diff options
Diffstat (limited to 'drivers/char/hw_random/atmel-rng.c')
| -rw-r--r-- | drivers/char/hw_random/atmel-rng.c | 200 |
1 files changed, 200 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..8cf0ef501 --- /dev/null +++ b/drivers/char/hw_random/atmel-rng.c @@ -0,0 +1,200 @@ +/* + * 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/hw_random.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> + +#define TRNG_CR 0x00 +#define TRNG_MR 0x04 +#define TRNG_ISR 0x1c +#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; +}; + +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; + + /* data ready? */ + if (readl(trng->base + TRNG_ISR) & 1) { + *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); + return 4; + } else + return 0; +} + +static void atmel_trng_enable(struct atmel_trng *trng) +{ + writel(TRNG_KEY | 1, trng->base + TRNG_CR); +} + +static void atmel_trng_disable(struct atmel_trng *trng) +{ + writel(TRNG_KEY, trng->base + TRNG_CR); +} + +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; + + if (data->has_half_rate) { + unsigned long rate = clk_get_rate(trng->clk); + + /* if peripheral clk is above 100MHz, set HALFR */ + if (rate > 100000000) + writel(TRNG_HALFR, trng->base + TRNG_MR); + } + + ret = clk_prepare_enable(trng->clk); + if (ret) + return ret; + + atmel_trng_enable(trng); + trng->rng.name = pdev->name; + trng->rng.read = atmel_trng_read; + + ret = devm_hwrng_register(&pdev->dev, &trng->rng); + if (ret) + goto err_register; + + platform_set_drvdata(pdev, trng); + + return 0; + +err_register: + clk_disable_unprepare(trng->clk); + atmel_trng_disable(trng); + return ret; +} + +static int atmel_trng_remove(struct platform_device *pdev) +{ + struct atmel_trng *trng = platform_get_drvdata(pdev); + + + atmel_trng_disable(trng); + clk_disable_unprepare(trng->clk); + + return 0; +} + +#ifdef CONFIG_PM +static int atmel_trng_suspend(struct device *dev) +{ + struct atmel_trng *trng = dev_get_drvdata(dev); + + atmel_trng_disable(trng); + clk_disable_unprepare(trng->clk); + + return 0; +} + +static int atmel_trng_resume(struct device *dev) +{ + struct atmel_trng *trng = dev_get_drvdata(dev); + int ret; + + ret = clk_prepare_enable(trng->clk); + if (ret) + return ret; + + atmel_trng_enable(trng); + + return 0; +} + +static const struct dev_pm_ops atmel_trng_pm_ops = { + .suspend = atmel_trng_suspend, + .resume = atmel_trng_resume, +}; +#endif /* CONFIG_PM */ + +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", +#ifdef CONFIG_PM + .pm = &atmel_trng_pm_ops, +#endif /* CONFIG_PM */ + .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"); |