1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * RNG driver for Freescale RNGA
4 *
5 * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
6 * Author: Alan Carvalho de Assis <acassis@gmail.com>
7 */
8
9 /*
10 *
11 * This driver is based on other RNG drivers.
12 */
13
14 #include <linux/clk.h>
15 #include <linux/delay.h>
16 #include <linux/hw_random.h>
17 #include <linux/io.h>
18 #include <linux/module.h>
19 #include <linux/of.h>
20 #include <linux/platform_device.h>
21
22 /* RNGA Registers */
23 #define RNGA_CONTROL 0x00
24 #define RNGA_STATUS 0x04
25 #define RNGA_ENTROPY 0x08
26 #define RNGA_OUTPUT_FIFO 0x0c
27 #define RNGA_MODE 0x10
28 #define RNGA_VERIFICATION_CONTROL 0x14
29 #define RNGA_OSC_CONTROL_COUNTER 0x18
30 #define RNGA_OSC1_COUNTER 0x1c
31 #define RNGA_OSC2_COUNTER 0x20
32 #define RNGA_OSC_COUNTER_STATUS 0x24
33
34 /* RNGA Registers Range */
35 #define RNG_ADDR_RANGE 0x28
36
37 /* RNGA Control Register */
38 #define RNGA_CONTROL_SLEEP 0x00000010
39 #define RNGA_CONTROL_CLEAR_INT 0x00000008
40 #define RNGA_CONTROL_MASK_INTS 0x00000004
41 #define RNGA_CONTROL_HIGH_ASSURANCE 0x00000002
42 #define RNGA_CONTROL_GO 0x00000001
43
44 #define RNGA_STATUS_LEVEL_MASK 0x0000ff00
45
46 /* RNGA Status Register */
47 #define RNGA_STATUS_OSC_DEAD 0x80000000
48 #define RNGA_STATUS_SLEEP 0x00000010
49 #define RNGA_STATUS_ERROR_INT 0x00000008
50 #define RNGA_STATUS_FIFO_UNDERFLOW 0x00000004
51 #define RNGA_STATUS_LAST_READ_STATUS 0x00000002
52 #define RNGA_STATUS_SECURITY_VIOLATION 0x00000001
53
54 struct mxc_rng {
55 struct device *dev;
56 struct hwrng rng;
57 void __iomem *mem;
58 struct clk *clk;
59 };
60
mxc_rnga_data_present(struct hwrng * rng,int wait)61 static int mxc_rnga_data_present(struct hwrng *rng, int wait)
62 {
63 int i;
64 struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
65
66 for (i = 0; i < 20; i++) {
67 /* how many random numbers are in FIFO? [0-16] */
68 int level = (__raw_readl(mxc_rng->mem + RNGA_STATUS) &
69 RNGA_STATUS_LEVEL_MASK) >> 8;
70 if (level || !wait)
71 return !!level;
72 udelay(10);
73 }
74 return 0;
75 }
76
mxc_rnga_data_read(struct hwrng * rng,u32 * data)77 static int mxc_rnga_data_read(struct hwrng *rng, u32 * data)
78 {
79 int err;
80 u32 ctrl;
81 struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
82
83 /* retrieve a random number from FIFO */
84 *data = __raw_readl(mxc_rng->mem + RNGA_OUTPUT_FIFO);
85
86 /* some error while reading this random number? */
87 err = __raw_readl(mxc_rng->mem + RNGA_STATUS) & RNGA_STATUS_ERROR_INT;
88
89 /* if error: clear error interrupt, but doesn't return random number */
90 if (err) {
91 dev_dbg(mxc_rng->dev, "Error while reading random number!\n");
92 ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
93 __raw_writel(ctrl | RNGA_CONTROL_CLEAR_INT,
94 mxc_rng->mem + RNGA_CONTROL);
95 return 0;
96 } else
97 return 4;
98 }
99
mxc_rnga_init(struct hwrng * rng)100 static int mxc_rnga_init(struct hwrng *rng)
