summaryrefslogtreecommitdiffstats
path: root/drivers/rtc/sysfs.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/rtc/sysfs.c')
-rw-r--r--drivers/rtc/sysfs.c354
1 files changed, 354 insertions, 0 deletions
diff --git a/drivers/rtc/sysfs.c b/drivers/rtc/sysfs.c
new file mode 100644
index 000000000..00f1945bc
--- /dev/null
+++ b/drivers/rtc/sysfs.c
@@ -0,0 +1,354 @@
+// 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);
+
+/**
+ * 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);