[RFC PATCH 06/10] alpha: Reorganize rtc handling

From: Richard Henderson
Date: Tue Jul 16 2013 - 13:35:16 EST

Discontinue use of GENERIC_CMOS_UPDATE; rely on the RTC subsystem.

The marvel platform requires that the rtc only be touched from the
boot cpu. This had been partially implemented with hooks for
get/set_rtc_time, but read/update_persistent_clock were not handled.
Fixed by adding an rtc_set_mmss hook along the way.

We had read_persistent_clock managing the epoch against which the
rtc hw is based, but this didn't apply to get_rtc_time or set_rtc_time.
This resulted in incorrect values when hwclock(8) gets involved.

Allow the epoch to be set from the kernel command-line, overriding
the autodetection, which is doomed to fail in 2028. Further, by
implementing the rtc ioctl function, we can expose this epoch to
userland.

Elide the alarm functions that RTC_DRV_CMOS implements. This was
highly questionable on Alpha, since the interrupt is used by the
system timer.

Cc: rtc-linux@xxxxxxxxxxxxxxxx
Signed-off-by: Richard Henderson <rth@xxxxxxxxxxx>
---
arch/alpha/Kconfig | 1 -
arch/alpha/include/asm/machvec.h | 4 +-
arch/alpha/include/asm/rtc.h | 11 --
arch/alpha/kernel/Makefile | 1 +
arch/alpha/kernel/machvec_impl.h | 5 +-
arch/alpha/kernel/proto.h | 9 ++
arch/alpha/kernel/rtc.c | 323 +++++++++++++++++++++++++++++++++++++++
arch/alpha/kernel/sys_jensen.c | 2 -
arch/alpha/kernel/sys_marvel.c | 55 +------
arch/alpha/kernel/time.c | 146 +-----------------
drivers/rtc/Kconfig | 10 +-
11 files changed, 346 insertions(+), 221 deletions(-)
create mode 100644 arch/alpha/kernel/rtc.c

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 5991a99..7e268cf 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -17,7 +17,6 @@ config ALPHA
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
select GENERIC_SMP_IDLE_THREAD
- select GENERIC_CMOS_UPDATE
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
select HAVE_MOD_ARCH_SPECIFIC
diff --git a/arch/alpha/include/asm/machvec.h b/arch/alpha/include/asm/machvec.h
index 4ac9016..75cb364 100644
--- a/arch/alpha/include/asm/machvec.h
+++ b/arch/alpha/include/asm/machvec.h
@@ -33,6 +33,7 @@ struct alpha_machine_vector

int nr_irqs;
int rtc_port;
+ int rtc_boot_cpu_only;
unsigned int max_asn;
unsigned long max_isa_dma_address;
unsigned long irq_probe_mask;
@@ -95,9 +96,6 @@ struct alpha_machine_vector

struct _alpha_agp_info *(*agp_info)(void);

- unsigned int (*rtc_get_time)(struct rtc_time *);
- int (*rtc_set_time)(struct rtc_time *);
-
const char *vector_name;

/* NUMA information */
diff --git a/arch/alpha/include/asm/rtc.h b/arch/alpha/include/asm/rtc.h
index d70408d..f71c3b0 100644
--- a/arch/alpha/include/asm/rtc.h
+++ b/arch/alpha/include/asm/rtc.h
@@ -1,12 +1 @@
-#ifndef _ALPHA_RTC_H
-#define _ALPHA_RTC_H
-
-#if defined(CONFIG_ALPHA_MARVEL) && defined(CONFIG_SMP) \
- || defined(CONFIG_ALPHA_GENERIC)
-# define get_rtc_time alpha_mv.rtc_get_time
-# define set_rtc_time alpha_mv.rtc_set_time
-#endif
-
#include <asm-generic/rtc.h>
-
-#endif
diff --git a/arch/alpha/kernel/Makefile b/arch/alpha/kernel/Makefile
index 84ec46b..0d54650 100644
--- a/arch/alpha/kernel/Makefile
+++ b/arch/alpha/kernel/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_PCI) += pci.o pci_iommu.o pci-sysfs.o
obj-$(CONFIG_SRM_ENV) += srm_env.o
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_PERF_EVENTS) += perf_event.o
+obj-$(CONFIG_RTC_DRV_ALPHA) += rtc.o

