redo the PCI configuration mode detection - should make some less

standard compliant PCI chipsets work (Compaq, Connectix emulated Triton)
fix the bug reported in PR port-i386/5727 (soda@sra.co.jp)

sys/arch/i386/pci/pci_machdep.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: pci_machdep.c,v 1.31 1998/06/03 06:35:49 thorpej Exp $	*/
+/*	$NetBSD: pci_machdep.c,v 1.32 1998/07/09 20:19:52 drochner Exp $	*/
 
 /*-
  * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
@@ -109,6 +109,28 @@ int pci_mode = -1;
 #define	PCI_MODE2_ENABLE_REG	0x0cf8
 #define	PCI_MODE2_FORWARD_REG	0x0cfa
 
+#define _m1tag(b, d, f) \
+	(PCI_MODE1_ENABLE | ((b) << 16) | ((d) << 11) | ((f) << 8))
+#define _id(v, p) \
+	(((v) << PCI_VENDOR_SHIFT) | ((p) << PCI_PRODUCT_SHIFT))
+#define _qe(bus, dev, fcn, vend, prod) \
+	{_m1tag(bus, dev, fcn), _id(vend, prod)}
+struct {
+	u_int32_t tag;
+	pcireg_t id;
+} pcim1_quirk_tbl[] = {
+	_qe(0, 0, 0, PCI_VENDOR_COMPAQ, PCI_PRODUCT_COMPAQ_TRIFLEX1),
+	/* XXX Triflex2 not tested */
+	_qe(0, 0, 0, PCI_VENDOR_COMPAQ, PCI_PRODUCT_COMPAQ_TRIFLEX2),
+	_qe(0, 0, 0, PCI_VENDOR_COMPAQ, PCI_PRODUCT_COMPAQ_TRIFLEX4),
+	/* Triton needed for Connectix Virtual PC */
+	_qe(0, 0, 0, PCI_VENDOR_INTEL, PCI_PRODUCT_INTEL_82437FX),
+	{0, 0xffffffff} /* patchable */
+};
+#undef _m1tag
+#undef _id
+#undef _qe
+
 /*
  * PCI doesn't have any special needs; just use the generic versions
  * of these functions.
@@ -313,6 +335,7 @@ mode1:
 	outl(PCI_MODE1_ADDRESS_REG, tag.mode1 | reg);
 	outl(PCI_MODE1_DATA_REG, data);
 	outl(PCI_MODE1_ADDRESS_REG, 0);
+	return;
 #endif
 
 #if !defined(PCI_CONF_MODE) || (PCI_CONF_MODE == 2)
@@ -337,35 +360,79 @@ pci_mode_detect()
 #error Invalid PCI configuration mode.
 #endif
 #else
+	u_int32_t sav, val;
+	int i;
+	pcireg_t idreg;
+
 	if (pci_mode != -1)
 		return pci_mode;
 
 	/*
-	 * We try to divine which configuration mode the host bridge wants.  We
+	 * We try to divine which configuration mode the host bridge wants.
-	 * try mode 2 first, because our probe for mode 1 is likely to succeed
-	 * for mode 2 also.
-	 *
-	 * XXX
-	 * This should really be done using the PCI BIOS.
 	 */
 
+	sav = inl(PCI_MODE1_ADDRESS_REG);
+
+	pci_mode = 1; /* assume this for now */
+	/*
+	 * catch some known buggy implementations of mode 1
+	 */
+	for (i = 0; i < sizeof(pcim1_quirk_tbl) / sizeof(pcim1_quirk_tbl[0]);
+	     i++) {
+		pcitag_t t;
+
+		if (!pcim1_quirk_tbl[i].tag)
+			break;
+		t.mode1 = pcim1_quirk_tbl[i].tag;
+		idreg = pci_conf_read(0, t, PCI_ID_REG); /* needs "pci_mode" */
+		if (idreg == pcim1_quirk_tbl[i].id) {
+#ifdef DEBUG
+			printf("known mode 1 PCI chipset (%08x)\n",
+			       idreg);
+#endif
+			return (pci_mode);
+		}
+	}
+
+	/*
+	 * Strong check for standard compliant mode 1:
+	 * 1. bit 31 ("enable") can be set
+	 * 2. byte/word access does not affect register
+	 */
+	outl(PCI_MODE1_ADDRESS_REG, PCI_MODE1_ENABLE);
+	outb(PCI_MODE1_ADDRESS_REG + 3, 0);
+	outw(PCI_MODE1_ADDRESS_REG + 2, 0);
+	val = inl(PCI_MODE1_ADDRESS_REG);
+	if ((val & 0x80fffffc) != PCI_MODE1_ENABLE) {
+#ifdef DEBUG
+		printf("pci_mode_detect: mode 1 enable failed (%x)\n",
+		       val);
+#endif
+		goto not1;
+	}
+	outl(PCI_MODE1_ADDRESS_REG, 0);
+	val = inl(PCI_MODE1_ADDRESS_REG);
+	if ((val & 0x80fffffc) != 0)
+		goto not1;
+	return (pci_mode);
+not1:
+	outl(PCI_MODE1_ADDRESS_REG, sav);
+
+	/*
+	 * This mode 2 check is quite weak (and known to give false
+	 * positives on some Compaq machines).
+	 * However, this doesn't matter, because this is the
+	 * last test, and simply no PCI devices will be found if
+	 * this happens.
+	 */
 	outb(PCI_MODE2_ENABLE_REG, 0);
 	outb(PCI_MODE2_FORWARD_REG, 0);
 	if (inb(PCI_MODE2_ENABLE_REG) != 0 ||
 	    inb(PCI_MODE2_FORWARD_REG) != 0)
 		goto not2;
 	return (pci_mode = 2);
-
 not2:
-	outl(PCI_MODE1_ADDRESS_REG, PCI_MODE1_ENABLE);
-	if (inl(PCI_MODE1_ADDRESS_REG) != PCI_MODE1_ENABLE)
-		goto not1;
-	outl(PCI_MODE1_ADDRESS_REG, 0);
-	if (inl(PCI_MODE1_ADDRESS_REG) != 0)
-		goto not1;
-	return (pci_mode = 1);
 
-not1:
 	return (pci_mode = 0);
 #endif
 }