cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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wm831x-otp.c (1760B)

      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