init_pci

Author: jtsiomb

src/int86.h

@@ -27,6 +27,19 @@ struct int86regs {
 	uint16_t es, ds, fs, gs;
 } __attribute__ ((packed));
 
+#define FLAGS_CARRY		0x0001
+#define FLAGS_PARITY	0x0004
+#define FLAGS_AUXC		0x0010
+#define FLAGS_ZERO		0x0040
+#define FLAGS_SIGN		0x0080
+#define FLAGS_TRAP		0x0100
+#define FLAGS_INTR		0x0200
+#define FLAGS_DIR		0x0400
+#define FLAGS_OVF		0x0800
+#define FLAGS_SIOPL(x)	(((uint16_t)(x) & 3) << 12)
+#define FLAGS_GIOPL(x)	(((x) >> 12) & 3)
+#define FLAGS_NTASK		0x4000
+
 void int86(int inum, struct int86regs *regs);
 
 #endif	/* INT86_H_ */

src/kmain.c

@@ -25,6 +25,7 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #include "timer.h"
 #include "contty.h"
 #include "video.h"
+#include "pci.h"
 #include "vbetest.h"
 
 
@@ -40,6 +41,8 @@ void pcboot_main(void)
 
 	init_mem();
 
+	init_pci();
+
 	/* initialize the timer */
 	init_timer();
 

src/pci.c

@@ -0,0 +1,82 @@
+/*
+pcboot - bootable PC demo/game kernel
+Copyright (C) 2018  John Tsiombikas <[email protected]>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY, without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+#include "pci.h"
+#include "int86.h"
+#include "asmops.h"
+#include "panic.h"
+
+#define CONFIG_ADDR_PORT	0xcf8
+#define CONFIG_DATA_PORT	0xcfc
+
+#define ADDR_ENABLE		0x80000000
+#define ADDR_BUSID(x)	(((uint32_t)(x) & 0xff) << 16)
+#define ADDR_DEVID(x)	(((uint32_t)(x) & 0x1f) << 11)
+#define ADDR_FUNC(x)	(((uint32_t)(x) & 3) << 8)
+
+/* signature returned in edx by the PCI BIOS present function: FOURCC "PCI " */
+#define PCI_SIG		0x20494350
+
+static uint16_t cfg_read32_acc1(int bus, int dev, int func, int reg);
+static uint16_t cfg_read32_acc2(int bus, int dev, int func, int reg);
+
+static uint16_t (*cfg_read32)(int, int, int, int);
+
+void init_pci(void)
+{
+	struct int86regs regs;
+
+	memset(&regs, 0, sizeof regs);
+	regs.eax = 0xb101;
+	int86(0x1a, &regs);
+
+	/* PCI BIOS present if CF=0, AH=0, and EDX has the "PCI " sig FOURCC */
+	if((regs.flags & FLAGS_CARRY) || (regs.eax & 0xff00) || regs.edx != PCI_SIG) {
+		printf("No PCI BIOS present\n");
+		return;
+	}
+
+	printf("PCI BIOS v%x.%x found\n", (regs.ebx & 0xff00) >> 8, regs.ebx & 0xff);
+	if(regs.eax & 1) {
+		cfg_read32 = cfg_read32_acc1;
+	} else {
+		if(!(regs.eax & 2)) {
+			printf("Failed to find supported PCI access mechanism\n");
+			return;
+		}
+		printf("PCI access mechanism #1 unsupported, falling back to mechanism #2\n");
+		cfg_read32 = cfg_read32_acc2;
+	}
+}
+
+static uint16_t cfg_read32_acc1(int bus, int dev, int func, int reg)
+{
+	uint32_t addr = ADDR_ENABLE | ADDR_BUSID(bus) | ADDR_DEVID(dev) |
+		ADDR_FUNC(func) | reg;
+
+	outl(addr, CONFIG_ADDR_PORT);
+	return inl(CONFIG_DATA_PORT);
+}
+
+static uint16_t cfg_read32_acc2(int bus, int dev, int func, int reg)
+{
+	panic("BUG: PCI access mechanism #2 not implemented yet!");
+	return 0;
+}

src/pci.h

@@ -0,0 +1,23 @@
+/*
+pcboot - bootable PC demo/game kernel
+Copyright (C) 2018  John Tsiombikas <[email protected]>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY, without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+#ifndef PCI_H_
+#define PCI_H_
+
+void init_pci(void);
+
+#endif	/* PCI_H_ */