cxgb4: fix thermal configuration dependencies

With CONFIG_THERMAL=m, we get a build error:

drivers/net/ethernet/chelsio/cxgb4/cxgb4_thermal.c: In function 'cxgb4_thermal_get_trip_type':
drivers/net/ethernet/chelsio/cxgb4/cxgb4_thermal.c:48:11: error: 'struct adapter' has no member named 'ch_thermal'

Once that is fixed by using IS_ENABLED() checks, we get a link error
against the thermal subsystem when cxgb4 is built-in:

drivers/net/ethernet/chelsio/cxgb4/cxgb4_thermal.o: In function `cxgb4_thermal_init':
cxgb4_thermal.c:(.text+0x180): undefined reference to `thermal_zone_device_register'
drivers/net/ethernet/chelsio/cxgb4/cxgb4_thermal.o: In function `cxgb4_thermal_remove':
cxgb4_thermal.c:(.text+0x1e0): undefined reference to `thermal_zone_device_unregister'

Finally, since CONFIG_THERMAL can be =m, the Makefile fails to pick up the
extra file into built-in.a, and we get another link failure against the
cxgb4_thermal_init/cxgb4_thermal_remove files, so the Makefile has to
be adapted as well to work for both CONFIG_THERMAL=y and =m.

Fixes: b187191 ("cxgb4: Add thermal zone support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/Kconfig

@@ -67,6 +67,7 @@ config CHELSIO_T3
 config CHELSIO_T4
 	tristate "Chelsio Communications T4/T5/T6 Ethernet support"
 	depends on PCI && (IPV6 || IPV6=n)
+	depends on THERMAL || !THERMAL
 	select FW_LOADER
 	select MDIO
 	select ZLIB_DEFLATE

drivers/net/ethernet/chelsio/cxgb4/Makefile

@@ -12,4 +12,6 @@ cxgb4-objs := cxgb4_main.o l2t.o smt.o t4_hw.o sge.o clip_tbl.o cxgb4_ethtool.o
 cxgb4-$(CONFIG_CHELSIO_T4_DCB) +=  cxgb4_dcb.o
 cxgb4-$(CONFIG_CHELSIO_T4_FCOE) +=  cxgb4_fcoe.o
 cxgb4-$(CONFIG_DEBUG_FS) += cxgb4_debugfs.o
-cxgb4-$(CONFIG_THERMAL) += cxgb4_thermal.o
+ifdef CONFIG_THERMAL
+cxgb4-objs += cxgb4_thermal.o
+endif

drivers/net/ethernet/chelsio/cxgb4/cxgb4.h

@@ -891,7 +891,7 @@ struct mps_encap_entry {
 	atomic_t refcnt;
 };
 
-#ifdef CONFIG_THERMAL
+#if IS_ENABLED(CONFIG_THERMAL)
 struct ch_thermal {
 	struct thermal_zone_device *tzdev;
 	int trip_temp;
@@ -1017,7 +1017,7 @@ struct adapter {
 
 	/* Dump buffer for collecting logs in kdump kernel */
 	struct vmcoredd_data vmcoredd;
-#ifdef CONFIG_THERMAL
+#if IS_ENABLED(CONFIG_THERMAL)
 	struct ch_thermal ch_thermal;
 #endif
 };
@@ -1875,9 +1875,7 @@ int t4_set_vlan_acl(struct adapter *adap, unsigned int mbox, unsigned int vf,
 		    u16 vlan);
 int cxgb4_dcb_enabled(const struct net_device *dev);
 
-#ifdef CONFIG_THERMAL
 int cxgb4_thermal_init(struct adapter *adap);
 int cxgb4_thermal_remove(struct adapter *adap);
-#endif /* CONFIG_THERMAL */
 
 #endif /* __CXGB4_H__ */

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -5864,10 +5864,9 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (!is_t4(adapter->params.chip))
 		cxgb4_ptp_init(adapter);
 
-#ifdef CONFIG_THERMAL
-	if (!is_t4(adapter->params.chip) && (adapter->flags & FW_OK))
+	if (IS_ENABLED(CONFIG_THERMAL) &&
+	    !is_t4(adapter->params.chip) && (adapter->flags & FW_OK))
 		cxgb4_thermal_init(adapter);
-#endif /* CONFIG_THERMAL */
 
 	print_adapter_info(adapter);
 	return 0;
@@ -5934,9 +5933,8 @@ static void remove_one(struct pci_dev *pdev)
 
 		if (!is_t4(adapter->params.chip))
 			cxgb4_ptp_stop(adapter);
-#ifdef CONFIG_THERMAL
-		cxgb4_thermal_remove(adapter);
-#endif
+		if (IS_ENABLED(CONFIG_THERMAL))
+			cxgb4_thermal_remove(adapter);
 
 		/* If we allocated filters, free up state associated with any
 		 * valid filters ...