ifdef CONFIG_ALPHA_GENERIC

diff --git a/arch/alpha/kernel/machvec_impl.h b/arch/alpha/kernel/machvec_impl.h
index 7fa6248..f54bdf6 100644
--- a/arch/alpha/kernel/machvec_impl.h
+++ b/arch/alpha/kernel/machvec_impl.h
@@ -43,10 +43,7 @@
#define CAT1(x,y) x##y
#define CAT(x,y) CAT1(x,y)

-#define DO_DEFAULT_RTC \
- .rtc_port = 0x70, \
- .rtc_get_time = common_get_rtc_time, \
- .rtc_set_time = common_set_rtc_time
+#define DO_DEFAULT_RTC .rtc_port = 0x70

#define DO_EV4_MMU \
.max_asn = EV4_MAX_ASN, \
diff --git a/arch/alpha/kernel/proto.h b/arch/alpha/kernel/proto.h
index d3e52d3..b0c8498 100644
--- a/arch/alpha/kernel/proto.h
+++ b/arch/alpha/kernel/proto.h
@@ -144,8 +144,17 @@ extern void smp_percpu_timer_interrupt(struct pt_regs *);
extern irqreturn_t timer_interrupt(int irq, void *dev);
extern void common_init_rtc(void);
extern unsigned long est_cycle_freq;
+
+/* rtc.c */
+#ifdef CONFIG_RTC_DRV_ALPHA
extern unsigned int common_get_rtc_time(struct rtc_time *time);
extern int common_set_rtc_time(struct rtc_time *time);
+extern int common_set_rtc_mmss(unsigned long);
+#else
+# define common_get_rtc_time NULL
+# define common_set_rtc_time NULL
+# define common_set_rtc_mmss NULL
+#endif

