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
  21 static const char nvram_warning[] = "Deprecated ABI, please use nvmem";
  22
  23 static ssize_t
  24 rtc_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
  35 static ssize_t
  36 rtc_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
  47 static 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
  77 static 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  */
  85 int 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 }
 106 EXPORT_SYMBOL_GPL(rtc_nvmem_register);
 107
 108 void 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 }