8 files changed, 855 insertions, 7 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 09660e2ab0..4bbca500d3 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1,4 +1,4 @@
-\#
+#
 # RTC class/drivers configuration
 #
 
@@ -95,6 +95,29 @@ config RTC_INTF_DEV_UIE_EMUL
 comment "RTC drivers"
         depends on RTC_CLASS
 
+# this 'CMOS' RTC driver is arch dependent because <asm-generic/rtc.h>
+# requires <asm/mc146818rtc.h> defining CMOS_READ/CMOS_WRITE, and a
+# global rtc_lock ... it's not yet just another platform_device.
+
+config RTC_DRV_CMOS
+        tristate "PC-style 'CMOS' real time clock"
+        depends on RTC_CLASS && (X86_PC || ALPHA || ARM26 || ARM \
+                || M32R || ATARI || POWERPC)
+        help
+          Say "yes" here to get direct support for the real time clock
+          found in every PC or ACPI-based system, and some other boards.
+          Specifically the original MC146818, compatibles like those in
+          PC south bridges, the DS12887 or M48T86, some multifunction
+          or LPC bus chips, and so on.
+
+          Your system will need to define the platform device used by
+          this driver, otherwise it won't be accessible.  This means
+          you can safely enable this driver if you don't know whether
+          or not your board has this kind of hardware.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-cmos.
+
 config RTC_DRV_X1205
         tristate "Xicor/Intersil X1205"
         depends on RTC_CLASS && I2C
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index e6beedacc9..92bfe1b3a5 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_RTC_INTF_SYSFS)	+= rtc-sysfs.o
 obj-$(CONFIG_RTC_INTF_PROC)     += rtc-proc.o
 obj-$(CONFIG_RTC_INTF_DEV)      += rtc-dev.o
 
+obj-$(CONFIG_RTC_DRV_CMOS)      += rtc-cmos.o
 obj-$(CONFIG_RTC_DRV_X1205)     += rtc-x1205.o
 obj-$(CONFIG_RTC_DRV_ISL1208)   += rtc-isl1208.o
 obj-$(CONFIG_RTC_DRV_TEST)      += rtc-test.o
diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
new file mode 100644
index 0000000000..85bf795abd
--- /dev/null
+++ b/drivers/rtc/rtc-cmos.c
@@ -0,0 +1,725 @@
+/*
+ * 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.
+ */
+#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/mod_devicetable.h>
+
+/* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
+#include <asm-generic/rtc.h>
+
+
+struct cmos_rtc {
+        struct rtc_device       *rtc;
+        struct device           *dev;
+        int                     irq;
+        struct resource         *iomem;
+
+        u8                      suspend_ctrl;
+
+        /* newer hardware extends the original register set */
+        u8                      day_alrm;
+        u8                      mon_alrm;
+        u8                      century;
+};
+
+/* both platform and pnp busses use negative numbers for invalid irqs */
+#define is_valid_irq(n)         ((n) >= 0)
+
+static const char driver_name[] = "rtc_cmos";
+
+/*----------------------------------------------------------------*/
+
+static int cmos_read_time(struct device *dev, struct rtc_time *t)
+{
+        /* REVISIT:  if the clock has a "century" register, use
+         * that instead of the heuristic in get_rtc_time().
+         * That'll make Y3K compatility (year > 2070) easy!
+         */
+        get_rtc_time(t);
+        return 0;
+}
+
+static int cmos_set_time(struct device *dev, struct rtc_time *t)
+{
+        /* REVISIT:  set the "century" register if available
+         *
+         * NOTE: this ignores the issue whereby updating the seconds
+         * takes effect exactly 500ms after we write the register.
+         * (Also queueing and other delays before we get this far.)
+         */
+        return set_rtc_time(t);
+}
+
+static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+        struct cmos_rtc *cmos = dev_get_drvdata(dev);
+        unsigned char   rtc_control;
+
+        if (!is_valid_irq(cmos->irq))
+                return -EIO;
+
+        /* Basic alarms only support hour, minute, and seconds fields.
+         * Some also support day and month, for alarms up to a year in
+         * the future.
