LXR linux/drivers/rtc/nvmem.c

   1/*
   2 * RTC subsystem, nvmem interface
   3 *
   4 * Copyright (C) 2017 Alexandre Belloni
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 */
  10
  11#include <linux/err.h>
  12#include <linux/types.h>
  13#include <linux/nvmem-consumer.h>
  14#include <linux/rtc.h>
  15#include <linux/sysfs.h>
  16
  17/*
  18 * Deprecated ABI compatibility, this should be removed at some point
  19 */
  20
  21static const char nvram_warning[] = "Deprecated ABI, please use nvmem";
  22
  23static ssize_t
  24rtc_nvram_read(struct file *filp, struct kobject *kobj,
  25               struct bin_attribute *attr,
  26               char *buf, loff_t off, size_t count)
  27{
  28        struct rtc_device *rtc = attr->private;
  29
  30        dev_warn_once(kobj_to_dev(kobj), nvram_warning);
  31
  32        return nvmem_device_read(rtc->nvmem, off, count, buf);
  33}
  34
  35static ssize_t
  36rtc_nvram_write(struct file *filp, struct kobject *kobj,
  37                struct bin_attribute *attr,
  38                char *buf, loff_t off, size_t count)
  39{
  40        struct rtc_device *rtc = attr->private;
  41
  42        dev_warn_once(kobj_to_dev(kobj), nvram_warning);
  43
  44        return nvmem_device_write(rtc->nvmem, off, count, buf);
  45}
  46
  47static int rtc_nvram_register(struct rtc_device *rtc, size_t size)
  48{
  49        int err;
  50
  51        rtc->nvram = devm_kzalloc(rtc->dev.parent,
  52                                sizeof(struct bin_attribute),
  53                                GFP_KERNEL);
  54        if (!rtc->nvram)
  55                return -ENOMEM;
  56
  57        rtc->nvram->attr.name = "nvram";
  58        rtc->nvram->attr.mode = 0644;
  59        rtc->nvram->private = rtc;
  60
  61        sysfs_bin_attr_init(rtc->nvram);
  62
  63        rtc->nvram->read = rtc_nvram_read;
  64        rtc->nvram->write = rtc_nvram_write;
  65        rtc->nvram->size = size;
  66
  67        err = sysfs_create_bin_file(&rtc->dev.parent->kobj,
  68                                    rtc->nvram);
  69        if (err) {
  70                devm_kfree(rtc->dev.parent, rtc->nvram);
  71                rtc->nvram = NULL;
  72        }
  73
  74        return err;
  75}
  76
  77static void rtc_nvram_unregister(struct rtc_device *rtc)
  78{
  79        sysfs_remove_bin_file(&rtc->dev.parent->kobj, rtc->nvram);
  80}
  81
  82/*
  83 * New ABI, uses nvmem
  84 */
  85int rtc_nvmem_register(struct rtc_device *rtc,
  86                       struct nvmem_config *nvmem_config)
  87{
  88        if (!IS_ERR_OR_NULL(rtc->nvmem))
  89                return -EBUSY;
  90
  91        if (!nvmem_config)
  92                return -ENODEV;
  93
  94        nvmem_config->dev = rtc->dev.parent;
  95        nvmem_config->owner = rtc->owner;
  96        rtc->nvmem = nvmem_register(nvmem_config);
  97        if (IS_ERR(rtc->nvmem))
  98                return PTR_ERR(rtc->nvmem);
  99
 100        /* Register the old ABI */
 101        if (rtc->nvram_old_abi)
 102                rtc_nvram_register(rtc, nvmem_config->size);
 103
 104        return 0;
 105}
 106EXPORT_SYMBOL_GPL(rtc_nvmem_register);
 107
 108void rtc_nvmem_unregister(struct rtc_device *rtc)
 109{
 110        if (IS_ERR_OR_NULL(rtc->nvmem))
 111                return;
 112
 113        /* unregister the old ABI */
 114        if (rtc->nvram)
 115                rtc_nvram_unregister(rtc);
 116
 117        nvmem_unregister(rtc->nvmem);
 118}
 119