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1// SPDX-License-Identifier: GPL-2.02/*3 * RTC subsystem, sysfs interface4 *5 * Copyright (C) 2005 Tower Technologies6 * Author: Alessandro Zummo <a.zummo@towertech.it>7 */8 9#include <linux/kstrtox.h>10#include <linux/module.h>11#include <linux/rtc.h>12 13#include "rtc-core.h"14 15/* device attributes */16 17/*18 * NOTE: RTC times displayed in sysfs use the RTC's timezone. That's19 * ideally UTC. However, PCs that also boot to MS-Windows normally use20 * the local time and change to match daylight savings time. That affects21 * attributes including date, time, since_epoch, and wakealarm.22 */23 24static ssize_t25name_show(struct device *dev, struct device_attribute *attr, char *buf)26{27 return sprintf(buf, "%s %s\n", dev_driver_string(dev->parent),28 dev_name(dev->parent));29}30static DEVICE_ATTR_RO(name);31 32static ssize_t33date_show(struct device *dev, struct device_attribute *attr, char *buf)34{35 ssize_t retval;36 struct rtc_time tm;37 38 retval = rtc_read_time(to_rtc_device(dev), &tm);39 if (retval)40 return retval;41 42 return sprintf(buf, "%ptRd\n", &tm);43}44static DEVICE_ATTR_RO(date);45 46static ssize_t47time_show(struct device *dev, struct device_attribute *attr, char *buf)48{49 ssize_t retval;50 struct rtc_time tm;51 52 retval = rtc_read_time(to_rtc_device(dev), &tm);53 if (retval)54 return retval;55 56 return sprintf(buf, "%ptRt\n", &tm);57}58static DEVICE_ATTR_RO(time);59 60static ssize_t61since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf)62{63 ssize_t retval;64 struct rtc_time tm;65 66 retval = rtc_read_time(to_rtc_device(dev), &tm);67 if (retval == 0) {68 time64_t time;69 70 time = rtc_tm_to_time64(&tm);71 retval = sprintf(buf, "%lld\n", time);72 }73 74 return retval;75}76static DEVICE_ATTR_RO(since_epoch);77 78static ssize_t79max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf)80{81 return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq);82}83 84static ssize_t85max_user_freq_store(struct device *dev, struct device_attribute *attr,86 const char *buf, size_t n)87{88 struct rtc_device *rtc = to_rtc_device(dev);89 unsigned long val;90 int err;91 92 err = kstrtoul(buf, 0, &val);93 if (err)94 return err;95 96 if (val >= 4096 || val == 0)97 return -EINVAL;98 99 rtc->max_user_freq = (int)val;100 101 return n;102}103static DEVICE_ATTR_RW(max_user_freq);104 105/**106 * hctosys_show - indicate if the given RTC set the system time107 * @dev: The device that the attribute belongs to.108 * @attr: The attribute being read.109 * @buf: The result buffer.110 *111 * buf is "1" if the system clock was set by this RTC at the last112 * boot or resume event.113 */114static ssize_t115hctosys_show(struct device *dev, struct device_attribute *attr, char *buf)116{117#ifdef CONFIG_RTC_HCTOSYS_DEVICE118 if (rtc_hctosys_ret == 0 &&119 strcmp(dev_name(&to_rtc_device(dev)->dev),120 CONFIG_RTC_HCTOSYS_DEVICE) == 0)121 return sprintf(buf, "1\n");122#endif123 return sprintf(buf, "0\n");124}125static DEVICE_ATTR_RO(hctosys);126 127static ssize_t128wakealarm_show(struct device *dev, struct device_attribute *attr, char *buf)129{130 ssize_t retval;131 time64_t alarm;132 struct rtc_wkalrm alm;133 134 /* Don't show disabled alarms. For uniformity, RTC alarms are135 * conceptually one-shot, even though some common RTCs (on PCs)136 * don't actually work that way.137 *138 * NOTE: RTC implementations where the alarm doesn't match an139 * exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC140 * alarms after they trigger, to ensure one-shot semantics.141 */142 retval = rtc_read_alarm(to_rtc_device(dev), &alm);143 if (retval == 0 && alm.enabled) {144 alarm = rtc_tm_to_time64(&alm.time);145 retval = sprintf(buf, "%lld\n", alarm);146 }147 148 return retval;149}150 151static ssize_t152wakealarm_store(struct device *dev, struct device_attribute *attr,153 const char *buf, size_t n)154{155 ssize_t retval;156 time64_t now, alarm;157 time64_t push = 0;158 struct rtc_wkalrm alm;159 struct rtc_device *rtc = to_rtc_device(dev);160 const char *buf_ptr;161 int adjust = 0;162 163 /* Only request alarms that trigger in the future. Disable them164 * by writing another time, e.g. 0 meaning Jan 1 1970 UTC.165 */166 retval = rtc_read_time(rtc, &alm.time);167 if (retval < 0)168 return retval;169 now = rtc_tm_to_time64(&alm.time);170 171 buf_ptr = buf;172 if (*buf_ptr == '+') {173 buf_ptr++;174 if (*buf_ptr == '=') {175 buf_ptr++;176 push = 1;177 } else {178 adjust = 1;179 }180 }181 retval = kstrtos64(buf_ptr, 0, &alarm);182 if (retval)183 return retval;184 if (adjust)185 alarm += now;186 if (alarm > now || push) {187 /* Avoid accidentally clobbering active alarms; we can't188 * entirely prevent that here, without even the minimal189 * locking from the /dev/rtcN api.190 */191 retval = rtc_read_alarm(rtc, &alm);192 if (retval < 0)193 return retval;194 if (alm.enabled) {195 if (push) {196 push = rtc_tm_to_time64(&alm.time);197 alarm += push;198 } else199 return -EBUSY;200 } else if (push)201 return -EINVAL;202 alm.enabled = 1;203 } else {204 alm.enabled = 0;205 206 /* Provide a valid future alarm time. Linux isn't EFI,207 * this time won't be ignored when disabling the alarm.208 */209 alarm = now + 300;210 }211 rtc_time64_to_tm(alarm, &alm.time);212 213 retval = rtc_set_alarm(rtc, &alm);214 return (retval < 0) ? retval : n;215}216static DEVICE_ATTR_RW(wakealarm);217 218static ssize_t219offset_show(struct device *dev, struct device_attribute *attr, char *buf)220{221 ssize_t retval;222 long offset;223 224 retval = rtc_read_offset(to_rtc_device(dev), &offset);225 if (retval == 0)226 retval = sprintf(buf, "%ld\n", offset);227 228 return retval;229}230 231static ssize_t232offset_store(struct device *dev, struct device_attribute *attr,233 const char *buf, size_t n)234{235 ssize_t retval;236 long offset;237 238 retval = kstrtol(buf, 10, &offset);239 if (retval == 0)240 retval = rtc_set_offset(to_rtc_device(dev), offset);241 242 return (retval < 0) ? retval : n;243}244static DEVICE_ATTR_RW(offset);245 246static ssize_t247range_show(struct device *dev, struct device_attribute *attr, char *buf)248{249 return sprintf(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min,250 to_rtc_device(dev)->range_max);251}252static DEVICE_ATTR_RO(range);253 254static struct attribute *rtc_attrs[] = {255 &dev_attr_name.attr,256 &dev_attr_date.attr,257 &dev_attr_time.attr,258 &dev_attr_since_epoch.attr,259 &dev_attr_max_user_freq.attr,260 &dev_attr_hctosys.attr,261 &dev_attr_wakealarm.attr,262 &dev_attr_offset.attr,263 &dev_attr_range.attr,264 NULL,265};266 267/* The reason to trigger an alarm with no process watching it (via sysfs)268 * is its side effect: waking from a system state like suspend-to-RAM or269 * suspend-to-disk. So: no attribute unless that side effect is possible.270 * (Userspace may disable that mechanism later.)271 */272static bool rtc_does_wakealarm(struct rtc_device *rtc)273{274 if (!device_can_wakeup(rtc->dev.parent))275 return false;276 277 return !!test_bit(RTC_FEATURE_ALARM, rtc->features);278}279 280static umode_t rtc_attr_is_visible(struct kobject *kobj,281 struct attribute *attr, int n)282{283 struct device *dev = kobj_to_dev(kobj);284 struct rtc_device *rtc = to_rtc_device(dev);285 umode_t mode = attr->mode;286 287 if (attr == &dev_attr_wakealarm.attr) {288 if (!rtc_does_wakealarm(rtc))289 mode = 0;290 } else if (attr == &dev_attr_offset.attr) {291 if (!rtc->ops->set_offset)292 mode = 0;293 } else if (attr == &dev_attr_range.attr) {294 if (!(rtc->range_max - rtc->range_min))295 mode = 0;296 }297 298 return mode;299}300 301static struct attribute_group rtc_attr_group = {302 .is_visible = rtc_attr_is_visible,303 .attrs = rtc_attrs,304};305 306static const struct attribute_group *rtc_attr_groups[] = {307 &rtc_attr_group,308 NULL309};310 311const struct attribute_group **rtc_get_dev_attribute_groups(void)312{313 return rtc_attr_groups;314}315 316int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps)317{318 size_t old_cnt = 0, add_cnt = 0, new_cnt;319 const struct attribute_group **groups, **old;320 321 if (!grps)322 return -EINVAL;323 324 groups = rtc->dev.groups;325 if (groups)326 for (; *groups; groups++)327 old_cnt++;328 329 for (groups = grps; *groups; groups++)330 add_cnt++;331 332 new_cnt = old_cnt + add_cnt + 1;333 groups = devm_kcalloc(&rtc->dev, new_cnt, sizeof(*groups), GFP_KERNEL);334 if (!groups)335 return -ENOMEM;336 memcpy(groups, rtc->dev.groups, old_cnt * sizeof(*groups));337 memcpy(groups + old_cnt, grps, add_cnt * sizeof(*groups));338 groups[old_cnt + add_cnt] = NULL;339 340 old = rtc->dev.groups;341 rtc->dev.groups = groups;342 if (old && old != rtc_attr_groups)343 devm_kfree(&rtc->dev, old);344 345 return 0;346}347EXPORT_SYMBOL(rtc_add_groups);348 349int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)350{351 const struct attribute_group *groups[] = { grp, NULL };352 353 return rtc_add_groups(rtc, groups);354}355EXPORT_SYMBOL(rtc_add_group);356