revert "x86, serial: convert legacy COM ports to platform devices"

Revert 7e92b4f.  It broke Sébastien Dugué's
machine and Jeff said (persuasively)

  This seems like it will break decades-long-working stuff, in favor of
  breaking new ground in our favorite area, "trusting the BIOS."

  It's just not worth it for serial ports, IMO.  Serial ports are something
  that just shouldn't break at this late stage in the game.  My new Intel
  platform boxes don't even have serial ports, so I question the value of
  messing with serial port probing even more...  because...  just wait a year,
  and your box won't have a serial port either!  :)

  I certainly don't object to the use of platform devices (or isa_driver),
  but the probe change seems questionable.  That's sorta analagous to
  rewriting the floppy driver probe routine.  Sure you could do it...  but why
  risk all that damage and go through debugging all over again?

  It seems clear from this report that we cannot, should not, trust BIOS for
  something (a) so simple and (b) that has been working for over a decade.

Much discussion ensued and we've decided to have another go at all of this.

Cc: Sébastien Dugué <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Adam Belay <[email protected]>
Cc: Matthew Garrett <[email protected]>
Cc: Russell King <[email protected]>
Cc: Jeff Garzik <[email protected]>
Acked-by: Alan Cox <[email protected]>
Cc: Michal Piotrowski <[email protected]>
Cc: Sascha Sommer <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Documentation/kernel-parameters.txt

@@ -864,11 +864,6 @@ 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,X86-32,X86-64]
-			Probe for COM ports at legacy addresses even
-			if PNPBIOS or ACPI should describe them.  This
-			is for working around firmware defects.
-
 	load_ramdisk=	[RAM] List of ramdisks to load from floppy
 			See Documentation/ramdisk.txt.
 

arch/i386/kernel/Makefile

@@ -35,7 +35,6 @@ 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/x86_64/kernel/Makefile

@@ -32,7 +32,6 @@ 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
@@ -51,7 +50,6 @@ 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

@@ -88,21 +88,17 @@ config SERIAL_8250_PCI
 	depends on SERIAL_8250 && PCI
 	default SERIAL_8250
 	help
-	  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.
+	  This builds standard PCI serial support. You may be able to
+	  disable this feature if you only need legacy serial support.
+	  Saves about 9K.
 
 config SERIAL_8250_PNP
 	tristate "8250/16550 PNP device support" if EMBEDDED
 	depends on SERIAL_8250 && PNP
 	default SERIAL_8250
 	help
-	  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.
+	  This builds standard PNP serial support. You may be able to
+	  disable this feature if you only need legacy serial support.
 
 config SERIAL_8250_HP300
 	tristate

include/asm-i386/serial.h

@@ -11,3 +11,19 @@
  * megabits/second; but this requires the faster clock.
  */
 #define BASE_BAUD ( 1843200 / 16 )
+
+/* Standard COM flags (except for COM4, because of the 8514 problem) */
+#ifdef CONFIG_SERIAL_DETECT_IRQ
+#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ)
+#define STD_COM4_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_AUTO_IRQ)
+#else
+#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST)
+#define STD_COM4_FLAGS ASYNC_BOOT_AUTOCONF
+#endif
+
+#define SERIAL_PORT_DFNS			\
+	/* UART CLK   PORT IRQ     FLAGS        */			\
+	{ 0, BASE_BAUD, 0x3F8, 4, STD_COM_FLAGS },	/* ttyS0 */	\
+	{ 0, BASE_BAUD, 0x2F8, 3, STD_COM_FLAGS },	/* ttyS1 */	\
+	{ 0, BASE_BAUD, 0x3E8, 4, STD_COM_FLAGS },	/* ttyS2 */	\
+	{ 0, BASE_BAUD, 0x2E8, 3, STD_COM4_FLAGS },	/* ttyS3 */

include/asm-x86_64/serial.h

@@ -11,3 +11,19 @@
  * megabits/second; but this requires the faster clock.
  */
 #define BASE_BAUD ( 1843200 / 16 )
+
+/* Standard COM flags (except for COM4, because of the 8514 problem) */
+#ifdef CONFIG_SERIAL_DETECT_IRQ
+#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ)
+#define STD_COM4_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_AUTO_IRQ)
+#else
+#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST)
+#define STD_COM4_FLAGS ASYNC_BOOT_AUTOCONF
+#endif
+
+#define SERIAL_PORT_DFNS			\
+	/* UART CLK   PORT IRQ     FLAGS        */			\
+	{ 0, BASE_BAUD, 0x3F8, 4, STD_COM_FLAGS },	/* ttyS0 */	\
+	{ 0, BASE_BAUD, 0x2F8, 3, STD_COM_FLAGS },	/* ttyS1 */	\
+	{ 0, BASE_BAUD, 0x3E8, 4, STD_COM_FLAGS },	/* ttyS2 */	\
+	{ 0, BASE_BAUD, 0x2E8, 3, STD_COM4_FLAGS },	/* ttyS3 */