Commit 3f17ea6d authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'next' (accumulated 3.16 merge window patches) into master

Now that 3.15 is released, this merges the 'next' branch into 'master',
bringing us to the normal situation where my 'master' branch is the
merge window.

* accumulated work in next: (6809 commits)
  ufs: sb mutex merge + mutex_destroy
  powerpc: update comments for generic idle conversion
  cris: update comments for generic idle conversion
  idle: remove cpu_idle() forward declarations
  nbd: zero from and len fields in NBD_CMD_DISCONNECT.
  mm: convert some level-less printks to pr_*
  MAINTAINERS: adi-buildroot-devel is moderated
  MAINTAINERS: add linux-api for review of API/ABI changes
  mm/kmemleak-test.c: use pr_fmt for logging
  fs/dlm/debug_fs.c: replace seq_printf by seq_puts
  fs/dlm/lockspace.c: convert simple_str to kstr
  fs/dlm/config.c: convert simple_str to kstr
  mm: mark remap_file_pages() syscall as deprecated
  mm: memcontrol: remove unnecessary memcg argument from soft limit functions
  mm: memcontrol: clean up memcg zoneinfo lookup
  mm/memblock.c: call kmemleak directly from memblock_(alloc|free)
  mm/mempool.c: update the kmemleak stack trace for mempool allocations
  lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations
  mm: introduce kmemleak_update_trace()
  mm/kmemleak.c: use %u to print ->checksum
  ...
parents 1860e379 1a5700bc

Too many changes to show.

