LXR linux/drivers/mfd/wm831x-otp.c

   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
  84