1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Ingenic True Random Number Generator driver
  4 * Copyright (c) 2019 漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>
  5 * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
  6 */
  7
  8#include <linux/clk.h>
  9#include <linux/err.h>
 10#include <linux/kernel.h>
 11#include <linux/hw_random.h>
 12#include <linux/io.h>
 13#include <linux/iopoll.h>
 14#include <linux/mod_devicetable.h>
 15#include <linux/module.h>
 16#include <linux/platform_device.h>
 17#include <linux/slab.h>
 18
 19/* DTRNG register offsets */
 20#define TRNG_REG_CFG_OFFSET			0x00
 21#define TRNG_REG_RANDOMNUM_OFFSET	0x04
 22#define TRNG_REG_STATUS_OFFSET		0x08
 23
 24/* bits within the CFG register */
 25#define CFG_GEN_EN					BIT(0)
 26
 27/* bits within the STATUS register */
 28#define STATUS_RANDOM_RDY			BIT(0)
 29
 30struct ingenic_trng {
 31	void __iomem *base;
 32	struct hwrng rng;
 33};
 34
 35static int ingenic_trng_init(struct hwrng *rng)
 36{
 37	struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
 38	unsigned int ctrl;
 39
 40	ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
 41	ctrl |= CFG_GEN_EN;
 42	writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
 43
 44	return 0;
 45}
 46
 47static void ingenic_trng_cleanup(struct hwrng *rng)
 48{
 49	struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
 50	unsigned int ctrl;
 51
 52	ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
 53	ctrl &= ~CFG_GEN_EN;
 54	writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
 55}
 56
 57static int ingenic_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
 58{
 59	struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
 60	u32 *data = buf;
 61	u32 status;
 62	int ret;
 63
 64	ret = readl_poll_timeout(trng->base + TRNG_REG_STATUS_OFFSET, status,
 65				 status & STATUS_RANDOM_RDY, 10, 1000);
 66	if (ret == -ETIMEDOUT) {
 67		pr_err("%s: Wait for DTRNG data ready timeout\n", __func__);
 68		return ret;
 69	}
 70
 71	*data = readl(trng->base + TRNG_REG_RANDOMNUM_OFFSET);
 72
 73	return 4;
 74}
 75
 76static int ingenic_trng_probe(struct platform_device *pdev)
 77{
 78	struct ingenic_trng *trng;
 79	struct clk *clk;
 80	int ret;
 81
 82	trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
 83	if (!trng)
 84		return -ENOMEM;
 85
 86	trng->base = devm_platform_ioremap_resource(pdev, 0);
 87	if (IS_ERR(trng->base))
 88		return dev_err_probe(&pdev->dev, PTR_ERR(trng->base),
 89				     "%s: Failed to map DTRNG registers\n", __func__);
 90
 91	clk = devm_clk_get_enabled(&pdev->dev, NULL);
 92	if (IS_ERR(clk))
 93		return dev_err_probe(&pdev->dev, PTR_ERR(clk),
 94				     "%s: Cannot get and enable DTRNG clock\n", __func__);
 95
 96	trng->rng.name = pdev->name;
 97	trng->rng.init = ingenic_trng_init;
 98	trng->rng.cleanup = ingenic_trng_cleanup;
 99	trng->rng.read = ingenic_trng_read;
100
101	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
102	if (ret)
103		return dev_err_probe(&pdev->dev, ret, "Failed to register hwrng\n");
104
105	platform_set_drvdata(pdev, trng);
106
107	dev_info(&pdev->dev, "Ingenic DTRNG driver registered\n");
108	return 0;
109}
110
111static const struct of_device_id ingenic_trng_of_match[] = {
112	{ .compatible = "ingenic,x1830-dtrng" },
113	{ /* sentinel */ }
114};
115MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
116
117static struct platform_driver ingenic_trng_driver = {
118	.probe		= ingenic_trng_probe,
119	.driver		= {
120		.name	= "ingenic-trng",
121		.of_match_table = ingenic_trng_of_match,
122	},
123};
124
125module_platform_driver(ingenic_trng_driver);
126
127MODULE_LICENSE("GPL");
128MODULE_AUTHOR("漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>");
129MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
130MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");