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
rtc_nvram_read(struct file * filp,struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t off,size_t count)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
rtc_nvram_write(struct file * filp,struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t off,size_t count)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
rtc_nvram_register(struct rtc_device * rtc,struct nvmem_device * nvmem,size_t size)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
rtc_nvram_unregister(struct rtc_device * rtc)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 */
rtc_nvmem_register(struct rtc_device * rtc,struct nvmem_config * nvmem_config)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
rtc_nvmem_unregister(struct rtc_device * rtc)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 }
108