From faa57a4ef4d9c7f86b6c8a25b1603eb92c549348 Mon Sep 17 00:00:00 2001
From: Alexander Malysh <amalysh@web.de>
Date: Sat, 21 Sep 2002 00:05:37 +0000
Subject: [PATCH] (amalysh) 	Added high_clock module option.If this option
 is set         used Host Master Clock 56KHz (default 14KHz).For now we are
 save old Host         Master Clock and after transaction completed restore
 (otherwise         it's confuse BIOS and hung Laptop).

git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@1540 7894878c-1315-0410-8ee3-d5d059ff63e0
---
 kernel/busses/i2c-sis630.c | 37 +++++++++++++++++++++++++++++++++----
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/kernel/busses/i2c-sis630.c b/kernel/busses/i2c-sis630.c
index 69d7bb44..ccf8f3b1 100644
--- a/kernel/busses/i2c-sis630.c
+++ b/kernel/busses/i2c-sis630.c
@@ -22,6 +22,11 @@
 
 /*
    Changes:
+   21.09.2002
+	Added high_clock module option.If this option is set 
+	used Host Master Clock 56KHz (default 14KHz).For now we are save old Host 
+	Master Clock and after transaction completed restore (otherwise
+	it's confuse BIOS and hung Laptop).
    18.09.2002
 	Added SIS730 as supported
    24.08.2002
@@ -38,6 +43,7 @@
 /*
    Supports:
 	SIS 630
+	SIS 730
 
    Note: we assume there can only be one device, with one SMBus interface.
 */
@@ -129,8 +135,11 @@ static struct sd supported[] = {
 /* If force is set to anything different from 0, we forcibly enable the
    SIS630. DANGEROUS! */
 static int force = 0;
+static int high_clock = 0;
 MODULE_PARM(force, "i");
 MODULE_PARM_DESC(force, "Forcibly enable the SIS630. DANGEROUS!");
+MODULE_PARM(high_clock, "i");
+MODULE_PARM_DESC(high_clock, "Set Host Master Clock to 56KHz (default 14KHz).");
 
 
 #ifdef MODULE
@@ -198,6 +207,7 @@ int sis630_transaction(int size) {
         int temp;
         int result = 0;
         int timeout = 0;
+	u8 oldclock;
 
         /*
 	  Make sure the SMBus host is ready to start transmitting.
@@ -223,8 +233,14 @@ int sis630_transaction(int size) {
 		}
         }
 
-	/* disable timeout interrupt , don't set Host Master Clock to 56KHz (it's hung my Laptop)*/
-	sis630_write(SMB_CNT, 0x00);
+	/* save old clock, so we can prevent machine to hung */
+	oldclock = sis630_read(SMB_CNT);
+
+	/* disable timeout interrupt , set Host Master Clock to 56KHz if requested */
+	if (high_clock > 0)
+		sis630_write(SMB_CNT, 0x20);
+	else
+		sis630_write(SMB_CNT, 0x00);
 
 	/* clear all sticky bits */
 	temp = sis630_read(SMB_STS);
@@ -259,14 +275,27 @@ int sis630_transaction(int size) {
                 result = -1;
                 printk(KERN_ERR "i2c-sis630.o: Bus collision! "
 			"SMBus may be locked until next hard reset (or not...)\n");
-		/* TBD: Datasheet say:
-		   the software should clear this bit and restart SMBUS operation
+		/* 
+		   TBD: Datasheet say:
+		   	the software should clear this bit and restart SMBUS operation
 		*/
         }
 
         /* clear all status "sticky" bits */
 	sis630_write(SMB_STS, temp);
 
+	/* restore old Host Master Clock */
+	if (!(oldclock & 0x20)) {
+#ifdef DEBUG
+		printk(KERN_DEBUG "i2c-sis630.o: SMB_CNT before clock restore 0x%02x\n", sis630_read(SMB_CNT));
+#endif
+		oldclock = sis630_read(SMB_CNT) & ~0x20;
+		sis630_write(SMB_CNT,oldclock);
+#ifdef DEBUG
+		printk(KERN_DEBUG "i2c-sis630.o: SMB_CNT after clock restore 0x%02x\n", sis630_read(SMB_CNT));
+#endif
+	}
+
         return result;
 }