Much like the atomic_dec_and_lock() function in which we take an hold a
spin_lock if we drop the atomic to 0 this function takes and holds the
mutex if we dec the atomic to 0.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090323172417.410913479@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add regulator header file missing kernel-doc:
Warning(include/linux/regulator/driver.h:117): No description found for parameter 'set_mode'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
cc: Liam Girdwood <lrg@slimlogic.co.uk>
cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
The old refok sections
.text.init.refok
.data.init.refok
.exit.text.refok
have been deprecated since commit
312b1485fb. After the other patches in
this patch series nothing is put in these sections, so clean things up
by eliminating all the remaining references to them.
Signed-off-by: Tim Abbott <tabbott@mit.edu>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
PCI: only save/restore existent registers in the PCIe capability
x86/PCI: don't bother with root quirks if _CRS is used
docbooks: add/fix PCI kernel-doc
PCI: cleanup debug output resources
x86/PCI: set_pci_bus_resources_arch_default cleanups
x86/PCI: Move set_pci_bus_resources_arch_default into arch/x86
x86/PCI: don't call e820_all_mapped with -1 in the mmconfig case
PCI quirk: disable MSI on VIA VT3364 chipsets
This patch is preparation for replacing all uses of ".head.text" or
".text.head" in the kernel with macros, so that the section name can
later be changed without having to touch a lot of the kernel.
Since some linker scripts do more complex things than referencing
HEAD_TEXT, we add a HEAD_TEXT_SECTION macro that just contains the
actual name.
I've defined HEAD_TEXT_SECTION in a new header,
include/linux/section-names.h, so that this section name only needs to
appear in one place. I anticipate creating similar macro structures
for a number of other section names.
The long-term goal here is to be able to change the kernel's magic
section names to those that are compatible with -ffunction-sections
-fdata-sections. This requires renaming all magic sections with names
of the form ".text.foo".
Signed-off-by: Tim Abbott <tabbott@mit.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (34 commits)
ACPI, i915: Register ACPI video even when not modesetting
Revert "ACPICA: delete check for AML access to port 0x81-83"
I/O port protection: update for windows compatibility.
sony-laptop: always try to unblock rfkill on load
sony-laptop: fix bogus error message display on resume
ACPI: EC: Fix ACPI EC resume non-query interrupt message
sony-laptop: SNC input event 38 fix
sony-laptop: SNC 127 Initialization Fix
sony-laptop: Duplicate SNC 127 Event Fix
ACPI: prevent processor.max_cstate=0 boot crash
ACPI/hpet: prevent boot hang when hpet=force used on ICH-4M
ACPI: delete obsolete "bus master activity" proc field
ACPI: idle: mark_tsc_unstable() at init-time, not run-time
ACPI: add /sys/firmware/acpi/interrupts/sci_not counter
ACPI video: fix an error when the brightness levels on AC and on Battery are same
acpi-cpufreq: Do not let get_measured perf depend on internal variable
acpi-cpufreq: style-only: add parens to math expression
acpi-cpufreq: Cleanup: Use printk_once
x86, acpi_cpufreq: Fix the NULL pointer dereference in get_measured_perf
thinkpad-acpi: bump up version to 0.23
...
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: Fix potential inode allocation soft lockup in Orlov allocator
ext4: Make the extent validity check more paranoid
jbd: use SWRITE_SYNC_PLUG when writing synchronous revoke records
jbd2: use SWRITE_SYNC_PLUG when writing synchronous revoke records
ext4: really print the find_group_flex fallback warning only once
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6:
USB: pwc : do not pass stack allocated buffers to USB core.
