// SPDX-License-Identifier: GPL-2.0 /* * RTC subsystem, sysfs interface * * Copyright (C) 2005 Tower Technologies * Author: Alessandro Zummo */ #include #include #include "rtc-core.h" /* device attributes */ /* * NOTE: RTC times displayed in sysfs use the RTC's timezone. That's * ideally UTC. However, PCs that also boot to MS-Windows normally use * the local time and change to match daylight savings time. That affects * attributes including date, time, since_epoch, and wakealarm. */ static ssize_t name_show(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%s %s\n", dev_driver_string(dev->parent), dev_name(dev->parent)); } static DEVICE_ATTR_RO(name); static ssize_t date_show(struct device *dev, struct device_attribute *attr, char *buf) { ssize_t retval; struct rtc_time tm; retval = rtc_read_time(to_rtc_device(dev), &tm); if (retval) return retval; return sprintf(buf, "%ptRd\n", &tm); } static DEVICE_ATTR_RO(date); static ssize_t time_show(struct device *dev, struct device_attribute *attr, char *buf) { ssize_t retval; struct rtc_time tm; retval = rtc_read_time(to_rtc_device(dev), &tm); if (retval) return retval; return sprintf(buf, "%ptRt\n", &tm); } static DEVICE_ATTR_RO(time); static ssize_t since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf) { ssize_t retval; struct rtc_time tm; retval = rtc_read_time(to_rtc_device(dev), &tm); if (retval == 0) { time64_t time; time = rtc_tm_to_time64(&tm); retval = sprintf(buf, "%lld\n", time); } return retval; } static DEVICE_ATTR_RO(since_epoch); static ssize_t max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq); } static ssize_t max_user_freq_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) { struct rtc_device *rtc = to_rtc_device(dev); unsigned long val; int err; err = kstrtoul(buf, 0, &val); if (err) return err; if (val >= 4096 || val == 0) return -EINVAL; rtc->max_user_freq = (int)val; return n; } static DEVICE_ATTR_RW(max_user_freq); /** * hctosys_show - indicate if the given RTC set the system time * @dev: The device that the attribute belongs to. * @attr: The attribute being read. * @buf: The result buffer. * * buf is "1" if the system clock was set by this RTC at the last * boot or resume event. */ static ssize_t hctosys_show(struct device *dev, struct device_attribute *attr, char *buf) { #ifdef CONFIG_RTC_HCTOSYS_DEVICE if (rtc_hctosys_ret == 0 && strcmp(dev_name(&to_rtc_device(dev)->dev), CONFIG_RTC_HCTOSYS_DEVICE) == 0) return sprintf(buf, "1\n"); #endif return sprintf(buf, "0\n"); } static DEVICE_ATTR_RO(hctosys); static ssize_t wakealarm_show(struct device *dev, struct device_attribute *attr, char *buf) { ssize_t retval; time64_t alarm; struct rtc_wkalrm alm; /* Don't show disabled alarms. For uniformity, RTC alarms are * conceptually one-shot, even though some common RTCs (on PCs) * don't actually work that way. * * NOTE: RTC implementations where the alarm doesn't match an * exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC * alarms after they trigger, to ensure one-shot semantics. */ retval = rtc_read_alarm(to_rtc_device(dev), &alm); if (retval == 0 && alm.enabled) { alarm = rtc_tm_to_time64(&alm.time); retval = sprintf(buf, "%lld\n", alarm); } return retval; } static ssize_t wakealarm_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) { ssize_t retval; time64_t now, alarm; time64_t push = 0; struct rtc_wkalrm alm; struct rtc_device *rtc = to_rtc_device(dev); const char *buf_ptr; int adjust = 0; /* Only request alarms that trigger in the future. Disable them * by writing another time, e.g. 0 meaning Jan 1 1970 UTC. */ retval = rtc_read_time(rtc, &alm.time); if (retval < 0) return retval; now = rtc_tm_to_time64(&alm.time); buf_ptr = buf; if (*buf_ptr == '+') { buf_ptr++; if (*buf_ptr == '=') { buf_ptr++; push = 1; } else { adjust = 1; } } retval = kstrtos64(buf_ptr, 