1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2006-2007 PA Semi, Inc
4 *
5 * Maintained by: Olof Johansson <olof@lixom.net>
6 *
7 * Driver for the PWRficient onchip rng
8 */
9
10 #include <linux/module.h>
11 #include <linux/kernel.h>
12 #include <linux/platform_device.h>
13 #include <linux/hw_random.h>
14 #include <linux/delay.h>
15 #include <linux/of_address.h>
16 #include <linux/of_platform.h>
17 #include <linux/io.h>
18
19 #define SDCRNG_CTL_REG 0x00
20 #define SDCRNG_CTL_FVLD_M 0x0000f000
21 #define SDCRNG_CTL_FVLD_S 12
22 #define SDCRNG_CTL_KSZ 0x00000800
23 #define SDCRNG_CTL_RSRC_CRG 0x00000010
24 #define SDCRNG_CTL_RSRC_RRG 0x00000000
25 #define SDCRNG_CTL_CE 0x00000004
26 #define SDCRNG_CTL_RE 0x00000002
27 #define SDCRNG_CTL_DR 0x00000001
28 #define SDCRNG_CTL_SELECT_RRG_RNG (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
29 #define SDCRNG_CTL_SELECT_CRG_RNG (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
30 #define SDCRNG_VAL_REG 0x20
31
32 #define MODULE_NAME "pasemi_rng"
33
pasemi_rng_data_present(struct hwrng * rng,int wait)34 static int pasemi_rng_data_present(struct hwrng *rng, int wait)
35 {
36 void __iomem *rng_regs = (void __iomem *)rng->priv;
37 int data, i;
38
39 for (i = 0; i < 20; i++) {
40 data = (in_le32(rng_regs + SDCRNG_CTL_REG)
41 & SDCRNG_CTL_FVLD_M) ? 1 : 0;
42 if (data || !wait)
43 break;
44 udelay(10);
45 }
46 return data;
47 }
48
pasemi_rng_data_read(struct hwrng * rng,u32 * data)49 static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
50 {
51 void __iomem *rng_regs = (void __iomem *)rng->priv;
52 *data = in_le32(rng_regs + SDCRNG_VAL_REG);
53 return 4;
54 }
55
pasemi_rng_init(struct hwrng * rng)56 static int pasemi_rng_init(struct hwrng *rng)
57 {
58 void __iomem *rng_regs = (void __iomem *)rng->priv;
59 u32 ctl;
60
61 ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
62 out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
63 out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
64
65 return 0;
66 }
67
pasemi_rng_cleanup(struct hwrng * rng)68 static void pasemi_rng_cleanup(struct hwrng *rng)
69 {
70 void __iomem *rng_regs = (void __iomem *)rng->priv;
71 u32 ctl;
72
73 ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
74 out_le32(rng_regs + SDCRNG_CTL_REG,
75 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
76 }
77
78 static struct hwrng pasemi_rng = {
79 .name = MODULE_NAME,
80 .init = pasemi_rng_init,
81 .cleanup = pasemi_rng_cleanup,
82 .data_present = pasemi_rng_data_present,
83 .data_read = pasemi_rng_data_read,
84 };
85
rng_probe(struct platform_device * pdev)86 static int rng_probe(struct platform_device *pdev)
87 {
88 void __iomem *rng_regs;
89
90 rng_regs = devm_platform_ioremap_resource(pdev, 0);
91 if (IS_ERR(rng_regs))
92 return PTR_ERR(rng_regs);
93
94 pasemi_rng.priv = (unsigned long)rng_regs;
95
96 pr_info("Registering PA Semi RNG\n");
97 return devm_hwrng_register(&pdev->dev, &pasemi_rng);
98 }
99
100 static const struct of_device_id rng_match[] = {
101 { .compatible = "1682m-rng", },
102 { .compatible = "pasemi,pwrficient-rng", },
103 { },
104 };
105 MODULE_DEVICE_TABLE(of, rng_match);
106
107 static struct platform_driver rng_driver = {
108 .driver = {
109 .name = "pasemi-rng",
110 .of_match_table = rng_match,
111 },
112 .probe = rng_probe,
113 };
114
115 module_platform_driver(rng_driver);
116
117 MODULE_LICENSE("GPL");
118 MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
119 MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");
120