[PATCH 1/3] drivers: char: mem: Make /dev/mem an optional device

[robert.ward114@googlemail.com]

From: Rob Ward <robert.ward114@googlemail.com>

Adds Kconfig option CONFIG_DEVMEM that allows the
/dev/mem device to be disabled.

Option defaults to /dev/mem enabled.

Signed-off-by: Rob Ward <robert.ward114@googlemail.com>
---
 drivers/char/Kconfig | 9 +++++++++
 drivers/char/mem.c   | 4 +++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index efefd12..a4af822 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -6,6 +6,15 @@ menu "Character devices"
 
 source "drivers/tty/Kconfig"
 
+config DEVMEM
+	bool "/dev/mem virtual device support"
+	default y
+	help
+	  Say Y here if you want to support the /dev/mem device.
+	  The /dev/mem device is used to access areas of physical
+	  memory.
+	  When in doubt, say "Y".
+
 config DEVKMEM
 	bool "/dev/kmem virtual device support"
 	default y
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 524b707..b2ca476 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -712,7 +712,7 @@ static int open_port(struct inode *inode, struct file *filp)
 #define open_mem	open_port
 #define open_kmem	open_mem
 
-static const struct file_operations mem_fops = {
+static const struct file_operations __maybe_unused mem_fops = {
 	.llseek		= memory_lseek,
 	.read		= read_mem,
 	.write		= write_mem,
@@ -782,7 +782,9 @@ static const struct memdev {
 	const struct file_operations *fops;
 	struct backing_dev_info *dev_info;
 } devlist[] = {
+#ifdef CONFIG_DEVMEM
 	 [1] = { "mem", 0, &mem_fops, &directly_mappable_cdev_bdi },
+#endif
 #ifdef CONFIG_DEVKMEM
 	 [2] = { "kmem", 0, &kmem_fops, &directly_mappable_cdev_bdi },
 #endif
-- 
2.0.2