[PATCH RFC] iwlwifi: add basic runtime PM support

["Yan, Zheng" <zheng.z.yan@intel.com>]

This simple patch adds open/close based runtime PM support to the iwlwifi driver.
Namely, make the driver suspend the device after shutting down the interface and
resume the device when activating the interface. In my test, suspending the device
can save about 0.4 watt power. The shortcoming is that the device no longer generate
rfkill changes interrupt.

Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
---
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.c b/drivers/net/wireless/iwlwifi/iwl-agn.c
index e0e9a3d..c0b7b85 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.c
@@ -38,6 +38,7 @@
 #include <linux/firmware.h>
 #include <linux/etherdevice.h>
 #include <linux/if_arp.h>
+#include <linux/pm_runtime.h>
 
 #include <net/mac80211.h>
 
@@ -1755,6 +1756,8 @@ static int iwlagn_mac_start(struct ieee80211_hw *hw)
 	struct iwl_priv *priv = hw->priv;
 	int ret;
 
+	pm_runtime_get_sync(bus(priv)->dev);
+
 	IWL_DEBUG_MAC80211(priv, "enter\n");
 
 	/* we should be verifying the device is ready to be opened */
@@ -1762,19 +1765,24 @@ static int iwlagn_mac_start(struct ieee80211_hw *hw)
 	ret = __iwl_up(priv);
 	mutex_unlock(&priv->shrd->mutex);
 	if (ret)
-		return ret;
+		goto out;
 
 	IWL_DEBUG_INFO(priv, "Start UP work done.\n");
 
 	/* Now we should be done, and the READY bit should be set. */
-	if (WARN_ON(!test_bit(STATUS_READY, &priv->shrd->status)))
+	if (WARN_ON(!test_bit(STATUS_READY, &priv->shrd->status))) {
 		ret = -EIO;
+		goto out;
+	}
 
 	iwlagn_led_enable(priv);
 
 	priv->is_open = 1;
 	IWL_DEBUG_MAC80211(priv, "leave\n");
-	return 0;
+	ret = 0;
+out:
+	pm_runtime_put(bus(priv)->dev);
+	return ret;
 }
 
 static void iwlagn_mac_stop(struct ieee80211_hw *hw)
@@ -1786,6 +1794,8 @@ static void iwlagn_mac_stop(struct ieee80211_hw *hw)
 	if (!priv->is_open)
 		return;
 
+	pm_runtime_get_sync(bus(priv)->dev);
+
 	priv->is_open = 0;
 
 	iwl_down(priv);
@@ -1798,6 +1808,8 @@ static void iwlagn_mac_stop(struct ieee80211_hw *hw)
 	iwl_enable_rfkill_int(priv);
 
 	IWL_DEBUG_MAC80211(priv, "leave\n");
+
+	pm_runtime_put(bus(priv)->dev);
 }
 
 #ifdef CONFIG_PM_SLEEP
diff --git a/drivers/net/wireless/iwlwifi/iwl-pci.c b/drivers/net/wireless/iwlwifi/iwl-pci.c
index 1800029..d3f39b2 100644
--- a/drivers/net/wireless/iwlwifi/iwl-pci.c
+++ b/drivers/net/wireless/iwlwifi/iwl-pci.c
@@ -63,6 +63,7 @@
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/pci-aspm.h>
+#include <linux/pm_runtime.h>
 
 #include "iwl-bus.h"
 #include "iwl-io.h"
@@ -465,6 +466,8 @@ static int iwl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	err = iwl_probe(bus, &trans_ops_pcie, cfg);
 	if (err)
 		goto out_disable_msi;
+
+	pm_runtime_put_noidle(&pdev->dev);
 	return 0;
 
 out_disable_msi:
@@ -487,6 +490,8 @@ static void __devexit iwl_pci_remove(struct pci_dev *pdev)
 	struct pci_dev *pci_dev = IWL_BUS_GET_PCI_DEV(bus);
 	struct iwl_shared *shrd = bus->shrd;
 
+	pm_runtime_get_noresume(&pdev->dev);
+
 	iwl_remove(shrd->priv);
 
 	pci_disable_msi(pci_dev);
@@ -534,7 +539,21 @@ static int iwl_pci_resume(struct device *device)
 	return iwl_trans_resume(shrd->trans);
 }
 
-static SIMPLE_DEV_PM_OPS(iwl_dev_pm_ops, iwl_pci_suspend, iwl_pci_resume);
+
+static int iwl_pci_runtime_idle(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct iwl_bus *bus = pci_get_drvdata(pdev);
+	struct iwl_shared *shrd = bus->shrd;
+
+	if (!test_bit(STATUS_ALIVE, &shrd->status))
+		return 0;
+
+	return -EBUSY;
+}
+
+static UNIVERSAL_DEV_PM_OPS(iwl_dev_pm_ops, iwl_pci_suspend,
+			iwl_pci_resume, iwl_pci_runtime_idle);
 
 #define IWL_PM_OPS	(&iwl_dev_pm_ops)