+         */
+        t->time.tm_mday = -1;
+        t->time.tm_mon = -1;
+
+        spin_lock_irq(&rtc_lock);
+        t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
+        t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
+        t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);
+
+        if (cmos->day_alrm) {
+                t->time.tm_mday = CMOS_READ(cmos->day_alrm);
+                if (!t->time.tm_mday)
+                        t->time.tm_mday = -1;
+
+                if (cmos->mon_alrm) {
+                        t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
+                        if (!t->time.tm_mon)
+                                t->time.tm_mon = -1;
+                }
+        }
+
+        rtc_control = CMOS_READ(RTC_CONTROL);
+        spin_unlock_irq(&rtc_lock);
+
+        /* REVISIT this assumes PC style usage:  always BCD */
+
+        if (((unsigned)t->time.tm_sec) < 0x60)
+                t->time.tm_sec = BCD2BIN(t->time.tm_sec);
+        else
+                t->time.tm_sec = -1;
+        if (((unsigned)t->time.tm_min) < 0x60)
+                t->time.tm_min = BCD2BIN(t->time.tm_min);
+        else
+                t->time.tm_min = -1;
+        if (((unsigned)t->time.tm_hour) < 0x24)
+                t->time.tm_hour = BCD2BIN(t->time.tm_hour);
+        else
+                t->time.tm_hour = -1;
+
+        if (cmos->day_alrm) {
+                if (((unsigned)t->time.tm_mday) <= 0x31)
+                        t->time.tm_mday = BCD2BIN(t->time.tm_mday);
+                else
+                        t->time.tm_mday = -1;
+                if (cmos->mon_alrm) {
+                        if (((unsigned)t->time.tm_mon) <= 0x12)
+                                t->time.tm_mon = BCD2BIN(t->time.tm_mon) - 1;
+                        else
+                                t->time.tm_mon = -1;
+                }
+        }
+        t->time.tm_year = -1;
+
+        t->enabled = !!(rtc_control & RTC_AIE);
+        t->pending = 0;
+
+        return 0;
+}
+
+static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+        struct cmos_rtc *cmos = dev_get_drvdata(dev);
+        unsigned char   mon, mday, hrs, min, sec;
+        unsigned char   rtc_control, rtc_intr;
+
+        if (!is_valid_irq(cmos->irq))
+                return -EIO;
+
+        /* REVISIT this assumes PC style usage:  always BCD */
+
+        /* Writing 0xff means "don't care" or "match all".  */
+
+        mon = t->time.tm_mon;
+        mon = (mon < 12) ? BIN2BCD(mon) : 0xff;
+        mon++;
+
+        mday = t->time.tm_mday;
+        mday = (mday >= 1 && mday <= 31) ? BIN2BCD(mday) : 0xff;
+
+        hrs = t->time.tm_hour;
+        hrs = (hrs < 24) ? BIN2BCD(hrs) : 0xff;
+
+        min = t->time.tm_min;
+        min = (min < 60) ? BIN2BCD(min) : 0xff;
+
+        sec = t->time.tm_sec;
+        sec = (sec < 60) ? BIN2BCD(sec) : 0xff;
+
+        spin_lock_irq(&rtc_lock);
+
+        /* next rtc irq must not be from previous alarm setting */
+        rtc_control = CMOS_READ(RTC_CONTROL);
+        rtc_control &= ~RTC_AIE;
+        CMOS_WRITE(rtc_control, RTC_CONTROL);
+        rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
+        if (rtc_intr)
+                rtc_update_irq(&cmos->rtc->class_dev, 1, rtc_intr);
+
+        /* update alarm */
+        CMOS_WRITE(hrs, RTC_HOURS_ALARM);
+        CMOS_WRITE(min, RTC_MINUTES_ALARM);
+        CMOS_WRITE(sec, RTC_SECONDS_ALARM);
+
+        /* the system may support an "enhanced" alarm */
+        if (cmos->day_alrm) {
