Commit | Line | Data |
---|---|---|
2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
6704e517 MB |
2 | /* |
3 | * wm831x-otp.c -- OTP for Wolfson WM831x PMICs | |
4 | * | |
5 | * Copyright 2009 Wolfson Microelectronics PLC. | |
6 | * | |
7 | * Author: Mark Brown <broonie@opensource.wolfsonmicro.com> | |
6704e517 MB |
8 | */ |
9 | ||
10 | #include <linux/kernel.h> | |
11 | #include <linux/module.h> | |
12 | #include <linux/i2c.h> | |
13 | #include <linux/bcd.h> | |
14 | #include <linux/delay.h> | |
15 | #include <linux/mfd/core.h> | |
27130f0c | 16 | #include <linux/random.h> |
6704e517 MB |
17 | |
18 | #include <linux/mfd/wm831x/core.h> | |
19 | #include <linux/mfd/wm831x/otp.h> | |
20 | ||
21 | /* In bytes */ | |
22 | #define WM831X_UNIQUE_ID_LEN 16 | |
23 | ||
24 | /* Read the unique ID from the chip into id */ | |
25 | static int wm831x_unique_id_read(struct wm831x *wm831x, char *id) | |
26 | { | |
27 | int i, val; | |
28 | ||
29 | for (i = 0; i < WM831X_UNIQUE_ID_LEN / 2; i++) { | |
30 | val = wm831x_reg_read(wm831x, WM831X_UNIQUE_ID_1 + i); | |
31 | if (val < 0) | |
32 | return val; | |
33 | ||
34 | id[i * 2] = (val >> 8) & 0xff; | |
35 | id[(i * 2) + 1] = val & 0xff; | |
36 | } | |
37 | ||
38 | return 0; | |
39 | } | |
40 | ||
41 | static ssize_t wm831x_unique_id_show(struct device *dev, | |
42 | struct device_attribute *attr, char *buf) | |
43 | { | |
44 | struct wm831x *wm831x = dev_get_drvdata(dev); | |
a5656a70 | 45 | int rval; |
6704e517 | 46 | char id[WM831X_UNIQUE_ID_LEN]; |
6704e517 MB |
47 | |
48 | rval = wm831x_unique_id_read(wm831x, id); | |
49 | if (rval < 0) | |
50 | return 0; | |
51 | ||
a5656a70 | 52 | return sprintf(buf, "%*phN\n", WM831X_UNIQUE_ID_LEN, id); |
6704e517 MB |
53 | } |
54 | ||
55 | static DEVICE_ATTR(unique_id, 0444, wm831x_unique_id_show, NULL); | |
56 | ||
57 | int wm831x_otp_init(struct wm831x *wm831x) | |
58 | { | |
27130f0c | 59 | char uuid[WM831X_UNIQUE_ID_LEN]; |
6704e517 MB |
60 | int ret; |
61 | ||
62 | ret = device_create_file(wm831x->dev, &dev_attr_unique_id); | |
63 | if (ret != 0) | |
64 | dev_err(wm831x->dev, "Unique ID attribute not created: %d\n", | |
65 | ret); | |
66 | ||
27130f0c MB |
67 | ret = wm831x_unique_id_read(wm831x, uuid); |
68 | if (ret == 0) | |
69 | add_device_randomness(uuid, sizeof(uuid)); | |
70 | else | |
71 | dev_err(wm831x->dev, "Failed to read UUID: %d\n", ret); | |
72 | ||
6704e517 MB |
73 | return ret; |
74 | } | |
75 | ||
76 | void wm831x_otp_exit(struct wm831x *wm831x) | |
77 | { | |
78 | device_remove_file(wm831x->dev, &dev_attr_unique_id); | |
79 | } | |
80 |