Commit | Line | Data |
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52527cf3 JB |
1 | /* |
2 | * Generic PowerPC 44x RNG driver | |
3 | * | |
4 | * Copyright 2011 IBM Corporation | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License as published by the | |
8 | * Free Software Foundation; version 2 of the License. | |
9 | */ | |
10 | ||
11 | #include <linux/module.h> | |
12 | #include <linux/kernel.h> | |
13 | #include <linux/platform_device.h> | |
14 | #include <linux/hw_random.h> | |
15 | #include <linux/delay.h> | |
c11eede6 | 16 | #include <linux/of_address.h> |
52527cf3 JB |
17 | #include <linux/of_platform.h> |
18 | #include <asm/io.h> | |
19 | ||
20 | #define PPC4XX_TRNG_DEV_CTRL 0x60080 | |
21 | ||
22 | #define PPC4XX_TRNGE 0x00020000 | |
23 | #define PPC4XX_TRNG_CTRL 0x0008 | |
24 | #define PPC4XX_TRNG_CTRL_DALM 0x20 | |
25 | #define PPC4XX_TRNG_STAT 0x0004 | |
26 | #define PPC4XX_TRNG_STAT_B 0x1 | |
27 | #define PPC4XX_TRNG_DATA 0x0000 | |
28 | ||
29 | #define MODULE_NAME "ppc4xx_rng" | |
30 | ||
31 | static int ppc4xx_rng_data_present(struct hwrng *rng, int wait) | |
32 | { | |
33 | void __iomem *rng_regs = (void __iomem *) rng->priv; | |
34 | int busy, i, present = 0; | |
35 | ||
36 | for (i = 0; i < 20; i++) { | |
37 | busy = (in_le32(rng_regs + PPC4XX_TRNG_STAT) & PPC4XX_TRNG_STAT_B); | |
38 | if (!busy || !wait) { | |
39 | present = 1; | |
40 | break; | |
41 | } | |
42 | udelay(10); | |
43 | } | |
44 | return present; | |
45 | } | |
46 | ||
47 | static int ppc4xx_rng_data_read(struct hwrng *rng, u32 *data) | |
48 | { | |
49 | void __iomem *rng_regs = (void __iomem *) rng->priv; | |
50 | *data = in_le32(rng_regs + PPC4XX_TRNG_DATA); | |
51 | return 4; | |
52 | } | |
53 | ||
54 | static int ppc4xx_rng_enable(int enable) | |
55 | { | |
56 | struct device_node *ctrl; | |
57 | void __iomem *ctrl_reg; | |
58 | int err = 0; | |
59 | u32 val; | |
60 | ||
61 | /* Find the main crypto device node and map it to turn the TRNG on */ | |
62 | ctrl = of_find_compatible_node(NULL, NULL, "amcc,ppc4xx-crypto"); | |
63 | if (!ctrl) | |
64 | return -ENODEV; | |
65 | ||
66 | ctrl_reg = of_iomap(ctrl, 0); | |
67 | if (!ctrl_reg) { | |
68 | err = -ENODEV; | |
69 | goto out; | |
70 | } | |
71 | ||
72 | val = in_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL); | |
73 | ||
74 | if (enable) | |
75 | val |= PPC4XX_TRNGE; | |
76 | else | |
77 | val = val & ~PPC4XX_TRNGE; | |
78 | ||
79 | out_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL, val); | |
80 | iounmap(ctrl_reg); | |
81 | ||
82 | out: | |
83 | of_node_put(ctrl); | |
84 | ||
85 | return err; | |
86 | } | |
87 | ||
88 | static struct hwrng ppc4xx_rng = { | |
89 | .name = MODULE_NAME, | |
90 | .data_present = ppc4xx_rng_data_present, | |
91 | .data_read = ppc4xx_rng_data_read, | |
92 | }; | |
93 | ||
bcd2982a | 94 | static int ppc4xx_rng_probe(struct platform_device *dev) |
52527cf3 JB |
95 | { |
96 | void __iomem *rng_regs; | |
97 | int err = 0; | |
98 | ||
99 | rng_regs = of_iomap(dev->dev.of_node, 0); | |
100 | if (!rng_regs) | |
101 | return -ENODEV; | |
102 | ||
103 | err = ppc4xx_rng_enable(1); | |
104 | if (err) | |
105 | return err; | |
106 | ||
107 | out_le32(rng_regs + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM); | |
108 | ppc4xx_rng.priv = (unsigned long) rng_regs; | |
109 | ||
110 | err = hwrng_register(&ppc4xx_rng); | |
111 | ||
112 | return err; | |
113 | } | |
114 | ||
39af33fc | 115 | static int ppc4xx_rng_remove(struct platform_device *dev) |
52527cf3 JB |
116 | { |
117 | void __iomem *rng_regs = (void __iomem *) ppc4xx_rng.priv; | |
118 | ||
119 | hwrng_unregister(&ppc4xx_rng); | |
120 | ppc4xx_rng_enable(0); | |
121 | iounmap(rng_regs); | |
122 | ||
123 | return 0; | |
124 | } | |
125 | ||
126 | static struct of_device_id ppc4xx_rng_match[] = { | |
127 | { .compatible = "ppc4xx-rng", }, | |
128 | { .compatible = "amcc,ppc460ex-rng", }, | |
129 | { .compatible = "amcc,ppc440epx-rng", }, | |
130 | {}, | |
131 | }; | |
132 | ||
133 | static struct platform_driver ppc4xx_rng_driver = { | |
134 | .driver = { | |
135 | .name = MODULE_NAME, | |
52527cf3 JB |
136 | .of_match_table = ppc4xx_rng_match, |
137 | }, | |
138 | .probe = ppc4xx_rng_probe, | |
139 | .remove = ppc4xx_rng_remove, | |
140 | }; | |
141 | ||
b21cb324 | 142 | module_platform_driver(ppc4xx_rng_driver); |
52527cf3 JB |
143 | |
144 | MODULE_LICENSE("GPL"); | |
145 | MODULE_AUTHOR("Josh Boyer <jwboyer@linux.vnet.ibm.com>"); | |
146 | MODULE_DESCRIPTION("HW RNG driver for PPC 4xx processors"); |