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469 lines
12 KiB
469 lines
12 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* RTC subsystem, base class |
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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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* class skeleton from drivers/hwmon/hwmon.c |
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*/ |
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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#include <linux/module.h> |
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#include <linux/of.h> |
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#include <linux/rtc.h> |
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#include <linux/kdev_t.h> |
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#include <linux/idr.h> |
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#include <linux/slab.h> |
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#include <linux/workqueue.h> |
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#include "rtc-core.h" |
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static DEFINE_IDA(rtc_ida); |
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struct class *rtc_class; |
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static void rtc_device_release(struct device *dev) |
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{ |
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struct rtc_device *rtc = to_rtc_device(dev); |
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ida_simple_remove(&rtc_ida, rtc->id); |
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mutex_destroy(&rtc->ops_lock); |
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kfree(rtc); |
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} |
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#ifdef CONFIG_RTC_HCTOSYS_DEVICE |
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/* Result of the last RTC to system clock attempt. */ |
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int rtc_hctosys_ret = -ENODEV; |
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|
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/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary |
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* whether it stores the most close value or the value with partial |
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* seconds truncated. However, it is important that we use it to store |
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* the truncated value. This is because otherwise it is necessary, |
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* in an rtc sync function, to read both xtime.tv_sec and |
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* xtime.tv_nsec. On some processors (i.e. ARM), an atomic read |
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* of >32bits is not possible. So storing the most close value would |
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* slow down the sync API. So here we have the truncated value and |
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* the best guess is to add 0.5s. |
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*/ |
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static void rtc_hctosys(struct rtc_device *rtc) |
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{ |
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int err; |
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struct rtc_time tm; |
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struct timespec64 tv64 = { |
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.tv_nsec = NSEC_PER_SEC >> 1, |
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}; |
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err = rtc_read_time(rtc, &tm); |
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if (err) { |
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dev_err(rtc->dev.parent, |
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"hctosys: unable to read the hardware clock\n"); |
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goto err_read; |
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} |
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tv64.tv_sec = rtc_tm_to_time64(&tm); |
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#if BITS_PER_LONG == 32 |
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if (tv64.tv_sec > INT_MAX) { |
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err = -ERANGE; |
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goto err_read; |
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} |
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#endif |
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err = do_settimeofday64(&tv64); |
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dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n", |
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&tm, (long long)tv64.tv_sec); |
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err_read: |
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rtc_hctosys_ret = err; |
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} |
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#endif |
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#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE) |
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/* |
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* On suspend(), measure the delta between one RTC and the |
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* system's wall clock; restore it on resume(). |
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*/ |
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static struct timespec64 old_rtc, old_system, old_delta; |
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static int rtc_suspend(struct device *dev) |
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{ |
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struct rtc_device *rtc = to_rtc_device(dev); |
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struct rtc_time tm; |
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struct timespec64 delta, delta_delta; |
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int err; |
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if (timekeeping_rtc_skipsuspend()) |
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return 0; |
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if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0) |
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return 0; |
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/* snapshot the current RTC and system time at suspend*/ |
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err = rtc_read_time(rtc, &tm); |
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if (err < 0) { |
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pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev)); |
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return 0; |
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} |
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ktime_get_real_ts64(&old_system); |
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old_rtc.tv_sec = rtc_tm_to_time64(&tm); |
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/* |
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* To avoid drift caused by repeated suspend/resumes, |
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* which each can add ~1 second drift error, |
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* try to compensate so the difference in system time |
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* and rtc time stays close to constant. |
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*/ |
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delta = timespec64_sub(old_system, old_rtc); |
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delta_delta = timespec64_sub(delta, old_delta); |
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if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) { |