/* smc37c93x.c */
extern void SMC93x_Init(void);
diff --git a/arch/alpha/kernel/rtc.c b/arch/alpha/kernel/rtc.c
new file mode 100644
index 0000000..c8d284d
--- /dev/null
+++ b/arch/alpha/kernel/rtc.c
@@ -0,0 +1,323 @@
+/*
+ * linux/arch/alpha/kernel/rtc.c
+ *
+ * Copyright (C) 1991, 1992, 1995, 1999, 2000 Linus Torvalds
+ *
+ * This file contains date handling.
+ */
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/param.h>
+#include <linux/string.h>
+#include <linux/mc146818rtc.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/platform_device.h>
+
+#include <asm/rtc.h>
+
+#include "proto.h"
+
+
+/*
+ * Support for the RTC device.
+ *
+ * We don't want to use the rtc-cmos driver, because we don't want to support
+ * alarms, as that would be indistinguishable from timer interrupts.
+ *
+ * Further, generic code is really, really tied to a 1900 epoch. This is
+ * true in __get_rtc_time as well as the users of struct rtc_time e.g.
+ * rtc_tm_to_time. Thankfully all of the other epochs in use are later
+ * than 1900, and so it's easy to adjust.
+ */
+
+static unsigned long rtc_epoch;
+
+static int __init
+specifiy_epoch(char *str)
+{
+ unsigned long epoch = simple_strtoul(str, NULL, 0);
+ if (epoch < 1900)
+ printk("Ignoring invalid user specified epoch %lu\n", epoch);
+ else
+ rtc_epoch = epoch;
+ return 1;
+}
+__setup("epoch=", specifiy_epoch);
+
+static void __init
+init_rtc_epoch(void)
+{
+ int epoch, year, ctrl;
+
+ if (rtc_epoch != 0) {
+ /* The epoch was specified on the command-line. */
+ return;
+ }
+
+ /* Detect the epoch in use on this computer. */
+ ctrl = CMOS_READ(RTC_CONTROL);
+ year = CMOS_READ(RTC_YEAR);
+ if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+ year = bcd2bin(year);
+
+ /* PC-like is standard; used for year >= 70 */
+ epoch = 1900;
+ if (year < 20) {
+ epoch = 2000;
+ } else if (year >= 20 && year < 48) {
+ /* NT epoch */
+ epoch = 1980;
+ } else if (year >= 48 && year < 70) {
+ /* Digital UNIX epoch */
+ epoch = 1952;
+ }
+ rtc_epoch = epoch;
+
+ printk(KERN_INFO "Using epoch %d for rtc year %d\n", epoch, year);
+}
+
+static int
+alpha_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ __get_rtc_time(tm);
+
+ /* Adjust for non-default epochs. It's easier to depend on the
+ generic __get_rtc_time and adjust the epoch here than create
+ a copy of __get_rtc_time with the edits we need. */
+ if (rtc_epoch != 1900) {
+ int year = tm->tm_year;
+ /* Undo the century adjustment made in __get_rtc_time. */
+ if (year >= 100)
+ year -= 100;
+ year += rtc_epoch - 1900;
+ /* Redo the century adjustment with the epoch in place. */
+ if (year <= 69)
+ year += 100;
+ tm->tm_year = year;
+ }
+
+ return rtc_valid_tm(tm);
+}
+
+static int
+alpha_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct rtc_time xtm;
+
+ if (rtc_epoch != 1900) {
+ xtm = *tm;
+ xtm.tm_year -= rtc_epoch - 1900;
+ tm = &xtm;
+ }
+
+ return __set_rtc_time(tm);
+}
+
+static int
+alpha_rtc_set_mmss(struct device *dev, unsigned long nowtime)
+{
+ int retval = 0;
+ int real_seconds, real_minutes, cmos_minutes;
+ unsigned char save_control, save_freq_select;
+
+ /* Note: This code only updates minutes and seconds. Comments
+ indicate this was to avoid messing with unknown time zones,
+ and with the epoch nonsense described above. In order for
+ this to work, the existing clock cannot be off by more than
+ 15 minutes.
+
+ ??? This choice is may be out of date. The x86 port does
+ not have problems with timezones, and the epoch processing has
+ now been fixed in alpha_set_rtc_time.
+
+ In either case, one can always force a full rtc update with
+ the userland hwclock program, so surely 15 minute accuracy
+ is no real burden. */
+
+ /* In order to set the CMOS clock precisely, we have to be called
+ 500 ms after the second nowtime has started, because when
+ nowtime is written into the registers of the CMOS clock, it will
+ jump to the next second precisely 500 ms later. Check the Motorola
+ MC146818A or Dallas DS12887 data sheet for details. */
+
+ /* irq are locally disabled here */
+ spin_lock(&rtc_lock);
+ /* Tell the clock it's being set */
+ save_control = CMOS_READ(RTC_CONTROL);
+ CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
+
+ /* Stop and reset prescaler */
+ save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
+ CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
+
+ cmos_minutes = CMOS_READ(RTC_MINUTES);
+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+ cmos_minutes = bcd2bin(cmos_minutes);
