iwlwifi: pcie: work around suspend/resume issue

In some platforms, having the device enabled with certain radio
frontends causes the platform to not be able to resume properly
from suspend, regardless of the wakeup cause. This was traced to
a hardware issue with the integrated 9000-series A-step variant.
Set the right hardware bit to disable the problematic state.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/iwl-csr.h

@@ -153,6 +153,10 @@
 /* GIO Chicken Bits (PCI Express bus link power management) */
 #define CSR_GIO_CHICKEN_BITS    (CSR_BASE+0x100)
 
+/* host chicken bits */
+#define CSR_HOST_CHICKEN	(CSR_BASE + 0x204)
+#define CSR_HOST_CHICKEN_PM_IDLE_SRC_DIS_SB_PME	BIT(19)
+
 /* Analog phase-lock-loop configuration  */
 #define CSR_ANA_PLL_CFG         (CSR_BASE+0x20c)
 

drivers/net/wireless/intel/iwlwifi/pcie/trans.c

@@ -3134,6 +3134,17 @@ struct iwl_trans *iwl_trans_pcie_alloc(struct pci_dev *pdev,
 		}
 	}
 
+	/*
+	 * 9000-series integrated A-step has a problem with suspend/resume
+	 * and sometimes even causes the whole platform to get stuck. This
+	 * workaround makes the hardware not go into the problematic state.
+	 */
+	if (trans->cfg->integrated &&
+	    trans->cfg->device_family == IWL_DEVICE_FAMILY_9000 &&
+	    CSR_HW_REV_STEP(trans->hw_rev) == SILICON_A_STEP)
+		iwl_set_bit(trans, CSR_HOST_CHICKEN,
+			    CSR_HOST_CHICKEN_PM_IDLE_SRC_DIS_SB_PME);
+
 	trans->hw_rf_id = iwl_read32(trans, CSR_HW_RF_ID);
 
 	iwl_pcie_set_interrupt_capa(pdev, trans);