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