+
+ real_seconds = nowtime % 60;
+ real_minutes = nowtime / 60;
+ if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1) {
+ /* correct for half hour time zone */
+ real_minutes += 30;
+ }
+ real_minutes %= 60;
+
+ if (abs(real_minutes - cmos_minutes) < 30) {
+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+ real_seconds = bin2bcd(real_seconds);
+ real_minutes = bin2bcd(real_minutes);
+ }
+ CMOS_WRITE(real_seconds,RTC_SECONDS);
+ CMOS_WRITE(real_minutes,RTC_MINUTES);
+ } else {
+ printk_once(KERN_NOTICE
+ "set_rtc_mmss: can't update from %d to %d\n",
+ cmos_minutes, real_minutes);
+ retval = -1;
+ }
+
+ /* The following flags have to be released exactly in this order,
+ * otherwise the DS12887 (popular MC146818A clone with integrated
+ * battery and quartz) will not reset the oscillator and will not
+ * update precisely 500 ms later. You won't find this mentioned in
+ * the Dallas Semiconductor data sheets, but who believes data
+ * sheets anyway ... -- Markus Kuhn
+ */
+ CMOS_WRITE(save_control, RTC_CONTROL);
+ CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
+ spin_unlock(&rtc_lock);
+
+ return retval;
+}
+
+static int
+alpha_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
+{
+ switch (cmd) {
+ case RTC_EPOCH_READ:
+ return put_user(rtc_epoch, (unsigned long __user *)arg);
+ case RTC_EPOCH_SET:
+ if (arg < 1900)
+ return -EINVAL;
+ rtc_epoch = arg;
+ return 0;
+ default:
+ return -ENOIOCTLCMD;
+ }
+}
+
+static const struct rtc_class_ops alpha_rtc_ops = {
+ .read_time = alpha_rtc_read_time,
+ .set_time = alpha_rtc_set_time,
+ .set_mmss = alpha_rtc_set_mmss,
+ .ioctl = alpha_rtc_ioctl,
+};
+
+/*
+ * Similarly, except do the actual CMOS access on the boot cpu only.
+ * This requires marshalling the data across an interprocessor call.
+ */
+
+#if defined(CONFIG_SMP) && \
+ (defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_MARVEL))
+# define HAVE_REMOTE_RTC 1
+
+union remote_data {
+ struct rtc_time *tm;
+ unsigned long now;
+ long retval;
+};
+
+static void
+do_remote_read(void *data)
+{
+ union remote_data *x = data;
+ x->retval = alpha_rtc_read_time(NULL, x->tm);
+}
+
+static int
+remote_read_time(struct device *dev, struct rtc_time *tm)
+{
+ union remote_data x;
+ if (smp_processor_id() != boot_cpuid) {
+ x.tm = tm;
+ smp_call_function_single(boot_cpuid, do_remote_read, &x, 1);
+ return x.retval;
+ }
+ return alpha_rtc_read_time(NULL, tm);
+}
+
+static void
+do_remote_set(void *data)
+{
+ union remote_data *x = data;
+ x->retval = alpha_rtc_set_time(NULL, x->tm);
+}
+
+static int
+remote_set_time(struct device *dev, struct rtc_time *tm)
+{
+ union remote_data x;
+ if (smp_processor_id() != boot_cpuid) {
+ x.tm = tm;
+ smp_call_function_single(boot_cpuid, do_remote_set, &x, 1);
+ return x.retval;
+ }
+ return alpha_rtc_set_time(NULL, tm);
+}
+
+static void
+do_remote_mmss(void *data)
+{
+ union remote_data *x = data;
+ x->retval = alpha_rtc_set_mmss(NULL, x->now);
+}
+
+static int
+remote_set_mmss(struct device *dev, unsigned long now)
+{
+ union remote_data x;
+ if (smp_processor_id() != boot_cpuid) {
+ x.now = now;
+ smp_call_function_single(boot_cpuid, do_remote_mmss, &x, 1);
+ return x.retval;
+ }
+ return alpha_rtc_set_mmss(NULL, now);
+}
+
+static const struct rtc_class_ops remote_rtc_ops = {
+ .read_time = remote_read_time,
+ .set_time = remote_set_time,
+ .set_mmss = remote_set_mmss,
+ .ioctl = alpha_rtc_ioctl,
+};
+#endif
+
+static int __init
+alpha_rtc_init(void)
+{
+ const struct rtc_class_ops *ops;
+ struct platform_device *pdev;
+ struct rtc_device *rtc;
+ const char *name;
+
+ init_rtc_epoch();
+ name = "rtc-alpha";
+ ops = &alpha_rtc_ops;
+
+#ifdef HAVE_REMOTE_RTC
+ if (alpha_mv.rtc_boot_cpu_only)
+ ops = &remote_rtc_ops;
+#endif
+
+ pdev = platform_device_register_simple(name, -1, NULL, 0);
+ rtc = devm_rtc_device_register(&pdev->dev, name, ops, THIS_MODULE);
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ platform_set_drvdata(pdev, rtc);
+ return 0;
+}
+device_initcall(alpha_rtc_init);
diff --git a/arch/alpha/kernel/sys_jensen.c b/arch/alpha/kernel/sys_jensen.c
index 5a0af11..608f2a7 100644
--- a/arch/alpha/kernel/sys_jensen.c
+++ b/arch/alpha/kernel/sys_jensen.c
@@ -224,8 +224,6 @@ struct alpha_machine_vector jensen_mv __initmv = {
.machine_check = jensen_machine_check,
.max_isa_dma_address = ALPHA_MAX_ISA_DMA_ADDRESS,
.rtc_port = 0x170,
- .rtc_get_time = common_get_rtc_time,
- .rtc_set_time = common_set_rtc_time,