USB: otg: Fix bug on remove path without transceiver
USB: correct error handling in cdc-wdm
USB: removal of tty->low_latency hack dating back to the old serial code
USB: serial: sierra driver bug fix for composite interface
USB: gadget: omap_udc uses platform_driver_probe()
USB: ci13xxx_udc: fix build error
USB: musb: Prevent multiple includes of musb.h
USB: pass mem_flags to dma_alloc_coherent
USB: g_file_storage: fix use-after-free bug when closing files
USB: ehci-sched.c: EHCI SITD scheduling bugfix
USB: fix mos7840 problem with minor numbers
USB: mos7840: add new device id
USB: musb: fix build when !CONFIG_PM
USB: musb: Remove my email address from few musb related drivers
USB: Gadget: MIPS CI13xxx UDC bugfixes
USB: Unusual Device support for Gold MP3 Player Energy
USB: serial: fix lifetime and locking problems
* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
cfq-iosched: cache prio_tree root in cfqq->p_root
cfq-iosched: fix bug with aliased request and cooperation detection
cfq-iosched: clear ->prio_trees[] on cfqd alloc
block: fix intermittent dm timeout based oops
umem: fix request_queue lock warning
block: simplify I/O stat accounting
pktcdvd.h should include mempool.h
cfq-iosched: use the default seek distance when there aren't enough seek samples
cfq-iosched: make seek_mean converge more quickly
block: make blk_abort_queue() ignore non-request based devices
block: include empty disks in /proc/diskstats
bio: use bio_kmalloc() in copy/map functions
bio: fix bio_kmalloc()
block: fix queue bounce limit setting
block: fix SG_IO vector request data length handling
scatterlist: make sure sg_miter_next() doesn't return 0 sized mappings
* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
powerpc: Fix modular build of ide-pmac when mediabay is built in
powerpc/pasemi: Fix build error on UP
powerpc: Make macintosh/mediabay driver depend on CONFIG_BLOCK
maintainers: Fix PS3 patterns
powerpc/ps3: Fix CONFIG_PS3_FLASH=n build warning
powerpc/32: Don't clobber personality flags on exec
powerpc: Fix crash on CPU hotplug
powerpc/85xx: Remove defconfigs that mpc85xx_{smp_}defconfig cover
powerpc/85xx: Added SMP defconfig
powerpc/85xx: Enabled a bunch of FSL specific drivers/options
powerpc/85xx: Updated generic mpc85xx_defconfig
powerpc: don't disable SATA interrupts on Freescale MPC8610 HPCD
fsl_rio: Pass the proper device to dma mapping routines
powerpc: Fix of_node_put() exit path in of_irq_map_one()
powerpc/5200: defconfig updates
powerpc/5200: Add FLASH nodes to lite5200 device tree
powerpc/device-tree: Document MTD nodes with multiple "reg" tuples
powerpc/of-device-tree: Factor MTD physmap bindings out of booting-without-of
powerpc/5200: Bring the legacy fsl_spi_platform_data hooks back
This simplifies I/O stat accounting switching code and separates it
completely from I/O scheduler switch code.
Requests are accounted according to the state of their request queue
at the time of the request allocation. There is no need anymore to
flush the request queue when switching I/O accounting state.
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Fix this build error:
In file included from fs/compat_ioctl.c:104:
include/linux/pktcdvd.h:285: error: expected specifier-qualifier-list before 'mempool_t'
Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Add #ifndef to musb header file to prevent multiple inclusions.
Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Finds the first set bit in a 64 bit word. This is required in order
to fix a bug in GFS2, but I think it should be a generic function
in case of future users.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Willy Tarreau <w@1wt.eu>
PCIe 1.1 base neither requires the endpoint to implement the entire
PCIe capability structure nor specifies default values of registers
that are not implemented by the device. So we only save and restore
registers that must be implemented by different device types if the
device PCIe capability version is 1.
PCIe 1.1 Capability Structure Expansion ECN and PCIe 2.0 requires
all registers in the PCIe capability to be either implemented or
hardwired to 0. Their PCIe capability version is 2.
Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
When checking for overlapping slots on registration of a new one, kvm
currently also considers zero-length (ie. deleted) slots and rejects
requests incorrectly. This finally denies user space from joining slots.
Fix the check by skipping deleted slots and advertise this via a
KVM_CAP_JOIN_MEMORY_REGIONS_WORKS.
