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 } 114