iwlwifi: pcie: implement Bz reset flow

Bz device reset flow changed, now the hardware (instead of
firmware) will reset the PCI bus etc., this can take up to
100ms.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210802215208.df30875c6ff9.I962ed0f2c3358903dc6ba1abb65726ce5acbbd48@changeidSigned-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/pcie/trans-gen2.c

@@ -131,9 +131,21 @@ void _iwl_trans_pcie_gen2_stop_device(struct iwl_trans *trans)
 	if (trans_pcie->is_down)
 		return;
 
-	if (trans_pcie->fw_reset_handshake &&
-	    trans->state >= IWL_TRANS_FW_STARTED)
-		iwl_trans_pcie_fw_reset_handshake(trans);
+	if (trans->state >= IWL_TRANS_FW_STARTED) {
+		if (trans->trans_cfg->device_family >= IWL_DEVICE_FAMILY_BZ) {
+			iwl_set_bit(trans, CSR_GP_CNTRL,
+				    CSR_GP_CNTRL_REG_FLAG_BUS_MASTER_DISABLE_REQ);
+			iwl_poll_bit(trans, CSR_GP_CNTRL,
+				     CSR_GP_CNTRL_REG_FLAG_BUS_MASTER_DISABLE_STATUS,
+				     CSR_GP_CNTRL_REG_FLAG_BUS_MASTER_DISABLE_STATUS,
+				     5000);
+			msleep(100);
+			iwl_set_bit(trans, CSR_GP_CNTRL,
+				    CSR_GP_CNTRL_REG_FLAG_SW_RESET);
+		} else if (trans_pcie->fw_reset_handshake) {
+			iwl_trans_pcie_fw_reset_handshake(trans);
+		}
+	}
 
 	trans_pcie->is_down = true;