+                CMOS_WRITE(mday, cmos->day_alrm);
+                if (cmos->mon_alrm)
+                        CMOS_WRITE(mon, cmos->mon_alrm);
+        }
+
+        if (t->enabled) {
+                rtc_control |= RTC_AIE;
+                CMOS_WRITE(rtc_control, RTC_CONTROL);
+                rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
+                if (rtc_intr)
+                        rtc_update_irq(&cmos->rtc->class_dev, 1, rtc_intr);
+        }
+
+        spin_unlock_irq(&rtc_lock);
+
+        return 0;
+}
+
+static int cmos_set_freq(struct device *dev, int freq)
+{
+        struct cmos_rtc *cmos = dev_get_drvdata(dev);
+        int             f;
+        unsigned long   flags;
+
+        if (!is_valid_irq(cmos->irq))
+                return -ENXIO;
+
+        /* 0 = no irqs; 1 = 2^15 Hz ... 15 = 2^0 Hz */
+        f = ffs(freq);
+        if (f != 0) {
+                if (f-- > 16 || freq != (1 << f))
+                        return -EINVAL;
+                f = 16 - f;
+        }
+
+        spin_lock_irqsave(&rtc_lock, flags);
+        CMOS_WRITE(RTC_REF_CLCK_32KHZ | f, RTC_FREQ_SELECT);
+        spin_unlock_irqrestore(&rtc_lock, flags);
+
+        return 0;
+}
+
+#if defined(CONFIG_RTC_INTF_DEV) || defined(CONFIG_RTC_INTF_DEV_MODULE)
+
+static int
+cmos_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+        struct cmos_rtc *cmos = dev_get_drvdata(dev);
+        unsigned char   rtc_control, rtc_intr;
+        unsigned long   flags;
+
+        switch (cmd) {
+        case RTC_AIE_OFF:
+        case RTC_AIE_ON:
+        case RTC_UIE_OFF:
+        case RTC_UIE_ON:
+        case RTC_PIE_OFF:
+        case RTC_PIE_ON:
+                if (!is_valid_irq(cmos->irq))
+                        return -EINVAL;
+                break;
+        default:
+                return -ENOIOCTLCMD;
+        }
+
+        spin_lock_irqsave(&rtc_lock, flags);
+        rtc_control = CMOS_READ(RTC_CONTROL);
+        switch (cmd) {
+        case RTC_AIE_OFF:       /* alarm off */
+                rtc_control &= ~RTC_AIE;
+                break;
+        case RTC_AIE_ON:        /* alarm on */
+                rtc_control |= RTC_AIE;
+                break;
+        case RTC_UIE_OFF:       /* update off */
+                rtc_control &= ~RTC_UIE;
+                break;
+        case RTC_UIE_ON:        /* update on */
+                rtc_control |= RTC_UIE;
+                break;
+        case RTC_PIE_OFF:       /* periodic off */
+                rtc_control &= ~RTC_PIE;
+                break;
+        case RTC_PIE_ON:        /* periodic on */
+                rtc_control |= RTC_PIE;
+                break;
+        }
+        CMOS_WRITE(rtc_control, RTC_CONTROL);
+        rtc_intr = CMOS_READ(RTC_INTR_FLAGS);
+        if (rtc_intr)
+                rtc_update_irq(&cmos->rtc->class_dev, 1, rtc_intr);
+        spin_unlock_irqrestore(&rtc_lock, flags);
+        return 0;
+}
+
+#else
+#define cmos_rtc_ioctl  NULL
+#endif
+
+#if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)
+
+static int cmos_procfs(struct device *dev, struct seq_file *seq)
+{
+        struct cmos_rtc *cmos = dev_get_drvdata(dev);
+        unsigned char   rtc_control, valid;
+
+        spin_lock_irq(&rtc_lock);
+        rtc_control = CMOS_READ(RTC_CONTROL);
+        valid = CMOS_READ(RTC_VALID);
+        spin_unlock_irq(&rtc_lock);
+
+        /* NOTE:  at least ICH6 reports battery status using a different
+         * (non-RTC) bit; and SQWE is ignored on many current systems.