.nr_irqs = 16,
.device_interrupt = jensen_device_interrupt,
diff --git a/arch/alpha/kernel/sys_marvel.c b/arch/alpha/kernel/sys_marvel.c
index 53d6e4a..03d63c6 100644
--- a/arch/alpha/kernel/sys_marvel.c
+++ b/arch/alpha/kernel/sys_marvel.c
@@ -22,7 +22,6 @@
#include <asm/hwrpb.h>
#include <asm/tlbflush.h>
#include <asm/vga.h>
-#include <asm/rtc.h>

#include "proto.h"
#include "err_impl.h"
@@ -400,57 +399,6 @@ marvel_init_rtc(void)
init_rtc_irq();
}

-struct marvel_rtc_time {
- struct rtc_time *time;
- int retval;
-};
-
-#ifdef CONFIG_SMP
-static void
-smp_get_rtc_time(void *data)
-{
- struct marvel_rtc_time *mrt = data;
- mrt->retval = __get_rtc_time(mrt->time);
-}
-
-static void
-smp_set_rtc_time(void *data)
-{
- struct marvel_rtc_time *mrt = data;
- mrt->retval = __set_rtc_time(mrt->time);
-}
-#endif
-
-static unsigned int
-marvel_get_rtc_time(struct rtc_time *time)
-{
-#ifdef CONFIG_SMP
- struct marvel_rtc_time mrt;
-
- if (smp_processor_id() != boot_cpuid) {
- mrt.time = time;
- smp_call_function_single(boot_cpuid, smp_get_rtc_time, &mrt, 1);
- return mrt.retval;
- }
-#endif
- return __get_rtc_time(time);
-}
-
-static int
-marvel_set_rtc_time(struct rtc_time *time)
-{
-#ifdef CONFIG_SMP
- struct marvel_rtc_time mrt;
-
- if (smp_processor_id() != boot_cpuid) {
- mrt.time = time;
- smp_call_function_single(boot_cpuid, smp_set_rtc_time, &mrt, 1);
- return mrt.retval;
- }
-#endif
- return __set_rtc_time(time);
-}
-
static void
marvel_smp_callin(void)
{
@@ -492,8 +440,7 @@ struct alpha_machine_vector marvel_ev7_mv __initmv = {
.vector_name = "MARVEL/EV7",
DO_EV7_MMU,
.rtc_port = 0x70,
- .rtc_get_time = marvel_get_rtc_time,
- .rtc_set_time = marvel_set_rtc_time,
+ .rtc_boot_cpu_only = 1,
DO_MARVEL_IO,
.machine_check = marvel_machine_check,
.max_isa_dma_address = ALPHA_MAX_ISA_DMA_ADDRESS,
diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c
index 7938bf9..dbd56ec 100644
--- a/arch/alpha/kernel/time.c
+++ b/arch/alpha/kernel/time.c
@@ -3,13 +3,7 @@
*
* Copyright (C) 1991, 1992, 1995, 1999, 2000 Linus Torvalds
*
- * This file contains the PC-specific time handling details:
- * reading the RTC at bootup, etc..
- * 1994-07-02 Alan Modra
- * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
- * 1995-03-26 Markus Kuhn
- * fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
- * precision CMOS clock update
+ * This file contains the clocksource time handling.
* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
* "A Kernel Model for Precision Timekeeping" by Dave Mills
* 1997-01-09 Adrian Sun
@@ -21,9 +15,6 @@
* 1999-04-16 Thorsten Kranzkowski (dl8bcu@xxxxxxx)
* fixed algorithm in do_gettimeofday() for calculating the precise time
* from processor cycle counter (now taking lost_ticks into account)
- * 2000-08-13 Jan-Benedict Glaw <jbglaw@xxxxxxxxxx>
- * Fixed time_init to be aware of epoches != 1900. This prevents
- * booting up in 2048 for me;) Code is stolen from rtc.c.
* 2003-06-03 R. Scott Bailey <scott.bailey@xxxxxxx>
* Tighten sanity in time_init from 1% (10,000 PPM) to 250 PPM
*/
@@ -46,7 +37,6 @@
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/hwrpb.h>
-#include <asm/rtc.h>

