diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/rtc/sysfs.c | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/drivers/rtc/sysfs.c b/drivers/rtc/sysfs.c new file mode 100644 index 000000000..950fac0d4 --- /dev/null +++ b/drivers/rtc/sysfs.c @@ -0,0 +1,356 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * RTC subsystem, sysfs interface + * + * Copyright (C) 2005 Tower Technologies + * Author: Alessandro Zummo <a.zummo@towertech.it> + */ + +#include <linux/module.h> +#include <linux/rtc.h> + +#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); + +/** + * rtc_sysfs_show_hctosys - 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 rtc->ops->set_alarm != NULL; +} + +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 (rtc->registered) + return -EINVAL; + 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); |