1 files changed, 358 insertions, 0 deletions

diff --git a/drivers/rtc/sysfs.c b/drivers/rtc/sysfs.c
new file mode 100644
index 000000000000..a8f22ee726bb
--- /dev/null
+++ b/drivers/rtc/sysfs.c
@@ -0,0 +1,358 @@
+/*
+ * RTC subsystem, sysfs interface
+ *
+ * Copyright (C) 2005 Tower Technologies
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#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
+ *
+ * Returns 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");
+        else
+#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 = container_of(kobj, struct device, 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);