LXR linux/drivers/rtc/nvmem.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * RTC subsystem, nvmem interface
   4 *
   5 * Copyright (C) 2017 Alexandre Belloni
   6 */
   7
   8#include <linux/err.h>
   9#include <linux/types.h>
  10#include <linux/nvmem-consumer.h>
  11#include <linux/rtc.h>
  12#include <linux/slab.h>
  13#include <linux/sysfs.h>
  14
  15/*
  16 * Deprecated ABI compatibility, this should be removed at some point
  17 */
  18
  19static const char nvram_warning[] = "Deprecated ABI, please use nvmem";
  20
  21static ssize_t
  22rtc_nvram_read(struct file *filp, struct kobject *kobj,
  23               struct bin_attribute *attr,
  24               char *buf, loff_t off, size_t count)
  25{
  26        dev_warn_once(kobj_to_dev(kobj), nvram_warning);
  27
  28        return nvmem_device_read(attr->private, off, count, buf);
  29}
  30
  31static ssize_t
  32rtc_nvram_write(struct file *filp, struct kobject *kobj,
  33                struct bin_attribute *attr,
  34                char *buf, loff_t off, size_t count)
  35{
  36        dev_warn_once(kobj_to_dev(kobj), nvram_warning);
  37
  38        return nvmem_device_write(attr->private, off, count, buf);
  39}
  40
  41static int rtc_nvram_register(struct rtc_device *rtc,
  42                              struct nvmem_device *nvmem, size_t size)
  43{
  44        int err;
  45
  46        rtc->nvram = kzalloc(sizeof(*rtc->nvram), GFP_KERNEL);
  47        if (!rtc->nvram)
  48                return -ENOMEM;
  49
  50        rtc->nvram->attr.name = "nvram";
  51        rtc->nvram->attr.mode = 0644;
  52        rtc->nvram->private = nvmem;
  53
  54        sysfs_bin_attr_init(rtc->nvram);
  55
  56        rtc->nvram->read = rtc_nvram_read;
  57        rtc->nvram->write = rtc_nvram_write;
  58        rtc->nvram->size = size;
  59
  60        err = sysfs_create_bin_file(&rtc->dev.parent->kobj,
  61                                    rtc->nvram);
  62        if (err) {
  63                kfree(rtc->nvram);
  64                rtc->nvram = NULL;
  65        }
  66
  67        return err;
  68}
  69
  70static void rtc_nvram_unregister(struct rtc_device *rtc)
  71{
  72        sysfs_remove_bin_file(&rtc->dev.parent->kobj, rtc->nvram);
  73        kfree(rtc->nvram);
  74        rtc->nvram = NULL;
  75}
  76
  77/*
  78 * New ABI, uses nvmem
  79 */
  80int rtc_nvmem_register(struct rtc_device *rtc,
  81                       struct nvmem_config *nvmem_config)
  82{
  83        struct nvmem_device *nvmem;
  84
  85        if (!nvmem_config)
  86                return -ENODEV;
  87
  88        nvmem_config->dev = rtc->dev.parent;
  89        nvmem_config->owner = rtc->owner;
  90        nvmem = devm_nvmem_register(rtc->dev.parent, nvmem_config);
  91        if (IS_ERR(nvmem))
  92                return PTR_ERR(nvmem);
  93
  94        /* Register the old ABI */
  95        if (rtc->nvram_old_abi)
  96                rtc_nvram_register(rtc, nvmem, nvmem_config->size);
  97
  98        return 0;
  99}
 100EXPORT_SYMBOL_GPL(rtc_nvmem_register);
 101
 102void rtc_nvmem_unregister(struct rtc_device *rtc)
 103{
 104        /* unregister the old ABI */
 105        if (rtc->nvram)
 106                rtc_nvram_unregister(rtc);
 107}
 108