#include <linux/mc146818rtc.h>
#include <linux/time.h>
@@ -56,8 +46,6 @@
#include "proto.h"
#include "irq_impl.h"

-static int set_rtc_mmss(unsigned long);
-
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);

@@ -110,53 +98,6 @@ static inline __u32 rpcc(void)
return result;
}

-int update_persistent_clock(struct timespec now)
-{
- return set_rtc_mmss(now.tv_sec);
-}
-
-void read_persistent_clock(struct timespec *ts)
-{
- unsigned int year, mon, day, hour, min, sec, epoch;
-
- sec = CMOS_READ(RTC_SECONDS);
- min = CMOS_READ(RTC_MINUTES);
- hour = CMOS_READ(RTC_HOURS);
- day = CMOS_READ(RTC_DAY_OF_MONTH);
- mon = CMOS_READ(RTC_MONTH);
- year = CMOS_READ(RTC_YEAR);
-
- if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
- sec = bcd2bin(sec);
- min = bcd2bin(min);
- hour = bcd2bin(hour);
- day = bcd2bin(day);
- mon = bcd2bin(mon);
- year = bcd2bin(year);
- }
-
- /* PC-like is standard; used for year >= 70 */
- epoch = 1900;
- if (year < 20)
- epoch = 2000;
- else if (year >= 20 && year < 48)
- /* NT epoch */
- epoch = 1980;
- else if (year >= 48 && year < 70)
- /* Digital UNIX epoch */
- epoch = 1952;
-
- printk(KERN_INFO "Using epoch = %d\n", epoch);
-
- if ((year += epoch) < 1970)
- year += 100;
-
- ts->tv_sec = mktime(year, mon, day, hour, min, sec);
- ts->tv_nsec = 0;
-}
-
-
-
/*
* timer_interrupt() needs to keep up the real-time clock,
* as well as call the "xtime_update()" routine every clocktick
@@ -245,16 +186,6 @@ common_init_rtc(void)
init_rtc_irq();
}