Cc: stable@kernel.org
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
/proc/diskstats used to show stats for all disks whether they're
zero-sized or not and their non-zero partitions. Commit
074a7aca7a accidentally changed the
behavior such that it doesn't print out zero sized disks. This patch
implements DISK_PITER_INCL_EMPTY_PART0 flag to partition iterator and
uses it in diskstats_show() such that empty part0 is shown in
/proc/diskstats.
Reported and bisectd by Dianel Collins.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Daniel Collins <solemnwarning@solemnwarning.no-ip.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Impact: fix bio_kmalloc() and its destruction path
bio_kmalloc() was broken in two ways.
* bvec_alloc_bs() first allocates bvec using kmalloc() and then
ignores it and allocates again like non-kmalloc bvecs.
* bio_kmalloc_destructor() didn't check for and free bio integrity
data.
This patch fixes the above problems. kmalloc patch is separated out
from bio_alloc_bioset() and allocates the requested number of bvecs as
inline bvecs.
* bio_alloc_bioset() no longer takes NULL @bs. None other than
bio_kmalloc() used it and outside users can't know how it was
allocated anyway.
* Define and use BIO_POOL_NONE so that pool index check in
bvec_free_bs() triggers if inline or kmalloc allocated bvec gets
there.
* Relocate destructors on top of each allocation function so that how
they're used is more clear.
Jens Axboe suggested allocating bvecs inline.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
There is currently only one way for userspace to say "wait for my storage
device to get ready for the modules I just loaded": to load the
scsi_wait_scan module. Expectations of userspace are that once this
module is loaded, all the (storage) devices for which the drivers
were loaded before the module load are present.
Now, there are some issues with the implementation, and the async
stuff got caught in the middle of this: The existing code only
waits for the scsy async probing to finish, but it did not take
into account at all that probing might not have begun yet.
(Russell ran into this problem on his computer and the fix works for him)
This patch fixes this more thoroughly than the previous "fix", which
had some bad side effects (namely, for kernel code that wanted to wait for
the scsi scan it would also do an async sync, which would deadlock if you did
it from async context already.. there's a report about that on lkml):
The patch makes the module first wait for all device driver probes, and then it
will wait for the scsi parallel scan to finish.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix a comment typo in slow-work.h
...a trivial mistake, but it will mess up kerneldoc if nothing else.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Collect the DECLARE/DEFINE declarations together in linux/percpu-defs.h so
that they're in one place, and give them descriptive comments, particularly
the SHARED_ALIGNED variant.
It would be nice to collect these in linux/percpu.h, but that's not possible
without sorting out the severe #include recursion between the x86 arch headers
and the general headers (and possibly other arches too).
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In non-SMP mode, the variable section attribute specified by DECLARE_PER_CPU()
does not agree with that specified by DEFINE_PER_CPU(). This means that
architectures that have a small data section references relative to a base
register may throw up linkage errors due to too great a displacement between
where the base register points and the per-CPU variable.
On FRV, the .h declaration says that the variable is in the .sdata section, but
the .c definition says it's actually in the .data section. The linker throws
up the following errors:
kernel/built-in.o: In function `release_task':
kernel/exit.c:78: relocation truncated to fit: R_FRV_GPREL12 against symbol `per_cpu__process_counts' defined in .data section in kernel/built-in.o
kernel/exit.c:78: relocation truncated to fit: R_FRV_GPREL12 against symbol `per_cpu__process_counts' defined in .data section in kernel/built-in.o
To fix this, DECLARE_PER_CPU() should simply apply the same section attribute
as does DEFINE_PER_CPU(). However, this is made slightly more complex by
virtue of the fact that there are several variants on DEFINE, so these need to
be matched by variants on DECLARE.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a doc-only patch which I hope will reduce the number of
spi_master controller driver patches starting out with a common
implementation bug.
(As in: almost every spi_master driver I see starts out with its
version of this bug. Sigh.)
