rework pm_ops pm_disk_mode, kill misuse

This patch series cleans up some misconceptions about pm_ops.  Some users of
the pm_ops structure attempt to use it to stop the user from entering suspend
to disk, this, however, is not possible since the user can always use
"shutdown" in /sys/power/disk and then the pm_ops are never invoked.  Also,
platforms that don't support suspend to disk simply should not allow
configuring SOFTWARE_SUSPEND (read the help text on it, it only selects
suspend to disk and nothing else, all the other stuff depends on PM).

The pm_ops structure is actually intended to provide a way to enter
platform-defined sleep states (currently supported states are "standby" and
"mem" (suspend to ram)) and additionally (if SOFTWARE_SUSPEND is configured)
allows a platform to support a platform specific way to enter low-power mode
once everything has been saved to disk.  This is currently only used by ACPI
(S4).

This patch:

The pm_ops.pm_disk_mode is used in totally bogus ways since nobody really
seems to understand what it actually does.

This patch clarifies the pm_disk_mode description.

It also removes all the arm and sh users that think they can veto suspend to
disk via pm_ops; not so since the user can always do echo shutdown >
/sys/power/disk, they need to find a better way involving Kconfig or such.

ACPI is the only user left with a non-zero pm_disk_mode.

The patch also sets the default mode to shutdown again, but when a new pm_ops
is registered its pm_disk_mode is selected as default, that way the default
stays for ACPI where it is apparently required.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: David Brownell <david-b@pacbell.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: <linux-pm@lists.linux-foundation.org>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Russell King <rmk@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

11 files changed, 56 insertions, 64 deletions

diff --git a/arch/arm/common/sharpsl_pm.c b/arch/arm/common/sharpsl_pm.c
index a9bc5b52218f..4cb895d4ae5b 100644
--- a/arch/arm/common/sharpsl_pm.c
+++ b/arch/arm/common/sharpsl_pm.c
@@ -766,7 +766,6 @@ static void sharpsl_apm_get_power_status(struct apm_power_info *info)
 }
 
 static struct pm_ops sharpsl_pm_ops = {
-        .pm_disk_mode   = PM_DISK_FIRMWARE,
         .prepare        = pxa_pm_prepare,
         .enter          = corgi_pxa_pm_enter,
         .finish         = pxa_pm_finish,
diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index b49bfda53d7f..ff8db29e989e 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -201,7 +201,6 @@ error:
 
 
 static struct pm_ops at91_pm_ops ={
-        .pm_disk_mode   = 0,
         .valid          = at91_pm_valid_state,
         .prepare        = at91_pm_prepare,
         .enter          = at91_pm_enter,
diff --git a/arch/arm/mach-omap1/pm.c b/arch/arm/mach-omap1/pm.c
index 49efe903dacd..4248117e5e3f 100644
--- a/arch/arm/mach-omap1/pm.c
+++ b/arch/arm/mach-omap1/pm.c
@@ -698,7 +698,6 @@ static struct irqaction omap_wakeup_irq = {
 
 
 static struct pm_ops omap_pm_ops ={
-        .pm_disk_mode   = 0,
         .prepare        = omap_pm_prepare,
         .enter          = omap_pm_enter,
         .finish         = omap_pm_finish,
diff --git a/arch/arm/mach-omap2/pm.c b/arch/arm/mach-omap2/pm.c
index d7eee99b7e3f..3e9a128feea1 100644
--- a/arch/arm/mach-omap2/pm.c
+++ b/arch/arm/mach-omap2/pm.c
@@ -370,7 +370,6 @@ static int omap2_pm_finish(suspend_state_t state)
 }
 
 static struct pm_ops omap_pm_ops = {
-        .pm_disk_mode   = 0,
         .prepare        = omap2_pm_prepare,
         .enter          = omap2_pm_enter,
         .finish         = omap2_pm_finish,
diff --git a/arch/arm/mach-pxa/pm.c b/arch/arm/mach-pxa/pm.c
index b4d8276d6050..0a99ef43b36f 100644
--- a/arch/arm/mach-pxa/pm.c
+++ b/arch/arm/mach-pxa/pm.c
@@ -223,11 +223,7 @@ int pxa_pm_finish(suspend_state_t state)
 
 EXPORT_SYMBOL_GPL(pxa_pm_finish);
 
-/*
- * Set to PM_DISK_FIRMWARE so we can quickly veto suspend-to-disk.
- */
 static struct pm_ops pxa_pm_ops = {
-        .pm_disk_mode   = PM_DISK_FIRMWARE,
         .prepare        = pxa_pm_prepare,
         .enter          = pxa_pm_enter,
         .finish         = pxa_pm_finish,
diff --git a/arch/arm/mach-sa1100/pm.c b/arch/arm/mach-sa1100/pm.c
index 786c8534231f..b0837113b2aa 100644
--- a/arch/arm/mach-sa1100/pm.c
+++ b/arch/arm/mach-sa1100/pm.c
@@ -59,9 +59,6 @@ static int sa11x0_pm_enter(suspend_state_t state)
         unsigned long gpio, sleep_save[SLEEP_SAVE_SIZE];
         struct timespec delta, rtc;
 
