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
  19 static const char nvram_warning[] = "Deprecated ABI, please use nvmem";
  20
  21 static ssize_t
  22 rtc_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
  31 static ssize_t
  32 rtc_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
  41 static 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
  70 static 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  */
  80 int 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 }
 100 EXPORT_SYMBOL_GPL(rtc_nvmem_register);
 101
 102 void rtc_nvmem_unregister(struct rtc_device *rtc)
 103 {
 104         /* unregister the old ABI */
 105         if (rtc->nvram)
 106                 rtc_nvram_unregister(rtc);
 107 }