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981ce06ab8
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>
80 lines
1.7 KiB
C
80 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* wm831x-otp.c -- OTP for Wolfson WM831x PMICs
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*
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* Copyright 2009 Wolfson Microelectronics PLC.
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*
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* Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/i2c.h>
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#include <linux/bcd.h>
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#include <linux/delay.h>
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#include <linux/mfd/core.h>
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#include <linux/random.h>
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#include <linux/mfd/wm831x/core.h>
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#include <linux/mfd/wm831x/otp.h>
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/* In bytes */
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#define WM831X_UNIQUE_ID_LEN 16
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/* Read the unique ID from the chip into id */
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static int wm831x_unique_id_read(struct wm831x *wm831x, char *id)
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{
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int i, val;
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for (i = 0; i < WM831X_UNIQUE_ID_LEN / 2; i++) {
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val = wm831x_reg_read(wm831x, WM831X_UNIQUE_ID_1 + i);
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if (val < 0)
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return val;
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id[i * 2] = (val >> 8) & 0xff;
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id[(i * 2) + 1] = val & 0xff;
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}
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return 0;
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}
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static ssize_t unique_id_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct wm831x *wm831x = dev_get_drvdata(dev);
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int rval;
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char id[WM831X_UNIQUE_ID_LEN];
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rval = wm831x_unique_id_read(wm831x, id);
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if (rval < 0)
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return 0;
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return sprintf(buf, "%*phN\n", WM831X_UNIQUE_ID_LEN, id);
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}
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static DEVICE_ATTR_RO(unique_id);
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int wm831x_otp_init(struct wm831x *wm831x)
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{
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char uuid[WM831X_UNIQUE_ID_LEN];
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int ret;
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ret = device_create_file(wm831x->dev, &dev_attr_unique_id);
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if (ret != 0)
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dev_err(wm831x->dev, "Unique ID attribute not created: %d\n",
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ret);
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ret = wm831x_unique_id_read(wm831x, uuid);
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if (ret == 0)
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add_device_randomness(uuid, sizeof(uuid));
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else
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dev_err(wm831x->dev, "Failed to read UUID: %d\n", ret);
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return ret;
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}
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void wm831x_otp_exit(struct wm831x *wm831x)
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{
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device_remove_file(wm831x->dev, &dev_attr_unique_id);
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}
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