1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * drivers/char/hw_random/ixp4xx-rng.c
4  *
5  * RNG driver for Intel IXP4xx family of NPUs
6  *
7  * Author: Deepak Saxena <dsaxena@plexity.net>
8  *
9  * Copyright 2005 (c) MontaVista Software, Inc.
10  *
11  * Fixes by Michael Buesch
12  */
13 
14 #include <linux/kernel.h>
15 #include <linux/types.h>
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/platform_device.h>
19 #include <linux/init.h>
20 #include <linux/bitops.h>
21 #include <linux/hw_random.h>
22 #include <linux/of.h>
23 #include <linux/soc/ixp4xx/cpu.h>
24 
25 #include <asm/io.h>
26 
27 static int ixp4xx_rng_data_read(struct hwrng *rng, u32 *buffer)
28 {
29 	void __iomem * rng_base = (void __iomem *)rng->priv;
30 
31 	*buffer = __raw_readl(rng_base);
32 
33 	return 4;
34 }
35 
36 static struct hwrng ixp4xx_rng_ops = {
37 	.name		= "ixp4xx",
38 	.data_read	= ixp4xx_rng_data_read,
39 };
40 
41 static int ixp4xx_rng_probe(struct platform_device *pdev)
42 {
43 	void __iomem * rng_base;
44 	struct device *dev = &pdev->dev;
45 
46 	if (!cpu_is_ixp46x()) /* includes IXP455 */
47 		return -ENOSYS;
48 
49 	rng_base = devm_platform_ioremap_resource(pdev, 0);
50 	if (IS_ERR(rng_base))
51 		return PTR_ERR(rng_base);
52 
53 	ixp4xx_rng_ops.priv = (unsigned long)rng_base;
54 	return devm_hwrng_register(dev, &ixp4xx_rng_ops);
55 }
56 
57 static const struct of_device_id ixp4xx_rng_of_match[] = {
58 	{
59 		.compatible = "intel,ixp46x-rng",
60 	},
61 	{},
62 };
63 MODULE_DEVICE_TABLE(of, ixp4xx_rng_of_match);
64 
65 static struct platform_driver ixp4xx_rng_driver = {
66 	.driver = {
67 		.name = "ixp4xx-hwrandom",
68 		.of_match_table = ixp4xx_rng_of_match,
69 	},
70 	.probe = ixp4xx_rng_probe,
71 };
72 module_platform_driver(ixp4xx_rng_driver);
73 
74 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
75 MODULE_DESCRIPTION("H/W Pseudo-Random Number Generator (RNG) driver for IXP45x/46x");
76 MODULE_LICENSE("GPL");
77