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 } 119