Save and restore the interrupt Edge/Level Control Registers (ELCR)

across system suspends on the Intel 82371AB PCI-ISA bridge. On a
Sony Vaio C1XD that I have, these registers are not set correctly
after an ACPI resume. The result is that after resuming, a shared
IRQ is left in edge-triggered mode so the interrupt can later become
jammed in a state where the line remains asserted, but the handler
is never called.

Reviewed by:	jhb

1 files changed, 88 insertions, 5 deletions

diff --git a/sys/dev/pci/isa_pci.c b/sys/dev/pci/isa_pci.c
index 85ef75d..5690df1 100644
--- a/sys/dev/pci/isa_pci.c
+++ b/sys/dev/pci/isa_pci.c
@@ -37,21 +37,36 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
+#include <machine/bus.h>
+#include <machine/resource.h>
 #include <sys/bus.h>
+#include <sys/rman.h>
 
 #include <pci/pcivar.h>
 #include <pci/pcireg.h>
 
+#define	ELCR_IOADDR	0x4d0	/* Interrupt Edge/Level Control Registers */
+#define	ELCR_IOLEN	2
+
+struct isab_softc {
+    struct resource *elcr_res;
+    u_char saved_elcr[ELCR_IOLEN];
+};
+
 static int	isab_probe(device_t dev);
 static int	isab_attach(device_t dev);
+static int	isab_detach(device_t dev);
+static int	isab_resume(device_t dev);
+static int	isab_suspend(device_t dev);
 
 static device_method_t isab_methods[] = {
     /* Device interface */
     DEVMETHOD(device_probe,		isab_probe),
     DEVMETHOD(device_attach,		isab_attach),
+    DEVMETHOD(device_detach,		isab_detach),
     DEVMETHOD(device_shutdown,		bus_generic_shutdown),
-    DEVMETHOD(device_suspend,		bus_generic_suspend),
-    DEVMETHOD(device_resume,		bus_generic_resume),
+    DEVMETHOD(device_suspend,		isab_suspend),
+    DEVMETHOD(device_resume,		isab_resume),
 
     /* Bus interface */
     DEVMETHOD(bus_print_child,		bus_generic_print_child),
@@ -68,7 +83,7 @@ static device_method_t isab_methods[] = {
 static driver_t isab_driver = {
     "isab",
     isab_methods,
-    0,
+    sizeof(struct isab_softc),
 };
 
 static devclass_t isab_devclass;
@@ -143,14 +158,82 @@ static int
 isab_attach(device_t dev)
 {
     device_t	child;
+    struct isab_softc *sc = device_get_softc(dev);
+    int error, rid;
 
     /*
      * Attach an ISA bus.  Note that we can only have one ISA bus.
      */
     child = device_add_child(dev, "isa", 0);
-    if (child != NULL)
-	return(bus_generic_attach(dev));
+    if (child != NULL) {
+	error = bus_generic_attach(dev);
+	if (error)
+	     return (error);
+    }
+
+    switch (pci_get_devid(dev)) {
+    case 0x71108086: /* Intel 82371AB */
+	/*
+	 * Sometimes the ELCR (Edge/Level Control Register) is not restored
+	 * correctly on resume by the BIOS, so we handle it ourselves.
+	 */
+	rid = 0;
+	bus_set_resource(dev, SYS_RES_IOPORT, rid, ELCR_IOADDR, ELCR_IOLEN);
+	sc->elcr_res = bus_alloc_resource(dev, SYS_RES_IOPORT, &rid, 0, ~0, 1,
+	    RF_ACTIVE);
+	if (sc->elcr_res == NULL)
+	    device_printf(dev, "failed to allocate ELCR resource\n");
+        break;
+    }
 
     return(0);
 }
 
+static int
+isab_detach(device_t dev)
+{
+    struct isab_softc *sc = device_get_softc(dev);
+
+    if (sc->elcr_res != NULL)
+	bus_release_resource(dev, SYS_RES_IOPORT, 0, sc->elcr_res);
+
+    return (bus_generic_detach(dev));
+}
+
+static int
+isab_suspend(device_t dev)
+{
+    struct isab_softc *sc = device_get_softc(dev);
+    bus_space_tag_t bst;
+    bus_space_handle_t bsh;
+    int i;
+
+    /* Save the ELCR if required. */
+    if (sc->elcr_res != NULL) {
+	bst = rman_get_bustag(sc->elcr_res);
+	bsh = rman_get_bushandle(sc->elcr_res);
+	for (i = 0; i < ELCR_IOLEN; i++)
+	    sc->saved_elcr[i] = bus_space_read_1(bst, bsh, i);
+    }
+
+    return (bus_generic_suspend(dev));
+}
+
+static int
+isab_resume(device_t dev)
+{
+    struct isab_softc *sc = device_get_softc(dev);
+    bus_space_tag_t bst;
+    bus_space_handle_t bsh;
+    int i;
+
+    /* Restore the ELCR if required. */
+    if (sc->elcr_res != NULL) {
+	bst = rman_get_bustag(sc->elcr_res);
+	bsh = rman_get_bushandle(sc->elcr_res);
+	for (i = 0; i < ELCR_IOLEN; i++)
+	    bus_space_write_1(bst, bsh, i, sc->saved_elcr[i]);
+    }
+
+    return (bus_generic_resume(dev));
+}