The driver_override implementation is susceptible to a race condition
when different threads are reading vs storing a different driver
override. Add locking to avoid this race condition.
Cfr. commits 6265539776 ("driver core: platform: fix race
condition with driver_override") and 9561475db6 ("PCI: Fix race
condition with driver_override").
Fixes: 3cf3857134 ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
For AMBA devices with unconfigured driver override, the
"driver_override" sysfs virtual file is empty, while it contains
"(null)" for platform and PCI devices.
Make AMBA consistent with other buses by dropping the test for a NULL
pointer.
Note that contrary to popular belief, sprintf() handles NULL pointers
fine; they are printed as "(null)".
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When printing the driver_override parameter when it is 4095 and 4094
bytes long, the printing code would access invalid memory because we
need count + 1 bytes for printing.
Cfr. commits 4efe874aac ("PCI: Don't read past the end of sysfs
"driver_override" buffer") and bf563b01c2 ("driver core: platform:
Don't read past the end of "driver_override" buffer").
Fixes: 3cf3857134 ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The driver_override implementation is susceptible to a race condition
when different threads are reading vs storing a different driver
override. Add locking to avoid this race condition.
Cfr. commits 6265539776 ("driver core: platform: fix race
condition with driver_override") and 9561475db6 ("PCI: Fix race
condition with driver_override").
Fixes: 3cf3857134 ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Todd Kjos <tkjos@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We do not want the common dma_configure() pathway to apply
indiscriminately to all devices, since there are plenty of buses which
do not have DMA capability, and if their child devices were used for
DMA API calls it would only be indicative of a driver bug. However,
there are a number of buses for which DMA is implicitly expected even
when not described by firmware - those we whitelist with an automatic
opt-in to dma_configure(), assuming that the DMA address space and the
physical address space are equivalent if not otherwise specified.
Commit 7232888366 ("of: restrict DMA configuration") introduced a
short-term fix by comparing explicit bus types, but this approach is far
from pretty, doesn't scale well, and fails to cope at all with bus
drivers which may be built as modules, like host1x. Let's refine things
by making that opt-in a property of the bus type, which neatly addresses
those problems and lets the decision of whether firmware description of
DMA capability should be optional or mandatory stay internal to the bus
drivers themselves.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
The dev_attrs field has long been "depreciated" and is finally being
removed, so move the driver to use the "correct" dev_groups field
instead for struct bus_type.
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add the call to of_clk_set_defaults() into the amba probe path so
that devices on the amba bus can use the assigned rates and
parents feature of the common clock framework.
Cc: Michael Turquette <mturquette@baylibre.com>
Tested-by: Jorge Ramirez Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
To read pid/cid registers, the probed device need to be properly turned on.
When it is inside a power domain, the bus code should ensure that the
given power domain is enabled before trying to access device's registers.
However in some cases power domain (or clocks) might not be yet available.
Returning -EPROBE_DEFER is not a solution in such case, because callers
don't handle this special error code. Instead such devices are added to the
special list and their registration is retried from periodic worker until
all resources are available.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Here's the big char/misc driver update for 3.19-rc1
Lots of little things all over the place in different drivers, and a new
subsystem, "coresight" has been added. Full details are in the
shortlog.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH:
"Here's the big char/misc driver update for 3.19-rc1
Lots of little things all over the place in different drivers, and a
new subsystem, "coresight" has been added. Full details are in the
shortlog"
* tag 'char-misc-3.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (73 commits)
parport: parport_pc, do not remove parent devices early
spmi: Remove shutdown/suspend/resume kernel-doc
carma-fpga-program: drop videobuf dependency
carma-fpga: drop videobuf dependency
carma-fpga-program.c: fix compile errors
i8k: Fix temperature bug handling in i8k_get_temp()
cxl: Name interrupts in /proc/interrupt
CXL: Return error to PSL if IRQ demultiplexing fails & print clearer warning
coresight-replicator: remove .owner field for driver
coresight: fixed comments in coresight.h
coresight: fix typo in comment in coresight-priv.h
coresight: bindings for coresight drivers
coresight: Adding ABI documentation
w1: support auto-load of w1_bq27000 module.
w1: avoid potential u16 overflow
cn: verify msg->len before making callback
mei: export fw status registers through sysfs
mei: read and print all six FW status registers
mei: txe: add cherrytrail device id
mei: kill cached host and me csr values
...
