tty: Added a CONFIG_TTY option to allow removal of TTY

The option allows you to remove TTY and compile without errors. This
saves space on systems that won't support TTY interfaces anyway.
bloat-o-meter output is below.

The bulk of this patch consists of Kconfig changes adding "depends on
TTY" to various serial devices and similar drivers that require the TTY
layer.  Ideally, these dependencies would occur on a common intermediate
symbol such as SERIO, but most drivers "select SERIO" rather than
"depends on SERIO", and "select" does not respect dependencies.

bloat-o-meter output comparing our previous minimal to new minimal by
removing TTY.  The list is filtered to not show removed entries with awk
'$3 != "-"' as the list was very long.

add/remove: 0/226 grow/shrink: 2/14 up/down: 6/-35356 (-35350)
function                                     old     new   delta
chr_dev_init                                 166     170      +4
allow_signal                                  80      82      +2
static.__warned                              143     142      -1
disallow_signal                               63      62      -1
__set_special_pids                            95      94      -1
unregister_console                           126     121      -5
start_kernel                                 546     541      -5
register_console                             593     588      -5
copy_from_user                                45      40      -5
sys_setsid                                   128     120      -8
sys_vhangup                                   32      19     -13
do_exit                                     1543    1526     -17
bitmap_zero                                   60      40     -20
arch_local_irq_save                          137     117     -20
release_task                                 674     652     -22
static.spin_unlock_irqrestore                308     260     -48

Signed-off-by: Joe Millenbach <jmillenbach@gmail.com>
Reviewed-by: Jamey Sharp <jamey@minilop.net>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

8 files changed, 12 insertions, 8 deletions

diff --git a/drivers/net/caif/Kconfig b/drivers/net/caif/Kconfig
index abf4d7a9dcc..60c2142373c 100644
--- a/drivers/net/caif/Kconfig
+++ b/drivers/net/caif/Kconfig
@@ -6,7 +6,7 @@ comment "CAIF transport drivers"
 
 config CAIF_TTY
 	tristate "CAIF TTY transport driver"
-	depends on CAIF
+	depends on CAIF && TTY
 	default n
 	---help---
 	The CAIF TTY transport driver is a Line Discipline (ldisc)
diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
index b56bd9e8095..72df3a306a0 100644
--- a/drivers/net/can/Kconfig
+++ b/drivers/net/can/Kconfig
@@ -13,7 +13,7 @@ config CAN_VCAN
 
 config CAN_SLCAN
 	tristate "Serial / USB serial CAN Adaptors (slcan)"
-	depends on CAN
+	depends on CAN && TTY
 	---help---
 	  CAN driver for several 'low cost' CAN interfaces that are attached
 	  via serial lines or via USB-to-serial adapters using the LAWICEL
diff --git a/drivers/net/hamradio/Kconfig b/drivers/net/hamradio/Kconfig
index 95dbcfdf131..bf5e5968768 100644
--- a/drivers/net/hamradio/Kconfig
+++ b/drivers/net/hamradio/Kconfig
@@ -1,6 +1,6 @@
 config MKISS
 	tristate "Serial port KISS driver"
-	depends on AX25
+	depends on AX25 && TTY
 	select CRC16
 	---help---
 	  KISS is a protocol used for the exchange of data between a computer
@@ -18,7 +18,7 @@ config MKISS
 
 config 6PACK
 	tristate "Serial port 6PACK driver"
-	depends on AX25
+	depends on AX25 && TTY
 	---help---
 	  6pack is a transmission protocol for the data exchange between your
 	  PC and your TNC (the Terminal Node Controller acts as a kind of
diff --git a/drivers/net/irda/Kconfig b/drivers/net/irda/Kconfig
index 595205406d7..e1454cdec14 100644
--- a/drivers/net/irda/Kconfig
+++ b/drivers/net/irda/Kconfig
@@ -5,7 +5,7 @@ comment "SIR device drivers"
 
 config IRTTY_SIR
 	tristate "IrTTY (uses Linux serial driver)"
-	depends on IRDA
+	depends on IRDA && TTY
 	help
 	  Say Y here if you want to build support for the IrTTY line
 	  discipline.  To compile it as a module, choose M here: the module
diff --git a/drivers/net/ppp/Kconfig b/drivers/net/ppp/Kconfig
index 872df3ef07a..3d9ef4f1e60 100644
--- a/drivers/net/ppp/Kconfig
+++ b/drivers/net/ppp/Kconfig
@@ -147,6 +147,7 @@ config PPPOL2TP
 	  Support for PPP-over-L2TP socket family. L2TP is a protocol
 	  used by ISPs and enterprises to tunnel PPP traffic over UDP
 	  tunnels. L2TP is replacing PPTP for VPN uses.
+if TTY
 
 config PPP_ASYNC
 	tristate "PPP support for async serial ports"
@@ -172,4 +173,6 @@ config PPP_SYNC_TTY
 
 	  To compile this driver as a module, choose M here.
 
+endif # TTY
+
 endif # PPP
diff --git a/drivers/net/slip/Kconfig b/drivers/net/slip/Kconfig
index 211b160e4e9..48e68714eef 100644
--- a/drivers/net/slip/Kconfig
+++ b/drivers/net/slip/Kconfig
@@ -4,6 +4,7 @@
 
 config SLIP
 	tristate "SLIP (serial line) support"
+	depends on TTY
 	---help---
 	  Say Y if you intend to use SLIP or CSLIP (compressed SLIP) to
 	  connect to your Internet service provider or to connect to some
diff --git a/drivers/net/usb/Kconfig b/drivers/net/usb/Kconfig
index ef976215b64..bd33153261c 100644
--- a/drivers/net/usb/Kconfig
+++ b/drivers/net/usb/Kconfig
@@ -445,7 +445,7 @@ config USB_NET_QMI_WWAN
 
 config USB_HSO
 	tristate "Option USB High Speed Mobile Devices"
-	depends on USB && RFKILL
+	depends on USB && RFKILL && TTY
 	default n
 	help
 	  Choose this option if you have an Option HSDPA/HSUPA card.
@@ -493,7 +493,7 @@ config USB_SIERRA_NET
 
 config USB_VL600
 	tristate "LG VL600 modem dongle"
-	depends on USB_NET_CDCETHER
+	depends on USB_NET_CDCETHER && TTY
 	select USB_ACM
 	help
 	  Select this if you want to use an LG Electronics 4G/LTE usb modem
diff --git a/drivers/net/wan/Kconfig b/drivers/net/wan/Kconfig
index d58431e99f7..61eb8994b34 100644
--- a/drivers/net/wan/Kconfig
+++ b/drivers/net/wan/Kconfig
@@ -429,7 +429,7 @@ config LAPBETHER
 
 config X25_ASY
 	tristate "X.25 async driver (EXPERIMENTAL)"
-	depends on LAPB && X25
+	depends on LAPB && X25 && TTY
 	---help---
 	  Send and receive X.25 frames over regular asynchronous serial
 	  lines such as telephone lines equipped with ordinary modems.