PM: Introduce core framework for run-time PM of I/O devices (rev. 17)

Introduce a core framework for run-time power management of I/O
devices.  Add device run-time PM fields to 'struct dev_pm_info'
and device run-time PM callbacks to 'struct dev_pm_ops'.  Introduce
a run-time PM workqueue and define some device run-time PM helper
functions at the core level.  Document all these things.

Special thanks to Alan Stern for his help with the design and
multiple detailed reviews of the pereceding versions of this patch
and to Magnus Damm for testing feedback.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@igel.co.jp>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index f0106875f01d..7b34b3a48f67 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -23,6 +23,7 @@
 #include <linux/kthread.h>
 #include <linux/wait.h>
 #include <linux/async.h>
+#include <linux/pm_runtime.h>
 
 #include "base.h"
 #include "power/power.h"
@@ -202,7 +203,10 @@ int driver_probe_device(struct device_driver *drv, struct device *dev)
         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
                  drv->bus->name, __func__, dev_name(dev), drv->name);
 
+        pm_runtime_get_noresume(dev);
+        pm_runtime_barrier(dev);
         ret = really_probe(dev, drv);
+        pm_runtime_put_sync(dev);
 
         return ret;
 }
@@ -245,7 +249,9 @@ int device_attach(struct device *dev)
                         ret = 0;
                 }
         } else {
+                pm_runtime_get_noresume(dev);
                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
+                pm_runtime_put_sync(dev);
         }
         up(&dev->sem);
         return ret;
@@ -306,6 +312,9 @@ static void __device_release_driver(struct device *dev)
 
         drv = dev->driver;
         if (drv) {
+                pm_runtime_get_noresume(dev);
+                pm_runtime_barrier(dev);
+
                 driver_sysfs_remove(dev);
 
                 if (dev->bus)
@@ -324,6 +333,8 @@ static void __device_release_driver(struct device *dev)
                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
                                                      BUS_NOTIFY_UNBOUND_DRIVER,
                                                      dev);
+
+                pm_runtime_put_sync(dev);
         }
 }