+         */
+        return seq_printf(seq,
+                        "periodic_IRQ\t: %s\n"
+                        "update_IRQ\t: %s\n"
+                        // "square_wave\t: %s\n"
+                        // "BCD\t\t: %s\n"
+                        "DST_enable\t: %s\n"
+                        "periodic_freq\t: %d\n"
+                        "batt_status\t: %s\n",
+                        (rtc_control & RTC_PIE) ? "yes" : "no",
+                        (rtc_control & RTC_UIE) ? "yes" : "no",
+                        // (rtc_control & RTC_SQWE) ? "yes" : "no",
+                        // (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
+                        (rtc_control & RTC_DST_EN) ? "yes" : "no",
+                        cmos->rtc->irq_freq,
+                        (valid & RTC_VRT) ? "okay" : "dead");
+}
+
+#else
+#define cmos_procfs     NULL
+#endif
+
+static const struct rtc_class_ops cmos_rtc_ops = {
+        .ioctl          = cmos_rtc_ioctl,
+        .read_time      = cmos_read_time,
+        .set_time       = cmos_set_time,
+        .read_alarm     = cmos_read_alarm,
+        .set_alarm      = cmos_set_alarm,
+        .proc           = cmos_procfs,
+        .irq_set_freq   = cmos_set_freq,
+};
+
+/*----------------------------------------------------------------*/
+
+static struct cmos_rtc  cmos_rtc;
+
+static irqreturn_t cmos_interrupt(int irq, void *p)
+{
+        u8              irqstat;
+
+        spin_lock(&rtc_lock);
+        irqstat = CMOS_READ(RTC_INTR_FLAGS);
+        spin_unlock(&rtc_lock);
+
+        if (irqstat) {
+                /* NOTE: irqstat may have e.g. RTC_PF set
+                 * even when RTC_PIE is clear...
+                 */
+                rtc_update_irq(p, 1, irqstat);
+                return IRQ_HANDLED;
+        } else
+                return IRQ_NONE;
+}
+
+#ifdef  CONFIG_PNPACPI
+#define is_pnpacpi()    1
+#define INITSECTION
+
+#else
+#define is_pnpacpi()    0
+#define INITSECTION     __init
+#endif
+
+static int INITSECTION
+cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
+{
+        struct cmos_rtc_board_info      *info = dev->platform_data;
+        int                             retval = 0;
+        unsigned char                   rtc_control;
+
+        /* there can be only one ... */
+        if (cmos_rtc.dev)
+                return -EBUSY;
+
+        if (!ports)
+                return -ENODEV;
+
+        cmos_rtc.irq = rtc_irq;
+        cmos_rtc.iomem = ports;
+
+        /* For ACPI systems the info comes from the FADT.  On others,
+         * board specific setup provides it as appropriate.
+         */
+        if (info) {
+                cmos_rtc.day_alrm = info->rtc_day_alarm;
+                cmos_rtc.mon_alrm = info->rtc_mon_alarm;
+                cmos_rtc.century = info->rtc_century;
+        }
+
+        cmos_rtc.rtc = rtc_device_register(driver_name, dev,
+                                &cmos_rtc_ops, THIS_MODULE);
+        if (IS_ERR(cmos_rtc.rtc))
+                return PTR_ERR(cmos_rtc.rtc);
+
+        cmos_rtc.dev = dev;
+        dev_set_drvdata(dev, &cmos_rtc);
+
+        /* platform and pnp busses handle resources incompatibly.
+         *
+         * REVISIT for non-x86 systems we may need to handle io memory
+         * resources: ioremap them, and request_mem_region().
+         */
+        if (is_pnpacpi()) {
+                retval = request_resource(&ioport_resource, ports);
+                if (retval < 0) {
+                        dev_dbg(dev, "i/o registers already in use\n");
+                        goto cleanup0;
+                }
+        }
+        rename_region(ports, cmos_rtc.rtc->class_dev.class_id);
+
+        spin_lock_irq(&rtc_lock);
+
+        /* force periodic irq to CMOS reset default of 1024Hz;
+         *
+         * REVISIT it's been reported that at least one x86_64 ALI mobo
+         * doesn't use 32KHz here ... for portability we might need to
+         * do something about other clock frequencies.
