diff options
Diffstat (limited to 'drivers/char/hw_random/mtk-rng.c')
| -rw-r--r-- | drivers/char/hw_random/mtk-rng.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/drivers/char/hw_random/mtk-rng.c b/drivers/char/hw_random/mtk-rng.c new file mode 100644 index 000000000000..df8eb54fd5a3 --- /dev/null +++ b/drivers/char/hw_random/mtk-rng.c @@ -0,0 +1,168 @@ +/* + * 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"); |