It just re-emphasizes that the setup() method may be called for one
device while a transfer is active on another ... which means that most
driver implementations shouldn't touch any registers.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Enable userspace to receive messages that a BMC transmits using an OEM
medium. This is used by the HP iLO2.
Based on code originally written by Patrick Schoeller.
Signed-off-by: dann frazier <dannf@hp.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The IPMI driver would attempt to use the event buffer even if that
didn't exist on the BMC. This patch modified the IPMI driver to check
for the event buffer's existence before trying to use it.
Signed-off-by: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add enable() and disable() callbacks for clocksources.
This allows us to put unused clocksources in power save mode. The
functions clocksource_enable() and clocksource_disable() wrap the
callbacks and are inserted in the timekeeping code to enable before use
and disable after switching to a new clocksource.
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pass clocksource pointer to the read() callback for clocksources. This
allows us to share the callback between multiple instances.
[hugh@veritas.com: fix powerpc build of clocksource pass clocksource mods]
[akpm@linux-foundation.org: cleanup]
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
reiserfs: fix j_last_flush_trans_id type
fs: Mark get_filesystem_list() as __init function.
kill vfs_stat_fd / vfs_lstat_fd
Separate out common fstatat code into vfs_fstatat
ecryptfs: use memdup_user()
ncpfs: use memdup_user()
xfs: use memdup_user()
sysfs: use memdup_user()
btrfs: use memdup_user()
xattr: use memdup_user()
autofs4: use memchr() in invalid_string()
Documentation/filesystems: remove out of date reference to BKL being held
Fix i_mutex vs. readdir handling in nfsd
fs/compat_ioctl: fix build when !BLOCK
Fix autofs_expire()
No need for crossing to mountpoint in audit_tag_tree()
Safer nfsd_cross_mnt()
Touch all affected namespaces on propagation of mount
Fix AUTOFS_DEV_IOCTL_REQUESTER_CMD
Older MIPS assembler don't support .set for defining aliases.
Using = works for old and new assembers.
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Conversion in commit 600ed41675 had missed
that one, but converted format from %lu to %u. As the result,
/proc/..../journal got buggered on 64bit boxen.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
"int get_filesystem_list(char * buf)" is called by only
"static void __init get_fs_names(char *page)".
We can mark get_filesystem_list() as "__init".
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There's really no reason to keep vfs_stat_fd and vfs_lstat_fd with
Oleg's vfs_fstatat. Use vfs_fstatat for the few cases having the
directory fd, and switch all others to vfs_stat / vfs_lstat.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This is a version incorporating Christoph's suggestion.
Separate out common *fstatat functionality into a single function
instead of duplicating it all over the code.
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 900af0d973 (PM: Change suspend
code ordering) changed the ordering of suspend code in such a way
that the platform .prepare() callback is now executed after the
device drivers' late suspend callbacks have run. Unfortunately, this
turns out to break ARM platforms that need to talk via I2C to power
control devices during the .prepare() callback.
For this reason introduce two new platform suspend callbacks,
.prepare_late() and .wake(), that will be called just prior to
disabling non-boot CPUs and right after bringing them back on line,
respectively, and use them instead of .prepare() and .finish() for
ACPI suspend. Make the PM core execute the .prepare() and .finish()
platform suspend callbacks where they were executed previously (that
is, right after calling the regular suspend methods provided by
device drivers and right before executing their regular resume
methods, respectively).
