2 * Copyright (c) 2011 Peter Korsgaard <jacmet@sunsite.dk>
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.
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>
16 #include <linux/hw_random.h>
17 #include <linux/platform_device.h>
21 #define TRNG_ODATA 0x50
23 #define TRNG_KEY 0x524e4700 /* RNG */
31 static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
34 struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
38 if (readl(trng->base + TRNG_ISR) & 1) {
39 *data = readl(trng->base + TRNG_ODATA);
41 ensure data ready is only set again AFTER the next data
42 word is ready in case it got set between checking ISR
43 and reading ODATA, so we don't risk re-reading the
46 readl(trng->base + TRNG_ISR);
52 static void atmel_trng_enable(struct atmel_trng *trng)
54 writel(TRNG_KEY | 1, trng->base + TRNG_CR);
57 static void atmel_trng_disable(struct atmel_trng *trng)
59 writel(TRNG_KEY, trng->base + TRNG_CR);
62 static int atmel_trng_probe(struct platform_device *pdev)
64 struct atmel_trng *trng;
68 trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
72 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
73 trng->base = devm_ioremap_resource(&pdev->dev, res);
74 if (IS_ERR(trng->base))
75 return PTR_ERR(trng->base);
77 trng->clk = devm_clk_get(&pdev->dev, NULL);
78 if (IS_ERR(trng->clk))
79 return PTR_ERR(trng->clk);
81 ret = clk_prepare_enable(trng->clk);
85 atmel_trng_enable(trng);
86 trng->rng.name = pdev->name;
87 trng->rng.read = atmel_trng_read;
89 ret = hwrng_register(&trng->rng);
93 platform_set_drvdata(pdev, trng);
98 clk_disable_unprepare(trng->clk);
99 atmel_trng_disable(trng);
103 static int atmel_trng_remove(struct platform_device *pdev)
105 struct atmel_trng *trng = platform_get_drvdata(pdev);
107 hwrng_unregister(&trng->rng);
109 atmel_trng_disable(trng);
110 clk_disable_unprepare(trng->clk);
116 static int atmel_trng_suspend(struct device *dev)
118 struct atmel_trng *trng = dev_get_drvdata(dev);
120 atmel_trng_disable(trng);
121 clk_disable_unprepare(trng->clk);
126 static int atmel_trng_resume(struct device *dev)
128 struct atmel_trng *trng = dev_get_drvdata(dev);
131 ret = clk_prepare_enable(trng->clk);
135 atmel_trng_enable(trng);
140 static const struct dev_pm_ops atmel_trng_pm_ops = {
141 .suspend = atmel_trng_suspend,
142 .resume = atmel_trng_resume,
144 #endif /* CONFIG_PM */
146 static const struct of_device_id atmel_trng_dt_ids[] = {
147 { .compatible = "atmel,at91sam9g45-trng" },
150 MODULE_DEVICE_TABLE(of, atmel_trng_dt_ids);
152 static struct platform_driver atmel_trng_driver = {
153 .probe = atmel_trng_probe,
154 .remove = atmel_trng_remove,
156 .name = "atmel-trng",
158 .pm = &atmel_trng_pm_ops,
159 #endif /* CONFIG_PM */
160 .of_match_table = atmel_trng_dt_ids,
164 module_platform_driver(atmel_trng_driver);
166 MODULE_LICENSE("GPL");
167 MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
168 MODULE_DESCRIPTION("Atmel true random number generator driver");