powerpc: Disable /dev/port interface on systems without an ISA bridge

Some power systems do not have legacy ISA devices. So, /dev/port is not
a valid interface on these systems. User level tools such as kbdrate is
trying to access the device using this interface which is causing the
system crash.

This patch will fix this issue by not creating this interface on these
powerpc systems.

Signed-off-by: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 67c3371723cc..e5eedfa24c91 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -27,14 +27,16 @@
 #include <linux/splice.h>
 #include <linux/pfn.h>
 #include <linux/export.h>
+#include <linux/io.h>
 
 #include <asm/uaccess.h>
-#include <asm/io.h>
 
 #ifdef CONFIG_IA64
 # include <linux/efi.h>
 #endif
 
+#define DEVPORT_MINOR   4
+
 static inline unsigned long size_inside_page(unsigned long start,
                                              unsigned long size)
 {
@@ -894,6 +896,13 @@ static int __init chr_dev_init(void)
         for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) {
                 if (!devlist[minor].name)
                         continue;
+
+                /*
+                 * Create /dev/port? 
+                 */
+                if ((minor == DEVPORT_MINOR) && !arch_has_dev_port())
+                        continue;
+
                 device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
                               NULL, devlist[minor].name);
         }