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