diff options
Diffstat (limited to 'drivers/char/hw_random/npcm-rng.c')
| -rw-r--r-- | drivers/char/hw_random/npcm-rng.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/drivers/char/hw_random/npcm-rng.c b/drivers/char/hw_random/npcm-rng.c new file mode 100644 index 000000000..1ec5f267a --- /dev/null +++ b/drivers/char/hw_random/npcm-rng.c @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2019 Nuvoton Technology corporation. + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/io.h> +#include <linux/iopoll.h> +#include <linux/init.h> +#include <linux/random.h> +#include <linux/err.h> +#include <linux/platform_device.h> +#include <linux/hw_random.h> +#include <linux/delay.h> +#include <linux/of_irq.h> +#include <linux/pm_runtime.h> + +#define NPCM_RNGCS_REG 0x00 /* Control and status register */ +#define NPCM_RNGD_REG 0x04 /* Data register */ +#define NPCM_RNGMODE_REG 0x08 /* Mode register */ + +#define NPCM_RNG_CLK_SET_25MHZ GENMASK(4, 3) /* 20-25 MHz */ +#define NPCM_RNG_DATA_VALID BIT(1) +#define NPCM_RNG_ENABLE BIT(0) +#define NPCM_RNG_M1ROSEL BIT(1) + +#define NPCM_RNG_TIMEOUT_USEC 20000 +#define NPCM_RNG_POLL_USEC 1000 + +#define to_npcm_rng(p) container_of(p, struct npcm_rng, rng) + +struct npcm_rng { + void __iomem *base; + struct hwrng rng; +}; + +static int npcm_rng_init(struct hwrng *rng) +{ + struct npcm_rng *priv = to_npcm_rng(rng); + + writel(NPCM_RNG_CLK_SET_25MHZ | NPCM_RNG_ENABLE, + priv->base + NPCM_RNGCS_REG); + + return 0; +} + +static void npcm_rng_cleanup(struct hwrng *rng) +{ + struct npcm_rng *priv = to_npcm_rng(rng); + + writel(NPCM_RNG_CLK_SET_25MHZ, priv->base + NPCM_RNGCS_REG); +} + +static int npcm_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) +{ + struct npcm_rng *priv = to_npcm_rng(rng); + int retval = 0; + int ready; + + pm_runtime_get_sync((struct device *)priv->rng.priv); + + while (max) { + if (wait) { + if (readb_poll_timeout(priv->base + NPCM_RNGCS_REG, + ready, + ready & NPCM_RNG_DATA_VALID, + NPCM_RNG_POLL_USEC, + NPCM_RNG_TIMEOUT_USEC)) + break; + } else { + if ((readb(priv->base + NPCM_RNGCS_REG) & + NPCM_RNG_DATA_VALID) == 0) + break; + } + + *(u8 *)buf = readb(priv->base + NPCM_RNGD_REG); + retval++; + buf++; + max--; + } + + pm_runtime_mark_last_busy((struct device *)priv->rng.priv); + pm_runtime_put_sync_autosuspend((struct device *)priv->rng.priv); + + return retval || !wait ? retval : -EIO; +} + +static int npcm_rng_probe(struct platform_device *pdev) +{ + struct npcm_rng *priv; + int ret; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(priv->base)) + return PTR_ERR(priv->base); + + dev_set_drvdata(&pdev->dev, priv); + pm_runtime_set_autosuspend_delay(&pdev->dev, 100); + pm_runtime_use_autosuspend(&pdev->dev); + pm_runtime_enable(&pdev->dev); + +#ifndef CONFIG_PM + priv->rng.init = npcm_rng_init; + priv->rng.cleanup = npcm_rng_cleanup; +#endif + priv->rng.name = pdev->name; + priv->rng.read = npcm_rng_read; + priv->rng.priv = (unsigned long)&pdev->dev; + priv->rng.quality = 1000; + + writel(NPCM_RNG_M1ROSEL, priv->base + NPCM_RNGMODE_REG); + + ret = devm_hwrng_register(&pdev->dev, &priv->rng); + if (ret) { + dev_err(&pdev->dev, "Failed to register rng device: %d\n", + ret); + pm_runtime_disable(&pdev->dev); + pm_runtime_set_suspended(&pdev->dev); + return ret; + } + + return 0; +} + +static int npcm_rng_remove(struct platform_device *pdev) +{ + struct npcm_rng *priv = platform_get_drvdata(pdev); + + devm_hwrng_unregister(&pdev->dev, &priv->rng); + pm_runtime_disable(&pdev->dev); + pm_runtime_set_suspended(&pdev->dev); + + return 0; +} + +#ifdef CONFIG_PM +static int npcm_rng_runtime_suspend(struct device *dev) +{ + struct npcm_rng *priv = dev_get_drvdata(dev); + + npcm_rng_cleanup(&priv->rng); + + return 0; +} + +static int npcm_rng_runtime_resume(struct device *dev) +{ + struct npcm_rng *priv = dev_get_drvdata(dev); + + return npcm_rng_init(&priv->rng); +} +#endif + +static const struct dev_pm_ops npcm_rng_pm_ops = { + SET_RUNTIME_PM_OPS(npcm_rng_runtime_suspend, + npcm_rng_runtime_resume, NULL) + SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, + pm_runtime_force_resume) +}; + +static const struct of_device_id rng_dt_id[] __maybe_unused = { + { .compatible = "nuvoton,npcm750-rng", }, + {}, +}; +MODULE_DEVICE_TABLE(of, rng_dt_id); + +static struct platform_driver npcm_rng_driver = { + .driver = { + .name = "npcm-rng", + .pm = &npcm_rng_pm_ops, + .of_match_table = of_match_ptr(rng_dt_id), + }, + .probe = npcm_rng_probe, + .remove = npcm_rng_remove, +}; + +module_platform_driver(npcm_rng_driver); + +MODULE_DESCRIPTION("Nuvoton NPCM Random Number Generator Driver"); +MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>"); +MODULE_LICENSE("GPL v2"); |