Pull ARM updates from Russell King:
"The major updates included in this update are:
- Clang compatible stack pointer accesses by Behan Webster.
- SA11x0 updates from Dmitry Eremin-Solenikov.
- kgdb handling of breakpoints with read-only text/modules
- Support for Privileged-no-execute feature on ARMv7 to prevent
userspace code execution by the kernel.
- AMBA primecell bus handling of irq-safe runtime PM
- Unwinding support for memset/memzero/memmove/memcpy functions
- VFP fixes for Krait CPUs and improvements in detecting the VFP
architecture
- A number of code cleanups (using pr_*, removing or reducing the
severity of a couple of kernel messages, splitting ftrace asm code
out to a separate file, etc.)
- Add machine name to stack dump output"
* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (62 commits)
ARM: 8247/2: pcmcia: sa1100: make use of device clock
ARM: 8246/2: pcmcia: sa1111: provide device clock
ARM: 8245/1: pcmcia: soc-common: enable/disable socket clocks
ARM: 8244/1: fbdev: sa1100fb: make use of device clock
ARM: 8243/1: sa1100: add a clock alias for sa1111 pcmcia device
ARM: 8242/1: sa1100: add cpu clock
ARM: 8221/1: PJ4: allow building in Thumb-2 mode
ARM: 8234/1: sa1100: reorder IRQ handling code
ARM: 8233/1: sa1100: switch to hwirq usage
ARM: 8232/1: sa1100: merge GPIO multiplexer IRQ to "normal" irq domain
ARM: 8231/1: sa1100: introduce irqdomains support
ARM: 8230/1: sa1100: shift IRQs by one
ARM: 8229/1: sa1100: replace irq numbers with names in irq driver
ARM: 8228/1: sa1100: drop entry-macro.S
ARM: 8227/1: sa1100: switch to MULTI_IRQ_HANDLER
ARM: 8241/1: Update processor_modes for hyp and monitor mode
ARM: 8240/1: MCPM: document mcpm_sync_init()
ARM: 8239/1: Introduce {set,clear}_pte_bit
ARM: 8238/1: mm: Refine set_memory_* functions
ARM: 8237/1: fix flush_pfn_alias
...
The SET_PM_RUNTIME_PM_OPS() and SET_RUNTIME_PM_OPS() macros are
identical except that one of them is not empty for CONFIG_PM set,
while the other one is not empty for CONFIG_PM_RUNTIME set,
respectively.
However, after commit b2b49ccbdd (PM: Kconfig: Set PM_RUNTIME if
PM_SLEEP is selected) PM_RUNTIME is always set if PM is set, so one
of these macros is now redundant.
For this reason, replace SET_PM_RUNTIME_PM_OPS() with
SET_RUNTIME_PM_OPS() everywhere and redefine the SET_PM_RUNTIME_PM_OPS
symbol as SET_RUNTIME_PM_OPS in case new code is starting to use the
macro being removed here.
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The AMBA bus driver defines runtime Power Management functions which
disable and unprepare AMBA bus clock. This is problematic for runtime PM
because unpreparing a clock might sleep so it is not interrupt safe.
However some drivers may want to implement runtime PM functions in
interrupt-safe way (see pm_runtime_irq_safe()). In such case the AMBA
bus driver should only disable/enable the clock in runtime suspend and
resume callbacks.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
CoreSight components are compliant with the ARM CoreSight
architecture specification and can be connected in various
topologies to suit a particular SoC tracing needs. These trace
components can generally be classified as sources, links and
sinks. Trace data produced by one or more sources flows through
the intermediate links connecting the source to the currently
selected sink.
