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/slab.h>
  16 #include <linux/sysfs.h>
  17
  18 /*
  19  * Deprecated ABI compatibility, this should be removed at some point
  20  */
  21
  22 static const char nvram_warning[] = "Deprecated ABI, please use nvmem";
  23
  24 static ssize_t
  25 rtc_nvram_read(struct file *filp, struct kobject *kobj,
  26                struct bin_attribute *attr,
  27                char *buf, loff_t off, size_t count)
  28 {
  29         dev_warn_once(kobj_to_dev(kobj), nvram_warning);
  30
  31         return nvmem_device_read(attr->private, off, count, buf);
  32 }
  33
  34 static ssize_t
  35 rtc_nvram_write(struct file *filp, struct kobject *kobj,
  36                 struct bin_attribute *attr,
  37                 char *buf, loff_t off, size_t count)
  38 {
  39         dev_warn_once(kobj_to_dev(kobj), nvram_warning);
  40
  41         return nvmem_device_write(attr->private, off, count, buf);
  42 }
  43
  44 static int rtc_nvram_register(struct rtc_device *rtc,
  45                               struct nvmem_device *nvmem, size_t size)
  46 {
  47         int err;
  48
  49         rtc->nvram = kzalloc(sizeof(struct bin_attribute), GFP_KERNEL);
  50         if (!rtc->nvram)
  51                 return -ENOMEM;
  52
  53         rtc->nvram->attr.name = "nvram";
  54         rtc->nvram->attr.mode = 0644;
  55         rtc->nvram->private = nvmem;
  56
  57         sysfs_bin_attr_init(rtc->nvram);
  58
  59         rtc->nvram->read = rtc_nvram_read;
  60         rtc->nvram->write = rtc_nvram_write;
  61         rtc->nvram->size = size;
  62
  63         err = sysfs_create_bin_file(&rtc->dev.parent->kobj,
  64                                     rtc->nvram);
  65         if (err) {
  66                 kfree(rtc->nvram);
  67                 rtc->nvram = NULL;
  68         }
  69
  70         return err;
  71 }
  72
  73 static void rtc_nvram_unregister(struct rtc_device *rtc)
  74 {
  75         sysfs_remove_bin_file(&rtc->dev.parent->kobj, rtc->nvram);
  76         kfree(rtc->nvram);
  77         rtc->nvram = NULL;
  78 }
  79
  80 /*
  81  * New ABI, uses nvmem
  82  */
  83 int rtc_nvmem_register(struct rtc_device *rtc,
  84                        struct nvmem_config *nvmem_config)
  85 {
  86         struct nvmem_device *nvmem;
  87
  88         if (!nvmem_config)
  89                 return -ENODEV;
  90
  91         nvmem_config->dev = rtc->dev.parent;
  92         nvmem_config->owner = rtc->owner;
  93         nvmem = devm_nvmem_register(rtc->dev.parent, nvmem_config);
  94         if (IS_ERR(nvmem))
  95                 return PTR_ERR(nvmem);
  96
  97         /* Register the old ABI */
  98         if (rtc->nvram_old_abi)
  99                 rtc_nvram_register(rtc, nvmem, nvmem_config->size);
 100
 101         return 0;
 102 }
 103 EXPORT_SYMBOL_GPL(rtc_nvmem_register);
 104
 105 void rtc_nvmem_unregister(struct rtc_device *rtc)
 106 {
 107         /* unregister the old ABI */
 108         if (rtc->nvram)
 109                 rtc_nvram_unregister(rtc);
 110 }