86 lines
2.0 KiB
C
86 lines
2.0 KiB
C
/*
|
|
* wm831x-otp.c -- OTP for Wolfson WM831x PMICs
|
|
*
|
|
* Copyright 2009 Wolfson Microelectronics PLC.
|
|
*
|
|
* Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License as published by the
|
|
* Free Software Foundation; either version 2 of the License, or (at your
|
|
* option) any later version.
|
|
*
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/bcd.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/mfd/core.h>
|
|
#include <linux/random.h>
|
|
|
|
#include <linux/mfd/wm831x/core.h>
|
|
#include <linux/mfd/wm831x/otp.h>
|
|
|
|
/* In bytes */
|
|
#define WM831X_UNIQUE_ID_LEN 16
|
|
|
|
/* Read the unique ID from the chip into id */
|
|
static int wm831x_unique_id_read(struct wm831x *wm831x, char *id)
|
|
{
|
|
int i, val;
|
|
|
|
for (i = 0; i < WM831X_UNIQUE_ID_LEN / 2; i++) {
|
|
val = wm831x_reg_read(wm831x, WM831X_UNIQUE_ID_1 + i);
|
|
if (val < 0)
|
|
return val;
|
|
|
|
id[i * 2] = (val >> 8) & 0xff;
|
|
id[(i * 2) + 1] = val & 0xff;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t wm831x_unique_id_show(struct device *dev,
|
|
struct device_attribute *attr, char *buf)
|
|
{
|
|
struct wm831x *wm831x = dev_get_drvdata(dev);
|
|
int rval;
|
|
char id[WM831X_UNIQUE_ID_LEN];
|
|
|
|
rval = wm831x_unique_id_read(wm831x, id);
|
|
if (rval < 0)
|
|
return 0;
|
|
|
|
return sprintf(buf, "%*phN\n", WM831X_UNIQUE_ID_LEN, id);
|
|
}
|
|
|
|
static DEVICE_ATTR(unique_id, 0444, wm831x_unique_id_show, NULL);
|
|
|
|
int wm831x_otp_init(struct wm831x *wm831x)
|
|
{
|
|
char uuid[WM831X_UNIQUE_ID_LEN];
|
|
int ret;
|
|
|
|
ret = device_create_file(wm831x->dev, &dev_attr_unique_id);
|
|
if (ret != 0)
|
|
dev_err(wm831x->dev, "Unique ID attribute not created: %d\n",
|
|
ret);
|
|
|
|
ret = wm831x_unique_id_read(wm831x, uuid);
|
|
if (ret == 0)
|
|
add_device_randomness(uuid, sizeof(uuid));
|
|
else
|
|
dev_err(wm831x->dev, "Failed to read UUID: %d\n", ret);
|
|
|
|
return ret;
|
|
}
|
|
|
|
void wm831x_otp_exit(struct wm831x *wm831x)
|
|
{
|
|
device_remove_file(wm831x->dev, &dev_attr_unique_id);
|
|
}
|
|
|