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/* |
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* if delta_delta is too large, assume time correction |
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* has occurred and set old_delta to the current delta. |
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*/ |
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old_delta = delta; |
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} else { |
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/* Otherwise try to adjust old_system to compensate */ |
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old_system = timespec64_sub(old_system, delta_delta); |
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} |
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return 0; |
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} |
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static int rtc_resume(struct device *dev) |
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{ |
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struct rtc_device *rtc = to_rtc_device(dev); |
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struct rtc_time tm; |
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struct timespec64 new_system, new_rtc; |
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struct timespec64 sleep_time; |
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int err; |
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if (timekeeping_rtc_skipresume()) |
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return 0; |
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rtc_hctosys_ret = -ENODEV; |
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if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0) |
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return 0; |
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/* snapshot the current rtc and system time at resume */ |
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ktime_get_real_ts64(&new_system); |
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err = rtc_read_time(rtc, &tm); |
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if (err < 0) { |
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pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev)); |
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return 0; |
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} |
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new_rtc.tv_sec = rtc_tm_to_time64(&tm); |
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new_rtc.tv_nsec = 0; |
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if (new_rtc.tv_sec < old_rtc.tv_sec) { |
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pr_debug("%s: time travel!\n", dev_name(&rtc->dev)); |
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return 0; |
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} |
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/* calculate the RTC time delta (sleep time)*/ |
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sleep_time = timespec64_sub(new_rtc, old_rtc); |
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/* |
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* Since these RTC suspend/resume handlers are not called |
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* at the very end of suspend or the start of resume, |
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* some run-time may pass on either sides of the sleep time |
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* so subtract kernel run-time between rtc_suspend to rtc_resume |
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* to keep things accurate. |
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*/ |
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sleep_time = timespec64_sub(sleep_time, |
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timespec64_sub(new_system, old_system)); |
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if (sleep_time.tv_sec >= 0) |
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timekeeping_inject_sleeptime64(&sleep_time); |
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rtc_hctosys_ret = 0; |
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return 0; |
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} |
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static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume); |
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#define RTC_CLASS_DEV_PM_OPS (&rtc_class_dev_pm_ops) |
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#else |
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#define RTC_CLASS_DEV_PM_OPS NULL |
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#endif |
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/* Ensure the caller will set the id before releasing the device */ |
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static struct rtc_device *rtc_allocate_device(void) |
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{ |
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struct rtc_device *rtc; |
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rtc = kzalloc(sizeof(*rtc), GFP_KERNEL); |
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if (!rtc) |
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return NULL; |
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device_initialize(&rtc->dev); |
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/* |
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* Drivers can revise this default after allocating the device. |
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* The default is what most RTCs do: Increment seconds exactly one |
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* second after the write happened. This adds a default transport |
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* time of 5ms which is at least halfways close to reality. |
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*/ |
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rtc->set_offset_nsec = NSEC_PER_SEC + 5 * NSEC_PER_MSEC; |
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rtc->irq_freq = 1; |
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rtc->max_user_freq = 64; |
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rtc->dev.class = rtc_class; |
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rtc->dev.groups = rtc_get_dev_attribute_groups(); |
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rtc->dev.release = rtc_device_release; |
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mutex_init(&rtc->ops_lock); |
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spin_lock_init(&rtc->irq_lock); |
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init_waitqueue_head(&rtc->irq_queue); |
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/* Init timerqueue */ |
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timerqueue_init_head(&rtc->timerqueue); |
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INIT_WORK(&rtc->irqwork, rtc_timer_do_work); |
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/* Init aie timer */ |
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rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, rtc); |
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/* Init uie timer */ |
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rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, rtc); |
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/* Init pie timer */ |
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hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
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rtc->pie_timer.function = rtc_pie_update_irq; |
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rtc->pie_enabled = 0; |
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set_bit(RTC_FEATURE_ALARM, rtc->features); |
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return rtc; |
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} |
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static int rtc_device_get_id(struct device *dev) |
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{ |
