[PATCH] Disable /dev/port interface on powerpc systems

[Haren Myneni <haren@linux.vnet.ibm.com>]

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>


diff -Naurp linux.orig/arch/powerpc/kernel/isa-bridge.c
linux/arch/powerpc/kernel/isa-bridge.c
--- linux.orig/arch/powerpc/kernel/isa-bridge.c	2012-02-11
02:08:08.780005293 -0800
+++ linux/arch/powerpc/kernel/isa-bridge.c	2012-02-11 02:16:25.080003386
-0800
@@ -255,6 +255,14 @@ static struct notifier_block isa_bridge_
 	.notifier_call = isa_bridge_notify
 };
 
+int __init legacy_isa_device_found(void)
+{
+	if (isa_bridge_pcidev)
+		return 1;
+	
+	return 0;
+}
+
 /**
  * isa_bridge_init - register to be notified of ISA bridge
addition/removal
  *
diff -Naurp linux.orig/drivers/char/mem.c linux/drivers/char/mem.c
--- linux.orig/drivers/char/mem.c	2012-02-11 02:08:42.710002440 -0800
+++ linux/drivers/char/mem.c	2012-03-20 20:40:43.650000003 -0700
@@ -35,6 +35,8 @@
 # include <linux/efi.h>
 #endif
 
+#define DEVPORT_MINOR	4
+
 static inline unsigned long size_inside_page(unsigned long start,
 					     unsigned long size)
 {
@@ -910,6 +912,11 @@ static char *mem_devnode(struct device *
 
 static struct class *mem_class;
 
+int __init __weak legacy_isa_device_found(void)
+{
+	return 1;
+}
+
 static int __init chr_dev_init(void)
 {
 	int minor;
@@ -930,6 +937,13 @@ 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) && !legacy_isa_device_found())
+			continue;
+
 		device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor),
 			      NULL, devlist[minor].name);
 	}
diff -Naurp linux.orig/include/linux/isa.h linux/include/linux/isa.h
--- linux.orig/include/linux/isa.h	2012-02-11 02:07:52.030019810 -0800
+++ linux/include/linux/isa.h	2012-02-11 02:16:49.810002296 -0800
@@ -36,4 +36,5 @@ static inline void isa_unregister_driver
 }
 #endif
 
+extern int __init legacy_isa_device_found(void);
 #endif /* __LINUX_ISA_H */