/*
   * 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
  ", 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
  ",
  			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
  ", ret);

  	return ret;
  }
  
  void wm831x_otp_exit(struct wm831x *wm831x)
  {
  	device_remove_file(wm831x->dev, &dev_attr_unique_id);
  }