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 #include "rtc-core.h"
  18
  19 /*
  20  * Deprecated ABI compatibility, this should be removed at some point
  21  */
  22
  23 static const char nvram_warning[] = "Deprecated ABI, please use nvmem";
  24
  25 static ssize_t
  26 rtc_nvram_read(struct file *filp, struct kobject *kobj,
  27                struct bin_attribute *attr,
  28                char *buf, loff_t off, size_t count)
  29 {
  30         struct rtc_device *rtc = attr->private;
  31
  32         dev_warn_once(kobj_to_dev(kobj), nvram_warning);
  33
  34         return nvmem_device_read(rtc->nvmem, off, count, buf);
  35 }
  36
  37 static ssize_t
  38 rtc_nvram_write(struct file *filp, struct kobject *kobj,
  39                 struct bin_attribute *attr,
  40                 char *buf, loff_t off, size_t count)
  41 {
  42         struct rtc_device *rtc = attr->private;
  43
  44         dev_warn_once(kobj_to_dev(kobj), nvram_warning);
  45
  46         return nvmem_device_write(rtc->nvmem, off, count, buf);
  47 }
  48
  49 static int rtc_nvram_register(struct rtc_device *rtc)
  50 {
  51         int err;
  52
  53         rtc->nvram = devm_kzalloc(rtc->dev.parent,
  54                                 sizeof(struct bin_attribute),
  55                                 GFP_KERNEL);
  56         if (!rtc->nvram)
  57                 return -ENOMEM;
  58
  59         rtc->nvram->attr.name = "nvram";
  60         rtc->nvram->attr.mode = 0644;
  61         rtc->nvram->private = rtc;
  62
  63         sysfs_bin_attr_init(rtc->nvram);
  64
  65         rtc->nvram->read = rtc_nvram_read;
  66         rtc->nvram->write = rtc_nvram_write;
  67         rtc->nvram->size = rtc->nvmem_config->size;
  68
  69         err = sysfs_create_bin_file(&rtc->dev.parent->kobj,
  70                                     rtc->nvram);
  71         if (err) {
  72                 devm_kfree(rtc->dev.parent, rtc->nvram);
  73                 rtc->nvram = NULL;
  74         }
  75
  76         return err;
  77 }
  78
  79 static void rtc_nvram_unregister(struct rtc_device *rtc)
  80 {
  81         sysfs_remove_bin_file(&rtc->dev.parent->kobj, rtc->nvram);
  82 }
  83
  84 /*
  85  * New ABI, uses nvmem
  86  */
  87 void rtc_nvmem_register(struct rtc_device *rtc)
  88 {
  89         if (!rtc->nvmem_config)
  90                 return;
  91
  92         rtc->nvmem_config->dev = &rtc->dev;
  93         rtc->nvmem_config->owner = rtc->owner;
  94         rtc->nvmem = nvmem_register(rtc->nvmem_config);
  95         if (IS_ERR_OR_NULL(rtc->nvmem))
  96                 return;
  97
  98         /* Register the old ABI */
  99         if (rtc->nvram_old_abi)
 100                 rtc_nvram_register(rtc);
 101 }
 102
 103 void rtc_nvmem_unregister(struct rtc_device *rtc)
 104 {
 105         if (IS_ERR_OR_NULL(rtc->nvmem))
 106                 return;
 107
 108         /* unregister the old ABI */
 109         if (rtc->nvram)
 110                 rtc_nvram_unregister(rtc);
 111
 112         nvmem_unregister(rtc->nvmem);
 113 }