3 files changed, 212 insertions, 2 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 01a2992b5754..4d705713cabc 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -87,7 +87,8 @@ parameter is applicable:
         SH      SuperH architecture is enabled.
         SMP     The kernel is an SMP kernel.
         SPARC   Sparc architecture is enabled.
-        SWSUSP  Software suspend is enabled.
+        SWSUSP  Software suspend (hibernation) is enabled.
+        SUSPEND System suspend states are enabled.
         TS      Appropriate touchscreen support is enabled.
         USB     USB support is enabled.
         USBHID  USB Human Interface Device support is enabled.
@@ -2123,6 +2124,12 @@ and is between 256 and 4096 characters. It is defined in the file
 
         tdfx=           [HW,DRM]
 
+        test_suspend=   [SUSPEND]
+                        Specify "mem" (for Suspend-to-RAM) or "standby" (for
+                        standby suspend) as the system sleep state to briefly
+                        enter during system startup.  The system is woken from
+                        this state using a wakeup-capable RTC alarm.
+
         thash_entries=  [KNL,NET]
                         Set number of hash buckets for TCP connection
 
diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 59dfdf1e1d20..dcd165f92a88 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -94,6 +94,17 @@ config SUSPEND
           powered and thus its contents are preserved, such as the
           suspend-to-RAM state (e.g. the ACPI S3 state).
 
+config PM_TEST_SUSPEND
+        bool "Test suspend/resume and wakealarm during bootup"
+        depends on SUSPEND && PM_DEBUG && RTC_LIB=y
+        ---help---
+        This option will let you suspend your machine during bootup, and
+        make it wake up a few seconds later using an RTC wakeup alarm.
+        Enable this with a kernel parameter like "test_suspend=mem".
+
+        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
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 3398f4651aa1..95bff23ecdaa 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -132,6 +132,61 @@ static inline int suspend_test(int level) { return 0; }
 
 #ifdef CONFIG_SUSPEND
 
+#ifdef CONFIG_PM_TEST_SUSPEND
+
+/*
+ * We test the system suspend code by setting an RTC wakealarm a short
+ * time in the future, then suspending.  Suspending the devices won't
+ * normally take long ... some systems only need a few milliseconds.
+ *
+ * The time it takes is system-specific though, so when we test this
+ * during system bootup we allow a LOT of time.
+ */
+#define TEST_SUSPEND_SECONDS    5
+
+static unsigned long suspend_test_start_time;
+
+static void suspend_test_start(void)
+{
+        /* FIXME Use better timebase than "jiffies", ideally a clocksource.
+         * What we want is a hardware counter that will work correctly even
+         * during the irqs-are-off stages of the suspend/resume cycle...
+         */
+        suspend_test_start_time = jiffies;
+}
+
+static void suspend_test_finish(const char *label)
+{
+        long nj = jiffies - suspend_test_start_time;
+        unsigned msec;
+
+        msec = jiffies_to_msecs(abs(nj));
+        pr_info("PM: %s took %d.%03d seconds\n", label,
+                        msec / 1000, msec % 1000);
+
+        /* Warning on suspend means the RTC alarm period needs to be
+         * larger -- the system was sooo slooowwww to suspend that the
+         * alarm (should have) fired before the system went to sleep!
+         *
+         * Warning on either suspend or resume also means the system
+         * has some performance issues.  The stack dump of a WARN_ON
+         * is more likely to get the right attention than a printk...
+         */
+        WARN_ON(msec > (TEST_SUSPEND_SECONDS * 1000));
+}
+
+#else
+
+static void suspend_test_start(void)
+{
+}
+
+static void suspend_test_finish(const char *label)
+{
+}
+
+#endif
+
 /* This is just an arbitrary number */
 #define FREE_PAGE_NUMBER (100)
 
@@ -266,12 +321,13 @@ int suspend_devices_and_enter(suspend_state_t state)
                         goto Close;
         }
         suspend_console();
+        suspend_test_start();
         error = device_suspend(PMSG_SUSPEND);
         if (error) {
                 printk(KERN_ERR "PM: Some devices failed to suspend\n");
                 goto Recover_platform;
         }
-
+        suspend_test_finish("suspend devices");
         if (suspend_test(TEST_DEVICES))
                 goto Recover_platform;
 
