Re: [linux-pm] sleepy linux self-test

[David Brownell <david-b@pacbell.net>]

On Saturday 02 February 2008, Ingo Molnar wrote:
> randconfig testing found the following build failure:
> 
> kernel/built-in.o: In function `be_sleepy':
> sleepy.c:(.init.text+0x1952): undefined reference to `rtc_class'
> sleepy.c:(.init.text+0x1963): undefined reference to `rtc_class_open'

Because:

> CONFIG_RTC_LIB=m

I think that the wakealarm test:

> +config PM_WAKEALARM_TEST
> +       bool "Test suspend/resume and wakealarm during bootup"
> +       depends on SUSPEND && PM_DEBUG && RTC_LIB

should depend on RTC_LIB=y ... which will prevent that build error,
but would still allow the RTC to live in a module.

Updated patch appended ... it should address most config issues.

- Dave


====== CUT HERE
Updated verion of Pavel's "sleepy" test.  This version doesn't depend on
x86-specific RTC support, or suspend-to-RAM capability, and describes
itself a bit better.

Partially tested on an ARM board ... for some reason system sleep states
are currently broken on that system (new behavior since 2.6.24), so this
won't yet complete.

Note a generic glitch:  the message strings aren't in the same section
as the function using them, so this has a bigger runtime footprint than
it should ...

---
 drivers/char/Kconfig  |    5 +-
 drivers/rtc/Kconfig   |    1 
 kernel/power/Kconfig  |   17 ++++++-
 kernel/power/Makefile |    2 
 kernel/power/sleepy.c |  113 ++++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 134 insertions(+), 4 deletions(-)

--- g26.orig/drivers/char/Kconfig	2008-02-02 22:42:15.000000000 -0800
+++ g26/drivers/char/Kconfig	2008-02-02 22:51:53.000000000 -0800
@@ -715,9 +715,12 @@ config NVRAM
 	  To compile this driver as a module, choose M here: the
 	  module will be called nvram.
 
+comment "You are using the RTC framework, not the legacy CMOS RTC driver"
+	depends on RTC_DRV_CMOS
+
 config RTC
 	tristate "Enhanced Real Time Clock Support"
-	depends on !PPC && !PARISC && !IA64 && !M68K && !SPARC && !FRV && !ARM && !SUPERH && !S390
+	depends on !PPC && !PARISC && !IA64 && !M68K && !SPARC && !FRV && !ARM && !SUPERH && !S390 && !RTC_DRV_CMOS
 	---help---
 	  If you say Y here and create a character special file /dev/rtc with
 	  major number 10 and minor number 135 using mknod ("man mknod"), you
--- g26.orig/drivers/rtc/Kconfig	2008-02-02 22:37:28.000000000 -0800
+++ g26/drivers/rtc/Kconfig	2008-02-02 22:38:23.000000000 -0800
@@ -281,6 +281,7 @@ comment "Platform RTC drivers"
 config RTC_DRV_CMOS
 	tristate "PC-style 'CMOS'"
 	depends on X86 || ALPHA || ARM || M32R || ATARI || PPC || MIPS
+	default y if X86
 	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.
--- g26.orig/kernel/power/Kconfig	2008-02-02 22:30:21.000000000 -0800
+++ g26/kernel/power/Kconfig	2008-02-02 23:28:56.000000000 -0800
@@ -1,3 +1,6 @@
+#
+# Note that power management involves more than just system sleep states...
+#
 config PM
 	bool "Power Management support"
 	depends on !IA64_HP_SIM
@@ -74,8 +77,8 @@ config PM_TRACE_RTC
 	RTC across reboots, so that you can debug a machine that just hangs
 	during suspend (or more commonly, during resume).
 
-	To use this debugging feature you should attempt to suspend the machine,
-	then reboot it, then run
+	To use this debugging feature you should attempt to suspend the
+	machine, then reboot it, then run
 
 		dmesg -s 1000000 | grep 'hash matches'
 
@@ -104,6 +107,16 @@ config SUSPEND
 	  powered and thus its contents are preserved, such as the
 	  suspend-to-RAM state (e.g. the ACPI S3 state).
 
