diff --git a/drivers/char/hw_random/mtk-rng.c b/drivers/char/hw_random/mtk-rng.c index 5808d09d12c4..1f9793010e6c 100644 --- a/drivers/char/hw_random/mtk-rng.c +++ b/drivers/char/hw_random/mtk-rng.c @@ -3,9 +3,11 @@ * Driver for Mediatek Hardware Random Number Generator * * Copyright (C) 2017 Sean Wang + * Copyright (C) 2026 Daniel Golle */ #define MTK_RNG_DEV KBUILD_MODNAME +#include #include #include #include @@ -17,6 +19,7 @@ #include #include #include +#include /* Runtime PM autosuspend timeout: */ #define RNG_AUTOSUSPEND_TIMEOUT 100 @@ -30,6 +33,11 @@ #define RNG_DATA 0x08 +/* Driver feature flags */ +#define MTK_RNG_SMC BIT(0) + +#define MTK_SIP_KERNEL_GET_RND MTK_SIP_SMC_CMD(0x550) + #define to_mtk_rng(p) container_of(p, struct mtk_rng, rng) struct mtk_rng { @@ -37,6 +45,7 @@ struct mtk_rng { struct clk *clk; struct hwrng rng; struct device *dev; + unsigned long flags; }; static int mtk_rng_init(struct hwrng *rng) @@ -103,6 +112,56 @@ static int mtk_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) return retval || !wait ? retval : -EIO; } +static int mtk_rng_read_smc(struct hwrng *rng, void *buf, size_t max, + bool wait) +{ + struct arm_smccc_res res; + int retval = 0; + + while (max >= sizeof(u32)) { + arm_smccc_smc(MTK_SIP_KERNEL_GET_RND, 0, 0, 0, 0, 0, 0, 0, + &res); + if (res.a0) + break; + + *(u32 *)buf = res.a1; + retval += sizeof(u32); + buf += sizeof(u32); + max -= sizeof(u32); + } + + return retval || !wait ? retval : -EIO; +} + +static bool mtk_rng_hw_accessible(struct mtk_rng *priv) +{ + u32 val; + int err; + + err = clk_prepare_enable(priv->clk); + if (err) + return false; + + val = readl(priv->base + RNG_CTRL); + val |= RNG_EN; + writel(val, priv->base + RNG_CTRL); + + val = readl(priv->base + RNG_CTRL); + + if (val & RNG_EN) { + /* HW is accessible, clean up: disable RNG and clock */ + writel(val & ~RNG_EN, priv->base + RNG_CTRL); + clk_disable_unprepare(priv->clk); + return true; + } + + /* + * If TF-A blocks direct access, the register reads back as 0. + * Leave the clock enabled as TF-A needs it. + */ + return false; +} + static int mtk_rng_probe(struct platform_device *pdev) { int ret; @@ -114,23 +173,42 @@ static int mtk_rng_probe(struct platform_device *pdev) priv->dev = &pdev->dev; priv->rng.name = pdev->name; -#ifndef CONFIG_PM - priv->rng.init = mtk_rng_init; - priv->rng.cleanup = mtk_rng_cleanup; -#endif - priv->rng.read = mtk_rng_read; priv->rng.quality = 900; + priv->flags = (unsigned long)device_get_match_data(&pdev->dev); - 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; + if (!(priv->flags & MTK_RNG_SMC)) { + 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_platform_ioremap_resource(pdev, 0); + if (IS_ERR(priv->base)) + return PTR_ERR(priv->base); + + if (IS_ENABLED(CONFIG_HAVE_ARM_SMCCC) && + of_device_is_compatible(pdev->dev.of_node, + "mediatek,mt7986-rng") && + !mtk_rng_hw_accessible(priv)) { + priv->flags |= MTK_RNG_SMC; + dev_info(&pdev->dev, + "HW RNG not MMIO accessible, using SMC\n"); + } } - priv->base = devm_platform_ioremap_resource(pdev, 0); - if (IS_ERR(priv->base)) - return PTR_ERR(priv->base); + if (priv->flags & MTK_RNG_SMC) { + if (!IS_ENABLED(CONFIG_HAVE_ARM_SMCCC)) + return -ENODEV; + priv->rng.read = mtk_rng_read_smc; + } else { +#ifndef CONFIG_PM + priv->rng.init = mtk_rng_init; + priv->rng.cleanup = mtk_rng_cleanup; +#endif + priv->rng.read = mtk_rng_read; + } ret = devm_hwrng_register(&pdev->dev, &priv->rng); if (ret) { @@ -139,12 +217,15 @@ static int mtk_rng_probe(struct platform_device *pdev) return ret; } - dev_set_drvdata(&pdev->dev, priv); - pm_runtime_set_autosuspend_delay(&pdev->dev, RNG_AUTOSUSPEND_TIMEOUT); - pm_runtime_use_autosuspend(&pdev->dev); - ret = devm_pm_runtime_enable(&pdev->dev); - if (ret) - return ret; + if (!(priv->flags & MTK_RNG_SMC)) { + dev_set_drvdata(&pdev->dev, priv); + pm_runtime_set_autosuspend_delay(&pdev->dev, + RNG_AUTOSUSPEND_TIMEOUT); + pm_runtime_use_autosuspend(&pdev->dev); + ret = devm_pm_runtime_enable(&pdev->dev); + if (ret) + return ret; + } dev_info(&pdev->dev, "registered RNG driver\n"); @@ -181,8 +262,11 @@ static const struct dev_pm_ops mtk_rng_pm_ops = { #endif /* CONFIG_PM */ static const struct of_device_id mtk_rng_match[] = { - { .compatible = "mediatek,mt7986-rng" }, { .compatible = "mediatek,mt7623-rng" }, + { .compatible = "mediatek,mt7981-rng", .data = (void *)MTK_RNG_SMC }, + { .compatible = "mediatek,mt7986-rng" }, + { .compatible = "mediatek,mt7987-rng", .data = (void *)MTK_RNG_SMC }, + { .compatible = "mediatek,mt7988-rng", .data = (void *)MTK_RNG_SMC }, {}, }; MODULE_DEVICE_TABLE(of, mtk_rng_match); @@ -200,4 +284,5 @@ module_platform_driver(mtk_rng_driver); MODULE_DESCRIPTION("Mediatek Random Number Generator Driver"); MODULE_AUTHOR("Sean Wang "); +MODULE_AUTHOR("Daniel Golle "); MODULE_LICENSE("GPL");