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* An rtc driver for the Dallas DS1511
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* Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
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* Copyright (C) 2007 Andrew Sharp <andy.sharp@lsi.com>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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* Real time clock driver for the Dallas 1511 chip, which also
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* contains a watchdog timer. There is a tiny amount of code that
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* platform code could use to mess with the watchdog device a little
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* bit, but not a full watchdog driver.
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#include <linux/bcd.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/gfp.h>
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#include <linux/delay.h>
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#include <linux/interrupt.h>
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#include <linux/rtc.h>
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#include <linux/platform_device.h>
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#include <linux/module.h>
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#define DRV_VERSION "0.6"
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DS1511_AM3_HOUR = 0xa,
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DS1511_AM4_DATE = 0xb,
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DS1511_CONTROL_A = 0xe,
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DS1511_CONTROL_B = 0xf,
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DS1511_RAMADDR_LSB = 0x10,
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#define DS1511_BLF1 0x80
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#define DS1511_BLF2 0x40
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#define DS1511_PRS 0x20
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#define DS1511_PAB 0x10
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#define DS1511_TDF 0x08
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#define DS1511_KSF 0x04
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#define DS1511_WDF 0x02
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#define DS1511_IRQF 0x01
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#define DS1511_TE 0x80
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#define DS1511_CS 0x40
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#define DS1511_BME 0x20
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#define DS1511_TPE 0x10
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#define DS1511_TIE 0x08
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#define DS1511_KIE 0x04
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#define DS1511_WDE 0x02
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#define DS1511_WDS 0x01
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#define DS1511_RAM_MAX 0xff
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#define RTC_CMD DS1511_CONTROL_B
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#define RTC_CMD1 DS1511_CONTROL_A
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#define RTC_ALARM_SEC DS1511_AM1_SEC
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#define RTC_ALARM_MIN DS1511_AM2_MIN
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#define RTC_ALARM_HOUR DS1511_AM3_HOUR
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#define RTC_ALARM_DATE DS1511_AM4_DATE
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#define RTC_SEC DS1511_SEC
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#define RTC_MIN DS1511_MIN
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#define RTC_HOUR DS1511_HOUR
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#define RTC_DOW DS1511_DOW
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#define RTC_DOM DS1511_DOM
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#define RTC_MON DS1511_MONTH
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#define RTC_YEAR DS1511_YEAR
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#define RTC_CENTURY DS1511_CENTURY
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#define RTC_TIE DS1511_TIE
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#define RTC_TE DS1511_TE
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struct rtc_plat_data {
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struct rtc_device *rtc;
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void __iomem *ioaddr; /* virtual base address */
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int size; /* amount of memory mapped */
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static DEFINE_SPINLOCK(ds1511_lock);
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static __iomem char *ds1511_base;
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static u32 reg_spacing = 1;
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rtc_write(uint8_t val, uint32_t reg)
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writeb(val, ds1511_base + (reg * reg_spacing));
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rtc_write_alarm(uint8_t val, enum ds1511reg reg)
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rtc_write((val | 0x80), reg);
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static noinline uint8_t
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rtc_read(enum ds1511reg reg)
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return readb(ds1511_base + (reg * reg_spacing));
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rtc_disable_update(void)
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rtc_write((rtc_read(RTC_CMD) & ~RTC_TE), RTC_CMD);
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rtc_enable_update(void)
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rtc_write((rtc_read(RTC_CMD) | RTC_TE), RTC_CMD);
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* #define DS1511_WDOG_RESET_SUPPORT
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* Uncomment this if you want to use these routines in
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* some platform code.
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#ifdef DS1511_WDOG_RESET_SUPPORT
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* just enough code to set the watchdog timer so that it
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* will reboot the system
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ds1511_wdog_set(unsigned long deciseconds)
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* the wdog timer can take 99.99 seconds
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deciseconds %= 10000;
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* set the wdog values in the wdog registers
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rtc_write(bin2bcd(deciseconds % 100), DS1511_WD_MSEC);
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rtc_write(bin2bcd(deciseconds / 100), DS1511_WD_SEC);
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* set wdog enable and wdog 'steering' bit to issue a reset
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rtc_write(DS1511_WDE | DS1511_WDS, RTC_CMD);
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ds1511_wdog_disable(void)
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* clear wdog enable and wdog 'steering' bits
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rtc_write(rtc_read(RTC_CMD) & ~(DS1511_WDE | DS1511_WDS), RTC_CMD);
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* clear the wdog counter
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rtc_write(0, DS1511_WD_MSEC);
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rtc_write(0, DS1511_WD_SEC);
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* set the rtc chip's idea of the time.
