ehci(4): properly handle failed attach

thinkpad a475 fails to attach an ehci instance:

   ehci0: pre-2.0 USB rev, device ignored

which ends up stopping suspend/resume working as the device has no
pmf handlers installed.  put most of the teardown code into a new
common function that is called from failed attach and detach.  if
attach fails, register NULL pmf handlers.

re-order several parts of detach to match the reverse attach order.

tested on rockpro64, thinkpad a475, and xps 1645, the a475 can now
suspend/resume almost fully successfully.


Index: dev/pci/ehci_pci.c
===================================================================
RCS file: /cvsroot/src/sys/dev/pci/ehci_pci.c,v
retrieving revision 1.76
diff -p -u -r1.76 ehci_pci.c
--- dev/pci/ehci_pci.c	24 Jan 2023 08:40:46 -0000	1.76
+++ dev/pci/ehci_pci.c	10 Mar 2024 09:48:49 -0000
@@ -89,6 +89,7 @@ struct ehci_pci_softc {
 	} sc_init_state;
 };
 
+static void ehci_pci_release_resources(struct ehci_pci_softc *);
 static int ehci_sb700_match(const struct pci_attach_args *);
 static int ehci_apply_amd_quirks(struct ehci_pci_softc *);
 static enum ehci_pci_quirk_flags ehci_pci_lookup_quirkdata(pci_vendor_id_t,
@@ -262,6 +263,7 @@ ehci_pci_attach(device_t parent, device_
 	int err = ehci_init(&sc->sc);
 	if (err) {
 		aprint_error_dev(self, "init failed, error=%d\n", err);
+		ehci_release_ownership(&sc->sc, sc->sc_pc, sc->sc_tag);
 		goto fail;
 	}
 	sc->sc_init_state = EHCI_INIT_INITED;
@@ -276,12 +278,25 @@ ehci_pci_attach(device_t parent, device_
 	return;
 
 fail:
+	ehci_pci_release_resources(sc);
+
+	if (!pmf_device_register(self, NULL, NULL))
+		aprint_error_dev(self, "couldn't establish power handler\n");
+
+	sc->sc_init_state = EHCI_INIT_NONE;
+}
+
+static void
+ehci_pci_release_resources(struct ehci_pci_softc *sc)
+{
+
 	if (sc->sc_ih) {
 		pci_intr_disestablish(sc->sc_pc, sc->sc_ih);
+		pci_intr_release(sc->sc_pc, sc->sc_pihp, 1);
 		sc->sc_ih = NULL;
 	}
+
 	if (sc->sc.sc_size) {
-		ehci_release_ownership(&sc->sc, sc->sc_pc, sc->sc_tag);
 		bus_space_unmap(sc->sc.iot, sc->sc.ioh, sc->sc.sc_size);
 		sc->sc.sc_size = 0;
 	}
@@ -302,27 +317,17 @@ ehci_pci_detach(device_t self, int flags
 	pmf_device_deregister(self);
 	ehci_shutdown(self, flags);
 
-	/* disable interrupts */
-	EOWRITE4(&sc->sc, EHCI_USBINTR, 0);
-	/* XXX grotty hack to flush the write */
-	(void)EOREAD4(&sc->sc, EHCI_USBINTR);
-
-	if (sc->sc_ih != NULL) {
-		pci_intr_disestablish(sc->sc_pc, sc->sc_ih);
-		sc->sc_ih = NULL;
-	}
-
-	if (sc->sc_pihp != NULL) {
-		pci_intr_release(sc->sc_pc, sc->sc_pihp, 1);
-		sc->sc_pihp = NULL;
-	}
+	if (sc->sc_init_state >= EHCI_INIT_INITED) {
+		/* disable interrupts */
+		EOWRITE4(&sc->sc, EHCI_USBINTR, 0);
+		/* XXX grotty hack to flush the write */
+		(void)EOREAD4(&sc->sc, EHCI_USBINTR);
 
-	if (sc->sc.sc_size) {
 		ehci_release_ownership(&sc->sc, sc->sc_pc, sc->sc_tag);
-		bus_space_unmap(sc->sc.iot, sc->sc.ioh, sc->sc.sc_size);
-		sc->sc.sc_size = 0;
 	}
 
+	ehci_pci_release_resources(sc);
+
 #if 1
 	/* XXX created in ehci.c */
 	if (sc->sc_init_state >= EHCI_INIT_INITED) {