-        if (state != PM_SUSPEND_MEM)
-                return -EINVAL;
-
         /* preserve current time */
         rtc.tv_sec = RCNR;
         rtc.tv_nsec = 0;
@@ -134,11 +131,7 @@ unsigned long sleep_phys_sp(void *sp)
         return virt_to_phys(sp);
 }
 
-/*
- * Set to PM_DISK_FIRMWARE so we can quickly veto suspend-to-disk.
- */
 static struct pm_ops sa11x0_pm_ops = {
-        .pm_disk_mode   = PM_DISK_FIRMWARE,
         .enter          = sa11x0_pm_enter,
 };
 
diff --git a/arch/arm/plat-s3c24xx/pm.c b/arch/arm/plat-s3c24xx/pm.c
index ecf68d611904..d6af3082af30 100644
--- a/arch/arm/plat-s3c24xx/pm.c
+++ b/arch/arm/plat-s3c24xx/pm.c
@@ -511,11 +511,6 @@ static int s3c2410_pm_enter(suspend_state_t state)
                 return -EINVAL;
         }
 
-        if (state != PM_SUSPEND_MEM) {
-                printk(KERN_ERR PFX "error: only PM_SUSPEND_MEM supported\n");
-                return -EINVAL;
-        }
-
         /* check if we have anything to wake-up with... bad things seem
          * to happen if you suspend with no wakeup (system will often
          * require a full power-cycle)
@@ -633,11 +628,7 @@ static int s3c2410_pm_finish(suspend_state_t state)
         return 0;
 }
 
-/*
- * Set to PM_DISK_FIRMWARE so we can quickly veto suspend-to-disk.
- */
 static struct pm_ops s3c2410_pm_ops = {
-        .pm_disk_mode   = PM_DISK_FIRMWARE,
         .prepare        = s3c2410_pm_prepare,
         .enter          = s3c2410_pm_enter,
         .finish         = s3c2410_pm_finish,
diff --git a/arch/sh/boards/hp6xx/pm.c b/arch/sh/boards/hp6xx/pm.c
index d1947732fb3e..4b2f29a4bde9 100644
--- a/arch/sh/boards/hp6xx/pm.c
+++ b/arch/sh/boards/hp6xx/pm.c
@@ -27,9 +27,6 @@ static int hp6x0_pm_enter(suspend_state_t state)
         u16 hd64461_stbcr;
 #endif
 
-        if (state != PM_SUSPEND_MEM)
-                return -EINVAL;
-
 #ifdef CONFIG_HD64461_ENABLER
         outb(0, HD64461_PCC1CSCIER);
 
@@ -70,11 +67,7 @@ static int hp6x0_pm_enter(suspend_state_t state)
         return 0;
 }
 
-/*
- * Set to PM_DISK_FIRMWARE so we can quickly veto suspend-to-disk.
- */
 static struct pm_ops hp6x0_pm_ops = {
-        .pm_disk_mode   = PM_DISK_FIRMWARE,
         .enter          = hp6x0_pm_enter,
 };
 
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 9bd86db4d395..dfced9188bdc 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -112,6 +112,8 @@ typedef int __bitwise suspend_state_t;
 
 typedef int __bitwise suspend_disk_method_t;
 
+/* invalid must be 0 so struct pm_ops initialisers can leave it out */
+#define PM_DISK_INVALID         ((__force suspend_disk_method_t) 0)
 #define PM_DISK_FIRMWARE        ((__force suspend_disk_method_t) 1)
 #define PM_DISK_PLATFORM        ((__force suspend_disk_method_t) 2)
 #define PM_DISK_SHUTDOWN        ((__force suspend_disk_method_t) 3)
@@ -137,17 +139,16 @@ typedef int __bitwise suspend_disk_method_t;
  * @finish: Called when the system has left the given state and all devices
  *      are resumed. The return value is ignored.
  *
- * @pm_disk_mode: Set to the disk method that the user should be able to
- *      configure for suspend-to-disk. Since %PM_DISK_SHUTDOWN,
- *      %PM_DISK_REBOOT, %PM_DISK_TEST and %PM_DISK_TESTPROC
- *      are always allowed, currently only %PM_DISK_PLATFORM
- *      makes sense. If the user then choses %PM_DISK_PLATFORM,
- *      the @prepare call will be called before suspending to disk
- *      (if present), the @enter call should be present and will
- *      be called after all state has been saved and the machine
- *      is ready to be shut down/suspended/..., and the @finish
- *      callback is called after state has been restored. All
- *      these calls are called with %PM_SUSPEND_DISK as the state.
+ * @pm_disk_mode: The generic code always allows one of the shutdown methods
+ *      %PM_DISK_SHUTDOWN, %PM_DISK_REBOOT, %PM_DISK_TEST and
+ *      %PM_DISK_TESTPROC. If this variable is set, the mode it is set
+ *      to is allowed in addition to those modes and is also made default.
+ *      When this mode is sent selected, the @prepare call will be called
+ *      before suspending to disk (if present), the @enter call should be
+ *      present and will be called after all state has been saved and the
+ *      machine is ready to be powered off; the @finish callback is called
+ *      after state has been restored. All these calls are called with
+ *      %PM_SUSPEND_DISK as the state.
  */
 struct pm_ops {
         int (*valid)(suspend_state_t state);
diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index aec19b063e3f..4de2f69fe095 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -39,7 +39,13 @@ static inline int platform_prepare(void)
 {
         int error = 0;
 