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* stupidly, some callers call with year unmolested;
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* and some call with year = year - 1900. thanks.
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static int ds1511_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
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u8 mon, day, dow, hrs, min, sec, yrs, cen;
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* won't have to change this for a while
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if (rtc_tm->tm_year < 1900) {
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rtc_tm->tm_year += 1900;
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if (rtc_tm->tm_year < 1970) {
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yrs = rtc_tm->tm_year % 100;
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cen = rtc_tm->tm_year / 100;
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mon = rtc_tm->tm_mon + 1; /* tm_mon starts at zero */
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day = rtc_tm->tm_mday;
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dow = rtc_tm->tm_wday & 0x7; /* automatic BCD */
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hrs = rtc_tm->tm_hour;
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min = rtc_tm->tm_min;
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sec = rtc_tm->tm_sec;
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if ((mon > 12) || (day == 0)) {
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if (day > rtc_month_days(rtc_tm->tm_mon, rtc_tm->tm_year)) {
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if ((hrs >= 24) || (min >= 60) || (sec >= 60)) {
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* each register is a different number of valid bits
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sec = bin2bcd(sec) & 0x7f;
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min = bin2bcd(min) & 0x7f;
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hrs = bin2bcd(hrs) & 0x3f;
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day = bin2bcd(day) & 0x3f;
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mon = bin2bcd(mon) & 0x1f;
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yrs = bin2bcd(yrs) & 0xff;
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cen = bin2bcd(cen) & 0xff;
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spin_lock_irqsave(&ds1511_lock, flags);
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rtc_disable_update();
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rtc_write(cen, RTC_CENTURY);
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rtc_write(yrs, RTC_YEAR);
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rtc_write((rtc_read(RTC_MON) & 0xe0) | mon, RTC_MON);
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rtc_write(day, RTC_DOM);
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rtc_write(hrs, RTC_HOUR);
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rtc_write(min, RTC_MIN);
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rtc_write(sec, RTC_SEC);
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rtc_write(dow, RTC_DOW);
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spin_unlock_irqrestore(&ds1511_lock, flags);
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static int ds1511_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
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unsigned int century;
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spin_lock_irqsave(&ds1511_lock, flags);
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rtc_disable_update();
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rtc_tm->tm_sec = rtc_read(RTC_SEC) & 0x7f;
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rtc_tm->tm_min = rtc_read(RTC_MIN) & 0x7f;
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rtc_tm->tm_hour = rtc_read(RTC_HOUR) & 0x3f;
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rtc_tm->tm_mday = rtc_read(RTC_DOM) & 0x3f;
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rtc_tm->tm_wday = rtc_read(RTC_DOW) & 0x7;
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rtc_tm->tm_mon = rtc_read(RTC_MON) & 0x1f;
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rtc_tm->tm_year = rtc_read(RTC_YEAR) & 0x7f;
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century = rtc_read(RTC_CENTURY);
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spin_unlock_irqrestore(&ds1511_lock, flags);
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rtc_tm->tm_sec = bcd2bin(rtc_tm->tm_sec);
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rtc_tm->tm_min = bcd2bin(rtc_tm->tm_min);
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rtc_tm->tm_hour = bcd2bin(rtc_tm->tm_hour);
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rtc_tm->tm_mday = bcd2bin(rtc_tm->tm_mday);
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rtc_tm->tm_wday = bcd2bin(rtc_tm->tm_wday);
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rtc_tm->tm_mon = bcd2bin(rtc_tm->tm_mon);
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rtc_tm->tm_year = bcd2bin(rtc_tm->tm_year);
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century = bcd2bin(century) * 100;
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* Account for differences between how the RTC uses the values
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* and how they are defined in a struct rtc_time;
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century += rtc_tm->tm_year;
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rtc_tm->tm_year = century - 1900;
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if (rtc_valid_tm(rtc_tm) < 0) {
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dev_err(dev, "retrieved date/time is not valid.\n");
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rtc_time_to_tm(0, rtc_tm);
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* write the alarm register settings
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* we only have the use to interrupt every second, otherwise
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* known as the update interrupt, or the interrupt if the whole
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* date/hours/mins/secs matches. the ds1511 has many more
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* permutations, but the kernel doesn't.
