1// SPDX-License-Identifier: GPL-2.0
  2// Copyright (c) 2019 Nuvoton Technology corporation.
  3
  4#include <linux/kernel.h>
  5#include <linux/module.h>
  6#include <linux/io.h>
  7#include <linux/iopoll.h>
  8#include <linux/init.h>
  9#include <linux/random.h>
 10#include <linux/err.h>
 11#include <linux/platform_device.h>
 12#include <linux/hw_random.h>
 13#include <linux/delay.h>
 14#include <linux/of_irq.h>
 15#include <linux/pm_runtime.h>
 16#include <linux/of_device.h>
 17
 18#define NPCM_RNGCS_REG		0x00	/* Control and status register */
 19#define NPCM_RNGD_REG		0x04	/* Data register */
 20#define NPCM_RNGMODE_REG	0x08	/* Mode register */
 21
 22#define NPCM_RNG_CLK_SET_62_5MHZ	BIT(2) /* 60-80 MHz */
 23#define NPCM_RNG_CLK_SET_25MHZ	GENMASK(4, 3) /* 20-25 MHz */
 24#define NPCM_RNG_DATA_VALID	BIT(1)
 25#define NPCM_RNG_ENABLE		BIT(0)
 26#define NPCM_RNG_M1ROSEL	BIT(1)
 27
 28#define NPCM_RNG_TIMEOUT_USEC	20000
 29#define NPCM_RNG_POLL_USEC	1000
 30
 31#define to_npcm_rng(p)	container_of(p, struct npcm_rng, rng)
 32
 33struct npcm_rng {
 34	void __iomem *base;
 35	struct hwrng rng;
 36	u32 clkp;
 37};
 38
 39static int npcm_rng_init(struct hwrng *rng)
 40{
 41	struct npcm_rng *priv = to_npcm_rng(rng);
 42
 43	writel(priv->clkp | NPCM_RNG_ENABLE, priv->base + NPCM_RNGCS_REG);
 44
 45	return 0;
 46}
 47
 48static void npcm_rng_cleanup(struct hwrng *rng)
 49{
 50	struct npcm_rng *priv = to_npcm_rng(rng);
 51
 52	writel(priv->clkp, priv->base + NPCM_RNGCS_REG);
 53}
 54
 55static int npcm_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 56{
 57	struct npcm_rng *priv = to_npcm_rng(rng);
 58	int retval = 0;
 59	int ready;
 60
 61	pm_runtime_get_sync((struct device *)priv->rng.priv);
 62
 63	while (max) {
 64		if (wait) {
 65			if (readb_poll_timeout(priv->base + NPCM_RNGCS_REG,
 66					       ready,
 67					       ready & NPCM_RNG_DATA_VALID,
 68					       NPCM_RNG_POLL_USEC,
 69					       NPCM_RNG_TIMEOUT_USEC))
 70				break;
 71		} else {
 72			if ((readb(priv->base + NPCM_RNGCS_REG) &
 73			    NPCM_RNG_DATA_VALID) == 0)
 74				break;
 75		}
 76
 77		*(u8 *)buf = readb(priv->base + NPCM_RNGD_REG);
 78		retval++;
 79		buf++;
 80		max--;
 81	}
 82
 83	pm_runtime_mark_last_busy((struct device *)priv->rng.priv);
 84	pm_runtime_put_sync_autosuspend((struct device *)priv->rng.priv);
 85
 86	return retval || !wait ? retval : -EIO;
 87}
 88
 89static int npcm_rng_probe(struct platform_device *pdev)
 90{
 91	struct npcm_rng *priv;
 92	int ret;
 93
 94	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
 95	if (!priv)
 96		return -ENOMEM;
 97
 98	priv->base = devm_platform_ioremap_resource(pdev, 0);
 99	if (IS_ERR(priv->base))
100		return PTR_ERR(priv->base);
101
102	dev_set_drvdata(&pdev->dev, priv);
103	pm_runtime_set_autosuspend_delay(&pdev->dev, 100);
104	pm_runtime_use_autosuspend(&pdev->dev);
105	pm_runtime_enable(&pdev->dev);
106
107#ifndef CONFIG_PM
108	priv->rng.init = npcm_rng_init;
109	priv->rng.cleanup = npcm_rng_cleanup;
110#endif
111	priv->rng.name = pdev->name;
112	priv->rng.read = npcm_rng_read;
113	priv->rng.priv = (unsigned long)&pdev->dev;
114	priv->clkp = (u32)(uintptr_t)of_device_get_match_data(&pdev->dev);
115
116	writel(NPCM_RNG_M1ROSEL, priv->base + NPCM_RNGMODE_REG);
117
118	ret = devm_hwrng_register(&pdev->dev, &priv->rng);
119	if (ret) {
120		dev_err(&pdev->dev, "Failed to register rng device: %d\n",
121			ret);
122		pm_runtime_disable(&pdev->dev);
123		pm_runtime_set_suspended(&pdev->dev);
124		return ret;
125	}
126
127	return 0;
128}
129
130static int npcm_rng_remove(struct platform_device *pdev)
131{
132	struct npcm_rng *priv = platform_get_drvdata(pdev);
133
134	devm_hwrng_unregister(&pdev->dev, &priv->rng);
135	pm_runtime_disable(&pdev->dev);
136	pm_runtime_set_suspended(&pdev->dev);
137
138	return 0;
139}
140
141#ifdef CONFIG_PM
142static int npcm_rng_runtime_suspend(struct device *dev)
143{
144	struct npcm_rng *priv = dev_get_drvdata(dev);
145
146	npcm_rng_cleanup(&priv->rng);
147
148	return 0;
149}
150
151static int npcm_rng_runtime_resume(struct device *dev)
152{
153	struct npcm_rng *priv = dev_get_drvdata(dev);
154
155	return npcm_rng_init(&priv->rng);
156}
157#endif
158
159static const struct dev_pm_ops npcm_rng_pm_ops = {
160	SET_RUNTIME_PM_OPS(npcm_rng_runtime_suspend,
161			   npcm_rng_runtime_resume, NULL)
162	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
163				pm_runtime_force_resume)
164};
165
166static const struct of_device_id rng_dt_id[] __maybe_unused = {
167	{ .compatible = "nuvoton,npcm750-rng",
168		.data = (void *)NPCM_RNG_CLK_SET_25MHZ },
169	{ .compatible = "nuvoton,npcm845-rng",
170		.data = (void *)NPCM_RNG_CLK_SET_62_5MHZ },
171	{},
172};
173MODULE_DEVICE_TABLE(of, rng_dt_id);
174
175static struct platform_driver npcm_rng_driver = {
176	.driver = {
177		.name		= "npcm-rng",
178		.pm		= &npcm_rng_pm_ops,
179		.of_match_table = of_match_ptr(rng_dt_id),
180	},
181	.probe		= npcm_rng_probe,
182	.remove		= npcm_rng_remove,
183};
184
185module_platform_driver(npcm_rng_driver);
186
187MODULE_DESCRIPTION("Nuvoton NPCM Random Number Generator Driver");
188MODULE_AUTHOR("Tomer Maimon <tomer.maimon@nuvoton.com>");
189MODULE_LICENSE("GPL v2");