From a93592e3043f5c7e1f39f5778a93d4334881e4b9 Mon Sep 17 00:00:00 2001
From: Haren Myneni <haren@us.ibm.com>
Date: Wed, 11 Jul 2012 15:18:44 +1000
Subject: [PATCH] --- yaml --- r: 313689 b: refs/heads/master c:
 e1612de9e4cdf375c3cf1c72434ab8abdcb3927e h: refs/heads/master i:   313687:
 21d381502aed60589794754eb389cc11c20c35f8 v: v3

---
 [refs]                              |  2 +-
 trunk/arch/powerpc/include/asm/io.h |  8 ++++++++
 trunk/drivers/char/mem.c            | 11 ++++++++++-
 trunk/include/linux/io.h            |  9 +++++++++
 4 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index d79f6469d06b..e1a507fa1d89 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 475d0094293b51353e342d1198377967dbc48169
+refs/heads/master: e1612de9e4cdf375c3cf1c72434ab8abdcb3927e
diff --git a/trunk/arch/powerpc/include/asm/io.h b/trunk/arch/powerpc/include/asm/io.h
index a3855b81eada..f94ef4213e9d 100644
--- a/trunk/arch/powerpc/include/asm/io.h
+++ b/trunk/arch/powerpc/include/asm/io.h
@@ -20,6 +20,14 @@ extern int check_legacy_ioport(unsigned long base_port);
 #define _PNPWRP		0xa79
 #define PNPBIOS_BASE	0xf000
 
+#if defined(CONFIG_PPC64) && defined(CONFIG_PCI)
+extern struct pci_dev *isa_bridge_pcidev;
+/*
+ * has legacy ISA devices ?
+ */
+#define arch_has_dev_port()	(isa_bridge_pcidev != NULL)
+#endif
+
 #include <linux/device.h>
 #include <linux/io.h>
 
diff --git a/trunk/drivers/char/mem.c b/trunk/drivers/char/mem.c
index 67c3371723cc..e5eedfa24c91 100644
--- a/trunk/drivers/char/mem.c
+++ b/trunk/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);
 	}
diff --git a/trunk/include/linux/io.h b/trunk/include/linux/io.h
index 7fd2d2138bf3..069e4075f872 100644
--- a/trunk/include/linux/io.h
+++ b/trunk/include/linux/io.h
@@ -67,4 +67,13 @@ int check_signature(const volatile void __iomem *io_addr,
 			const unsigned char *signature, int length);
 void devm_ioremap_release(struct device *dev, void *res);
 
+/*
+ * Some systems do not have legacy ISA devices.
+ * /dev/port is not a valid interface on these systems.
+ * So for those archs, <asm/io.h> should define the following symbol.
+ */
+#ifndef arch_has_dev_port
+#define arch_has_dev_port()     (1)
+#endif
+
 #endif /* _LINUX_IO_H */