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