x86, serial: convert legacy COM ports to platform devices

Make x86 COM ports into platform devices and don't probe for them
if we have PNP.

This prevents double discovery, where a device was found both by
the legacy probe and by 8250_pnp, e.g.,

    serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
    00:02: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

This also means IRDA devices without a UART PNP ID will no longer be
claimed by the serial driver, which might require changes in IRDA
drivers and administration.

In addition to this patch, you may need to configure a setserial init
script, e.g., /etc/init.d/setserial, so it doesn't poke legacy UART
stuff back in.  On Debian, "dpkg-reconfigure setserial" with the "kernel"
option does this.

To force the old legacy probe behavior even when we have PNPBIOS or
ACPI, load the new legacy_serial module (or build 8250 static) with
the "legacy_serial.force" option.

[akpm@linux-foundation.org: fix makefiles]
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Keith Owens <kaos@ocs.com.au>
Cc: Len Brown <lenb@kernel.org>
Cc: Adam Belay <ambx1@neo.rr.com>
Cc: Matthieu CASTET <castet.matthieu@free.fr>
Cc: Jean Tourrilhes <jt@hpl.hp.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Ville Syrjala <syrjala@sci.fi>
Cc: Russell King <rmk+serial@arm.linux.org.uk>
Cc: Samuel Ortiz <samuel@sortiz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 5 deletions

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 924e9bd757f0..e8efe938c4e7 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -73,17 +73,21 @@ config SERIAL_8250_PCI
         depends on SERIAL_8250 && PCI
         default SERIAL_8250
         help
-          This builds standard PCI serial support. You may be able to
-          disable this feature if you only need legacy serial support.
-          Saves about 9K.
+          Say Y here if you have PCI serial ports.
+
+          To compile this driver as a module, choose M here: the module
+          will be called 8250_pci.
 
 config SERIAL_8250_PNP
         tristate "8250/16550 PNP device support" if EMBEDDED
         depends on SERIAL_8250 && PNP
         default SERIAL_8250
         help
-          This builds standard PNP serial support. You may be able to
-          disable this feature if you only need legacy serial support.
+          Say Y here if you have serial ports described by PNPBIOS or ACPI.
+          These are typically ports built into the system board.
+
+          To compile this driver as a module, choose M here: the module
+          will be called 8250_pnp.
 
 config SERIAL_8250_HP300
         tristate