101 {
102 u32 ctrl, osc;
103 struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
104
105 /* wake up */
106 ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
107 __raw_writel(ctrl & ~RNGA_CONTROL_SLEEP, mxc_rng->mem + RNGA_CONTROL);
108
109 /* verify if oscillator is working */
110 osc = __raw_readl(mxc_rng->mem + RNGA_STATUS);
111 if (osc & RNGA_STATUS_OSC_DEAD) {
112 dev_err(mxc_rng->dev, "RNGA Oscillator is dead!\n");
113 return -ENODEV;
114 }
115
116 /* go running */
117 ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
118 __raw_writel(ctrl | RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL);
119
120 return 0;
121 }
122
mxc_rnga_cleanup(struct hwrng * rng)123 static void mxc_rnga_cleanup(struct hwrng *rng)
124 {
125 u32 ctrl;
126 struct mxc_rng *mxc_rng = container_of(rng, struct mxc_rng, rng);
127
128 ctrl = __raw_readl(mxc_rng->mem + RNGA_CONTROL);
129
130 /* stop rnga */
131 __raw_writel(ctrl & ~RNGA_CONTROL_GO, mxc_rng->mem + RNGA_CONTROL);
132 }
133
mxc_rnga_probe(struct platform_device * pdev)134 static int mxc_rnga_probe(struct platform_device *pdev)
135 {
136 int err;
137 struct mxc_rng *mxc_rng;
138
139 mxc_rng = devm_kzalloc(&pdev->dev, sizeof(*mxc_rng), GFP_KERNEL);
140 if (!mxc_rng)
141 return -ENOMEM;
142
143 mxc_rng->dev = &pdev->dev;
144 mxc_rng->rng.name = "mxc-rnga";
145 mxc_rng->rng.init = mxc_rnga_init;
146 mxc_rng->rng.cleanup = mxc_rnga_cleanup;
147 mxc_rng->rng.data_present = mxc_rnga_data_present;
148 mxc_rng->rng.data_read = mxc_rnga_data_read;
149
150 mxc_rng->clk = devm_clk_get_enabled(&pdev->dev, NULL);
151 if (IS_ERR(mxc_rng->clk)) {
152 dev_err(&pdev->dev, "Could not get rng_clk!\n");
153 return PTR_ERR(mxc_rng->clk);
154 }
155
156 mxc_rng->mem = devm_platform_ioremap_resource(pdev, 0);
157 if (IS_ERR(mxc_rng->mem)) {
158 err = PTR_ERR(mxc_rng->mem);
159 return err;
160 }
161
162 err = hwrng_register(&mxc_rng->rng);
163 if (err) {
164 dev_err(&pdev->dev, "MXC RNGA registering failed (%d)\n", err);
165 return err;
166 }
167
168 return 0;
169 }
170
mxc_rnga_remove(struct platform_device * pdev)171 static void mxc_rnga_remove(struct platform_device *pdev)
172 {
173 struct mxc_rng *mxc_rng = platform_get_drvdata(pdev);
174
175 hwrng_unregister(&mxc_rng->rng);
176 }
177
178 static const struct of_device_id mxc_rnga_of_match[] = {
179 { .compatible = "fsl,imx21-rnga", },
180 { .compatible = "fsl,imx31-rnga", },
181 { /* sentinel */ },
182 };
183 MODULE_DEVICE_TABLE(of, mxc_rnga_of_match);
184
185 static struct platform_driver mxc_rnga_driver = {
186 .driver = {
187 .name = "mxc_rnga",
188 .of_match_table = mxc_rnga_of_match,
189 },
190 .probe = mxc_rnga_probe,
191 .remove_new = mxc_rnga_remove,
192 };
193
194 module_platform_driver(mxc_rnga_driver);
195
196 MODULE_AUTHOR("Freescale Semiconductor, Inc.");
197 MODULE_DESCRIPTION("H/W RNGA driver for i.MX");
198 MODULE_LICENSE("GPL");
199