2 files changed, 79 insertions, 20 deletions

diff --git a/Documentation/driver-model/platform.txt b/Documentation/driver-model/platform.txt
index 83009fdcbbc8..2e2c2ea90ceb 100644
--- a/Documentation/driver-model/platform.txt
+++ b/Documentation/driver-model/platform.txt
@@ -169,3 +169,62 @@ three different ways to find such a match:
       be probed later if another device registers.  (Which is OK, since
       this interface is only for use with non-hotpluggable devices.)
 
+
+Early Platform Devices and Drivers
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The early platform interfaces provide platform data to platform device
+drivers early on during the system boot. The code is built on top of the
+early_param() command line parsing and can be executed very early on.
+
+Example: "earlyprintk" class early serial console in 6 steps
+
+1. Registering early platform device data
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The architecture code registers platform device data using the function
+early_platform_add_devices(). In the case of early serial console this
+should be hardware configuration for the serial port. Devices registered
+at this point will later on be matched against early platform drivers.
+
+2. Parsing kernel command line
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The architecture code calls parse_early_param() to parse the kernel
+command line. This will execute all matching early_param() callbacks.
+User specified early platform devices will be registered at this point.
+For the early serial console case the user can specify port on the
+kernel command line as "earlyprintk=serial.0" where "earlyprintk" is
+the class string, "serial" is the name of the platfrom driver and
+0 is the platform device id. If the id is -1 then the dot and the
+id can be omitted.
+
+3. Installing early platform drivers belonging to a certain class
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The architecture code may optionally force registration of all early
+platform drivers belonging to a certain class using the function
+early_platform_driver_register_all(). User specified devices from
+step 2 have priority over these. This step is omitted by the serial
+driver example since the early serial driver code should be disabled
+unless the user has specified port on the kernel command line.
+
+4. Early platform driver registration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Compiled-in platform drivers making use of early_platform_init() are
+automatically registered during step 2 or 3. The serial driver example
+should use early_platform_init("earlyprintk", &platform_driver).
+
+5. Probing of early platform drivers belonging to a certain class
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The architecture code calls early_platform_driver_probe() to match
+registered early platform devices associated with a certain class with
+registered early platform drivers. Matched devices will get probed().
+This step can be executed at any point during the early boot. As soon
+as possible may be good for the serial port case.
+
+6. Inside the early platform driver probe()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The driver code needs to take special care during early boot, especially
+when it comes to memory allocation and interrupt registration. The code
+in the probe() function can use is_early_platform_device() to check if
+it is called at early platform device or at the regular platform device
+time. The early serial driver performs register_console() at this point.
+
+For further information, see <linux/platform_device.h>.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 6172e4360f60..a19f021f081a 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -134,7 +134,7 @@ and is between 256 and 4096 characters. It is defined in the file
 ./include/asm/setup.h as COMMAND_LINE_SIZE.
 
 
-        acpi=           [HW,ACPI,X86-64,i386]
+        acpi=           [HW,ACPI,X86]
                         Advanced Configuration and Power Interface
                         Format: { force | off | ht | strict | noirq | rsdt }
                         force -- enable ACPI if default was off
@@ -218,7 +218,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         acpi_osi="!string2"     # remove built-in string2
                         acpi_osi=               # disable all strings
 
-        acpi_pm_good    [X86-32,X86-64]
+        acpi_pm_good    [X86]
                         Override the pmtimer bug detection: force the kernel
                         to assume that this machine's pmtimer latches its value
                         and always returns good values.
@@ -459,7 +459,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         Also note the kernel might malfunction if you disable
                         some critical bits.
 
-        code_bytes      [IA32/X86_64] How many bytes of object code to print
+        code_bytes      [X86] How many bytes of object code to print
                         in an oops report.
                         Range: 0 - 8192
                         Default: 64
@@ -592,7 +592,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         MTRR settings.  This parameter disables that behavior,
                         possibly causing your machine to run very slowly.
 
-        disable_timer_pin_1 [i386,x86-64]
+        disable_timer_pin_1 [X86]
                         Disable PIN 1 of APIC timer
                         Can be useful to work around chipset bugs.
 
@@ -624,7 +624,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         UART at the specified I/O port or MMIO address.
                         The options are the same as for ttyS, above.
 
-        earlyprintk=    [X86-32,X86-64,SH,BLACKFIN]
+        earlyprintk=    [X86,SH,BLACKFIN]
                         earlyprintk=vga
                         earlyprintk=serial[,ttySn[,baudrate]]
                         earlyprintk=dbgp
@@ -659,7 +659,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         See Documentation/block/as-iosched.txt and
                         Documentation/block/deadline-iosched.txt for details.
 
-        elfcorehdr=     [IA64,PPC,SH,X86-32,X86_64]
+        elfcorehdr=     [IA64,PPC,SH,X86]
                         Specifies physical address of start of kernel core
                         image elf header. Generally kexec loader will
                         pass this option to capture kernel.
@@ -938,7 +938,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         See comment before marvel_specify_io7 in
                         arch/alpha/kernel/core_marvel.c.
 