@@ -293,7 +349,9 @@ int suspend_devices_and_enter(suspend_state_t state)
         if (suspend_ops->finish)
                 suspend_ops->finish();
  Resume_devices:
+        suspend_test_start();
         device_resume(PMSG_RESUME);
+        suspend_test_finish("resume devices");
         resume_console();
  Close:
         if (suspend_ops->end)
@@ -521,3 +579,137 @@ static int __init pm_init(void)
 }
 
 core_initcall(pm_init);
+
+
+#ifdef CONFIG_PM_TEST_SUSPEND
+
+#include <linux/rtc.h>
+
+/*
+ * To test system suspend, we need a hands-off mechanism to resume the
+ * system.  RTCs wake alarms are a common self-contained mechanism.
+ */
+
+static void __init test_wakealarm(struct rtc_device *rtc, suspend_state_t state)
+{
+        static char err_readtime[] __initdata =
+                KERN_ERR "PM: can't read %s time, err %d\n";
+        static char err_wakealarm [] __initdata =
+                KERN_ERR "PM: can't set %s wakealarm, err %d\n";
+        static char err_suspend[] __initdata =
+                KERN_ERR "PM: suspend test failed, error %d\n";
+        static char info_test[] __initdata =
+                KERN_INFO "PM: test RTC wakeup from '%s' suspend\n";
+
+        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) {
+                printk(err_readtime, rtc->dev.bus_id, status);
+                return;
+        }
+        rtc_tm_to_time(&alm.time, &now);
+
+        memset(&alm, 0, sizeof alm);
+        rtc_time_to_tm(now + TEST_SUSPEND_SECONDS, &alm.time);
+        alm.enabled = true;
+
+        status = rtc_set_alarm(rtc, &alm);
+        if (status < 0) {
+                printk(err_wakealarm, rtc->dev.bus_id, status);
+                return;
+        }
+
+        if (state == PM_SUSPEND_MEM) {
+                printk(info_test, pm_states[state]);
+                status = pm_suspend(state);
+                if (status == -ENODEV)
+                        state = PM_SUSPEND_STANDBY;
+        }
+        if (state == PM_SUSPEND_STANDBY) {
+                printk(info_test, pm_states[state]);
+                status = pm_suspend(state);
+        }
+        if (status < 0)
+                printk(err_suspend, status);
+}
+
+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;
+}
+
+/*
+ * Kernel options like "test_suspend=mem" force suspend/resume sanity tests
+ * at startup time.  They're normally disabled, for faster boot and because
+ * we can't know which states really work on this particular system.
+ */
+static suspend_state_t test_state __initdata = PM_SUSPEND_ON;
+
+static char warn_bad_state[] __initdata =
+        KERN_WARNING "PM: can't test '%s' suspend state\n";
+
+static int __init setup_test_suspend(char *value)
+{
+        unsigned i;
+
+        /* "=mem" ==> "mem" */
+        value++;
+        for (i = 0; i < PM_SUSPEND_MAX; i++) {
+                if (!pm_states[i])
+                        continue;
+                if (strcmp(pm_states[i], value) != 0)
+                        continue;
+                test_state = (__force suspend_state_t) i;
+                return 0;
+        }
+        printk(warn_bad_state, value);
+        return 0;
+}
+__setup("test_suspend", setup_test_suspend);
+
+static int __init test_suspend(void)
+{
+        static char             warn_no_rtc[] __initdata =
+                KERN_WARNING "PM: no wakealarm-capable RTC driver is ready\n";
+
+        char                    *pony = NULL;
+        struct rtc_device       *rtc = NULL;
+
+        /* PM is initialized by now; is that state testable? */
+        if (test_state == PM_SUSPEND_ON)
+                goto done;
+        if (!valid_state(test_state)) {
+                printk(warn_bad_state, pm_states[test_state]);
+                goto done;
+        }
+
+        /* RTCs have initialized by now too ... can we use one? */
+        class_find_device(rtc_class, NULL, &pony, has_wakealarm);
+        if (pony)
+                rtc = rtc_class_open(pony);
+        if (!rtc) {
+                printk(warn_no_rtc);
+                goto done;
+        }
+
+        /* go for it */
+        test_wakealarm(rtc, test_state);
+        rtc_class_close(rtc);
+done:
+        return 0;
+}
+late_initcall(test_suspend);
+
+#endif /* CONFIG_PM_TEST_SUSPEND */