+         */
+        CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);
+        cmos_rtc.rtc->irq_freq = 1024;
+
+        /* disable irqs.
+         *
+         * NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
+         * allegedly some older rtcs need that to handle irqs properly
+         */
+        rtc_control = CMOS_READ(RTC_CONTROL);
+        rtc_control &= ~(RTC_PIE | RTC_AIE | RTC_UIE);
+        CMOS_WRITE(rtc_control, RTC_CONTROL);
+        CMOS_READ(RTC_INTR_FLAGS);
+
+        spin_unlock_irq(&rtc_lock);
+
+        /* FIXME teach the alarm code how to handle binary mode;
+         * <asm-generic/rtc.h> doesn't know 12-hour mode either.
+         */
+        if (!(rtc_control & RTC_24H) || (rtc_control & (RTC_DM_BINARY))) {
+                dev_dbg(dev, "only 24-hr BCD mode supported\n");
+                retval = -ENXIO;
+                goto cleanup1;
+        }
+
+        if (is_valid_irq(rtc_irq))
+                retval = request_irq(rtc_irq, cmos_interrupt, IRQF_DISABLED,
+                                cmos_rtc.rtc->class_dev.class_id,
+                                &cmos_rtc.rtc->class_dev);
+        if (retval < 0) {
+                dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
+                goto cleanup1;
+        }
+
+        /* REVISIT optionally make 50 or 114 bytes NVRAM available,
+         * like rtc-ds1553, rtc-ds1742 ... this will often include
+         * registers for century, and day/month alarm.
+         */
+
+        pr_info("%s: alarms up to one %s%s\n",
+                        cmos_rtc.rtc->class_dev.class_id,
+                        is_valid_irq(rtc_irq)
+                                ?  (cmos_rtc.mon_alrm
+                                        ? "year"
+                                        : (cmos_rtc.day_alrm
+                                                ? "month" : "day"))
+                                : "no",
+                        cmos_rtc.century ? ", y3k" : ""
+                        );
+
+        return 0;
+
+cleanup1:
+        rename_region(ports, NULL);
+cleanup0:
+        rtc_device_unregister(cmos_rtc.rtc);
+        return retval;
+}
+
+static void cmos_do_shutdown(void)
+{
+        unsigned char   rtc_control;
+
+        spin_lock_irq(&rtc_lock);
+        rtc_control = CMOS_READ(RTC_CONTROL);
+        rtc_control &= ~(RTC_PIE|RTC_AIE|RTC_UIE);
+        CMOS_WRITE(rtc_control, RTC_CONTROL);
+        CMOS_READ(RTC_INTR_FLAGS);
+        spin_unlock_irq(&rtc_lock);
+}
+
+static void __exit cmos_do_remove(struct device *dev)
+{
+        struct cmos_rtc *cmos = dev_get_drvdata(dev);
+
+        cmos_do_shutdown();
+
+        if (is_pnpacpi())
+                release_resource(cmos->iomem);
+        rename_region(cmos->iomem, NULL);
+
+        if (is_valid_irq(cmos->irq))
+                free_irq(cmos->irq, &cmos_rtc.rtc->class_dev);
+
+        rtc_device_unregister(cmos_rtc.rtc);
+
+        cmos_rtc.dev = NULL;
+        dev_set_drvdata(dev, NULL);
+}
+
+#ifdef  CONFIG_PM
+
+static int cmos_suspend(struct device *dev, pm_message_t mesg)
+{
+        struct cmos_rtc *cmos = dev_get_drvdata(dev);
+        int             do_wake = device_may_wakeup(dev);
+        unsigned char   tmp, irqstat;
+
+        /* only the alarm might be a wakeup event source */
+        spin_lock_irq(&rtc_lock);
+        cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
+        if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
+                if (do_wake)
+                        tmp &= ~(RTC_PIE|RTC_UIE);
+                else
+                        tmp &= ~(RTC_PIE|RTC_AIE|RTC_UIE);
+                CMOS_WRITE(tmp, RTC_CONTROL);
+                irqstat = CMOS_READ(RTC_INTR_FLAGS);
+        } else
+                irqstat = 0;
+        spin_unlock_irq(&rtc_lock);
+
+        if (irqstat)
+                rtc_update_irq(&cmos->rtc->class_dev, 1, irqstat);
+
+        /* ACPI HOOK:  enable ACPI_EVENT_RTC when (tmp & RTC_AIE)
+         * ... it'd be best if we could do that under rtc_lock.
