/* * exynos-rng.c - Random Number Generator driver for the exynos * * Copyright (C) 2012 Samsung Electronics * Jonghwa Lee <jonghwa3.lee@samsung.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; * * 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. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * */ #include <linux/hw_random.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/io.h> #include <linux/platform_device.h> #include <linux/clk.h> #include <linux/pm_runtime.h> #include <linux/err.h> #define EXYNOS_PRNG_STATUS_OFFSET 0x10 #define EXYNOS_PRNG_SEED_OFFSET 0x140 #define EXYNOS_PRNG_OUT1_OFFSET 0x160 #define SEED_SETTING_DONE BIT(1) #define PRNG_START 0x18 #define PRNG_DONE BIT(5) #define EXYNOS_AUTOSUSPEND_DELAY 100 struct exynos_rng { struct device *dev; struct hwrng rng; void __iomem *mem; struct clk *clk; }; static u32 exynos_rng_readl(struct exynos_rng *rng, u32 offset) { return __raw_readl(rng->mem + offset); } static void exynos_rng_writel(struct exynos_rng *rng, u32 val, u32 offset) { __raw_writel(val, rng->mem + offset); } static int exynos_rng_configure(struct exynos_rng *exynos_rng) { int i; int ret = 0; for (i = 0 ; i < 5 ; i++) exynos_rng_writel(exynos_rng, jiffies, EXYNOS_PRNG_SEED_OFFSET + 4*i); if (!(exynos_rng_readl(exynos_rng, EXYNOS_PRNG_STATUS_OFFSET) & SEED_SETTING_DONE)) ret = -EIO; return ret; } static int exynos_init(struct hwrng *rng) { struct exynos_rng *exynos_rng = container_of(rng, struct exynos_rng, rng); int ret = 0; pm_runtime_get_sync(exynos_rng->dev); ret = exynos_rng_configure(exynos_rng); pm_runtime_mark_last_busy(exynos_rng->dev); pm_runtime_put_autosuspend(exynos_rng->dev); return ret; } static int exynos_read(struct hwrng *rng, void *buf, size_t max, bool wait) { struct exynos_rng *exynos_rng = container_of(rng, struct exynos_rng, rng); u32 *data = buf; int retry = 100; int ret = 4; pm_runtime_get_sync(exynos_rng->dev); exynos_rng_writel(exynos_rng, PRNG_START, 0); while (!(exynos_rng_readl(exynos_rng, EXYNOS_PRNG_STATUS_OFFSET) & PRNG_DONE) && --retry) cpu_relax(); if (!retry) { ret = -ETIMEDOUT; goto out; } exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET); *data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET); out: pm_runtime_mark_last_busy(exynos_rng->dev); pm_runtime_put_sync_autosuspend(exynos_rng->dev); return ret; } static int exynos_rng_probe(struct platform_device *pdev) { struct exynos_rng *exynos_rng; struct resource *res; int ret; exynos_rng = devm_kzalloc(&pdev->dev, sizeof(struct exynos_rng), GFP_KERNEL); if (!exynos_rng) return -ENOMEM; exynos_rng->dev = &pdev->dev; exynos_rng->rng.name = "exynos"; exynos_rng->rng.init = exynos_init; exynos_rng->rng.read = exynos_read; exynos_rng->clk = devm_clk_get(&pdev->dev, "secss"); if (IS_ERR(exynos_rng->clk)) { dev_err(&pdev->dev, "Couldn't get clock.\n"); return -ENOENT; } res = platform_get_resource(pdev, IORESOURCE_MEM, 0); exynos_rng->mem = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(exynos_rng->mem)) return PTR_ERR(exynos_rng->mem); platform_set_drvdata(pdev, exynos_rng); pm_runtime_set_autosuspend_delay(&pdev->dev, EXYNOS_AUTOSUSPEND_DELAY); pm_runtime_use_autosuspend(&pdev->dev); pm_runtime_enable(&pdev->dev); ret = devm_hwrng_register(&pdev->dev, &exynos_rng->rng); if (ret) { pm_runtime_dont_use_autosuspend(&pdev->dev); pm_runtime_disable(&pdev->dev); } return ret; } static int exynos_rng_remove(struct platform_device *pdev) { pm_runtime_dont_use_autosuspend(&pdev->dev); pm_runtime_disable(&pdev->dev); return 0; } static int __maybe_unused exynos_rng_runtime_suspend(struct device *dev) { struct platform_device *pdev = to_platform_device(dev); struct exynos_rng *exynos_rng = platform_get_drvdata(pdev); clk_disable_unprepare(exynos_rng->clk); return 0; } static int __maybe_unused exynos_rng_runtime_resume(struct device *dev) { struct platform_device *pdev = to_platform_device(dev); struct exynos_rng *exynos_rng = platform_get_drvdata(pdev); return clk_prepare_enable(exynos_rng->clk); } static int __maybe_unused exynos_rng_suspend(struct device *dev) { return pm_runtime_force_suspend(dev); } static int __maybe_unused exynos_rng_resume(struct device *dev) { struct platform_device *pdev = to_platform_device(dev); struct exynos_rng *exynos_rng = platform_get_drvdata(pdev); int ret; ret = pm_runtime_force_resume(dev); if (ret) return ret; return exynos_rng_configure(exynos_rng); } static const struct dev_pm_ops exynos_rng_pm_ops = { SET_SYSTEM_SLEEP_PM_OPS(exynos_rng_suspend, exynos_rng_resume) SET_RUNTIME_PM_OPS(exynos_rng_runtime_suspend, exynos_rng_runtime_resume, NULL) }; static const struct of_device_id exynos_rng_dt_match[] = { { .compatible = "samsung,exynos4-rng", }, { }, }; MODULE_DEVICE_TABLE(of, exynos_rng_dt_match); static struct platform_driver exynos_rng_driver = { .driver = { .name = "exynos-rng", .pm = &exynos_rng_pm_ops, .of_match_table = exynos_rng_dt_match, }, .probe = exynos_rng_probe, .remove = exynos_rng_remove, }; module_platform_driver(exynos_rng_driver); MODULE_DESCRIPTION("EXYNOS 4 H/W Random Number Generator driver"); MODULE_AUTHOR("Jonghwa Lee <jonghwa3.lee@samsung.com>"); MODULE_LICENSE("GPL");