projects / mirror_ubuntu-artful-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| 6704e517 MB |
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> | |
| 27130f0c | 21 | #include <linux/random.h> |
| 6704e517 MB |
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); | |
| a5656a70 | 50 | int rval; |
| 6704e517 | 51 | char id[WM831X_UNIQUE_ID_LEN]; |
| 6704e517 MB |
52 | |
| 53 | rval = wm831x_unique_id_read(wm831x, id); | |
| 54 | if (rval < 0) | |
| 55 | return 0; | |
| 56 | ||
| a5656a70 | 57 | return sprintf(buf, "%*phN\n", WM831X_UNIQUE_ID_LEN, id); |
| 6704e517 MB |
58 | } |
| 59 | ||
| 60 | static DEVICE_ATTR(unique_id, 0444, wm831x_unique_id_show, NULL); | |
| 61 | ||
| 62 | int wm831x_otp_init(struct wm831x *wm831x) | |
| 63 | { | |
| 27130f0c | 64 | char uuid[WM831X_UNIQUE_ID_LEN]; |
| 6704e517 MB |
65 | int ret; |
| 66 | ||
| 67 | ret = device_create_file(wm831x->dev, &dev_attr_unique_id); | |
| 68 | if (ret != 0) | |
| 69 | dev_err(wm831x->dev, "Unique ID attribute not created: %d\n", | |
| 70 | ret); | |
| 71 | ||
| 27130f0c MB |
72 | ret = wm831x_unique_id_read(wm831x, uuid); |
| 73 | if (ret == 0) | |
| 74 | add_device_randomness(uuid, sizeof(uuid)); | |
| 75 | else | |
| 76 | dev_err(wm831x->dev, "Failed to read UUID: %d\n", ret); | |
| 77 | ||
| 6704e517 MB |
78 | return ret; |
| 79 | } | |
| 80 | ||
| 81 | void wm831x_otp_exit(struct wm831x *wm831x) | |
| 82 | { | |
| 83 | device_remove_file(wm831x->dev, &dev_attr_unique_id); | |
| 84 | } | |
| 85 |