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// 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");
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