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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 <[email protected]>");
- MODULE_LICENSE("GPL v2");
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