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int of_id = -1, id = -1; |
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if (dev->of_node) |
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of_id = of_alias_get_id(dev->of_node, "rtc"); |
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else if (dev->parent && dev->parent->of_node) |
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of_id = of_alias_get_id(dev->parent->of_node, "rtc"); |
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if (of_id >= 0) { |
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id = ida_simple_get(&rtc_ida, of_id, of_id + 1, GFP_KERNEL); |
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if (id < 0) |
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dev_warn(dev, "/aliases ID %d not available\n", of_id); |
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} |
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if (id < 0) |
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id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL); |
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return id; |
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} |
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static void rtc_device_get_offset(struct rtc_device *rtc) |
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{ |
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time64_t range_secs; |
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u32 start_year; |
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int ret; |
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/* |
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* If RTC driver did not implement the range of RTC hardware device, |
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* then we can not expand the RTC range by adding or subtracting one |
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* offset. |
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*/ |
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if (rtc->range_min == rtc->range_max) |
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return; |
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ret = device_property_read_u32(rtc->dev.parent, "start-year", |
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&start_year); |
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if (!ret) { |
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rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0); |
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rtc->set_start_time = true; |
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} |
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/* |
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* If user did not implement the start time for RTC driver, then no |
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* need to expand the RTC range. |
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*/ |
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if (!rtc->set_start_time) |
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return; |
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range_secs = rtc->range_max - rtc->range_min + 1; |
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/* |
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* If the start_secs is larger than the maximum seconds (rtc->range_max) |
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* supported by RTC hardware or the maximum seconds of new expanded |
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* range (start_secs + rtc->range_max - rtc->range_min) is less than |
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* rtc->range_min, which means the minimum seconds (rtc->range_min) of |
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* RTC hardware will be mapped to start_secs by adding one offset, so |
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* the offset seconds calculation formula should be: |
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* rtc->offset_secs = rtc->start_secs - rtc->range_min; |
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* |
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* If the start_secs is larger than the minimum seconds (rtc->range_min) |
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* supported by RTC hardware, then there is one region is overlapped |
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* between the original RTC hardware range and the new expanded range, |
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* and this overlapped region do not need to be mapped into the new |
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* expanded range due to it is valid for RTC device. So the minimum |
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* seconds of RTC hardware (rtc->range_min) should be mapped to |
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* rtc->range_max + 1, then the offset seconds formula should be: |
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* rtc->offset_secs = rtc->range_max - rtc->range_min + 1; |
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* |
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* If the start_secs is less than the minimum seconds (rtc->range_min), |
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* which is similar to case 2. So the start_secs should be mapped to |
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* start_secs + rtc->range_max - rtc->range_min + 1, then the |
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* offset seconds formula should be: |
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* rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1); |
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* |
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* Otherwise the offset seconds should be 0. |
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*/ |
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if (rtc->start_secs > rtc->range_max || |
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rtc->start_secs + range_secs - 1 < rtc->range_min) |
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rtc->offset_secs = rtc->start_secs - rtc->range_min; |
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else if (rtc->start_secs > rtc->range_min) |
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rtc->offset_secs = range_secs; |
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else if (rtc->start_secs < rtc->range_min) |
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rtc->offset_secs = -range_secs; |
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else |
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rtc->offset_secs = 0; |
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} |
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static void devm_rtc_unregister_device(void *data) |
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{ |
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struct rtc_device *rtc = data; |
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mutex_lock(&rtc->ops_lock); |
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/* |
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* Remove innards of this RTC, then disable it, before |
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* letting any rtc_class_open() users access it again |
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*/ |
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rtc_proc_del_device(rtc); |
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cdev_device_del(&rtc->char_dev, &rtc->dev); |
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rtc->ops = NULL; |
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mutex_unlock(&rtc->ops_lock); |
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} |
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static void devm_rtc_release_device(void *res) |
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{ |
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struct rtc_device *rtc = res; |
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put_device(&rtc->dev); |
