pci: device enumeration with MCFG and legacy access

kernel-src/include/x86-64/arch/pci.h

@@ -0,0 +1,84 @@
+#ifdef _PCIARCH_H
+#error this file should only be included ONCE and only in the io/pci.c file
+#else
+#define _PCIARCH_H
+
+#include <stdint.h>
+#include <stddef.h>
+#include <arch/io.h>
+#include <arch/acpi.h>
+#include <kernel/pmm.h>
+
+static size_t mcfgentrycount;
+static mcfgentry_t *mcfgentries;
+static uint32_t (*pci_archread32)(int bus, int device, int function, uint32_t offset);
+static void (*pci_archwrite32)(int bus, int device, int function, uint32_t offset, uint32_t value);
+
+#define CONFADD 0xcf8
+#define CONFDATA 0xcfc
+
+static uint32_t legacy_read32(int bus, int device, int function, uint32_t offset) {
+	uint32_t confadd = 0x80000000 | (offset & ~0x3) | (function << 8) | (device << 11) | (bus << 16);
+	outd(CONFADD, confadd);
+	return ind(CONFDATA);
+}
+
+static void legacy_write32(int bus, int device, int function, uint32_t offset, uint32_t value) {
+	uint32_t confadd = 0x80000000 | (offset & ~0x3) | (function << 8) | (device << 11) | (bus << 16);
+	outd(CONFADD, confadd);
+	outd(CONFDATA, value);
+}
+
+static inline mcfgentry_t *getmcfgentry(int bus) {
+	mcfgentry_t *entry;
+	int i;
+
+	for (i = 0; i < mcfgentrycount; ++i) {
+		entry = &mcfgentries[i];
+		if (bus >= entry->startbus && bus <= entry->endbus)
+			break;
+	}
+
+	if (i == mcfgentrycount)
+		entry = NULL;
+
+	return entry;
+}
+
+static uint32_t mcfg_read32(int bus, int device, int function, uint32_t offset) {
+	mcfgentry_t *entry = getmcfgentry(bus);
+	if (entry == NULL)
+		return 0xffffffff;
+
+	uint64_t base = (uint64_t)MAKE_HHDM(entry->address);
+	uint32_t *address = (uint32_t *)(base + ((bus - entry->startbus) << 20) + (device << 15) + (function << 12));
+
+	return *address;
+}
+
+static void mcfg_write32(int bus, int device, int function, uint32_t offset, uint32_t value) {
+	mcfgentry_t *entry = getmcfgentry(bus);
+
+	uint64_t base = (uint64_t)MAKE_HHDM(entry->address);
+	uint32_t *address = (uint32_t *)(base + ((bus - entry->startbus) << 20) + (device << 15) + (function << 12));
+
+	*address = value;
+}
+
+static void pci_archinit() {
+	mcfg_t *mcfg = arch_acpi_findtable("MCFG", 0);
+	if (mcfg) {
+		printf("pci: MCFG table found. Using extended configuration space\n");
+		mcfgentries = mcfg->entries;
+		pci_archread32 = mcfg_read32;
+		pci_archwrite32 = mcfg_write32;
+		mcfgentrycount = (mcfg->header.length - sizeof(sdtheader_t)) / sizeof(mcfgentry_t);
+		// TODO map mcfg entries as UC
+	} else {
+		printf("pci: MCFG table not found. Falling back to legacy access mechanism\n");
+		pci_archread32 = legacy_read32;
+		pci_archwrite32 = legacy_write32;
+	}
+}
+
+#endif