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1 | /* |
2 | * wm831x-otp.c -- OTP for Wolfson WM831x PMICs | |
3 | * | |
4 | * Copyright 2009 Wolfson Microelectronics PLC. | |
5 | * | |
6 | * Author: Mark Brown <broonie@opensource.wolfsonmicro.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify it | |
9 | * under the terms of the GNU General Public License as published by the | |
10 | * Free Software Foundation; either version 2 of the License, or (at your | |
11 | * option) any later version. | |
12 | * | |
13 | */ | |
14 | ||
15 | #include <linux/kernel.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/i2c.h> | |
18 | #include <linux/bcd.h> | |
19 | #include <linux/delay.h> | |
20 | #include <linux/mfd/core.h> | |
27130f0c | 21 | #include <linux/random.h> |
6704e517 MB |
22 | |
23 | #include <linux/mfd/wm831x/core.h> | |
24 | #include <linux/mfd/wm831x/otp.h> | |
25 | ||
26 | /* In bytes */ | |
27 | #define WM831X_UNIQUE_ID_LEN 16 | |
28 | ||
29 | /* Read the unique ID from the chip into id */ | |
30 | static int wm831x_unique_id_read(struct wm831x *wm831x, char *id) | |
31 | { | |
32 | int i, val; | |
33 | ||
34 | for (i = 0; i < WM831X_UNIQUE_ID_LEN / 2; i++) { | |
35 | val = wm831x_reg_read(wm831x, WM831X_UNIQUE_ID_1 + i); | |
36 | if (val < 0) | |
37 | return val; | |
38 | ||
39 | id[i * 2] = (val >> 8) & 0xff; | |
40 | id[(i * 2) + 1] = val & 0xff; | |
41 | } | |
42 | ||
43 | return 0; | |
44 | } | |
45 | ||
46 | static ssize_t wm831x_unique_id_show(struct device *dev, | |
47 | struct device_attribute *attr, char *buf) | |
48 | { | |
49 | struct wm831x *wm831x = dev_get_drvdata(dev); | |
a5656a70 | 50 | int rval; |
6704e517 | 51 | char id[WM831X_UNIQUE_ID_LEN]; |
6704e517 MB |
52 | |
53 | rval = wm831x_unique_id_read(wm831x, id); | |
54 | if (rval < 0) | |
55 | return 0; | |
56 | ||
a5656a70 | 57 | return sprintf(buf, "%*phN\n", WM831X_UNIQUE_ID_LEN, id); |
6704e517 MB |
58 | } |
59 | ||
60 | static DEVICE_ATTR(unique_id, 0444, wm831x_unique_id_show, NULL); | |
61 | ||
62 | int wm831x_otp_init(struct wm831x *wm831x) | |
63 | { | |
27130f0c | 64 | char uuid[WM831X_UNIQUE_ID_LEN]; |
6704e517 MB |
65 | int ret; |
66 | ||
67 | ret = device_create_file(wm831x->dev, &dev_attr_unique_id); | |
68 | if (ret != 0) | |
69 | dev_err(wm831x->dev, "Unique ID attribute not created: %d\n", | |
70 | ret); | |
71 | ||
27130f0c MB |
72 | ret = wm831x_unique_id_read(wm831x, uuid); |
73 | if (ret == 0) | |
74 | add_device_randomness(uuid, sizeof(uuid)); | |
75 | else | |
76 | dev_err(wm831x->dev, "Failed to read UUID: %d\n", ret); | |
77 | ||
6704e517 MB |
78 | return ret; |
79 | } | |
80 | ||
81 | void wm831x_otp_exit(struct wm831x *wm831x) | |
82 | { | |
83 | device_remove_file(wm831x->dev, &dev_attr_unique_id); | |
84 | } | |
85 |