diff options
Diffstat (limited to 'drivers/char/hw_random/exynos-rng.c')
| -rw-r--r-- | drivers/char/hw_random/exynos-rng.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/drivers/char/hw_random/exynos-rng.c b/drivers/char/hw_random/exynos-rng.c new file mode 100644 index 000000000..dc4701fd8 --- /dev/null +++ b/drivers/char/hw_random/exynos-rng.c @@ -0,0 +1,172 @@ +/* + * exynos-rng.c - Random Number Generator driver for the exynos + * + * Copyright (C) 2012 Samsung Electronics + * Jonghwa Lee <jonghwa3.lee@smasung.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_init(struct hwrng *rng) +{ + struct exynos_rng *exynos_rng = container_of(rng, + struct exynos_rng, rng); + int i; + int ret = 0; + + pm_runtime_get_sync(exynos_rng->dev); + + 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; + + pm_runtime_put_noidle(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; + + 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)) + cpu_relax(); + + exynos_rng_writel(exynos_rng, PRNG_DONE, EXYNOS_PRNG_STATUS_OFFSET); + + *data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET); + + pm_runtime_mark_last_busy(exynos_rng->dev); + pm_runtime_autosuspend(exynos_rng->dev); + + return 4; +} + +static int exynos_rng_probe(struct platform_device *pdev) +{ + struct exynos_rng *exynos_rng; + struct resource *res; + + 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); + + return devm_hwrng_register(&pdev->dev, &exynos_rng->rng); +} + +#ifdef CONFIG_PM +static int 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 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); +} +#endif + +static UNIVERSAL_DEV_PM_OPS(exynos_rng_pm_ops, exynos_rng_runtime_suspend, + exynos_rng_runtime_resume, NULL); + +static struct platform_driver exynos_rng_driver = { + .driver = { + .name = "exynos-rng", + .pm = &exynos_rng_pm_ops, + }, + .probe = exynos_rng_probe, +}; + +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"); |