+         */
+
+        pr_debug("%s: suspend%s, ctrl %02x\n",
+                        cmos_rtc.rtc->class_dev.class_id,
+                        (tmp & RTC_AIE) ? ", alarm may wake" : "",
+                        tmp);
+
+        return 0;
+}
+
+static int cmos_resume(struct device *dev)
+{
+        struct cmos_rtc *cmos = dev_get_drvdata(dev);
+        unsigned char   tmp = cmos->suspend_ctrl;
+
+        /* REVISIT:  a mechanism to resync the system clock (jiffies)
+         * on resume should be portable between platforms ...
+         */
+
+        /* re-enable any irqs previously active */
+        if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
+
+                /* ACPI HOOK:  disable ACPI_EVENT_RTC when (tmp & RTC_AIE) */
+
+                spin_lock_irq(&rtc_lock);
+                CMOS_WRITE(tmp, RTC_CONTROL);
+                tmp = CMOS_READ(RTC_INTR_FLAGS);
+                spin_unlock_irq(&rtc_lock);
+                if (tmp)
+                        rtc_update_irq(&cmos->rtc->class_dev, 1, tmp);
+        }
+
+        pr_debug("%s: resume, ctrl %02x\n",
+                        cmos_rtc.rtc->class_dev.class_id,
+                        cmos->suspend_ctrl);
+
+
+        return 0;
+}
+
+#else
+#define cmos_suspend    NULL
+#define cmos_resume     NULL
+#endif
+
+/*----------------------------------------------------------------*/
+
+/* The "CMOS" RTC normally lives on the platform_bus.  On ACPI systems,
+ * the device node may alternatively be created as a PNP device.
+ */
+
+#ifdef  CONFIG_PNPACPI
+
+#include <linux/pnp.h>
+
+static int __devinit
+cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
+{
+        /* REVISIT paranoia argues for a shutdown notifier, since PNP
+         * drivers can't provide shutdown() methods to disable IRQs.
+         * Or better yet, fix PNP to allow those methods...
+         */
+        return cmos_do_probe(&pnp->dev,
+                        &pnp->res.port_resource[0],
+                        pnp->res.irq_resource[0].start);
+}
+
+static void __exit cmos_pnp_remove(struct pnp_dev *pnp)
+{
+        cmos_do_remove(&pnp->dev);
+}
+
+#ifdef  CONFIG_PM
+
+static int cmos_pnp_suspend(struct pnp_dev *pnp, pm_message_t mesg)
+{
+        return cmos_suspend(&pnp->dev, mesg);
+}
+
+static int cmos_pnp_resume(struct pnp_dev *pnp)
+{
+        return cmos_resume(&pnp->dev);
+}
+
+#else
+#define cmos_pnp_suspend        NULL
+#define cmos_pnp_resume         NULL
+#endif
+
+
+static const struct pnp_device_id rtc_ids[] = {
+        { .id = "PNP0b00", },
+        { .id = "PNP0b01", },
+        { .id = "PNP0b02", },
+        { },
+};
+MODULE_DEVICE_TABLE(pnp, rtc_ids);
+
+static struct pnp_driver cmos_pnp_driver = {
+        .name           = (char *) driver_name,
+        .id_table       = rtc_ids,
+        .probe          = cmos_pnp_probe,
+        .remove         = __exit_p(cmos_pnp_remove),
+
+        /* flag ensures resume() gets called, and stops syslog spam */
+        .flags          = PNP_DRIVER_RES_DO_NOT_CHANGE,
+        .suspend        = cmos_pnp_suspend,
+        .resume         = cmos_pnp_resume,
+};
+
+static int __init cmos_init(void)
+{
+        return pnp_register_driver(&cmos_pnp_driver);
+}
+module_init(cmos_init);
+
+static void __exit cmos_exit(void)
+{
+        pnp_unregister_driver(&cmos_pnp_driver);
+}
+module_exit(cmos_exit);
+
+#else   /* no PNPACPI */
+
+/*----------------------------------------------------------------*/
+
+/* Platform setup should have set up an RTC device, when PNPACPI is
+ * unavailable ... this is the normal case, common even on PCs.