+config PM_WAKEALARM_TEST
+	bool "Test suspend/resume and wakealarm during bootup"
+	depends on SUSPEND && PM_DEBUG && RTC_LIB=y
+	---help---
+	This option will suspend your machine during bootup, and make
+	it wake up a few seconds later using the RTC's wakeup alarm.
+
+	You probably want to have your system's RTC driver statically
+	linked, ensuring that it's available when this test runs.
+
 config SUSPEND_FREEZER
 	bool "Enable freezer for suspend to RAM/standby" \
 		if ARCH_WANTS_FREEZER_CONTROL || BROKEN
--- g26.orig/kernel/power/Makefile	2008-02-02 22:30:21.000000000 -0800
+++ g26/kernel/power/Makefile	2008-02-02 22:37:18.000000000 -0800
@@ -5,7 +5,7 @@ endif
 
 obj-y				:= main.o
 obj-$(CONFIG_PM_LEGACY)		+= pm.o
-obj-$(CONFIG_PM_SLEEP)		+= process.o console.o
+obj-$(CONFIG_PM_SLEEP)		+= process.o console.o sleepy.o
 obj-$(CONFIG_HIBERNATION)	+= swsusp.o disk.o snapshot.o swap.o user.o
 
 obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ g26/kernel/power/sleepy.c	2008-02-02 23:29:53.000000000 -0800
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2007 Pavel Machek <pavel@suse.cz>
+ * Copyright (c) 2008 David Brownell
+ *
+ * This file is released under the GPLv2
+ */
+
+#include <linux/module.h>
+#include <linux/suspend.h>
+#include <linux/kobject.h>
+#include <linux/string.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/cpu.h>
+#include <linux/resume-trace.h>
+#include <linux/freezer.h>
+#include <linux/vmstat.h>
+#include <linux/syscalls.h>
+#include <linux/rtc.h>
+
+#include <asm/percpu.h>
+
+#include "power.h"
+
+
+static struct rtc_device *rtc;
+static suspend_state_t sleepy_state;
+
+static int __init has_wakealarm(struct device *dev, void *name_ptr)
+{
+	struct rtc_device *candidate = to_rtc_device(dev);
+
+	if (!candidate->ops->set_alarm)
+		return 0;
+	if (!device_may_wakeup(candidate->dev.parent))
+		return 0;
+
+	*(char **)name_ptr = dev->bus_id;
+	return 1;
+}
+
+#ifdef CONFIG_PM_WAKEALARM_TEST
+
+/* This needs to be long enough for the system to suspend all its devices
+ * and enter a suspend-to-RAM (or, potentially, standby) state no matter
+ * what else is going on.  But suspending can take arbitrarily long...
+ */
+#define ALARM_SECONDS	5
+
+static void __init test_wakealarm(void)
+{
+	unsigned long		now;
+	struct rtc_wkalrm	alm;
+	int			status;
+
+	/* this may fail if the RTC hasn't been initialized */
+	status = rtc_read_time(rtc, &alm.time);
+	if (status < 0) {
+		pr_err("PM: can't read %s time, err %d\n",
+				rtc->dev.bus_id, status);
+		return;
+	}
+	rtc_tm_to_time(&alm.time, &now);
+
+	memset(&alm, 0, sizeof alm);
+	rtc_time_to_tm(now + ALARM_SECONDS, &alm.time);
+	alm.enabled = true;
+
+	status = rtc_set_alarm(rtc, &alm);
+	if (status < 0) {
+		pr_err("PM: can't set %s wakealarm, err %d\n",
+				rtc->dev.bus_id, status);
+		return;
+	}
+
+	pr_info("PM: wakealarm test with Suspend-to-RAM\n");
+	sleepy_state = PM_SUSPEND_MEM;
+	status = pm_suspend(sleepy_state);
+	if (status == -ENODEV) {
+		pr_warning("PM: no Suspend-To-RAM, trying standby...\n");
+		sleepy_state = PM_SUSPEND_STANDBY;
+		status = pm_suspend(sleepy_state);
+	}
+	if (status)
+		pr_err("PM: wakealarm test failed, error %d\n", status);
+}
+
+#else
+
+static void __init test_wakealarm(void)
+{
+	/* FIXME sleepy_state is PM_SUSPEND_ON; not useful ... */
+}
+
+#endif
+
+static int __init be_sleepy(void)
+{
+	char *pony = NULL;
+
+	class_find_device(rtc_class, &pony, has_wakealarm);
+	if (pony)
+		rtc = rtc_class_open(pony);
+	else
+		pr_warning("PM: no wakealarm-capable RTC driver is ready\n");
+
+	if (rtc)
+		test_wakealarm();
+	return 0;
+}
+late_initcall(be_sleepy);