parport_pc: after superio probing restore original register values

CONFIG_PARPORT_PC_SUPERIO probes for various superio chips by writing
byte sequences to a set of different potential I/O ranges.  But the
probed ranges are not exclusive to parallel ports.  Some of our boards
just happen to have a watchdog in one of them.  Took us almost a week
to figure out why some distros reboot without warning after running
flawlessly for 3 hours.  For exactly 170 = 0xAA minutes, that is ...

Fixed by restoring original values after probing.  Also fixed too small
request_region() in detect_and_report_it87().

Signed-off-by: Jens Rottmann <JRottmann@LiPPERTEmbedded.de>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: <stable@kernel.org>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 25 insertions, 6 deletions

diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c
index 151bf5bc8afe..7f1cca701c11 100644
--- a/drivers/parport/parport_pc.c
+++ b/drivers/parport/parport_pc.c
@@ -1471,11 +1471,13 @@ static void __devinit decode_smsc(int efer, int key, int devid, int devrev)
 
 static void __devinit winbond_check(int io, int key)
 {
-        int devid, devrev, oldid, x_devid, x_devrev, x_oldid;
+        int origval, devid, devrev, oldid, x_devid, x_devrev, x_oldid;
 
         if (!request_region(io, 3, __func__))
                 return;
 
+        origval = inb(io); /* Save original value */
+
         /* First probe without key */
         outb(0x20, io);
         x_devid = inb(io + 1);
@@ -1495,6 +1497,8 @@ static void __devinit winbond_check(int io, int key)
         oldid = inb(io + 1);
         outb(0xaa, io);    /* Magic Seal */
 
+        outb(origval, io); /* in case we poked some entirely different hardware */
+
         if ((x_devid == devid) && (x_devrev == devrev) && (x_oldid == oldid))
                 goto out; /* protection against false positives */
 
@@ -1505,11 +1509,15 @@ out:
 
 static void __devinit winbond_check2(int io, int key)
 {
-        int devid, devrev, oldid, x_devid, x_devrev, x_oldid;
+        int origval[3], devid, devrev, oldid, x_devid, x_devrev, x_oldid;
 
         if (!request_region(io, 3, __func__))
                 return;
 
+        origval[0] = inb(io); /* Save original values */
+        origval[1] = inb(io + 1);
+        origval[2] = inb(io + 2);
+
         /* First probe without the key */
         outb(0x20, io + 2);
         x_devid = inb(io + 2);
@@ -1528,6 +1536,10 @@ static void __devinit winbond_check2(int io, int key)
         oldid = inb(io + 2);
         outb(0xaa, io);    /* Magic Seal */
 
+        outb(origval[0], io); /* in case we poked some entirely different hardware */
+        outb(origval[1], io + 1);
+        outb(origval[2], io + 2);
+
         if (x_devid == devid && x_devrev == devrev && x_oldid == oldid)
                 goto out; /* protection against false positives */
 
@@ -1538,11 +1550,13 @@ out:
 
 static void __devinit smsc_check(int io, int key)
 {
-        int id, rev, oldid, oldrev, x_id, x_rev, x_oldid, x_oldrev;
+        int origval, id, rev, oldid, oldrev, x_id, x_rev, x_oldid, x_oldrev;
 
         if (!request_region(io, 3, __func__))
                 return;
 
+        origval = inb(io); /* Save original value */
+
         /* First probe without the key */
         outb(0x0d, io);
         x_oldid = inb(io + 1);
@@ -1566,6 +1580,8 @@ static void __devinit smsc_check(int io, int key)
         rev = inb(io + 1);
         outb(0xaa, io);    /* Magic Seal */
 
+        outb(origval, io); /* in case we poked some entirely different hardware */
+
         if (x_id == id && x_oldrev == oldrev &&
             x_oldid == oldid && x_rev == rev)
                 goto out; /* protection against false positives */
@@ -1602,11 +1618,12 @@ static void __devinit detect_and_report_smsc(void)
 static void __devinit detect_and_report_it87(void)
 {
         u16 dev;
-        u8 r;
+        u8 origval, r;
         if (verbose_probing)
                 printk(KERN_DEBUG "IT8705 Super-IO detection, now testing port 2E ...\n");
-        if (!request_region(0x2e, 1, __func__))
+        if (!request_region(0x2e, 2, __func__))
                 return;
+        origval = inb(0x2e);            /* Save original value */
         outb(0x87, 0x2e);
         outb(0x01, 0x2e);
         outb(0x55, 0x2e);
@@ -1626,8 +1643,10 @@ static void __devinit detect_and_report_it87(void)
                 outb(r | 8, 0x2F);
                 outb(0x02, 0x2E);       /* Lock */
                 outb(0x02, 0x2F);
+        } else {
+                outb(origval, 0x2e);    /* Oops, sorry to disturb */
         }
-        release_region(0x2e, 1);
+        release_region(0x2e, 2);
 }
 #endif /* CONFIG_PARPORT_PC_SUPERIO */