1// SPDX-License-Identifier: GPL-2.0-or-later
 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>
 
 
 
 
 
 
 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>
16#include <linux/random.h>
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 */
25static 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
41static ssize_t unique_id_show(struct device *dev,
42			      struct device_attribute *attr, char *buf)
43{
44	struct wm831x *wm831x = dev_get_drvdata(dev);
45	int rval;
46	char id[WM831X_UNIQUE_ID_LEN];
 
47
48	rval = wm831x_unique_id_read(wm831x, id);
49	if (rval < 0)
50		return 0;
51
52	return sprintf(buf, "%*phN\n", WM831X_UNIQUE_ID_LEN, id);
 
 
 
 
 
53}
54
55static DEVICE_ATTR_RO(unique_id);
56
57int wm831x_otp_init(struct wm831x *wm831x)
58{
59	char uuid[WM831X_UNIQUE_ID_LEN];
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
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
73	return ret;
74}
75
76void wm831x_otp_exit(struct wm831x *wm831x)
77{
78	device_remove_file(wm831x->dev, &dev_attr_unique_id);
79}
80

 
 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>
 
21
22#include <linux/mfd/wm831x/core.h>
23#include <linux/mfd/wm831x/otp.h>
24
25/* In bytes */
26#define WM831X_UNIQUE_ID_LEN 16
27
28/* Read the unique ID from the chip into id */
29static int wm831x_unique_id_read(struct wm831x *wm831x, char *id)
30{
31	int i, val;
32
33	for (i = 0; i < WM831X_UNIQUE_ID_LEN / 2; i++) {
34		val = wm831x_reg_read(wm831x, WM831X_UNIQUE_ID_1 + i);
35		if (val < 0)
36			return val;
37
38		id[i * 2]       = (val >> 8) & 0xff;
39		id[(i * 2) + 1] = val & 0xff;
40	}
41
42	return 0;
43}
44
45static ssize_t wm831x_unique_id_show(struct device *dev,
46				     struct device_attribute *attr, char *buf)
47{
48	struct wm831x *wm831x = dev_get_drvdata(dev);
49	int i, rval;
50	char id[WM831X_UNIQUE_ID_LEN];
51	ssize_t ret = 0;
52
53	rval = wm831x_unique_id_read(wm831x, id);
54	if (rval < 0)
55		return 0;
56
57	for (i = 0; i < WM831X_UNIQUE_ID_LEN; i++)
58		ret += sprintf(&buf[ret], "%02x", buf[i]);
59
60	ret += sprintf(&buf[ret], "\n");
61
62	return ret;
63}
64
65static DEVICE_ATTR(unique_id, 0444, wm831x_unique_id_show, NULL);
66
67int wm831x_otp_init(struct wm831x *wm831x)
68{
 
69	int ret;
70
71	ret = device_create_file(wm831x->dev, &dev_attr_unique_id);
72	if (ret != 0)
73		dev_err(wm831x->dev, "Unique ID attribute not created: %d\n",
74			ret);
 
 
 
 
 
 
75
76	return ret;
77}
78
79void wm831x_otp_exit(struct wm831x *wm831x)
80{
81	device_remove_file(wm831x->dev, &dev_attr_unique_id);
82}
83