tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk>
3 *
4 * This file is licensed under the terms of the GNU General Public
5 * License version 2. This program is licensed "as is" without any
6 * warranty of any kind, whether express or implied.
7 */
8
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/mod_devicetable.h>
12#include <linux/slab.h>
13#include <linux/err.h>
14#include <linux/clk.h>
15#include <linux/io.h>
16#include <linux/hw_random.h>
17#include <linux/of_device.h>
18#include <linux/platform_device.h>
19
20#define TRNG_CR 0x00
21#define TRNG_MR 0x04
22#define TRNG_ISR 0x1c
23#define TRNG_ODATA 0x50
24
25#define TRNG_KEY 0x524e4700 /* RNG */
26
27#define TRNG_HALFR BIT(0) /* generate RN every 168 cycles */
28
29struct atmel_trng_data {
30 bool has_half_rate;
31};
32
33struct atmel_trng {
34 struct clk *clk;
35 void __iomem *base;
36 struct hwrng rng;
37};
38
39static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
40 bool wait)
41{
42 struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
43 u32 *data = buf;
44
45 /* data ready? */
46 if (readl(trng->base + TRNG_ISR) & 1) {
47 *data = readl(trng->base + TRNG_ODATA);
48 /*
49 ensure data ready is only set again AFTER the next data
50 word is ready in case it got set between checking ISR
51 and reading ODATA, so we don't risk re-reading the
52 same word
53 */
54 readl(trng->base + TRNG_ISR);
55 return 4;
56 } else
57 return 0;
58}
59
60static void atmel_trng_enable(struct atmel_trng *trng)
61{
62 writel(TRNG_KEY | 1, trng->base + TRNG_CR);
63}
64
65static void atmel_trng_disable(struct atmel_trng *trng)
66{
67 writel(TRNG_KEY, trng->base + TRNG_CR);
68}
69
70static int atmel_trng_probe(struct platform_device *pdev)
71{
72 struct atmel_trng *trng;
73 const struct atmel_trng_data *data;
74 int ret;
75
76 trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
77 if (!trng)
78 return -ENOMEM;
79
80 trng->base = devm_platform_ioremap_resource(pdev, 0);
81 if (IS_ERR(trng->base))
82 return PTR_ERR(trng->base);
83
84 trng->clk = devm_clk_get(&pdev->dev, NULL);
85 if (IS_ERR(trng->clk))
86 return PTR_ERR(trng->clk);
87 data = of_device_get_match_data(&pdev->dev);
88 if (!data)
89 return -ENODEV;
90
91 if (data->has_half_rate) {
92 unsigned long rate = clk_get_rate(trng->clk);
93
94 /* if peripheral clk is above 100MHz, set HALFR */
95 if (rate > 100000000)
96 writel(TRNG_HALFR, trng->base + TRNG_MR);
97 }
98
99 ret = clk_prepare_enable(trng->clk);
100 if (ret)
101 return ret;
102
103 atmel_trng_enable(trng);
104 trng->rng.name = pdev->name;
105 trng->rng.read = atmel_trng_read;
106
107 ret = devm_hwrng_register(&pdev->dev, &trng->rng);
108 if (ret)
109 goto err_register;
110
111 platform_set_drvdata(pdev, trng);
112
113 return 0;
114
115err_register:
116 clk_disable_unprepare(trng->clk);
117 return ret;
118}
119
120static int atmel_trng_remove(struct platform_device *pdev)
121{
122 struct atmel_trng *trng = platform_get_drvdata(pdev);
123
124
125 atmel_trng_disable(trng);
126 clk_disable_unprepare(trng->clk);
127
128 return 0;
129}
130
131#ifdef CONFIG_PM
132static int atmel_trng_suspend(struct device *dev)
133{
134 struct atmel_trng *trng = dev_get_drvdata(dev);
135
136 atmel_trng_disable(trng);
137 clk_disable_unprepare(trng->clk);
138
139 return 0;
140}
141
142static int atmel_trng_resume(struct device *dev)
143{
144 struct atmel_trng *trng = dev_get_drvdata(dev);
145 int ret;
146
147 ret = clk_prepare_enable(trng->clk);
148 if (ret)
149 return ret;
150
151 atmel_trng_enable(trng);
152
153 return 0;
154}
155
156static const struct dev_pm_ops atmel_trng_pm_ops = {
157 .suspend = atmel_trng_suspend,
158 .resume = atmel_trng_resume,
159};
160#endif /* CONFIG_PM */
161
162static const struct atmel_trng_data at91sam9g45_config = {
163 .has_half_rate = false,
164};
165
166static const struct atmel_trng_data sam9x60_config = {
167 .has_half_rate = true,
168};
169
170static const struct of_device_id atmel_trng_dt_ids[] = {
171 {
172 .compatible = "atmel,at91sam9g45-trng",
173 .data = &at91sam9g45_config,
174 }, {
175 .compatible = "microchip,sam9x60-trng",
176 .data = &sam9x60_config,
177 }, {
178 /* sentinel */
179 }
180};
181MODULE_DEVICE_TABLE(of, atmel_trng_dt_ids);
182
183static struct platform_driver atmel_trng_driver = {
184 .probe = atmel_trng_probe,
185 .remove = atmel_trng_remove,
186 .driver = {
187 .name = "atmel-trng",
188#ifdef CONFIG_PM
189 .pm = &atmel_trng_pm_ops,
190#endif /* CONFIG_PM */
191 .of_match_table = atmel_trng_dt_ids,
192 },
193};
194
195module_platform_driver(atmel_trng_driver);
196
197MODULE_LICENSE("GPL");
198MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
199MODULE_DESCRIPTION("Atmel true random number generator driver");