1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2006-2007 PA Semi, Inc
4 *
5 * Maintained by: Olof Johansson <olof@lixom.net>
6 *
7 * Driver for the PWRficient onchip rng
8 */
9
10#include <linux/module.h>
11#include <linux/kernel.h>
12#include <linux/mod_devicetable.h>
13#include <linux/platform_device.h>
14#include <linux/hw_random.h>
15#include <linux/delay.h>
16#include <linux/io.h>
17
18#define SDCRNG_CTL_REG			0x00
19#define   SDCRNG_CTL_FVLD_M		0x0000f000
20#define   SDCRNG_CTL_FVLD_S		12
21#define   SDCRNG_CTL_KSZ		0x00000800
22#define   SDCRNG_CTL_RSRC_CRG		0x00000010
23#define   SDCRNG_CTL_RSRC_RRG		0x00000000
24#define   SDCRNG_CTL_CE			0x00000004
25#define   SDCRNG_CTL_RE			0x00000002
26#define   SDCRNG_CTL_DR			0x00000001
27#define   SDCRNG_CTL_SELECT_RRG_RNG	(SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
28#define   SDCRNG_CTL_SELECT_CRG_RNG	(SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
29#define SDCRNG_VAL_REG			0x20
30
31#define MODULE_NAME "pasemi_rng"
32
33static int pasemi_rng_data_present(struct hwrng *rng, int wait)
34{
35	void __iomem *rng_regs = (void __iomem *)rng->priv;
36	int data, i;
37
38	for (i = 0; i < 20; i++) {
39		data = (in_le32(rng_regs + SDCRNG_CTL_REG)
40			& SDCRNG_CTL_FVLD_M) ? 1 : 0;
41		if (data || !wait)
42			break;
43		udelay(10);
44	}
45	return data;
46}
47
48static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
49{
50	void __iomem *rng_regs = (void __iomem *)rng->priv;
51	*data = in_le32(rng_regs + SDCRNG_VAL_REG);
52	return 4;
53}
54
55static int pasemi_rng_init(struct hwrng *rng)
56{
57	void __iomem *rng_regs = (void __iomem *)rng->priv;
58	u32 ctl;
59
60	ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
61	out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
62	out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
63
64	return 0;
65}
66
67static void pasemi_rng_cleanup(struct hwrng *rng)
68{
69	void __iomem *rng_regs = (void __iomem *)rng->priv;
70	u32 ctl;
71
72	ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
73	out_le32(rng_regs + SDCRNG_CTL_REG,
74		 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
75}
76
77static struct hwrng pasemi_rng = {
78	.name		= MODULE_NAME,
79	.init		= pasemi_rng_init,
80	.cleanup	= pasemi_rng_cleanup,
81	.data_present	= pasemi_rng_data_present,
82	.data_read	= pasemi_rng_data_read,
83};
84
85static int rng_probe(struct platform_device *pdev)
86{
87	void __iomem *rng_regs;
88
89	rng_regs = devm_platform_ioremap_resource(pdev, 0);
90	if (IS_ERR(rng_regs))
91		return PTR_ERR(rng_regs);
92
93	pasemi_rng.priv = (unsigned long)rng_regs;
94
95	pr_info("Registering PA Semi RNG\n");
96	return devm_hwrng_register(&pdev->dev, &pasemi_rng);
97}
98
99static const struct of_device_id rng_match[] = {
100	{ .compatible      = "1682m-rng", },
101	{ .compatible      = "pasemi,pwrficient-rng", },
102	{ },
103};
104MODULE_DEVICE_TABLE(of, rng_match);
105
106static struct platform_driver rng_driver = {
107	.driver = {
108		.name = "pasemi-rng",
109		.of_match_table = rng_match,
110	},
111	.probe		= rng_probe,
112};
113
114module_platform_driver(rng_driver);
115
116MODULE_LICENSE("GPL");
117MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
118MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");
119