mm: fix null pointer dereference in wait_iff_congested()

An unintended consequence of commit 4ae0a48b5efc ("mm: modify
pgdat_balanced() so that it also handles order-0") is that
wait_iff_congested() can now be called with NULL 'struct zone *'
producing kernel oops like this:

  BUG: unable to handle kernel NULL pointer dereference
  IP: [<ffffffff811542d9>] wait_iff_congested+0x59/0x140

This trivial patch fixes it.

Reported-by: Zhouping Liu <zliu@redhat.com>
Reported-and-tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Zlatko Calusic <zlatko.calusic@iskon.hr>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
video: st7735fb: add st7735 framebuffer driver

Add driver for the SPI-connected ST7735 display controller.
This driver requires that the platform support DT booting.

Signed-off-by: Matt Porter <mporter@ti.com>
dmaengine: add helper function to request a slave DMA channel

Currently slave DMA channels are requested by calling dma_request_channel()
and requires DMA clients to pass various filter parameters to obtain the
appropriate channel.

With device-tree being used by architectures such as arm and the addition of
device-tree helper functions to extract the relevant DMA client information
from device-tree, add a new function to request a slave DMA channel using
device-tree. This function is currently a simple wrapper that calls the
device-tree of_dma_request_slave_channel() function.

Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <djbw@fb.com>

Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Reviewed-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
of: Add generic device tree DMA helpers

This is based upon the work by Benoit Cousson [1] and Nicolas Ferre [2]
to add some basic helpers to retrieve a DMA controller device_node and the
DMA request/channel information.

Aim of DMA helpers
- The purpose of device-tree is to describe the capabilites of the hardware.
  Thinking about DMA controllers purely from the context of the hardware to
  begin with, we can describe a device in terms of a DMA controller as
  follows ...
  	1. Number of DMA controllers
	2. Number of channels (maybe physical or logical)
	3. Mapping of DMA requests signals to DMA controller
	4. Number of DMA interrupts
	5. Mapping of DMA interrupts to channels
- With the above in mind the aim of the DT DMA helper functions is to extract
  the above information from the DT and provide to the appropriate driver.
  However, due to the vast number of DMA controllers and not all are using a
  common driver (such as DMA Engine) it has been seen that this is not a
  trivial task. In previous discussions on this topic the following concerns
  have been raised ...
	1. How does the binding support devices with multiple DMA controllers?
  	2. How to support both legacy DMA controllers not using DMA Engine as
	   well as those that support DMA Engine.
	3. When using with DMA Engine how do we support the various
	   implementations where the opaque filter function parameter differs
	   between implementations?
	4. How do we handle DMA channels that are identified with a string
	   versus a integer?
- Hence the design of the DMA helpers has to accomodate the above or align on
  an agreement what can be or should be supported.

Design of DMA helpers

1. Registering DMA controllers

   In the case of DMA controllers that are using DMA Engine, requesting a
   channel is performed by calling the following function.

	struct dma_chan *dma_request_channel(dma_cap_mask_t mask,
			dma_filter_fn filter_fn,
			void *filter_param);

   The mask variable is used to match a type of the device controller in a list
   of controllers. The filter_fn and filter_param are used to identify the
   required dma channel and return a handle to the dma channel of type dma_chan.

   From the examples I have seen, the mask and filter_fn are constant
   for a given DMA controller and therefore, we can specify these as controller
   specific data when registering the DMA controller with the device-tree DMA
   helpers.

   The filter_param variable is of an unknown type and is typically specific
   to the DMA engine implementation for a given DMA controller. To allow some
   flexibility in the type and formating of this filter_param we employ an
   xlate to translate the device-tree binding information into the appropriate
   format. The xlate function used for a DMA controller can also be specified
   when registering the DMA controller with the device-tree DMA helpers.

   Based upon the above, a function for registering the DMA controller with the
   DMA helpers now looks like the below. The data variable is used to pass a
   pointer to DMA controller specific data used by the xlate function.

	int of_dma_controller_register(struct device_node *np,
		struct dma_chan *(*of_dma_xlate)
		(struct of_phandle_args *, struct of_dma *),
		void *data)

   For example, in the case where DMA engine is used, we define the following
   structure (that stores the DMA engine capability mask and filter function)
   and pass this to the data variable in the above function.

	struct of_dma_filter_info {
		dma_cap_mask_t  dma_cap;
		dma_filter_fn   filter_fn;
	};

2. Representing and requesting channel information

   Please see the dma binding documentation included in this patch for a
   description of how DMA controllers and client information should be
   represented with device-tree. For more information on how this binding
   came about please see [3]. In addition to this, feedback received from
   the Linux kernel summit showed a consensus (among those who attended) to
   use a name to identify DMA client information [4].

   A DMA channel can be requested by calling the following function, where name
   is a required parameter used for identifying a DMA channel. This function
   has been designed to return a structure of type dma_chan to work with the
   DMA engine driver. Note that if DMA engine is used then drivers should be
   using the DMA engine API dma_request_slave_channel() (implemented in part 2
   of this series, "dmaengine: add helper function to request a slave DMA
   channel") which will in turn call the below function if device-tree is
   present. The aim being to have a common DMA engine interface regardless of
   whether device tree is being used.

	struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
						      char *name)

3. Supporting legacy devices not using DMA Engine

   These devices present a problem, as there may not be a uniform way to easily
   support them with regard to device tree. Ideally, these should be migrated
   to DMA engine. However, if this is not possible, then they should still be
   able to use this binding, the only constaint imposed by this implementation
   is that when requesting a DMA channel via of_dma_request_slave_channel(), it
   will return a type of dma_chan.