+ */
+
+static int __init cmos_platform_probe(struct platform_device *pdev)
+{
+        return cmos_do_probe(&pdev->dev,
+                        platform_get_resource(pdev, IORESOURCE_IO, 0),
+                        platform_get_irq(pdev, 0));
+}
+
+static int __exit cmos_platform_remove(struct platform_device *pdev)
+{
+        cmos_do_remove(&pdev->dev);
+        return 0;
+}
+
+static void cmos_platform_shutdown(struct platform_device *pdev)
+{
+        cmos_do_shutdown();
+}
+
+static struct platform_driver cmos_platform_driver = {
+        .remove         = __exit_p(cmos_platform_remove),
+        .shutdown       = cmos_platform_shutdown,
+        .driver = {
+                .name           = (char *) driver_name,
+                .suspend        = cmos_suspend,
+                .resume         = cmos_resume,
+        }
+};
+
+static int __init cmos_init(void)
+{
+        return platform_driver_probe(&cmos_platform_driver,
+                        cmos_platform_probe);
+}
+module_init(cmos_init);
+
+static void __exit cmos_exit(void)
+{
+        platform_driver_unregister(&cmos_platform_driver);
+}
+module_exit(cmos_exit);
+
+
+#endif  /* !PNPACPI */
+
+MODULE_AUTHOR("David Brownell");
+MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
+MODULE_LICENSE("GPL");
diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
index 82f2ac87cc..137330b863 100644
--- a/drivers/rtc/rtc-dev.c
+++ b/drivers/rtc/rtc-dev.c
@@ -384,7 +384,7 @@ static int rtc_dev_fasync(int fd, struct file *file, int on)
         return fasync_helper(fd, file, on, &rtc->async_queue);
 }
 
-static struct file_operations rtc_dev_fops = {
+static const struct file_operations rtc_dev_fops = {
         .owner          = THIS_MODULE,
         .llseek         = no_llseek,
         .read           = rtc_dev_read,
diff --git a/drivers/rtc/rtc-ds1553.c b/drivers/rtc/rtc-ds1553.c
index 001eb1123a..e27176c0e1 100644
--- a/drivers/rtc/rtc-ds1553.c
+++ b/drivers/rtc/rtc-ds1553.c
@@ -297,7 +297,7 @@ static struct bin_attribute ds1553_nvram_attr = {
         .write = ds1553_nvram_write,
 };
 
-static int __init ds1553_rtc_probe(struct platform_device *pdev)
+static int __devinit ds1553_rtc_probe(struct platform_device *pdev)
 {
         struct rtc_device *rtc;
         struct resource *res;
diff --git a/drivers/rtc/rtc-ds1742.c b/drivers/rtc/rtc-ds1742.c
index 17633bfa84..d68288b389 100644
--- a/drivers/rtc/rtc-ds1742.c
+++ b/drivers/rtc/rtc-ds1742.c
@@ -165,7 +165,7 @@ static struct bin_attribute ds1742_nvram_attr = {
         .write = ds1742_nvram_write,
 };
 
-static int __init ds1742_rtc_probe(struct platform_device *pdev)
+static int __devinit ds1742_rtc_probe(struct platform_device *pdev)
 {
         struct rtc_device *rtc;
         struct resource *res;
diff --git a/drivers/rtc/rtc-proc.c b/drivers/rtc/rtc-proc.c
index c272afd621..1bd624fc68 100644
--- a/drivers/rtc/rtc-proc.c
+++ b/drivers/rtc/rtc-proc.c
@@ -96,7 +96,7 @@ static int rtc_proc_release(struct inode *inode, struct file *file)
         return res;
 }
 
-static struct file_operations rtc_proc_fops = {
+static const struct file_operations rtc_proc_fops = {
         .open           = rtc_proc_open,
         .read           = seq_read,
         .llseek         = seq_lseek,
diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index 2ddd0cf071..899ab8c514 100644
--- a/drivers/rtc/rtc-sysfs.c
+++ b/drivers/rtc/rtc-sysfs.c
@@ -78,6 +78,92 @@ static struct attribute_group rtc_attr_group = {
         .attrs = rtc_attrs,
 };
 
+
+static ssize_t
+rtc_sysfs_show_wakealarm(struct class_device *dev, char *buf)
+{
+        ssize_t retval;
+        unsigned long alarm;
+        struct rtc_wkalrm alm;
+
+        /* Don't show disabled alarms; but the RTC could leave the
+         * alarm enabled after it's already triggered.  Alarms are
+         * conceptually one-shot, even though some common hardware
+         * (PCs) doesn't actually work that way.