It is not necessary to make analogous changes to the hibernation
code and data structures at the moment, because they are only used
by ACPI platforms.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Len Brown <len.brown@intel.com>
<linux/seccomp.h> uses EINVAL so should include <linux/errno.h>. This
fixes a build error on 64-bit MIPS if CONFIG_SECCOMP is disabled.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6:
UIO: fix specific device driver missing statement for depmod
Driver core: remove pr_fmt() from dynamic_dev_dbg() printk
driver core: prevent device_for_each_child from oopsing
dynamic debug: resurrect old pr_debug() semantics as pr_devel()
Driver Core: early platform driver
proc: mounts_poll() make consistent to mdstat_poll
sysfs: sysfs poll keep the poll rule of regular file.
driver core: allow non-root users to listen to uevents
driver core: fix driver_match_device
sysfs: don't use global workqueue in sysfs_schedule_callback()
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6: (22 commits)
WUSB: correct format of wusb_chid sysfs file
WUSB: fix oops when completing URBs for disconnected devices
WUSB: disconnect all devices when stopping a WUSB HCD
USB: whci-hcd: check return value of usb_hcd_link_urb_to_ep()
USB: whci-hcd: provide a endpoint_reset method
USB: add reset endpoint operations
USB device codes for Motorola phone.
usb-storage: fix mistake in Makefile
USB: usb-serial ch341: support for DTR/RTS/CTS
Revert USB: usb-serial ch341: support for DTR/RTS/CTS
USB: musb: fix possible panic while resuming
USB: musb: fix isochronous TXDMA (take 2)
USB: musb: sanitize clearing TXCSR DMA bits (take 2)
USB: musb: bugfixes for multi-packet TXDMA support
USB: musb_host, fix ep0 fifo flushing
USB: usb-storage: augment unusual_devs entry for Simple Tech/Datafab
USB: musb_host, minor enqueue locking fix (v2)
USB: fix oops in cdc-wdm in case of malformed descriptors
USB: qcserial: Add extra device IDs
USB: option: Add ids for D-Link DWM-652 3.5G modem
...
Wireless USB endpoint state has a sequence number and a current
window and not just a single toggle bit. So allow HCDs to provide a
endpoint_reset method and call this or clear the software toggles as
required (after a clear halt, set configuration etc.).
usb_settoggle() and friends are then HCD internal and are moved into
core/hcd.h and all device drivers call usb_reset_endpoint() instead.
If the device endpoint state has been reset (with a clear halt) but
the host endpoint state has not then subsequent data transfers will
not complete. The device will only work again after it is reset or
disconnected.
Signed-off-by: David Vrabel <david.vrabel@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
kernel/softirq.c: fix sparse warning
rcu: Make hierarchical RCU less IPI-happy
When pr_fmt() was added to the pr_debug() code, we added it not only to the
dynamic_pr_debug() function, but also to the dynamic_dev_dbg() funciton.
However, dev_dbg() doesn't make use of pr_fmt(), so neither should
dynamic_dev_dbg().
Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
pr_debug() used to produce zero code unless DEBUG was #defined. This is
now no longer the case in practice[1].
There are places where it's useful to have debugging printks, but we don't
want them to generate any code in production kernels.
So add a new macro, pr_devel(), for _devel_opment, to provide the old
semantics, ie. if the programmer doesn't explicitly enable debugging, no
code is produced.
[1]: You can turn CONFIG_DYNAMIC_DEBUG off, but it's enabled in at least
one distro kernel, so it's not really a solution.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Greg Banks <gnb@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
V3 of the early platform driver implementation.
Platform drivers are great for embedded platforms because we can separate
driver configuration from the actual driver. So base addresses,
interrupts and other configuration can be kept with the processor or board
code, and the platform driver can be reused by many different platforms.
For early devices we have nothing today. For instance, to configure early
timers and early serial ports we cannot use platform devices. This
because the setup order during boot. Timers are needed before the
platform driver core code is available. The same goes for early printk
support. Early in this case means before initcalls.
These early drivers today have their configuration either hard coded or
they receive it using some special configuration method. This is working
quite well, but if we want to support both regular kernel modules and
early devices then we need to have two ways of configuring the same
driver. A single way would be better.
The early platform driver patch is basically a set of functions that allow
drivers to register themselves and architecture code to locate them and
probe. Registration happens through early_param(). The time for the
probe is decided by the architecture code.
See Documentation/driver-model/platform.txt for more details.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: David Brownell <david-b@pacbell.net>
Cc: Tejun Heo <htejun@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
