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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Nomadik RNG support
4 * Copyright 2009 Alessandro Rubini
5 */
6
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <linux/device.h>
10#include <linux/amba/bus.h>
11#include <linux/hw_random.h>
12#include <linux/io.h>
13#include <linux/clk.h>
14#include <linux/err.h>
15
16static struct clk *rng_clk;
17
18static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
19{
20 void __iomem *base = (void __iomem *)rng->priv;
21
22 /*
23 * The register is 32 bits and gives 16 random bits (low half).
24 * A subsequent read will delay the core for 400ns, so we just read
25 * once and accept the very unlikely very small delay, even if wait==0.
26 */
27 *(u16 *)data = __raw_readl(base + 8) & 0xffff;
28 return 2;
29}
30
31/* we have at most one RNG per machine, granted */
32static struct hwrng nmk_rng = {
33 .name = "nomadik",
34 .read = nmk_rng_read,
35};
36
37static int nmk_rng_probe(struct amba_device *dev, const struct amba_id *id)
38{
39 void __iomem *base;
40 int ret;
41
42 rng_clk = devm_clk_get(&dev->dev, NULL);
43 if (IS_ERR(rng_clk)) {
44 dev_err(&dev->dev, "could not get rng clock\n");
45 ret = PTR_ERR(rng_clk);
46 return ret;
47 }
48
49 clk_prepare_enable(rng_clk);
50
51 ret = amba_request_regions(dev, dev->dev.init_name);
52 if (ret)
53 goto out_clk;
54 ret = -ENOMEM;
55 base = devm_ioremap(&dev->dev, dev->res.start,
56 resource_size(&dev->res));
57 if (!base)
58 goto out_release;
59 nmk_rng.priv = (unsigned long)base;
60 ret = devm_hwrng_register(&dev->dev, &nmk_rng);
61 if (ret)
62 goto out_release;
63 return 0;
64
65out_release:
66 amba_release_regions(dev);
67out_clk:
68 clk_disable(rng_clk);
69 return ret;
70}
71
72static void nmk_rng_remove(struct amba_device *dev)
73{
74 amba_release_regions(dev);
75 clk_disable(rng_clk);
76}
77
78static const struct amba_id nmk_rng_ids[] = {
79 {
80 .id = 0x000805e1,
81 .mask = 0x000fffff, /* top bits are rev and cfg: accept all */
82 },
83 {0, 0},
84};
85
86MODULE_DEVICE_TABLE(amba, nmk_rng_ids);
87
88static struct amba_driver nmk_rng_driver = {
89 .drv = {
90 .owner = THIS_MODULE,
91 .name = "rng",
92 },
93 .probe = nmk_rng_probe,
94 .remove = nmk_rng_remove,
95 .id_table = nmk_rng_ids,
96};
97
98module_amba_driver(nmk_rng_driver);
99
100MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Nomadik RNG support
4 * Copyright 2009 Alessandro Rubini
5 */
6
7#include <linux/kernel.h>
8#include <linux/module.h>
9#include <linux/device.h>
10#include <linux/amba/bus.h>
11#include <linux/hw_random.h>
12#include <linux/io.h>
13#include <linux/clk.h>
14#include <linux/err.h>
15
16static struct clk *rng_clk;
17
18static int nmk_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
19{
20 void __iomem *base = (void __iomem *)rng->priv;
21
22 /*
23 * The register is 32 bits and gives 16 random bits (low half).
24 * A subsequent read will delay the core for 400ns, so we just read
25 * once and accept the very unlikely very small delay, even if wait==0.
26 */
27 *(u16 *)data = __raw_readl(base + 8) & 0xffff;
28 return 2;
29}
30
31/* we have at most one RNG per machine, granted */
32static struct hwrng nmk_rng = {
33 .name = "nomadik",
34 .read = nmk_rng_read,
35};
36
37static int nmk_rng_probe(struct amba_device *dev, const struct amba_id *id)
38{
39 void __iomem *base;
40 int ret;
41
42 rng_clk = devm_clk_get(&dev->dev, NULL);
43 if (IS_ERR(rng_clk)) {
44 dev_err(&dev->dev, "could not get rng clock\n");
45 ret = PTR_ERR(rng_clk);
46 return ret;
47 }
48
49 clk_prepare_enable(rng_clk);
50
51 ret = amba_request_regions(dev, dev->dev.init_name);
52 if (ret)
53 goto out_clk;
54 ret = -ENOMEM;
55 base = devm_ioremap(&dev->dev, dev->res.start,
56 resource_size(&dev->res));
57 if (!base)
58 goto out_release;
59 nmk_rng.priv = (unsigned long)base;
60 ret = devm_hwrng_register(&dev->dev, &nmk_rng);
61 if (ret)
62 goto out_release;
63 return 0;
64
65out_release:
66 amba_release_regions(dev);
67out_clk:
68 clk_disable_unprepare(rng_clk);
69 return ret;
70}
71
72static void nmk_rng_remove(struct amba_device *dev)
73{
74 amba_release_regions(dev);
75 clk_disable_unprepare(rng_clk);
76}
77
78static const struct amba_id nmk_rng_ids[] = {
79 {
80 .id = 0x000805e1,
81 .mask = 0x000fffff, /* top bits are rev and cfg: accept all */
82 },
83 {0, 0},
84};
85
86MODULE_DEVICE_TABLE(amba, nmk_rng_ids);
87
88static struct amba_driver nmk_rng_driver = {
89 .drv = {
90 .owner = THIS_MODULE,
91 .name = "rng",
92 },
93 .probe = nmk_rng_probe,
94 .remove = nmk_rng_remove,
95 .id_table = nmk_rng_ids,
96};
97
98module_amba_driver(nmk_rng_driver);
99
100MODULE_LICENSE("GPL");