linux/drivers/mfd/wm831x-otp.c
Zhen Lei 981ce06ab8 mfd: wm831x: Use DEVICE_ATTR_RO macro
Use DEVICE_ATTR_RO macro helper instead of plain DEVICE_ATTR, which makes
the code a bit shorter and easier to read.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2021-06-15 13:01:45 +01:00

81 lines
1.7 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* wm831x-otp.c -- OTP for Wolfson WM831x PMICs
*
* Copyright 2009 Wolfson Microelectronics PLC.
*
* Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
*/
#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 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_RO(unique_id);
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);
}