+         *
+         * REVISIT maybe we should require RTC implementations to
+         * disable the RTC alarm after it triggers, for uniformity.
+         */
+        retval = rtc_read_alarm(dev, &alm);
+        if (retval == 0 && alm.enabled) {
+                rtc_tm_to_time(&alm.time, &alarm);
+                retval = sprintf(buf, "%lu\n", alarm);
+        }
+
+        return retval;
+}
+
+static ssize_t
+rtc_sysfs_set_wakealarm(struct class_device *dev, const char *buf, size_t n)
+{
+        ssize_t retval;
+        unsigned long now, alarm;
+        struct rtc_wkalrm alm;
+
+        /* 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(dev, &alm.time);
+        if (retval < 0)
+                return retval;
+        rtc_tm_to_time(&alm.time, &now);
+
+        alarm = simple_strtoul(buf, NULL, 0);
+        if (alarm > now) {
+                /* 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(dev, &alm);
+                if (retval < 0)
+                        return retval;
+                if (alm.enabled)
+                        return -EBUSY;
+
+                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_time_to_tm(alarm, &alm.time);
+
+        retval = rtc_set_alarm(dev, &alm);
+        return (retval < 0) ? retval : n;
+}
+static const CLASS_DEVICE_ATTR(wakealarm, S_IRUGO | S_IWUSR,
+                rtc_sysfs_show_wakealarm, rtc_sysfs_set_wakealarm);
+
+
+/* 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 inline int rtc_does_wakealarm(struct class_device *class_dev)
+{
+        struct rtc_device *rtc;
+
+        if (!device_can_wakeup(class_dev->dev))
+                return 0;
+        rtc = to_rtc_device(class_dev);
+        return rtc->ops->set_alarm != NULL;
+}
+
+
 static int rtc_sysfs_add_device(struct class_device *class_dev,
                                         struct class_interface *class_intf)
 {
@@ -87,8 +173,18 @@ static int rtc_sysfs_add_device(struct class_device *class_dev,
 
         err = sysfs_create_group(&class_dev->kobj, &rtc_attr_group);
         if (err)
-                dev_err(class_dev->dev,
-                        "failed to create sysfs attributes\n");
+                dev_err(class_dev->dev, "failed to create %s\n",
+                                "sysfs attributes");
+        else if (rtc_does_wakealarm(class_dev)) {
+                /* not all RTCs support both alarms and wakeup */
+                err = class_device_create_file(class_dev,
+                                        &class_device_attr_wakealarm);
+                if (err) {
+                        dev_err(class_dev->dev, "failed to create %s\n",
+                                        "alarm attribute");
+                        sysfs_remove_group(&class_dev->kobj, &rtc_attr_group);
+                }
+        }
 
         return err;
 }
@@ -96,6 +192,9 @@ static int rtc_sysfs_add_device(struct class_device *class_dev,
 static void rtc_sysfs_remove_device(struct class_device *class_dev,
                                 struct class_interface *class_intf)
 {
+        if (rtc_does_wakealarm(class_dev))
+                class_device_remove_file(class_dev,
+                                &class_device_attr_wakealarm);
         sysfs_remove_group(&class_dev->kobj, &rtc_attr_group);
 }