From 91291042274de728fce6f7ffad79152d68fccd2f Mon Sep 17 00:00:00 2001
From: Will Andrews <will@FreeBSD.org>
Date: Wed, 21 Jan 2015 20:08:24 +0000
Subject: [PATCH] Fix remote DMA based firewire debugging when targeting
 systems with more than 4GB of physical memory.

To remotely debug the system 'stealthy' which has a kernel
with this change installed and firewire properly configured:

	% fwcontrol -m stealthy (or stealthy's firewire EUI64)
	% kgdb kernel /dev/fwmem0.0

sys/dev/firewire/fwohci.c:
	Rather than hard code the upper limit for hw based
	automatic responses to remote DMA requests at 4GB,
	program the hardware using Maxmem, the page number
	one higher than the highest physical page detected
	in the system.

	While here, garbage collect more useless splfw()
	calls.

Submitted by:	gibbs
MFC after:	1 week
Sponsored by:	Spectra Logic
MFSpectraBSD:	1110994 on 2015/01/06
---
 sys/dev/firewire/fwohci.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/sys/dev/firewire/fwohci.c b/sys/dev/firewire/fwohci.c
index 00a54e28da6d..70134af686e6 100644
--- a/sys/dev/firewire/fwohci.c
+++ b/sys/dev/firewire/fwohci.c
@@ -48,6 +48,7 @@
 #include <sys/kdb.h>
 
 #include <machine/bus.h>
+#include <machine/md_var.h>
 
 #include <dev/firewire/firewire.h>
 #include <dev/firewire/firewirereg.h>
@@ -188,6 +189,7 @@ static void fwohci_task_dma(void *, int);
 #define	OHCI_PREQLO		0x118
 #define	OHCI_PREQLOCLR		0x11c
 #define	OHCI_PREQUPPER		0x120
+#define OHCI_PREQUPPER_MAX	0xffff0000
 
 #define	OHCI_SID_BUF		0x64
 #define	OHCI_SID_CNT		0x68
@@ -854,7 +856,7 @@ fwohci_execute_db2(void *arg, bus_dma_segment_t *segs, int nseg,
 static void
 fwohci_start(struct fwohci_softc *sc, struct fwohci_dbch *dbch)
 {
-	int i, s;
+	int i;
 	int tcode, hdr_len, pl_off;
 	int fsegment = -1;
 	uint32_t off;
@@ -880,7 +882,6 @@ fwohci_start(struct fwohci_softc *sc, struct fwohci_dbch *dbch)
 	if (dbch->flags & FWOHCI_DBCH_FULL)
 		return;
 
-	s = splfw();
 	db_tr = dbch->top;
 txloop:
 	xfer = STAILQ_FIRST(&dbch->xferq.q);
@@ -1030,7 +1031,6 @@ fwohci_start(struct fwohci_softc *sc, struct fwohci_dbch *dbch)
 	}
 
 	dbch->top = db_tr;
-	splx(s);
 	return;
 }
 
@@ -1821,6 +1821,7 @@ static void
 fwohci_intr_core(struct fwohci_softc *sc, uint32_t stat, int count)
 {
 	struct firewire_comm *fc = (struct firewire_comm *)sc;
+	uintmax_t prequpper;
 	uint32_t node_id, plen;
 
 	FW_GLOCK_ASSERT(fc);
@@ -1852,8 +1853,17 @@ fwohci_intr_core(struct fwohci_softc *sc, uint32_t stat, int count)
 			/* allow from all nodes */
 			OWRITE(sc, OHCI_PREQHI, 0x7fffffff);
 			OWRITE(sc, OHCI_PREQLO, 0xffffffff);
-			/* 0 to 4GB region */
-			OWRITE(sc, OHCI_PREQUPPER, 0x10000);
+			prequpper = ((uintmax_t)Maxmem << PAGE_SHIFT) >> 16;
+			if (prequpper > OHCI_PREQUPPER_MAX) {
+				device_printf(fc->dev,
+				    "Physical memory size of 0x%jx exceeds "
+				    "fire wire address space.  Limiting dma "
+				    "to memory below 0x%jx\n",
+				    (uintmax_t)Maxmem << PAGE_SHIFT,
+				    (uintmax_t)OHCI_PREQUPPER_MAX << 16);
+				prequpper = OHCI_PREQUPPER_MAX;
+			}
+			OWRITE(sc, OHCI_PREQUPPER, prequpper & 0xffffffff);
 		}
 		/* Set ATRetries register */
 		OWRITE(sc, OHCI_ATRETRY, 1<<(13 + 16) | 0xfff);
@@ -2171,7 +2181,7 @@ fwohci_rbuf_update(struct fwohci_softc *sc, int dmach)
 	struct fw_bulkxfer *chunk;
 	struct fw_xferq *ir;
 	uint32_t stat;
-	int s, w = 0, ldesc;
+	int w = 0, ldesc;
 
 	ir = fc->ir[dmach];
 	ldesc = sc->ir[dmach].ndesc - 1;
@@ -2179,7 +2189,6 @@ fwohci_rbuf_update(struct fwohci_softc *sc, int dmach)
 #if 0
 	dump_db(sc, dmach);
 #endif
-	s = splfw();
 	if ((ir->flag & FWXFERQ_HANDLER) == 0)
 		FW_GLOCK(fc);
 	fwdma_sync_multiseg_all(sc->ir[dmach].am, BUS_DMASYNC_POSTREAD);
@@ -2218,7 +2227,6 @@ fwohci_rbuf_update(struct fwohci_softc *sc, int dmach)
 	}
 	if ((ir->flag & FWXFERQ_HANDLER) == 0)
 		FW_GUNLOCK(fc);
-	splx(s);
 	if (w == 0)
 		return;