The CoreSight framework provides an interface for the CoreSight trace
drivers to register themselves with. It's intended to build up a
topological view of the CoreSight components and configure the
correct serie of components on user input via sysfs.
For eg., when enabling a source, the framework builds up a path
consisting of all the components connecting the source to the
currently selected sink(s) and enables all of them.
The framework also supports switching between available sinks
and provides status information to user space applications
through the debugfs interface.
Signed-off-by: Pratik Patel <pratikp@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The commit 46420dd73b (PM / Domains: Add APIs to attach/detach a PM
domain for a device) started using errno values in pm.h header file.
It also failed to include the header for these, thus it caused
compiler errors.
Instead of including the errno header to pm.h, let's move the functions
to pm_domain.h, since it's a better match.
Fixes: 46420dd73b (PM / Domains: Add APIs to attach/detach a PM domain for a device)
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
AMBA devices may on some SoCs resides in PM domains. To be able to
manage these devices from there, let's try to attach devices to their
corresponding PM domain during the probe phase.
To reverse these actions at the remove phase, we try to detach the
device from its PM domain.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Convert to the SET_PM_RUNTIME_PM macro while defining the runtime PM
callbacks. This means the callbacks becomes available for both
CONFIG_PM_SLEEP and CONFIG_PM_RUNTIME, which is needed by drivers and
power domains.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
To fully gate the clock and thus potentially also save more power in
runtime suspend state, extend clock handling with clk_prepare|unprepare
in the runtime PM callbacks.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
To simplify code and error handling let's use clk_prepare_enable
and clk_disable_unprepare. No functional change.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
All AMBA drivers have converted to use the modern PM ops thus we can
safely drop the legacy PM support from the bus.
While using the modern PM ops it also makes sense to convert to use the
pm_generic callback functions.
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
AMBA Primecell devices always treat streaming and coherent DMA exactly
the same, so there's no point in having the masks separated.
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The "runtime idle" helper routine, rpm_idle(), currently ignores
return values from .runtime_idle() callbacks executed by it.
However, it turns out that many subsystems use
pm_generic_runtime_idle() which checks the return value of the
driver's callback and executes pm_runtime_suspend() for the device
unless that value is not 0. If that logic is moved to rpm_idle()
instead, pm_generic_runtime_idle() can be dropped and its users
will not need any .runtime_idle() callbacks any more.
Moreover, the PCI, SCSI, and SATA subsystems' .runtime_idle()
routines, pci_pm_runtime_idle(), scsi_runtime_idle(), and
ata_port_runtime_idle(), respectively, as well as a few drivers'
ones may be simplified if rpm_idle() calls rpm_suspend() after 0 has
been returned by the .runtime_idle() callback executed by it.
To reduce overall code bloat, make the changes described above.
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Kevin Hilman <khilman@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
CONFIG_HOTPLUG is going away as an option. As a result, the __dev*
markings need to be removed, as well as the use of CONFIG_HOTPLUG.
This patch does both, removing the use of CONFIG_HOTPLUG in the
amba/bus.c file, and __devinit and __devinitconst in the tegra-ahb.c
driver.
Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This creates amba_apb_device_add_res() and
amba_ahb_device_add_res() respectively, to add devices with
another parent than iomem_resource. This is needed to specify
that a device is contained in a specific IO range.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add two functions to add APB and AHB devices to the amba (PrimeCell)
bus dynamically. This is modeled after the static definition
macros recently introduced into <linux/amba/bus.h> and can
help us in factoring out a bunch of code across the kernel.
