Commit | Line | Data |
---|---|---|
730d02e2 JH |
1 | /* |
2 | * PIC32 RNG driver | |
3 | * | |
4 | * Joshua Henderson <joshua.henderson@microchip.com> | |
5 | * Copyright (C) 2016 Microchip Technology Inc. All rights reserved. | |
6 | * | |
7 | * This program is free software; you can distribute it and/or modify it | |
8 | * under the terms of the GNU General Public License (Version 2) as | |
9 | * published by the Free Software Foundation. | |
10 | * | |
11 | * This program is distributed in the hope it will be useful, but WITHOUT | |
12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | * for more details. | |
15 | */ | |
16 | ||
17 | #include <linux/clk.h> | |
18 | #include <linux/clkdev.h> | |
19 | #include <linux/err.h> | |
20 | #include <linux/hw_random.h> | |
21 | #include <linux/io.h> | |
22 | #include <linux/kernel.h> | |
23 | #include <linux/module.h> | |
24 | #include <linux/of.h> | |
25 | #include <linux/of_device.h> | |
26 | #include <linux/platform_device.h> | |
27 | #include <linux/slab.h> | |
28 | ||
29 | #define RNGCON 0x04 | |
30 | #define TRNGEN BIT(8) | |
31 | #define PRNGEN BIT(9) | |
32 | #define PRNGCONT BIT(10) | |
33 | #define TRNGMOD BIT(11) | |
34 | #define SEEDLOAD BIT(12) | |
35 | #define RNGPOLY1 0x08 | |
36 | #define RNGPOLY2 0x0C | |
37 | #define RNGNUMGEN1 0x10 | |
38 | #define RNGNUMGEN2 0x14 | |
39 | #define RNGSEED1 0x18 | |
40 | #define RNGSEED2 0x1C | |
41 | #define RNGRCNT 0x20 | |
42 | #define RCNT_MASK 0x7F | |
43 | ||
44 | struct pic32_rng { | |
45 | void __iomem *base; | |
46 | struct hwrng rng; | |
47 | struct clk *clk; | |
48 | }; | |
49 | ||
50 | /* | |
51 | * The TRNG can generate up to 24Mbps. This is a timeout that should be safe | |
52 | * enough given the instructions in the loop and that the TRNG may not always | |
53 | * be at maximum rate. | |
54 | */ | |
55 | #define RNG_TIMEOUT 500 | |
56 | ||
57 | static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max, | |
58 | bool wait) | |
59 | { | |
60 | struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng); | |
61 | u64 *data = buf; | |
62 | u32 t; | |
63 | unsigned int timeout = RNG_TIMEOUT; | |
64 | ||
65 | if (max < 8) | |
66 | return 0; | |
67 | ||
68 | do { | |
69 | t = readl(priv->base + RNGRCNT) & RCNT_MASK; | |
70 | if (t == 64) { | |
71 | /* TRNG value comes through the seed registers */ | |
72 | *data = ((u64)readl(priv->base + RNGSEED2) << 32) + | |
73 | readl(priv->base + RNGSEED1); | |
74 | return 8; | |
75 | } | |
76 | } while (wait && --timeout); | |
77 | ||
78 | return -EIO; | |
79 | } | |
80 | ||
81 | static int pic32_rng_probe(struct platform_device *pdev) | |
82 | { | |
83 | struct pic32_rng *priv; | |
84 | struct resource *res; | |
85 | u32 v; | |
86 | int ret; | |
87 | ||
88 | priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); | |
89 | if (!priv) | |
90 | return -ENOMEM; | |
91 | ||
92 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
93 | priv->base = devm_ioremap_resource(&pdev->dev, res); | |
94 | if (IS_ERR(priv->base)) | |
95 | return PTR_ERR(priv->base); | |
96 | ||
97 | priv->clk = devm_clk_get(&pdev->dev, NULL); | |
98 | if (IS_ERR(priv->clk)) | |
99 | return PTR_ERR(priv->clk); | |
100 | ||
101 | ret = clk_prepare_enable(priv->clk); | |
102 | if (ret) | |
103 | return ret; | |
104 | ||
105 | /* enable TRNG in enhanced mode */ | |
106 | v = TRNGEN | TRNGMOD; | |
107 | writel(v, priv->base + RNGCON); | |
108 | ||
109 | priv->rng.name = pdev->name; | |
110 | priv->rng.read = pic32_rng_read; | |
111 | ||
112 | ret = hwrng_register(&priv->rng); | |
113 | if (ret) | |
114 | goto err_register; | |
115 | ||
116 | platform_set_drvdata(pdev, priv); | |
117 | ||
118 | return 0; | |
119 | ||
120 | err_register: | |
121 | clk_disable_unprepare(priv->clk); | |
122 | return ret; | |
123 | } | |
124 | ||
125 | static int pic32_rng_remove(struct platform_device *pdev) | |
126 | { | |
127 | struct pic32_rng *rng = platform_get_drvdata(pdev); | |
128 | ||
129 | hwrng_unregister(&rng->rng); | |
130 | writel(0, rng->base + RNGCON); | |
131 | clk_disable_unprepare(rng->clk); | |
132 | return 0; | |
133 | } | |
134 | ||
135 | static const struct of_device_id pic32_rng_of_match[] = { | |
136 | { .compatible = "microchip,pic32mzda-rng", }, | |
137 | { /* sentinel */ } | |
138 | }; | |
139 | MODULE_DEVICE_TABLE(of, pic32_rng_of_match); | |
140 | ||
141 | static struct platform_driver pic32_rng_driver = { | |
142 | .probe = pic32_rng_probe, | |
143 | .remove = pic32_rng_remove, | |
144 | .driver = { | |
145 | .name = "pic32-rng", | |
146 | .owner = THIS_MODULE, | |
147 | .of_match_table = of_match_ptr(pic32_rng_of_match), | |
148 | }, | |
149 | }; | |
150 | ||
151 | module_platform_driver(pic32_rng_driver); | |
152 | ||
153 | MODULE_LICENSE("GPL"); | |
154 | MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>"); | |
155 | MODULE_DESCRIPTION("Microchip PIC32 RNG Driver"); |