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} |
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struct rtc_device *devm_rtc_allocate_device(struct device *dev) |
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{ |
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struct rtc_device *rtc; |
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int id, err; |
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id = rtc_device_get_id(dev); |
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if (id < 0) |
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return ERR_PTR(id); |
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rtc = rtc_allocate_device(); |
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if (!rtc) { |
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ida_simple_remove(&rtc_ida, id); |
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return ERR_PTR(-ENOMEM); |
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} |
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rtc->id = id; |
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rtc->dev.parent = dev; |
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dev_set_name(&rtc->dev, "rtc%d", id); |
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err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc); |
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if (err) |
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return ERR_PTR(err); |
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return rtc; |
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} |
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EXPORT_SYMBOL_GPL(devm_rtc_allocate_device); |
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int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc) |
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{ |
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struct rtc_wkalrm alrm; |
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int err; |
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if (!rtc->ops) { |
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dev_dbg(&rtc->dev, "no ops set\n"); |
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return -EINVAL; |
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} |
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if (!rtc->ops->set_alarm) |
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clear_bit(RTC_FEATURE_ALARM, rtc->features); |
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rtc->owner = owner; |
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rtc_device_get_offset(rtc); |
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/* Check to see if there is an ALARM already set in hw */ |
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err = __rtc_read_alarm(rtc, &alrm); |
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if (!err && !rtc_valid_tm(&alrm.time)) |
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rtc_initialize_alarm(rtc, &alrm); |
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rtc_dev_prepare(rtc); |
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err = cdev_device_add(&rtc->char_dev, &rtc->dev); |
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if (err) |
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dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n", |
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MAJOR(rtc->dev.devt), rtc->id); |
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else |
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dev_dbg(rtc->dev.parent, "char device (%d:%d)\n", |
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MAJOR(rtc->dev.devt), rtc->id); |
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rtc_proc_add_device(rtc); |
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dev_info(rtc->dev.parent, "registered as %s\n", |
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dev_name(&rtc->dev)); |
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#ifdef CONFIG_RTC_HCTOSYS_DEVICE |
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if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE)) |
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rtc_hctosys(rtc); |
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#endif |
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return devm_add_action_or_reset(rtc->dev.parent, |
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devm_rtc_unregister_device, rtc); |
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} |
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EXPORT_SYMBOL_GPL(__devm_rtc_register_device); |
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/** |
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* devm_rtc_device_register - resource managed rtc_device_register() |
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* @dev: the device to register |
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* @name: the name of the device (unused) |
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* @ops: the rtc operations structure |
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* @owner: the module owner |
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* |
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* @return a struct rtc on success, or an ERR_PTR on error |
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* |
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* Managed rtc_device_register(). The rtc_device returned from this function |
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* are automatically freed on driver detach. |
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* This function is deprecated, use devm_rtc_allocate_device and |
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* rtc_register_device instead |
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*/ |
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struct rtc_device *devm_rtc_device_register(struct device *dev, |
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const char *name, |
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const struct rtc_class_ops *ops, |
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struct module *owner) |
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{ |
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struct rtc_device *rtc; |
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int err; |
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rtc = devm_rtc_allocate_device(dev); |
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if (IS_ERR(rtc)) |
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return rtc; |
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rtc->ops = ops; |
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err = __devm_rtc_register_device(owner, rtc); |
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if (err) |
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return ERR_PTR(err); |
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return rtc; |
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} |
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EXPORT_SYMBOL_GPL(devm_rtc_device_register); |
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static int __init rtc_init(void) |
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{ |
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rtc_class = class_create(THIS_MODULE, "rtc"); |
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if (IS_ERR(rtc_class)) { |
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pr_err("couldn't create class\n"); |
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return PTR_ERR(rtc_class); |
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} |
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rtc_class->pm = RTC_CLASS_DEV_PM_OPS; |
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rtc_dev_init(); |
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return 0; |
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} |
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subsys_initcall(rtc_init);
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