1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * wm831x-otp.c -- OTP for Wolfson WM831x PMICs
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright 2009 Wolfson Microelectronics PLC.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #include <linux/kernel.h>
11*4882a593Smuzhiyun #include <linux/module.h>
12*4882a593Smuzhiyun #include <linux/i2c.h>
13*4882a593Smuzhiyun #include <linux/bcd.h>
14*4882a593Smuzhiyun #include <linux/delay.h>
15*4882a593Smuzhiyun #include <linux/mfd/core.h>
16*4882a593Smuzhiyun #include <linux/random.h>
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun #include <linux/mfd/wm831x/core.h>
19*4882a593Smuzhiyun #include <linux/mfd/wm831x/otp.h>
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun /* In bytes */
22*4882a593Smuzhiyun #define WM831X_UNIQUE_ID_LEN 16
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun /* Read the unique ID from the chip into id */
wm831x_unique_id_read(struct wm831x * wm831x,char * id)25*4882a593Smuzhiyun static int wm831x_unique_id_read(struct wm831x *wm831x, char *id)
26*4882a593Smuzhiyun {
27*4882a593Smuzhiyun int i, val;
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun for (i = 0; i < WM831X_UNIQUE_ID_LEN / 2; i++) {
30*4882a593Smuzhiyun val = wm831x_reg_read(wm831x, WM831X_UNIQUE_ID_1 + i);
31*4882a593Smuzhiyun if (val < 0)
32*4882a593Smuzhiyun return val;
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun id[i * 2] = (val >> 8) & 0xff;
35*4882a593Smuzhiyun id[(i * 2) + 1] = val & 0xff;
36*4882a593Smuzhiyun }
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun return 0;
39*4882a593Smuzhiyun }
40*4882a593Smuzhiyun
wm831x_unique_id_show(struct device * dev,struct device_attribute * attr,char * buf)41*4882a593Smuzhiyun static ssize_t wm831x_unique_id_show(struct device *dev,
42*4882a593Smuzhiyun struct device_attribute *attr, char *buf)
43*4882a593Smuzhiyun {
44*4882a593Smuzhiyun struct wm831x *wm831x = dev_get_drvdata(dev);
45*4882a593Smuzhiyun int rval;
46*4882a593Smuzhiyun char id[WM831X_UNIQUE_ID_LEN];
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun rval = wm831x_unique_id_read(wm831x, id);
49*4882a593Smuzhiyun if (rval < 0)
50*4882a593Smuzhiyun return 0;
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun return sprintf(buf, "%*phN\n", WM831X_UNIQUE_ID_LEN, id);
53*4882a593Smuzhiyun }
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun static DEVICE_ATTR(unique_id, 0444, wm831x_unique_id_show, NULL);
56*4882a593Smuzhiyun
wm831x_otp_init(struct wm831x * wm831x)57*4882a593Smuzhiyun int wm831x_otp_init(struct wm831x *wm831x)
58*4882a593Smuzhiyun {
59*4882a593Smuzhiyun char uuid[WM831X_UNIQUE_ID_LEN];
60*4882a593Smuzhiyun int ret;
61*4882a593Smuzhiyun
62*4882a593Smuzhiyun ret = device_create_file(wm831x->dev, &dev_attr_unique_id);
63*4882a593Smuzhiyun if (ret != 0)
64*4882a593Smuzhiyun dev_err(wm831x->dev, "Unique ID attribute not created: %d\n",
65*4882a593Smuzhiyun ret);
66*4882a593Smuzhiyun
67*4882a593Smuzhiyun ret = wm831x_unique_id_read(wm831x, uuid);
68*4882a593Smuzhiyun if (ret == 0)
69*4882a593Smuzhiyun add_device_randomness(uuid, sizeof(uuid));
70*4882a593Smuzhiyun else
71*4882a593Smuzhiyun dev_err(wm831x->dev, "Failed to read UUID: %d\n", ret);
72*4882a593Smuzhiyun
73*4882a593Smuzhiyun return ret;
74*4882a593Smuzhiyun }
75*4882a593Smuzhiyun
wm831x_otp_exit(struct wm831x * wm831x)76*4882a593Smuzhiyun void wm831x_otp_exit(struct wm831x *wm831x)
77*4882a593Smuzhiyun {
78*4882a593Smuzhiyun device_remove_file(wm831x->dev, &dev_attr_unique_id);
79*4882a593Smuzhiyun }
80*4882a593Smuzhiyun
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