// SPDX-License-Identifier: GPL-2.0

  /*
   * RTC subsystem, nvmem interface
   *
   * Copyright (C) 2017 Alexandre Belloni

   */
  
  #include <linux/err.h>
  #include <linux/types.h>
  #include <linux/nvmem-consumer.h>
  #include <linux/rtc.h>

  #include <linux/slab.h>

  #include <linux/sysfs.h>

  /*
   * Deprecated ABI compatibility, this should be removed at some point
   */
  
  static const char nvram_warning[] = "Deprecated ABI, please use nvmem";
  
  static ssize_t
  rtc_nvram_read(struct file *filp, struct kobject *kobj,
  	       struct bin_attribute *attr,
  	       char *buf, loff_t off, size_t count)
  {

  	dev_warn_once(kobj_to_dev(kobj), nvram_warning);

  	return nvmem_device_read(attr->private, off, count, buf);

  }
  
  static ssize_t
  rtc_nvram_write(struct file *filp, struct kobject *kobj,
  		struct bin_attribute *attr,
  		char *buf, loff_t off, size_t count)
  {

  	dev_warn_once(kobj_to_dev(kobj), nvram_warning);

  	return nvmem_device_write(attr->private, off, count, buf);

  }

  static int rtc_nvram_register(struct rtc_device *rtc,
  			      struct nvmem_device *nvmem, size_t size)

  {
  	int err;

  	rtc->nvram = kzalloc(sizeof(*rtc->nvram), GFP_KERNEL);

  	if (!rtc->nvram)
  		return -ENOMEM;
  
  	rtc->nvram->attr.name = "nvram";
  	rtc->nvram->attr.mode = 0644;

  	rtc->nvram->private = nvmem;

  
  	sysfs_bin_attr_init(rtc->nvram);
  
  	rtc->nvram->read = rtc_nvram_read;
  	rtc->nvram->write = rtc_nvram_write;

  	rtc->nvram->size = size;

  
  	err = sysfs_create_bin_file(&rtc->dev.parent->kobj,
  				    rtc->nvram);
  	if (err) {

  		kfree(rtc->nvram);

  		rtc->nvram = NULL;
  	}
  
  	return err;
  }
  
  static void rtc_nvram_unregister(struct rtc_device *rtc)
  {
  	sysfs_remove_bin_file(&rtc->dev.parent->kobj, rtc->nvram);

  	kfree(rtc->nvram);
  	rtc->nvram = NULL;

  }
  
  /*
   * New ABI, uses nvmem
   */

  int rtc_nvmem_register(struct rtc_device *rtc,
  		       struct nvmem_config *nvmem_config)

  {

  	struct nvmem_device *nvmem;

  	if (!nvmem_config)

  		return -ENODEV;

  	nvmem_config->dev = rtc->dev.parent;

  	nvmem_config->owner = rtc->owner;

  	nvmem = devm_nvmem_register(rtc->dev.parent, nvmem_config);
  	if (IS_ERR(nvmem))
  		return PTR_ERR(nvmem);

  
  	/* Register the old ABI */
  	if (rtc->nvram_old_abi)

  		rtc_nvram_register(rtc, nvmem, nvmem_config->size);

  
  	return 0;

  }

  EXPORT_SYMBOL_GPL(rtc_nvmem_register);

  
  void rtc_nvmem_unregister(struct rtc_device *rtc)
  {

  	/* unregister the old ABI */
  	if (rtc->nvram)
  		rtc_nvram_unregister(rtc);

  }