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aux/realemu: use #$/pci/B.D.Fraw to access pci config space

This prevents VESA bios from accessing the pci
CONFIG_ADDRESS/CONFIG_DATA registers (0xCF8/0xCFC)
directly to access pci config space.

This makes sure the access to pci config space is
properly serialized by the kernel.

--- a/sys/src/cmd/aux/realemu/dat.h

+++ b/sys/src/cmd/aux/realemu/dat.h

@@ -3,6 +3,7 @@

 typedef struct Bus Bus;

 typedef struct Cpu Cpu;

 typedef struct Pit Pit;

+typedef struct Pcidev Pcidev;

 enum {

 	RAX,

@@ -103,6 +104,13 @@

 	/* argument buffers */

 	ulong iabuf;

 	Iarg abuf[0x80];

+};

+

+struct Pcidev

+{

+	Pcidev	*next;

+	int	bdf;

+	int	fd;

 };

 struct Pit

--- a/sys/src/cmd/aux/realemu/fns.h

+++ b/sys/src/cmd/aux/realemu/fns.h

@@ -29,3 +29,12 @@

 void setgate(Pit *ch, uchar gate);

 uchar rpit(Pit *pit, uchar addr);

 void wpit(Pit *pit, uchar addr, uchar data);

+

+/* pci */

+Pcidev *pciopen(int bdf);

+int pcicfgr(Pcidev *pci, void *data, int len, int addr);

+int pcicfgw(Pcidev *pci, void *data, int len, int addr);

+

+#define BDFBNO(bdf)	(((int)bdf >> 16) & 0xFF)

+#define BDFDNO(bdf)	(((int)bdf >> 11) & 0x1F)

+#define BDFFNO(bdf)	(((int)bdf >>  8) & 0x07)

--- a/sys/src/cmd/aux/realemu/main.c

+++ b/sys/src/cmd/aux/realemu/main.c

@@ -29,6 +29,7 @@

 static int cputrace;

 static int porttrace;

 static Pit pit[3];

+static ulong pcicfgaddr;

 static uchar rtcaddr;

 static vlong pitclock;

@@ -155,8 +156,9 @@

 static ulong

 rport(void *, ulong p, int len)

 {

+	Pcidev *pci;

 	uchar data[4];

-	ulong w;

+	ulong w, addr;

 	switch(p){

 	case 0x20:	/* PIC 1 */

@@ -210,6 +212,24 @@

 	case 0xa1:

 		w = 0;

 		break;

+	case 0xcf8:

+		w = pcicfgaddr & ~0x7F000003;

+		break;

+	case 0xcfc: case 0xcfd: case 0xcfe: case 0xcff:

+		w = -1;

+		if((pcicfgaddr & (1<<31)) == 0)

+			break;

+		addr = (pcicfgaddr & 0xFC) | (p & 3);

+		if((pci = pciopen(pcicfgaddr & 0xFFFF00)) == nil)

+			break;

+		if(pcicfgr(pci, data, len, addr) != len)

+			break;

+		w = gw[len](data);

+		if(porttrace)

+			fprint(2, "pcicfgr %d.%d.%d %.2lux %.*lux\n",

+				BDFBNO(pcicfgaddr), BDFDNO(pcicfgaddr), BDFFNO(pcicfgaddr),

+				addr, len<<1, w);

+		break;

 	default:

 		if(pread(portfd[len], data, len, p) != len){

 			fprint(2, "bad %d bit port read %.4lux: %r\n", len*8, p);

@@ -225,7 +245,9 @@

 static void

 wport(void *, ulong p, ulong w, int len)

 {

+	Pcidev *pci;

 	uchar data[4];

+	ulong addr;

 	if(porttrace)

 		fprint(2, "wport %.4lux %.*lux\n", p, len<<1, w);

@@ -274,6 +296,22 @@

 	case 0xA1:

 		break;

+	case 0xcf8:

+		pcicfgaddr = w;

+		break;

+	case 0xcfc: case 0xcfd: case 0xcfe: case 0xcff:

+		if((pcicfgaddr & (1<<31)) == 0)

+			break;

+		addr = (pcicfgaddr & 0xFC) | (p & 3);

+		if(porttrace)

+			fprint(2, "pcicfgw %d.%d.%d %.2lux %.*lux\n",

+				BDFBNO(pcicfgaddr), BDFDNO(pcicfgaddr), BDFFNO(pcicfgaddr),

+				addr, len<<1, w);

+		if((pci = pciopen(pcicfgaddr & 0xFFFF00)) == nil)

+			break;

+		pw[len](data, w);

+		pcicfgw(pci, data, len, addr);

+		break;

 	default:

 		pw[len](data, w);

 		if(pwrite(portfd[len], data, len, p) != len){

--- a/sys/src/cmd/aux/realemu/mkfile

+++ b/sys/src/cmd/aux/realemu/mkfile

@@ -3,7 +3,7 @@

 BIN=/$objtype/bin/aux

 TARG=realemu

-OFILES=decode.$O arg.$O xec.$O fmt.$O pit.$O main.$O

+OFILES=decode.$O arg.$O xec.$O fmt.$O pci.$O pit.$O main.$O

 HFILES=dat.h fns.h

 </sys/src/cmd/mkone

--- /dev/null

+++ b/sys/src/cmd/aux/realemu/pci.c

@@ -1,0 +1,45 @@

+#include <u.h>

+#include <libc.h>

+#include "dat.h"

+#include "fns.h"

+

+static Pcidev *devs;

+

+Pcidev*

+pciopen(int bdf)

+{

+	char path[64];

+	Pcidev *pci;

+

+	for(pci = devs; pci != nil; pci = pci->next){

+		if(pci->bdf == bdf){

+			if(pci->fd < 0)

+				return nil;

+			return pci;

+		}

+	}

+

+	pci = malloc(sizeof(Pcidev));

+	pci->bdf = bdf;

+

+	snprint(path, sizeof(path), "#$/pci/%d.%d.%draw",

+		BDFBNO(bdf), BDFDNO(bdf), BDFFNO(bdf));

+	pci->fd = open(path, ORDWR);

+

+	pci->next = devs;

+	devs = pci;

+

+	return pci;

+}

+

+int

+pcicfgr(Pcidev *pci, void *data, int len, int addr)

+{

+	return pread(pci->fd, data, len, addr);

+}

+

+int

+pcicfgw(Pcidev *pci, void *data, int len, int addr)

+{

+	return pwrite(pci->fd, data, len, addr);

+}