0, &alarm); if (retval) return retval; if (adjust) alarm += now; if (alarm > now || push) { /* Avoid accidentally clobbering active alarms; we can't * entirely prevent that here, without even the minimal * locking from the /dev/rtcN api. */ retval = rtc_read_alarm(rtc, &alm); if (retval < 0) return retval; if (alm.enabled) { if (push) { push = rtc_tm_to_time64(&alm.time); alarm += push; } else return -EBUSY; } else if (push) return -EINVAL; alm.enabled = 1; } else { alm.enabled = 0; /* Provide a valid future alarm time. Linux isn't EFI, * this time won't be ignored when disabling the alarm. */ alarm = now + 300; } rtc_time64_to_tm(alarm, &alm.time); retval = rtc_set_alarm(rtc, &alm); return (retval < 0) ? retval : n; } static DEVICE_ATTR_RW(wakealarm); static ssize_t offset_show(struct device *dev, struct device_attribute *attr, char *buf) { ssize_t retval; long offset; retval = rtc_read_offset(to_rtc_device(dev), &offset); if (retval == 0) retval = sprintf(buf, "%ld\n", offset); return retval; } static ssize_t offset_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t n) { ssize_t retval; long offset; retval = kstrtol(buf, 10, &offset); if (retval == 0) retval = rtc_set_offset(to_rtc_device(dev), offset); return (retval < 0) ? retval : n; } static DEVICE_ATTR_RW(offset); static ssize_t range_show(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min, to_rtc_device(dev)->range_max); } static DEVICE_ATTR_RO(range); static struct attribute *rtc_attrs[] = { &dev_attr_name.attr, &dev_attr_date.attr, &dev_attr_time.attr, &dev_attr_since_epoch.attr, &dev_attr_max_user_freq.attr, &dev_attr_hctosys.attr, &dev_attr_wakealarm.attr, &dev_attr_offset.attr, &dev_attr_range.attr, NULL, }; /* The reason to trigger an alarm with no process watching it (via sysfs) * is its side effect: waking from a system state like suspend-to-RAM or * suspend-to-disk. So: no attribute unless that side effect is possible. * (Userspace may disable that mechanism later.) */ static bool rtc_does_wakealarm(struct rtc_device *rtc) { if (!device_can_wakeup(rtc->dev.parent)) return false; return !!test_bit(RTC_FEATURE_ALARM, rtc->features); } static umode_t rtc_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n) { struct device *dev = kobj_to_dev(kobj); struct rtc_device *rtc = to_rtc_device(dev); umode_t mode = attr->mode; if (attr == &dev_attr_wakealarm.attr) { if (!rtc_does_wakealarm(rtc)) mode = 0; } else if (attr == &dev_attr_offset.attr) { if (!rtc->ops->set_offset) mode = 0; } else if (attr == &dev_attr_range.attr) { if (!(rtc->range_max - rtc->range_min)) mode = 0; } return mode; } static struct attribute_group rtc_attr_group = { .is_visible = rtc_attr_is_visible, .attrs = rtc_attrs, }; static const struct attribute_group *rtc_attr_groups[] = { &rtc_attr_group, NULL }; const struct attribute_group **rtc_get_dev_attribute_groups(void) { return rtc_attr_groups; } int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps) { size_t old_cnt = 0, add_cnt = 0, new_cnt; const struct attribute_group **groups, **old; if (!grps) return -EINVAL; groups = rtc->dev.groups; if (groups) for (; *groups; groups++) old_cnt++; for (groups = grps; *groups; groups++) add_cnt++; new_cnt = old_cnt + add_cnt + 1; groups = devm_kcalloc(&rtc->dev, new_cnt, sizeof(*groups), GFP_KERNEL); if (!groups) return -ENOMEM; memcpy(groups, rtc->dev.groups, old_cnt * sizeof(*groups)); memcpy(groups + old_cnt, grps, add_cnt * sizeof(*groups)); groups[old_cnt + add_cnt] = NULL; old = rtc->dev.groups; rtc->dev.groups = groups; if (old && old != rtc_attr_groups) devm_kfree(&rtc->dev, old); return 0; } EXPORT_SYMBOL(rtc_add_groups); int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp) { const struct attribute_group *groups[] = { grp, NULL }; return rtc_add_groups(rtc, groups); } EXPORT_SYMBOL(rtc_add_group);