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| 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 | #include <linux/random.h> |
| 22 | |
| 23 | #include <linux/mfd/wm831x/core.h> |
| 24 | #include <linux/mfd/wm831x/otp.h> |
| 25 | |
| 26 | /* In bytes */ |
| 27 | #define WM831X_UNIQUE_ID_LEN 16 |
| 28 | |
| 29 | /* Read the unique ID from the chip into id */ |
| 30 | static int wm831x_unique_id_read(struct wm831x *wm831x, char *id) |
| 31 | { |
| 32 | int i, val; |
| 33 | |
| 34 | for (i = 0; i < WM831X_UNIQUE_ID_LEN / 2; i++) { |
| 35 | val = wm831x_reg_read(wm831x, WM831X_UNIQUE_ID_1 + i); |
| 36 | if (val < 0) |
| 37 | return val; |
| 38 | |
| 39 | id[i * 2] = (val >> 8) & 0xff; |
| 40 | id[(i * 2) + 1] = val & 0xff; |
| 41 | } |
| 42 | |
| 43 | return 0; |
| 44 | } |
| 45 | |
| 46 | static ssize_t wm831x_unique_id_show(struct device *dev, |
| 47 | struct device_attribute *attr, char *buf) |
| 48 | { |
| 49 | struct wm831x *wm831x = dev_get_drvdata(dev); |
| 50 | int i, rval; |
| 51 | char id[WM831X_UNIQUE_ID_LEN]; |
| 52 | ssize_t ret = 0; |
| 53 | |
| 54 | rval = wm831x_unique_id_read(wm831x, id); |
| 55 | if (rval < 0) |
| 56 | return 0; |
| 57 | |
| 58 | for (i = 0; i < WM831X_UNIQUE_ID_LEN; i++) |
| 59 | ret += sprintf(&buf[ret], "%02x", buf[i]); |
| 60 | |
| 61 | ret += sprintf(&buf[ret], "\n"); |
| 62 | |
| 63 | return ret; |
| 64 | } |
| 65 | |
| 66 | static DEVICE_ATTR(unique_id, 0444, wm831x_unique_id_show, NULL); |
| 67 | |
| 68 | int wm831x_otp_init(struct wm831x *wm831x) |
| 69 | { |
| 70 | char uuid[WM831X_UNIQUE_ID_LEN]; |
| 71 | int ret; |
| 72 | |
| 73 | ret = device_create_file(wm831x->dev, &dev_attr_unique_id); |
| 74 | if (ret != 0) |
| 75 | dev_err(wm831x->dev, "Unique ID attribute not created: %d\n", |
| 76 | ret); |
| 77 | |
| 78 | ret = wm831x_unique_id_read(wm831x, uuid); |
| 79 | if (ret == 0) |
| 80 | add_device_randomness(uuid, sizeof(uuid)); |
| 81 | else |
| 82 | dev_err(wm831x->dev, "Failed to read UUID: %d\n", ret); |
| 83 | |
| 84 | return ret; |
| 85 | } |
| 86 | |
| 87 | void wm831x_otp_exit(struct wm831x *wm831x) |
| 88 | { |
| 89 | device_remove_file(wm831x->dev, &dev_attr_unique_id); |
| 90 | } |
| 91 | |
| 92 |
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Tags:
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