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ds1511_rtc_update_alarm(struct rtc_plat_data *pdata)
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spin_lock_irqsave(&pdata->lock, flags);
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rtc_write(pdata->alrm_mday < 0 || (pdata->irqen & RTC_UF) ?
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0x80 : bin2bcd(pdata->alrm_mday) & 0x3f,
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rtc_write(pdata->alrm_hour < 0 || (pdata->irqen & RTC_UF) ?
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0x80 : bin2bcd(pdata->alrm_hour) & 0x3f,
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rtc_write(pdata->alrm_min < 0 || (pdata->irqen & RTC_UF) ?
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0x80 : bin2bcd(pdata->alrm_min) & 0x7f,
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rtc_write(pdata->alrm_sec < 0 || (pdata->irqen & RTC_UF) ?
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0x80 : bin2bcd(pdata->alrm_sec) & 0x7f,
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rtc_write(rtc_read(RTC_CMD) | (pdata->irqen ? RTC_TIE : 0), RTC_CMD);
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rtc_read(RTC_CMD1); /* clear interrupts */
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spin_unlock_irqrestore(&pdata->lock, flags);
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ds1511_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
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struct platform_device *pdev = to_platform_device(dev);
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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pdata->alrm_mday = alrm->time.tm_mday;
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pdata->alrm_hour = alrm->time.tm_hour;
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pdata->alrm_min = alrm->time.tm_min;
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pdata->alrm_sec = alrm->time.tm_sec;
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pdata->irqen |= RTC_AF;
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ds1511_rtc_update_alarm(pdata);
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ds1511_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
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struct platform_device *pdev = to_platform_device(dev);
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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alrm->time.tm_mday = pdata->alrm_mday < 0 ? 0 : pdata->alrm_mday;
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alrm->time.tm_hour = pdata->alrm_hour < 0 ? 0 : pdata->alrm_hour;
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alrm->time.tm_min = pdata->alrm_min < 0 ? 0 : pdata->alrm_min;
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alrm->time.tm_sec = pdata->alrm_sec < 0 ? 0 : pdata->alrm_sec;
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alrm->enabled = (pdata->irqen & RTC_AF) ? 1 : 0;
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ds1511_interrupt(int irq, void *dev_id)
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struct platform_device *pdev = dev_id;
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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unsigned long events = 0;
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spin_lock(&pdata->lock);
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* read and clear interrupt
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if (rtc_read(RTC_CMD1) & DS1511_IRQF) {
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if (rtc_read(RTC_ALARM_SEC) & 0x80)
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if (likely(pdata->rtc))
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rtc_update_irq(pdata->rtc, 1, events);
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spin_unlock(&pdata->lock);
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return events ? IRQ_HANDLED : IRQ_NONE;
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static int ds1511_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
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struct platform_device *pdev = to_platform_device(dev);
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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pdata->irqen |= RTC_AF;
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pdata->irqen &= ~RTC_AF;
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ds1511_rtc_update_alarm(pdata);
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static const struct rtc_class_ops ds1511_rtc_ops = {
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.read_time = ds1511_rtc_read_time,
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.set_time = ds1511_rtc_set_time,
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.read_alarm = ds1511_rtc_read_alarm,
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.set_alarm = ds1511_rtc_set_alarm,
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.alarm_irq_enable = ds1511_rtc_alarm_irq_enable,
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ds1511_nvram_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *ba,
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char *buf, loff_t pos, size_t size)
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* if count is more than one, turn on "burst" mode
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* turn it off when you're done
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rtc_write((rtc_read(RTC_CMD) | DS1511_BME), RTC_CMD);
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if (pos > DS1511_RAM_MAX) {
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pos = DS1511_RAM_MAX;
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if (size + pos > DS1511_RAM_MAX + 1) {
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size = DS1511_RAM_MAX - pos + 1;
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rtc_write(pos, DS1511_RAMADDR_LSB);
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for (count = 0; size > 0; count++, size--) {
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*buf++ = rtc_read(DS1511_RAMDATA);
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rtc_write((rtc_read(RTC_CMD) & ~DS1511_BME), RTC_CMD);