-        if (pm_disk_mode == PM_DISK_PLATFORM) {
+        switch (pm_disk_mode) {
+        case PM_DISK_TEST:
+        case PM_DISK_TESTPROC:
+        case PM_DISK_SHUTDOWN:
+        case PM_DISK_REBOOT:
+                break;
+        default:
                 if (pm_ops && pm_ops->prepare)
                         error = pm_ops->prepare(PM_SUSPEND_DISK);
         }
@@ -48,40 +54,48 @@ static inline int platform_prepare(void)
 
 /**
  *      power_down - Shut machine down for hibernate.
- *      @mode:          Suspend-to-disk mode
  *
- *      Use the platform driver, if configured so, and return gracefully if it
- *      fails.
- *      Otherwise, try to power off and reboot. If they fail, halt the machine,
- *      there ain't no turning back.
+ *      Use the platform driver, if configured so; otherwise try
+ *      to power off or reboot.
  */
 
-static void power_down(suspend_disk_method_t mode)
+static void power_down(void)
 {
-        switch(mode) {
-        case PM_DISK_PLATFORM:
-                if (pm_ops && pm_ops->enter) {
-                        kernel_shutdown_prepare(SYSTEM_SUSPEND_DISK);
-                        pm_ops->enter(PM_SUSPEND_DISK);
-                        break;
-                }
+        switch (pm_disk_mode) {
+        case PM_DISK_TEST:
+        case PM_DISK_TESTPROC:
+                break;
         case PM_DISK_SHUTDOWN:
                 kernel_power_off();
                 break;
         case PM_DISK_REBOOT:
                 kernel_restart(NULL);
                 break;
+        default:
+                if (pm_ops && pm_ops->enter) {
+                        kernel_shutdown_prepare(SYSTEM_SUSPEND_DISK);
+                        pm_ops->enter(PM_SUSPEND_DISK);
+                        break;
+                }
         }
         kernel_halt();
-        /* Valid image is on the disk, if we continue we risk serious data corruption
-           after resume. */
+        /*
+         * Valid image is on the disk, if we continue we risk serious data
+         * corruption after resume.
+         */
         printk(KERN_CRIT "Please power me down manually\n");
         while(1);
 }
 
 static inline void platform_finish(void)
 {
-        if (pm_disk_mode == PM_DISK_PLATFORM) {
+        switch (pm_disk_mode) {
+        case PM_DISK_TEST:
+        case PM_DISK_TESTPROC:
+        case PM_DISK_SHUTDOWN:
+        case PM_DISK_REBOOT:
+                break;
+        default:
                 if (pm_ops && pm_ops->finish)
                         pm_ops->finish(PM_SUSPEND_DISK);
         }
@@ -166,7 +180,7 @@ int pm_suspend_disk(void)
                 pr_debug("PM: writing image.\n");
                 error = swsusp_write();
                 if (!error)
-                        power_down(pm_disk_mode);
+                        power_down();
                 else {
                         swsusp_free();
                         goto Thaw;
@@ -338,10 +352,14 @@ static ssize_t disk_store(struct subsystem * s, const char * buf, size_t n)
                 }
         }
         if (mode) {
-                if (mode == PM_DISK_SHUTDOWN || mode == PM_DISK_REBOOT ||
-                     mode == PM_DISK_TEST || mode == PM_DISK_TESTPROC) {
+                switch (mode) {
+                case PM_DISK_SHUTDOWN:
+                case PM_DISK_REBOOT:
+                case PM_DISK_TEST:
+                case PM_DISK_TESTPROC:
                         pm_disk_mode = mode;
-                } else {
+                        break;
+                default:
                         if (pm_ops && pm_ops->enter &&
                             (mode == pm_ops->pm_disk_mode))
                                 pm_disk_mode = mode;
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 3062e940d1fa..053c0a7d7f57 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -30,7 +30,7 @@
 DEFINE_MUTEX(pm_mutex);
 
 struct pm_ops *pm_ops;
-suspend_disk_method_t pm_disk_mode = PM_DISK_PLATFORM;
+suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
 
 /**
  *      pm_set_ops - Set the global power method table. 
@@ -41,6 +41,10 @@ void pm_set_ops(struct pm_ops * ops)
 {
         mutex_lock(&pm_mutex);
         pm_ops = ops;
+        if (ops && ops->pm_disk_mode != PM_DISK_INVALID) {
+                pm_disk_mode = ops->pm_disk_mode;
+        } else
+                pm_disk_mode = PM_DISK_SHUTDOWN;
         mutex_unlock(&pm_mutex);
 }