Since a lot of call sites seem to be using a returned struct
amba device* pointer, let's use that.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The AMBA bus regulator support is being used to model on/off switches
for power domains which isn't terribly idiomatic for modern kernels with
the generic power domain code and creates integration problems on platforms
which don't use regulators for their power domains as it's hard to tell
the difference between a regulator that is needed but failed to be provided
and one that isn't supposed to be there (though DT does make that easier).
Platforms that wish to use the regulator API to manage their power domains
can indirect via the power domain interface.
This feature is only used with the vape supply of the db8500 PRCMU
driver which supplies the UARTs and MMC controllers, none of which have
support for managing vcore at runtime in mainline (only pl022 SPI
controller does). Update that supply to have an always_on constraint
until the power domain support for the system is updated so that it is
enabled for these users, this is likely to have no impact on practical
systems as probably at least one of these devices will be active and
cause AMBA to hold the supply on anyway.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add functions to allocate and initialize AMBA device structures, and
add them to the Linux device manager. This allows us to kill this
type of operation from individual platforms, moving it to core code.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
* 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (76 commits)
PM / Hibernate: Implement compat_ioctl for /dev/snapshot
PM / Freezer: fix return value of freezable_schedule_timeout_killable()
PM / shmobile: Allow the A4R domain to be turned off at run time
PM / input / touchscreen: Make st1232 use device PM QoS constraints
PM / QoS: Introduce dev_pm_qos_add_ancestor_request()
PM / shmobile: Remove the stay_on flag from SH7372's PM domains
PM / shmobile: Don't include SH7372's INTCS in syscore suspend/resume
PM / shmobile: Add support for the sh7372 A4S power domain / sleep mode
PM: Drop generic_subsys_pm_ops
PM / Sleep: Remove forward-only callbacks from AMBA bus type
PM / Sleep: Remove forward-only callbacks from platform bus type
PM: Run the driver callback directly if the subsystem one is not there
PM / Sleep: Make pm_op() and pm_noirq_op() return callback pointers
PM/Devfreq: Add Exynos4-bus device DVFS driver for Exynos4210/4212/4412.
PM / Sleep: Merge internal functions in generic_ops.c
PM / Sleep: Simplify generic system suspend callbacks
PM / Hibernate: Remove deprecated hibernation snapshot ioctls
PM / Sleep: Fix freezer failures due to racy usermodehelper_is_disabled()
ARM: S3C64XX: Implement basic power domain support
PM / shmobile: Use common always on power domain governor
...
Fix up trivial conflict in fs/xfs/xfs_buf.c due to removal of unused
XBT_FORCE_SLEEP bit
The forward-only PM callbacks provided by the AMBA bus type are not
necessary any more, because the PM core executes driver callbacks
when the corresponding subsystem callbacks are not present, so drop
them.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
This patch adds the necessary support in file2alias.c to define
suitable aliases based on the amba_id table in AMBA driver modules.
This should be sufficient to allow such modules to be auto-loaded
via udev. The AMBA bus driver's uevent hotplug code is also
modified to pass an approriate MODALIAS string in the event.
For simplicity, the AMBA ID is treated an an opaque 32-bit numeber.
Module alises use patterns as appropriate to describe the value-
mask pairs described in the driver's amba_id list.
The proposed alias format is (extended regex):
^amba:d(HEX){8}$
Where HEX is a single upper-case HEX digit or a pattern (? or []
expression) matching a single upper-case HEX digit, as expected by
udev.
"d" is short for "device", following existing alias naming
conventions for other device types. This adds some flexibility for
unambiguously extending the alias format in the future by adding
additional leading and trailing fields, if this turns out to be
necessary.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Pawel Moll <pawel.moll@arm.com>
Add runtime PM support to the core Primecell driver, following the PCI
model of how this is done.
Rather than having every driver fiddle about with enabling runtime PM,
that's dealt with in the core and instead, drivers just do a put() in
their probe and a balancing get() in their remove function to activate
runtime PM for the device.