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ds1511_nvram_write(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t pos, size_t size)
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* if count is more than one, turn on "burst" mode
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* turn it off when you're done
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rtc_write((rtc_read(RTC_CMD) | DS1511_BME), RTC_CMD);
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if (pos > DS1511_RAM_MAX) {
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pos = DS1511_RAM_MAX;
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if (size + pos > DS1511_RAM_MAX + 1) {
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size = DS1511_RAM_MAX - pos + 1;
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rtc_write(pos, DS1511_RAMADDR_LSB);
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for (count = 0; size > 0; count++, size--) {
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rtc_write(*buf++, DS1511_RAMDATA);
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rtc_write((rtc_read(RTC_CMD) & ~DS1511_BME), RTC_CMD);
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static struct bin_attribute ds1511_nvram_attr = {
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.mode = S_IRUGO | S_IWUSR,
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.size = DS1511_RAM_MAX,
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.read = ds1511_nvram_read,
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.write = ds1511_nvram_write,
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ds1511_rtc_probe(struct platform_device *pdev)
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struct rtc_device *rtc;
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struct resource *res;
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struct rtc_plat_data *pdata;
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
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pdata->size = resource_size(res);
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if (!devm_request_mem_region(&pdev->dev, res->start, pdata->size,
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ds1511_base = devm_ioremap(&pdev->dev, res->start, pdata->size);
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pdata->ioaddr = ds1511_base;
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pdata->irq = platform_get_irq(pdev, 0);
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* turn on the clock and the crystal, etc.
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rtc_write(0, RTC_CMD);
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rtc_write(0, RTC_CMD1);
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* clear the wdog counter
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rtc_write(0, DS1511_WD_MSEC);
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rtc_write(0, DS1511_WD_SEC);
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* check for a dying bat-tree
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if (rtc_read(RTC_CMD1) & DS1511_BLF1) {
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dev_warn(&pdev->dev, "voltage-low detected.\n");
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spin_lock_init(&pdata->lock);
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platform_set_drvdata(pdev, pdata);
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* if the platform has an interrupt in mind for this device,
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* then by all means, set it
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if (pdata->irq > 0) {
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if (devm_request_irq(&pdev->dev, pdata->irq, ds1511_interrupt,
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IRQF_DISABLED | IRQF_SHARED, pdev->name, pdev) < 0) {
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dev_warn(&pdev->dev, "interrupt not available.\n");
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rtc = rtc_device_register(pdev->name, &pdev->dev, &ds1511_rtc_ops,
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ret = sysfs_create_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);
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rtc_device_unregister(pdata->rtc);
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ds1511_rtc_remove(struct platform_device *pdev)
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struct rtc_plat_data *pdata = platform_get_drvdata(pdev);
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sysfs_remove_bin_file(&pdev->dev.kobj, &ds1511_nvram_attr);
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rtc_device_unregister(pdata->rtc);
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if (pdata->irq > 0) {
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* disable the alarm interrupt
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rtc_write(rtc_read(RTC_CMD) & ~RTC_TIE, RTC_CMD);
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/* work with hotplug and coldplug */
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MODULE_ALIAS("platform:ds1511");
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static struct platform_driver ds1511_rtc_driver = {
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.probe = ds1511_rtc_probe,
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.remove = __devexit_p(ds1511_rtc_remove),
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.owner = THIS_MODULE,
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ds1511_rtc_init(void)
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return platform_driver_register(&ds1511_rtc_driver);
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ds1511_rtc_exit(void)
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platform_driver_unregister(&ds1511_rtc_driver);
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module_init(ds1511_rtc_init);
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module_exit(ds1511_rtc_exit);
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MODULE_AUTHOR("Andrew Sharp <andy.sharp@lsi.com>");
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MODULE_DESCRIPTION("Dallas DS1511 RTC driver");
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MODULE_LICENSE("GPL");
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MODULE_VERSION(DRV_VERSION);