linux-imx

/*

 * RTC class driver for "CMOS RTC":  PCs, ACPI, etc

 *

 * Copyright (C) 1996 Paul Gortmaker (drivers/char/rtc.c)

 * Copyright (C) 2006 David Brownell (convert to new framework)

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version

 * 2 of the License, or (at your option) any later version.

 */

​

/*

 * The original "cmos clock" chip was an MC146818 chip, now obsolete.

 * That defined the register interface now provided by all PCs, some

 * non-PC systems, and incorporated into ACPI.  Modern PC chipsets

 * integrate an MC146818 clone in their southbridge, and boards use

 * that instead of discrete clones like the DS12887 or M48T86.  There

 * are also clones that connect using the LPC bus.

 *

 * That register API is also used directly by various other drivers

 * (notably for integrated NVRAM), infrastructure (x86 has code to

 * bypass the RTC framework, directly reading the RTC during boot

 * and updating minutes/seconds for systems using NTP synch) and

 * utilities (like userspace 'hwclock', if no /dev node exists).

 *

 * So **ALL** calls to CMOS_READ and CMOS_WRITE must be done with

 * interrupts disabled, holding the global rtc_lock, to exclude those

 * other drivers and utilities on correctly configured systems.

 */

​

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

​

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/interrupt.h>

#include <linux/spinlock.h>

#include <linux/platform_device.h>

#include <linux/log2.h>

#include <linux/pm.h>

#include <linux/of.h>

#include <linux/of_platform.h>

#ifdef CONFIG_X86

#include <asm/i8259.h>

#include <asm/processor.h>

#include <linux/dmi.h>

#endif

​

/* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */

#include <linux/mc146818rtc.h>

​

#ifdef CONFIG_ACPI

/*

 * Use ACPI SCI to replace HPET interrupt for RTC Alarm event

 *

 * If cleared, ACPI SCI is only used to wake up the system from suspend

 *

 * If set, ACPI SCI is used to handle UIE/AIE and system wakeup

 */

​

static bool use_acpi_alarm;

module_param(use_acpi_alarm, bool, 0444);

​

static inline int cmos_use_acpi_alarm(void)

{

    return use_acpi_alarm;

}

#else /* !CONFIG_ACPI */

​

static inline int cmos_use_acpi_alarm(void)

{

    return 0;

}

#endif

​

struct cmos_rtc {

    struct rtc_device   *rtc;

    struct device       *dev;

    int         irq;

    struct resource     *iomem;

    time64_t        alarm_expires;

​

    void            (*wake_on)(struct device *);

    void            (*wake_off)(struct device *);

​

    u8          enabled_wake;

    u8          suspend_ctrl;

​

    /* newer hardware extends the original register set */

    u8          day_alrm;

    u8          mon_alrm;