As we're dealing with enabling runtime PM in the core, fix up spi-pl022
as it must not enable and disable runtime PM itself anymore.
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This makes a hardcoded periphid from the platform override any
magic number found in the hardware. This shall henceforth be used
when the information found in the hardware is either missing,
i.e. not encoding the CID with the magic cookie 0xb105f00d, or
incorrect such that the revision number should have been bumped in
hardware, but the silicon designer has failed to do so.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Xen save/restore is going to use hibernate device callbacks for
quiescing devices and putting them back to normal operations and it
would need to select CONFIG_HIBERNATION for this purpose. However,
that also would cause the hibernate interfaces for user space to be
enabled, which might confuse user space, because the Xen kernels
don't support hibernation. Moreover, it would be wasteful, as it
would make the Xen kernels include a substantial amount of code that
they would never use.
To address this issue introduce new power management Kconfig option
CONFIG_HIBERNATE_CALLBACKS, such that it will only select the code
that is necessary for the hibernate device callbacks to work and make
CONFIG_HIBERNATION select it. Then, Xen save/restore will be able to
select CONFIG_HIBERNATE_CALLBACKS without dragging the entire
hibernate code along with it.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
Support pm_ops in the AMBA bus, required to allow drivers to use runtime pm.
The implementation of AMBA bus pm ops is based on the platform bus
implementation.
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
As all probe() functions now take a const pointer, we can make the bus
level code deal with const pointers too.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Export amba_bustype struct so it can be used for things like registering
bus notifiers.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
On some contemporary sub-micron SoCs, peripherals on the chip have
power domain switches, i.e. the voltage to the core may be turned
off to conserve power. In the Ux500 we have this for out PrimeCell
derivates.
This patch makes it possible to specify an (optional) regulator to
handle the voltage domain switch on AMBA PrimeCells, modeled very
similar to how block clocks are handled.
Additional amba_vcore_[enable|disable] calls are supplied to make
it possible introduce optional powering off of the core voltage.
Using this will require code to spool/unspool any core HW state.
Cc: Rabin Vincent <rabin.vincent@stericsson.com>
Cc: Bengt Jonsson <bengt.g.jonsson@stericsson.com>
Cc: Jonas Aaberg <jonas.aberg@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This make four macros for the PrimeCell ID register available to
drivers that use them witout using the PrimeCell/AMBA bus
abstraction and struct amba_device. It also moves the magic
PrimeCell CID "B105F00D" to the bus.h header file.
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Some platforms gate the pclk (APB - the bus - clock) to the peripherals
for power saving, along with the functional clock. When devices are
accessed without pclk enabled, the kernel will oops.
This gives them two options:
1. Leave all clocks on all the time.
2. Attempt to gate pclk along with the functional clock.
(With some hardware, pclk and the functional clock are gated by a single
bit in a register.)
(1) has the disadvantage that it causes increased power usage, which is
bad news for battery operated devices. (2) can lead to kernel oops if
registers are accessed without the functional clock being enabled.
So, introduce the apb_pclk signal in such a way existing drivers don't
need to be updated. Essentially, this means we guarantee that:
1. pclk will be enabled whenever the driver is bound to a device -
from probe() to remove() time.
2. pclk will also be enabled when reading the primecell IDs from the device.
In order to allow drivers to be incrementally updated to achieve greater
power savings, we provide two additional calls to allow drivers to
manage the pclk - amba_pclk_enable()/amba_pclk_disable().
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch modifies the amba bus detection logic in the kernel
to detect the AMBA devices using the calculated resource
size information rather than the hard coded 4K size.
It also calculates the resource size when request mem region
and release mem region.
Signed-off-by: Leo Chen <leochen@broadcom.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
AMBA device resources were being reported as:
10004000-10004fff : <BAD>
This is because dev_name() was returning NULL prior to device_register.
Ensure that the struct device is properly initialized, and the name is
set before adding it to the device tree.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Geert Uytterhoeven