This implementation has been tested on OMAP4430 using the kernel v3.6-rc5. I
have validated that MMC is working on the PANDA board with this implementation.
My development branch for testing on OMAP can be found here [5].

v6: - minor corrections in DMA binding documentation
v5: - minor update to binding documentation
    - added loop to exhaustively search for a slave channel in the case where
      there could be alternative channels available
v4: - revert the removal of xlate function from v3
    - update the proposed binding format and APIs based upon discussions [3]
v3: - avoid passing an xlate function and instead pass DMA engine parameters
    - define number of dma channels and requests in dma-controller node
v2: - remove of_dma_to_resource API
    - make property #dma-cells required (no fallback anymore)
    - another check in of_dma_xlate_onenumbercell() function

[1] http://article.gmane.org/gmane.linux.drivers.devicetree/12022
[2] http://article.gmane.org/gmane.linux.ports.arm.omap/73622
[3] http://marc.info/?l=linux-omap&m=133582085008539&w=2
[4] http://pad.linaro.org/arm-mini-summit-2012
[5] https://github.com/jonhunter/linux/tree/dev-dt-dma

Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <djbw@fb.com>

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Reviewed-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
of: dma- fix build break for !CONFIG_OF

Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
of: dma: fix typos in generic dma binding definition

Some semicolons were left out in the examples.

The #dma-channels and #dma-requests properties have a prefix
that is, by convention, reserved for cell size properties.
Rename those properties to dma-channels and dma-requests.

Signed-off-by: Matt Porter <mporter@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
dmaengine: fix build failure due to missing semi-colon

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
dmaengine: edma: fix slave config dependency on direction

The edma_slave_config() implementation depends on the
direction field such that it will not properly configure
a slave channel when called without direction set.

This fixes the implementation so that the slave config
is copied as is and prep_slave_sg() handles the
direction dependent handling. spi-omap2-mcspi and
omap_hsmmc both expose this bug as they configure the
slave channel config from a common path with an unconfigured
direction field.

Signed-off-by: Matt Porter <mporter@ti.com>
ARM: davinci: move private EDMA API to arm/common

Move mach-davinci/dma.c to common/edma.c so it can be used
by OMAP (specifically AM33xx) as well. This just moves the
private EDMA API but does not support OMAP.

Signed-off-by: Matt Porter <mporter@ti.com>
ARM: edma: remove unused transfer controller handlers

Fix build on OMAP, the irqs are undefined on AM33xx.
These error interrupt handlers were hardcoded as disabled
so since they are unused code, simply remove them.

Signed-off-by: Matt Porter <mporter@ti.com>
ARM: edma: add DT and runtime PM support for AM33XX

Adds support for parsing the TI EDMA DT data into the required
EDMA private API platform data.

Calls runtime PM API only in the DT case in order to unidle the
associated hwmods on AM33XX.

Signed-off-by: Matt Porter <mporter@ti.com>
ARM: edma: add AM33XX crossbar event support

Adds support for the per-EDMA channel event mux. This is required
for any peripherals using DMA crossbar mapped events.

Signed-off-by: Matt Porter <mporter@ti.com>
dmaengine: edma: enable build for AM33XX

Enable TI EDMA option on OMAP.

Signed-off-by: Matt Porter <mporter@ti.com>
dmaengine: edma: Add TI EDMA device tree binding

The binding definition is based on the generic DMA controller
binding.

Signed-off-by: Matt Porter <mporter@ti.com>
ARM: dts: add AM33XX EDMA support

Adds AM33XX EDMA support to the am33xx.dtsi as documented in
Documentation/devicetree/bindings/dma/ti-edma.txt

Signed-off-by: Matt Porter <mporter@ti.com>
dmaengine: add dma_request_slave_channel_compat()

Adds a dma_request_slave_channel_compat() wrapper which accepts
both the arguments from dma_request_channel() and
dma_request_slave_channel(). Based on whether the driver is
instantiated via DT, the appropriate channel request call will be
made.

This allows for a much cleaner migration of drivers to the
dmaengine DT API as platforms continue to be mixed between those
that boot using DT and those that do not.

Suggested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Matt Porter <mporter@ti.com>
mmc: omap_hsmmc: convert to dma_request_slave_channel_compat()

Convert dmaengine channel requests to use
dma_request_slave_channel_compat(). This supports the DT case of
platforms requiring channel selection from either the OMAP DMA or
the EDMA engine. AM33xx only boots from DT and is the only user
implementing EDMA so in the !DT case we can default to the OMAP DMA
filter.

Signed-off-by: Matt Porter <mporter@ti.com>
mmc: omap_hsmmc: limit max_segs with the EDMA DMAC

The EDMA DMAC has a hardware limitation that prevents supporting
scatter gather lists with any number of segments. Since the EDMA
DMA Engine driver sets the maximum segments to 16, we do the
same.

TODO: this will be replaced once the DMA Engine API supports an
API to query the DMAC's segment size limit.

Signed-off-by: Matt Porter <mporter@ti.com>
mmc: omap_hsmmc: add generic DMA request support to the DT binding

The binding definition is based on the generic DMA request binding.

Signed-off-by: Matt Porter <mporter@ti.com>
ARM: dts: add AM33XX MMC support

Adds AM33XX MMC support for am335x-bone and am335x-evm.

Signed-off-by: Matt Porter <mporter@ti.com>