diff options
Diffstat (limited to 'drivers/mfd/wm831x-otp.c')
| -rw-r--r-- | drivers/mfd/wm831x-otp.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/drivers/mfd/wm831x-otp.c b/drivers/mfd/wm831x-otp.c new file mode 100644 index 000000000..ebac0027f --- /dev/null +++ b/drivers/mfd/wm831x-otp.c @@ -0,0 +1,85 @@ +/* + * 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\n", 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\n", + 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\n", ret); + + return ret; +} + +void wm831x_otp_exit(struct wm831x *wm831x) +{ + device_remove_file(wm831x->dev, &dev_attr_unique_id); +} + |