->base + RNG_CTRL, ready, |
| ready & RNG_READY, USEC_POLL, |
| TIMEOUT_POLL); |
| return !!ready; |
| } |
| |
| static int mtk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) |
| { |
| struct mtk_rng *priv = to_mtk_rng(rng); |
| int retval = 0; |
| |
| while (max >= sizeof(u32)) { |
| if (!mtk_rng_wait_ready(rng, wait)) |
| break; |
| |
| *(u32 *)buf = readl(priv->base + RNG_DATA); |
| retval += sizeof(u32); |
| buf += sizeof(u32); |
| max -= sizeof(u32); |
| } |
| |
| return retval || !wait ? retval : -EIO; |
| } |
| |
| static int mtk_rng_probe(struct platform_device *pdev) |
| { |
| struct resource *res; |
| int ret; |
| struct mtk_rng *priv; |
| |
| res = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
| if (!res) { |
| dev_err(&pdev->dev, "no iomem resource\n"); |
| return -ENXIO; |
| } |
| |
| priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); |
| if (!priv) |
| return -ENOMEM; |
| |
| priv->rng.name = pdev->name; |
| priv->rng.init = mtk_rng_init; |
| priv->rng.cleanup = mtk_rng_cleanup; |
| priv->rng.read = mtk_rng_read; |
| |
| priv->clk = devm_clk_get(&pdev->dev, "rng"); |
| if (IS_ERR(priv->clk)) { |
| ret = PTR_ERR(priv->clk); |
| dev_err(&pdev->dev, "no clock for device: %d\n", ret); |
| return ret; |
| } |
| |
| priv->base = devm_ioremap_resource(&pdev->dev, res); |
| if (IS_ERR(priv->base)) |
| return PTR_ERR(priv->base); |
| |
| ret = devm_hwrng_register(&pdev->dev, &priv->rng); |
| if (ret) { |
| dev_err(&pdev->dev, "failed to register rng device: %d\n", |
| ret); |
| return ret; |
| } |
| |
| dev_info(&pdev->dev, "registered RNG driver\n"); |
| |
| return 0; |
| } |
| |
| static const struct of_device_id mtk_rng_match[] = { |
| { .compatible = "mediatek,mt7623-rng" }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(of, mtk_rng_match); |
| |
| static struct platform_driver mtk_rng_driver = { |
| .probe = mtk_rng_probe, |
| .driver = { |
| .name = MTK_RNG_DEV, |
| .of_match_table = mtk_rng_match, |
| }, |
| }; |
| |
| module_platform_driver(mtk_rng_driver); |
| |
| MODULE_DESCRIPTION("Mediatek Random Number Generator Driver"); |
| MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>"); |
| MODULE_LICENSE("GPL"); |