diff options
Diffstat (limited to 'drivers/char/hw_random/atmel-rng.c')
| -rw-r--r-- | drivers/char/hw_random/atmel-rng.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c new file mode 100644 index 000000000..b8effe77d --- /dev/null +++ b/drivers/char/hw_random/atmel-rng.c @@ -0,0 +1,233 @@ +/* + * Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mod_devicetable.h> +#include <linux/slab.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/io.h> +#include <linux/iopoll.h> +#include <linux/hw_random.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/pm_runtime.h> + +#define TRNG_CR 0x00 +#define TRNG_MR 0x04 +#define TRNG_ISR 0x1c +#define TRNG_ISR_DATRDY BIT(0) +#define TRNG_ODATA 0x50 + +#define TRNG_KEY 0x524e4700 /* RNG */ + +#define TRNG_HALFR BIT(0) /* generate RN every 168 cycles */ + +struct atmel_trng_data { + bool has_half_rate; +}; + +struct atmel_trng { + struct clk *clk; + void __iomem *base; + struct hwrng rng; + bool has_half_rate; +}; + +static bool atmel_trng_wait_ready(struct atmel_trng *trng, bool wait) +{ + int ready; + + ready = readl(trng->base + TRNG_ISR) & TRNG_ISR_DATRDY; + if (!ready && wait) + readl_poll_timeout(trng->base + TRNG_ISR, ready, + ready & TRNG_ISR_DATRDY, 1000, 20000); + + return !!ready; +} + +static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max, + bool wait) +{ + struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng); + u32 *data = buf; + int ret; + + ret = pm_runtime_get_sync((struct device *)trng->rng.priv); + if (ret < 0) { + pm_runtime_put_sync((struct device *)trng->rng.priv); + return ret; + } + + ret = atmel_trng_wait_ready(trng, wait); + if (!ret) + goto out; + + *data = readl(trng->base + TRNG_ODATA); + /* + * ensure data ready is only set again AFTER the next data word is ready + * in case it got set between checking ISR and reading ODATA, so we + * don't risk re-reading the same word + */ + readl(trng->base + TRNG_ISR); + ret = 4; + +out: + pm_runtime_mark_last_busy((struct device *)trng->rng.priv); + pm_runtime_put_sync_autosuspend((struct device *)trng->rng.priv); + return ret; +} + +static int atmel_trng_init(struct atmel_trng *trng) +{ + unsigned long rate; + int ret; + + ret = clk_prepare_enable(trng->clk); + if (ret) + return ret; + + if (trng->has_half_rate) { + rate = clk_get_rate(trng->clk); + + /* if peripheral clk is above 100MHz, set HALFR */ + if (rate > 100000000) + writel(TRNG_HALFR, trng->base + TRNG_MR); + } + + writel(TRNG_KEY | 1, trng->base + TRNG_CR); + + return 0; +} + +static void atmel_trng_cleanup(struct atmel_trng *trng) +{ + writel(TRNG_KEY, trng->base + TRNG_CR); + clk_disable_unprepare(trng->clk); +} + +static int atmel_trng_probe(struct platform_device *pdev) +{ + struct atmel_trng *trng; + const struct atmel_trng_data *data; + int ret; + + trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL); + if (!trng) + return -ENOMEM; + + trng->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(trng->base)) + return PTR_ERR(trng->base); + + trng->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(trng->clk)) + return PTR_ERR(trng->clk); + data = of_device_get_match_data(&pdev->dev); + if (!data) + return -ENODEV; + + trng->has_half_rate = data->has_half_rate; + trng->rng.name = pdev->name; + trng->rng.read = atmel_trng_read; + trng->rng.priv = (unsigned long)&pdev->dev; + platform_set_drvdata(pdev, trng); + +#ifndef CONFIG_PM + ret = atmel_trng_init(trng); + if (ret) + return ret; +#endif + + pm_runtime_set_autosuspend_delay(&pdev->dev, 100); + pm_runtime_use_autosuspend(&pdev->dev); + pm_runtime_enable(&pdev->dev); + + ret = devm_hwrng_register(&pdev->dev, &trng->rng); + if (ret) { + pm_runtime_disable(&pdev->dev); + pm_runtime_set_suspended(&pdev->dev); +#ifndef CONFIG_PM + atmel_trng_cleanup(trng); +#endif + } + + return ret; +} + +static int atmel_trng_remove(struct platform_device *pdev) +{ + struct atmel_trng *trng = platform_get_drvdata(pdev); + + atmel_trng_cleanup(trng); + pm_runtime_disable(&pdev->dev); + pm_runtime_set_suspended(&pdev->dev); + + return 0; +} + +static int __maybe_unused atmel_trng_runtime_suspend(struct device *dev) +{ + struct atmel_trng *trng = dev_get_drvdata(dev); + + atmel_trng_cleanup(trng); + + return 0; +} + +static int __maybe_unused atmel_trng_runtime_resume(struct device *dev) +{ + struct atmel_trng *trng = dev_get_drvdata(dev); + + return atmel_trng_init(trng); +} + +static const struct dev_pm_ops __maybe_unused atmel_trng_pm_ops = { + SET_RUNTIME_PM_OPS(atmel_trng_runtime_suspend, + atmel_trng_runtime_resume, NULL) + SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, + pm_runtime_force_resume) +}; + +static const struct atmel_trng_data at91sam9g45_config = { + .has_half_rate = false, +}; + +static const struct atmel_trng_data sam9x60_config = { + .has_half_rate = true, +}; + +static const struct of_device_id atmel_trng_dt_ids[] = { + { + .compatible = "atmel,at91sam9g45-trng", + .data = &at91sam9g45_config, + }, { + .compatible = "microchip,sam9x60-trng", + .data = &sam9x60_config, + }, { + /* sentinel */ + } +}; +MODULE_DEVICE_TABLE(of, atmel_trng_dt_ids); + +static struct platform_driver atmel_trng_driver = { + .probe = atmel_trng_probe, + .remove = atmel_trng_remove, + .driver = { + .name = "atmel-trng", + .pm = pm_ptr(&atmel_trng_pm_ops), + .of_match_table = atmel_trng_dt_ids, + }, +}; + +module_platform_driver(atmel_trng_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>"); +MODULE_DESCRIPTION("Atmel true random number generator driver"); |