-unsigned int common_get_rtc_time(struct rtc_time *time)
-{
- return __get_rtc_time(time);
-}
-
-int common_set_rtc_time(struct rtc_time *time)
-{
- return __set_rtc_time(time);
-}
-
/* Validate a computed cycle counter result against the known bounds for
the given processor core. There's too much brokenness in the way of
timing hardware for any one method to work everywhere. :-(
@@ -455,78 +386,3 @@ time_init(void)
/* Startup the timer source. */
alpha_mv.init_rtc();
}
-
-/*
- * In order to set the CMOS clock precisely, set_rtc_mmss has to be
- * called 500 ms after the second nowtime has started, because when
- * nowtime is written into the registers of the CMOS clock, it will
- * jump to the next second precisely 500 ms later. Check the Motorola
- * MC146818A or Dallas DS12887 data sheet for details.
- *
- * BUG: This routine does not handle hour overflow properly; it just
- * sets the minutes. Usually you won't notice until after reboot!
- */
-
-
-static int
-set_rtc_mmss(unsigned long nowtime)
-{
- int retval = 0;
- int real_seconds, real_minutes, cmos_minutes;
- unsigned char save_control, save_freq_select;
-
- /* irq are locally disabled here */
- spin_lock(&rtc_lock);
- /* Tell the clock it's being set */
- save_control = CMOS_READ(RTC_CONTROL);
- CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
-
- /* Stop and reset prescaler */
- save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
- CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
-
- cmos_minutes = CMOS_READ(RTC_MINUTES);
- if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
- cmos_minutes = bcd2bin(cmos_minutes);
-
- /*
- * since we're only adjusting minutes and seconds,
- * don't interfere with hour overflow. This avoids
- * messing with unknown time zones but requires your
- * RTC not to be off by more than 15 minutes
- */
- real_seconds = nowtime % 60;
- real_minutes = nowtime / 60;
- if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) {
- /* correct for half hour time zone */
- real_minutes += 30;
- }
- real_minutes %= 60;
-
- if (abs(real_minutes - cmos_minutes) < 30) {
- if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
- real_seconds = bin2bcd(real_seconds);
- real_minutes = bin2bcd(real_minutes);
- }
- CMOS_WRITE(real_seconds,RTC_SECONDS);
- CMOS_WRITE(real_minutes,RTC_MINUTES);
- } else {
- printk_once(KERN_NOTICE
- "set_rtc_mmss: can't update from %d to %d\n",
- cmos_minutes, real_minutes);
- retval = -1;
- }
-
- /* The following flags have to be released exactly in this order,
- * otherwise the DS12887 (popular MC146818A clone with integrated
- * battery and quartz) will not reset the oscillator and will not
- * update precisely 500 ms later. You won't find this mentioned in
- * the Dallas Semiconductor data sheets, but who believes data
- * sheets anyway ... -- Markus Kuhn
- */
- CMOS_WRITE(save_control, RTC_CONTROL);
- CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
- spin_unlock(&rtc_lock);
-
- return retval;
-}
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 9e3498b..a4d3f9a 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -606,7 +606,7 @@ comment "Platform RTC drivers"

config RTC_DRV_CMOS
tristate "PC-style 'CMOS'"
- depends on X86 || ALPHA || ARM || M32R || ATARI || PPC || MIPS || SPARC64
+ depends on X86 || ARM || M32R || ATARI || PPC || MIPS || SPARC64
default y if X86
help
Say "yes" here to get direct support for the real time clock
@@ -623,6 +623,14 @@ config RTC_DRV_CMOS
This driver can also be built as a module. If so, the module
will be called rtc-cmos.

+config RTC_DRV_ALPHA
+ bool "Alpha PC-style CMOS"
+ depends on ALPHA
+ default y
+ help
+ Direct support for the real-time clock found on every Alpha
+ system, specifically MC146818 compatibles. If in doubt, say Y.
+
config RTC_DRV_VRTC
tristate "Virtual RTC for Intel MID platforms"
depends on X86_INTEL_MID
--
1.8.1.4

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