Commit 7e92b4fc authored by Bjorn Helgaas's avatar Bjorn Helgaas Committed by Linus Torvalds
Browse files

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: default avatarBjorn 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d0d4f69b

Documentation/kernel-parameters.txt

+5 −0
Original line number Diff line number Diff line
@@ -816,6 +816,11 @@ and is between 256 and 4096 characters. It is defined in the file 
	lasi=		[HW,SCSI] PARISC LASI driver for the 53c700 chip

			Format: addr:<io>,irq:<irq>



	legacy_serial.force [HW,IA-32,X86-64]

			Probe for COM ports at legacy addresses even

			if PNPBIOS or ACPI should describe them.  This

			is for working around firmware defects.



	llsc*=		[IA64] See function print_params() in

			arch/ia64/sn/kernel/llsc4.c.

arch/i386/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ obj-y += sysenter.o vsyscall.o 
obj-$(CONFIG_ACPI_SRAT) 	+= srat.o

obj-$(CONFIG_EFI) 		+= efi.o efi_stub.o

obj-$(CONFIG_DOUBLEFAULT) 	+= doublefault.o

obj-$(CONFIG_SERIAL_8250)	+= legacy_serial.o

obj-$(CONFIG_VM86)		+= vm86.o

obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o

obj-$(CONFIG_HPET_TIMER) 	+= hpet.o

arch/i386/kernel/legacy_serial.c

0 → 100644
+67 −0
Original line number Diff line number Diff line 
/*

 * Legacy COM port devices for x86 platforms without PNPBIOS or ACPI.

 * Data taken from include/asm-i386/serial.h.

 *

 * (c) Copyright 2007 Hewlett-Packard Development Company, L.P.

 *	Bjorn Helgaas <bjorn.helgaas@hp.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */

#include <linux/module.h>

#include <linux/init.h>

#include <linux/pnp.h>

#include <linux/serial_8250.h>



/* Standard COM flags (except for COM4, because of the 8514 problem) */

#ifdef CONFIG_SERIAL_DETECT_IRQ

#define COM_FLAGS (UPF_BOOT_AUTOCONF | UPF_SKIP_TEST | UPF_AUTO_IRQ)

#define COM4_FLAGS (UPF_BOOT_AUTOCONF | UPF_AUTO_IRQ)

#else

#define COM_FLAGS (UPF_BOOT_AUTOCONF | UPF_SKIP_TEST)

#define COM4_FLAGS UPF_BOOT_AUTOCONF

#endif



#define PORT(_base,_irq,_flags)				\

	{						\

		.iobase		= _base,		\

		.irq		= _irq,			\

		.uartclk	= 1843200,		\

		.iotype		= UPIO_PORT,		\

		.flags		= _flags,		\

	}



static struct plat_serial8250_port x86_com_data[] = {

	PORT(0x3F8, 4, COM_FLAGS),

	PORT(0x2F8, 3, COM_FLAGS),

	PORT(0x3E8, 4, COM_FLAGS),

	PORT(0x2E8, 3, COM4_FLAGS),

	{ },

};



static struct platform_device x86_com_device = {

	.name			= "serial8250",

	.id			= PLAT8250_DEV_PLATFORM,

	.dev			= {

		.platform_data	= x86_com_data,

	},

};



static int force_legacy_probe;

module_param_named(force, force_legacy_probe, bool, 0);

MODULE_PARM_DESC(force, "Force legacy serial port probe");



static int __init serial8250_x86_com_init(void)

{

	if (pnp_platform_devices && !force_legacy_probe)

		return -ENODEV;



	return platform_device_register(&x86_com_device);

}



module_init(serial8250_x86_com_init);



MODULE_AUTHOR("Bjorn Helgaas");

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("Generic 8250/16x50 legacy probe module");

arch/x86_64/kernel/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ obj-$(CONFIG_EARLY_PRINTK) += early_printk.o 
obj-$(CONFIG_IOMMU)		+= pci-gart.o aperture.o

obj-$(CONFIG_CALGARY_IOMMU)	+= pci-calgary.o tce.o

obj-$(CONFIG_SWIOTLB)		+= pci-swiotlb.o

obj-$(CONFIG_SERIAL_8250)	+= legacy_serial.o

obj-$(CONFIG_KPROBES)		+= kprobes.o

obj-$(CONFIG_X86_PM_TIMER)	+= pmtimer.o

obj-$(CONFIG_X86_VSMP)		+= vsmp.o
@@ -49,6 +50,7 @@ CFLAGS_vsyscall.o := $(PROFILING) -g0 


therm_throt-y                   += ../../i386/kernel/cpu/mcheck/therm_throt.o

bootflag-y			+= ../../i386/kernel/bootflag.o

legacy_serial-y			+= ../../i386/kernel/legacy_serial.o

cpuid-$(subst m,y,$(CONFIG_X86_CPUID))  += ../../i386/kernel/cpuid.o

topology-y                     += ../../i386/kernel/topology.o

microcode-$(subst m,y,$(CONFIG_MICROCODE))  += ../../i386/kernel/microcode.o

drivers/serial/Kconfig

+9 −5
Original line number Diff line number Diff line
@@ -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

CRA Git | Maintained and supported by SUSTech CRA and CCSE