-        io_delay=       [X86-32,X86-64] I/O delay method
+        io_delay=       [X86] I/O delay method
                 0x80
                         Standard port 0x80 based delay
                 0xed
@@ -1000,7 +1000,7 @@ and is between 256 and 4096 characters. It is defined in the file
 
         keepinitrd      [HW,ARM]
 
-        kernelcore=nn[KMG]      [KNL,X86-32,IA-64,PPC,X86-64] This parameter
+        kernelcore=nn[KMG]      [KNL,X86,IA-64,PPC] This parameter
                         specifies the amount of memory usable by the kernel
                         for non-movable allocations.  The requested amount is
                         spread evenly throughout all nodes in the system. The
@@ -1034,7 +1034,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         Configure the RouterBoard 532 series on-chip
                         Ethernet adapter MAC address.
 
-        kstack=N        [X86-32,X86-64] Print N words from the kernel stack
+        kstack=N        [X86] Print N words from the kernel stack
                         in oops dumps.
 
         l2cr=           [PPC]
@@ -1044,7 +1044,7 @@ and is between 256 and 4096 characters. It is defined in the file
         lapic           [X86-32,APIC] Enable the local APIC even if BIOS
                         disabled it.
 
-        lapic_timer_c2_ok       [X86-32,x86-64,APIC] trust the local apic timer
+        lapic_timer_c2_ok       [X86,APIC] trust the local apic timer
                         in C2 power state.
 
         libata.dma=     [LIBATA] DMA control
@@ -1229,7 +1229,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         [KNL,SH] Allow user to override the default size for
                         per-device physically contiguous DMA buffers.
 
-        memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
+        memmap=exactmap [KNL,X86] Enable setting of an exact
                         E820 memory map, as specified by the user.
                         Such memmap=exactmap lines can be constructed based on
                         BIOS output or other requirements. See the memmap=nn@ss
@@ -1320,7 +1320,7 @@ and is between 256 and 4096 characters. It is defined in the file
         mousedev.yres=  [MOUSE] Vertical screen resolution, used for devices
                         reporting absolute coordinates, such as tablets
 
-        movablecore=nn[KMG]     [KNL,X86-32,IA-64,PPC,X86-64] This parameter
+        movablecore=nn[KMG]     [KNL,X86,IA-64,PPC] This parameter
                         is similar to kernelcore except it specifies the
                         amount of memory used for migratable allocations.
                         If both kernelcore and movablecore is specified,
@@ -1422,7 +1422,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         when a NMI is triggered.
                         Format: [state][,regs][,debounce][,die]
 
-        nmi_watchdog=   [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
+        nmi_watchdog=   [KNL,BUGS=X86] Debugging features for SMP kernels
                         Format: [panic,][num]
                         Valid num: 0,1,2
                         0 - turn nmi_watchdog off
@@ -1475,11 +1475,11 @@ and is between 256 and 4096 characters. It is defined in the file
 
         nodsp           [SH] Disable hardware DSP at boot time.
 
-        noefi           [X86-32,X86-64] Disable EFI runtime services support.
+        noefi           [X86] Disable EFI runtime services support.
 
         noexec          [IA-64]
 
-        noexec          [X86-32,X86-64]
+        noexec          [X86]
                         On X86-32 available only on PAE configured kernels.
                         noexec=on: enable non-executable mappings (default)
                         noexec=off: disable non-executable mappings
@@ -1525,7 +1525,7 @@ and is between 256 and 4096 characters. It is defined in the file
         noirqdebug      [X86-32] Disables the code which attempts to detect and
                         disable unhandled interrupt sources.
 
-        no_timer_check  [X86-32,X86_64,APIC] Disables the code which tests for
+        no_timer_check  [X86,APIC] Disables the code which tests for
                         broken timer IRQ sources.
 
         noisapnp        [ISAPNP] Disables ISA PnP code.
@@ -1689,7 +1689,7 @@ and is between 256 and 4096 characters. It is defined in the file
                                 disable the use of PCIE advanced error reporting.
                 nodomains       [PCI] Disable support for multiple PCI
                                 root domains (aka PCI segments, in ACPI-speak).
-                nommconf        [X86-32,X86_64] Disable use of MMCONFIG for PCI
+                nommconf        [X86] Disable use of MMCONFIG for PCI
                                 Configuration
                 nomsi           [MSI] If the PCI_MSI kernel config parameter is
                                 enabled, this kernel boot option can be used to
@@ -2380,7 +2380,7 @@ and is between 256 and 4096 characters. It is defined in the file
                         reported either.
 
         unknown_nmi_panic
-                        [X86-32,X86-64]
+                        [X86]
                         Set unknown_nmi_panic=1 early on boot.
 
         usbcore.autosuspend=
@@ -2447,12 +2447,12 @@ and is between 256 and 4096 characters. It is defined in the file
                                         medium is write-protected).
                         Example: quirks=0419:aaf5:rl,0421:0433:rc
 
-        vdso=           [X86-32,SH,x86-64]
+        vdso=           [X86,SH]
                         vdso=2: enable compat VDSO (default with COMPAT_VDSO)
                         vdso=1: enable VDSO (default)
                         vdso=0: disable VDSO mapping
 
-        vdso32=         [X86-32,X86-64]
+        vdso32=         [X86]
                         vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
                         vdso32=1: enable 32-bit VDSO (default)
                         vdso32=0: disable 32-bit VDSO mapping