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 */
  29 static 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
  45 static 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
  65 static DEVICE_ATTR(unique_id, 0444, wm831x_unique_id_show, NULL);
  66
  67 int 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
  79 void wm831x_otp_exit(struct wm831x *wm831x)
  80 {
  81         device_remove_file(wm831x->dev, &dev_attr_unique_id);
  82 }
  83