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697e5a47aa
Many RTCs have an on board non volatile storage. It can be battery backed RAM or an EEPROM. Use the nvmem subsystem to export it to both userspace and in-kernel consumers. This stays compatible with the previous (non documented) ABI that was using /sys/class/rtc/rtcx/device/nvram to export that memory. But will warn about the deprecation. Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
114 lines
2.4 KiB
C
114 lines
2.4 KiB
C
/*
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* RTC subsystem, nvmem interface
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*
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* Copyright (C) 2017 Alexandre Belloni
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/err.h>
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#include <linux/types.h>
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#include <linux/nvmem-consumer.h>
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#include <linux/rtc.h>
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#include <linux/sysfs.h>
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#include "rtc-core.h"
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/*
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* Deprecated ABI compatibility, this should be removed at some point
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*/
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static const char nvram_warning[] = "Deprecated ABI, please use nvmem";
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static ssize_t
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rtc_nvram_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr,
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char *buf, loff_t off, size_t count)
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{
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struct rtc_device *rtc = attr->private;
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dev_warn_once(kobj_to_dev(kobj), nvram_warning);
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return nvmem_device_read(rtc->nvmem, off, count, buf);
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}
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static ssize_t
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rtc_nvram_write(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr,
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char *buf, loff_t off, size_t count)
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{
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struct rtc_device *rtc = attr->private;
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dev_warn_once(kobj_to_dev(kobj), nvram_warning);
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return nvmem_device_write(rtc->nvmem, off, count, buf);
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}
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static int rtc_nvram_register(struct rtc_device *rtc)
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{
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int err;
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rtc->nvram = devm_kzalloc(rtc->dev.parent,
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sizeof(struct bin_attribute),
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GFP_KERNEL);
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if (!rtc->nvram)
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return -ENOMEM;
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rtc->nvram->attr.name = "nvram";
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rtc->nvram->attr.mode = 0644;
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rtc->nvram->private = rtc;
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sysfs_bin_attr_init(rtc->nvram);
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rtc->nvram->read = rtc_nvram_read;
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rtc->nvram->write = rtc_nvram_write;
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rtc->nvram->size = rtc->nvmem_config->size;
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err = sysfs_create_bin_file(&rtc->dev.parent->kobj,
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rtc->nvram);
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if (err) {
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devm_kfree(rtc->dev.parent, rtc->nvram);
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rtc->nvram = NULL;
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}
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return err;
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}
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static void rtc_nvram_unregister(struct rtc_device *rtc)
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{
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sysfs_remove_bin_file(&rtc->dev.parent->kobj, rtc->nvram);
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}
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/*
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* New ABI, uses nvmem
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*/
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void rtc_nvmem_register(struct rtc_device *rtc)
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{
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if (!rtc->nvmem_config)
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return;
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rtc->nvmem_config->dev = &rtc->dev;
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rtc->nvmem_config->owner = rtc->owner;
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rtc->nvmem = nvmem_register(rtc->nvmem_config);
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if (IS_ERR_OR_NULL(rtc->nvmem))
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return;
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/* Register the old ABI */
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if (rtc->nvram_old_abi)
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rtc_nvram_register(rtc);
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}
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void rtc_nvmem_unregister(struct rtc_device *rtc)
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{
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if (IS_ERR_OR_NULL(rtc->nvmem))
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return;
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/* unregister the old ABI */
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if (rtc->nvram)
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rtc_nvram_unregister(rtc);
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nvmem_unregister(rtc->nvmem);
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}
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