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22#include <linux/module.h>
23#include <linux/kernel.h>
24#include <linux/platform_device.h>
25#include <linux/hw_random.h>
26#include <linux/delay.h>
27#include <linux/of_platform.h>
28#include <asm/io.h>
29
30#define SDCRNG_CTL_REG 0x00
31#define SDCRNG_CTL_FVLD_M 0x0000f000
32#define SDCRNG_CTL_FVLD_S 12
33#define SDCRNG_CTL_KSZ 0x00000800
34#define SDCRNG_CTL_RSRC_CRG 0x00000010
35#define SDCRNG_CTL_RSRC_RRG 0x00000000
36#define SDCRNG_CTL_CE 0x00000004
37#define SDCRNG_CTL_RE 0x00000002
38#define SDCRNG_CTL_DR 0x00000001
39#define SDCRNG_CTL_SELECT_RRG_RNG (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
40#define SDCRNG_CTL_SELECT_CRG_RNG (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
41#define SDCRNG_VAL_REG 0x20
42
43#define MODULE_NAME "pasemi_rng"
44
45static int pasemi_rng_data_present(struct hwrng *rng, int wait)
46{
47 void __iomem *rng_regs = (void __iomem *)rng->priv;
48 int data, i;
49
50 for (i = 0; i < 20; i++) {
51 data = (in_le32(rng_regs + SDCRNG_CTL_REG)
52 & SDCRNG_CTL_FVLD_M) ? 1 : 0;
53 if (data || !wait)
54 break;
55 udelay(10);
56 }
57 return data;
58}
59
60static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
61{
62 void __iomem *rng_regs = (void __iomem *)rng->priv;
63 *data = in_le32(rng_regs + SDCRNG_VAL_REG);
64 return 4;
65}
66
67static int pasemi_rng_init(struct hwrng *rng)
68{
69 void __iomem *rng_regs = (void __iomem *)rng->priv;
70 u32 ctl;
71
72 ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
73 out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
74 out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
75
76 return 0;
77}
78
79static void pasemi_rng_cleanup(struct hwrng *rng)
80{
81 void __iomem *rng_regs = (void __iomem *)rng->priv;
82 u32 ctl;
83
84 ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
85 out_le32(rng_regs + SDCRNG_CTL_REG,
86 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
87}
88
89static struct hwrng pasemi_rng = {
90 .name = MODULE_NAME,
91 .init = pasemi_rng_init,
92 .cleanup = pasemi_rng_cleanup,
93 .data_present = pasemi_rng_data_present,
94 .data_read = pasemi_rng_data_read,
95};
96
97static int __devinit rng_probe(struct of_device *ofdev,
98 const struct of_device_id *match)
99{
100 void __iomem *rng_regs;
101 struct device_node *rng_np = ofdev->node;
102 struct resource res;
103 int err = 0;
104
105 err = of_address_to_resource(rng_np, 0, &res);
106 if (err)
107 return -ENODEV;
108
109 rng_regs = ioremap(res.start, 0x100);
110
111 if (!rng_regs)
112 return -ENOMEM;
113
114 pasemi_rng.priv = (unsigned long)rng_regs;
115
116 printk(KERN_INFO "Registering PA Semi RNG\n");
117
118 err = hwrng_register(&pasemi_rng);
119
120 if (err)
121 iounmap(rng_regs);
122
123 return err;
124}
125
126static int __devexit rng_remove(struct of_device *dev)
127{
128 void __iomem *rng_regs = (void __iomem *)pasemi_rng.priv;
129
130 hwrng_unregister(&pasemi_rng);
131 iounmap(rng_regs);
132
133 return 0;
134}
135
136static struct of_device_id rng_match[] = {
137 { .compatible = "1682m-rng", },
138 { .compatible = "pasemi,pwrficient-rng", },
139 { },
140};
141
142static struct of_platform_driver rng_driver = {
143 .name = "pasemi-rng",
144 .match_table = rng_match,
145 .probe = rng_probe,
146 .remove = rng_remove,
147};
148
149static int __init rng_init(void)
150{
151 return of_register_platform_driver(&rng_driver);
152}
153module_init(rng_init);
154
155static void __exit rng_exit(void)
156{
157 of_unregister_platform_driver(&rng_driver);
158}
159module_exit(rng_exit);
160
161MODULE_LICENSE("GPL");
162MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
163MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");
164