To preserve performance only 1000 of 1000+ files are displayed.
......@@ -62,6 +62,40 @@ KernelVersion: 3.11
Description:
This group contains functions available to this USB gadget.
What: /config/usb-gadget/gadget/functions/<func>.<inst>/interface.<n>
Date: May 2014
KernelVersion: 3.16
Description:
This group contains "Feature Descriptors" specific for one
gadget's USB interface or one interface group described
by an IAD.
The attributes:
compatible_id - 8-byte string for "Compatible ID"
sub_compatible_id - 8-byte string for "Sub Compatible ID"
What: /config/usb-gadget/gadget/functions/<func>.<inst>/interface.<n>/<property>
Date: May 2014
KernelVersion: 3.16
Description:
This group contains "Extended Property Descriptors" specific for one
gadget's USB interface or one interface group described
by an IAD.
The attributes:
type - value 1..7 for interpreting the data
1: unicode string
2: unicode string with environment variable
3: binary
4: little-endian 32-bit
5: big-endian 32-bit
6: unicode string with a symbolic link
7: multiple unicode strings
data - blob of data to be interpreted depending on
type
What: /config/usb-gadget/gadget/strings
Date: Jun 2013
KernelVersion: 3.11
......@@ -79,3 +113,14 @@ Description:
product - gadget's product description
manufacturer - gadget's manufacturer description
What: /config/usb-gadget/gadget/os_desc
Date: May 2014
KernelVersion: 3.16
Description:
This group contains "OS String" extension handling attributes.
use - flag turning "OS Desctiptors" support on/off
b_vendor_code - one-byte value used for custom per-device and
per-interface requests
qw_sign - an identifier to be reported as "OS String"
proper
......@@ -114,14 +114,17 @@ What: /sys/bus/iio/devices/iio:deviceX/in_temp_raw
What: /sys/bus/iio/devices/iio:deviceX/in_tempX_raw
What: /sys/bus/iio/devices/iio:deviceX/in_temp_x_raw
What: /sys/bus/iio/devices/iio:deviceX/in_temp_y_raw
What: /sys/bus/iio/devices/iio:deviceX/in_temp_z_raw
What: /sys/bus/iio/devices/iio:deviceX/in_temp_ambient_raw
What: /sys/bus/iio/devices/iio:deviceX/in_temp_object_raw
KernelVersion: 2.6.35
Contact: linux-iio@vger.kernel.org
Description:
Raw (unscaled no bias removal etc.) temperature measurement.
If an axis is specified it generally means that the temperature
sensor is associated with one part of a compound device (e.g.
a gyroscope axis). Units after application of scale and offset
a gyroscope axis). The ambient and object modifiers distinguish
between ambient (reference) and distant temperature for contact-
less measurements. Units after application of scale and offset
are milli degrees Celsius.
What: /sys/bus/iio/devices/iio:deviceX/in_tempX_input
......@@ -210,6 +213,14 @@ Contact: linux-iio@vger.kernel.org
Description:
Scaled humidity measurement in milli percent.
What: /sys/bus/iio/devices/iio:deviceX/in_X_mean_raw
KernelVersion: 3.5
Contact: linux-iio@vger.kernel.org
Description:
Averaged raw measurement from channel X. The number of values
used for averaging is device specific. The converting rules for
normal raw values also applies to the averaged raw values.
What: /sys/bus/iio/devices/iio:deviceX/in_accel_offset
What: /sys/bus/iio/devices/iio:deviceX/in_accel_x_offset
What: /sys/bus/iio/devices/iio:deviceX/in_accel_y_offset
......@@ -784,6 +795,7 @@ What: /sys/.../iio:deviceX/scan_elements/in_incli_x_en
What: /sys/.../iio:deviceX/scan_elements/in_incli_y_en
What: /sys/.../iio:deviceX/scan_elements/in_pressureY_en
What: /sys/.../iio:deviceX/scan_elements/in_pressure_en
What: /sys/.../iio:deviceX/scan_elements/in_rot_quaternion_en
KernelVersion: 2.6.37
Contact: linux-iio@vger.kernel.org
Description:
......@@ -799,6 +811,7 @@ What: /sys/.../iio:deviceX/scan_elements/in_voltageY_supply_type
What: /sys/.../iio:deviceX/scan_elements/in_timestamp_type
What: /sys/.../iio:deviceX/scan_elements/in_pressureY_type
What: /sys/.../iio:deviceX/scan_elements/in_pressure_type
What: /sys/.../iio:deviceX/scan_elements/in_rot_quaternion_type
KernelVersion: 2.6.37
Contact: linux-iio@vger.kernel.org
Description:
......@@ -845,6 +858,7 @@ What: /sys/.../iio:deviceX/scan_elements/in_incli_y_index
What: /sys/.../iio:deviceX/scan_elements/in_timestamp_index
What: /sys/.../iio:deviceX/scan_elements/in_pressureY_index
What: /sys/.../iio:deviceX/scan_elements/in_pressure_index
What: /sys/.../iio:deviceX/scan_elements/in_rot_quaternion_index
KernelVersion: 2.6.37
Contact: linux-iio@vger.kernel.org
Description:
......@@ -881,6 +895,25 @@ Description:
on-chip EEPROM. After power-up or chip reset the device will
automatically load the saved configuration.
What: /sys/.../iio:deviceX/in_illuminanceY_input
What: /sys/.../iio:deviceX/in_illuminanceY_raw
What: /sys/.../iio:deviceX/in_illuminanceY_mean_raw
KernelVersion: 3.4
Contact: linux-iio@vger.kernel.org
Description:
Illuminance measurement, units after application of scale
and offset are lux.
What: /sys/.../iio:deviceX/in_intensityY_raw
What: /sys/.../iio:deviceX/in_intensityY_ir_raw
What: /sys/.../iio:deviceX/in_intensityY_both_raw
KernelVersion: 3.4
Contact: linux-iio@vger.kernel.org
Description:
Unit-less light intensity. Modifiers both and ir indicate
that measurements contains visible and infrared light
components or just infrared light, respectively.
What: /sys/.../iio:deviceX/in_intensity_red_integration_time
What: /sys/.../iio:deviceX/in_intensity_green_integration_time
What: /sys/.../iio:deviceX/in_intensity_blue_integration_time
......@@ -891,3 +924,12 @@ Contact: linux-iio@vger.kernel.org
Description:
This attribute is used to get/set the integration time in
seconds.
What: /sys/bus/iio/devices/iio:deviceX/in_rot_quaternion_raw
KernelVersion: 3.15
Contact: linux-iio@vger.kernel.org
Description:
Raw value of quaternion components using a format
x y z w. Here x, y, and z component represents the axis about
which a rotation will occur and w component represents the
amount of rotation.
What /sys/bus/iio/devices/iio:deviceX/in_proximity_raw
Date: March 2014
KernelVersion: 3.15
Contact: Matt Ranostay <mranostay@gmail.com>
Description:
Get the current distance in meters of storm (1km steps)
1000-40000 = distance in meters
What /sys/bus/iio/devices/iio:deviceX/sensor_sensitivity
Date: March 2014
KernelVersion: 3.15
Contact: Matt Ranostay <mranostay@gmail.com>
Description:
Show or set the gain boost of the amp, from 0-31 range.
18 = indoors (default)
14 = outdoors
......@@ -250,3 +250,24 @@ Description:
valid. For example, writing a 2 to this file when sriov_numvfs
is not 0 and not 2 already will return an error. Writing a 10
when the value of sriov_totalvfs is 8 will return an error.
What: /sys/bus/pci/devices/.../driver_override
Date: April 2014
Contact: Alex Williamson <alex.williamson@redhat.com>
Description:
This file allows the driver for a device to be specified which
will override standard static and dynamic ID matching. When
specified, only a driver with a name matching the value written
to driver_override will have an opportunity to bind to the
device. The override is specified by writing a string to the
driver_override file (echo pci-stub > driver_override) and
may be cleared with an empty string (echo > driver_override).
This returns the device to standard matching rules binding.
Writing to driver_override does not automatically unbind the
device from its current driver or make any attempt to
automatically load the specified driver. If no driver with a
matching name is currently loaded in the kernel, the device
will not bind to any driver. This also allows devices to
opt-out of driver binding using a driver_override name such as
"none". Only a single driver may be specified in the override,
there is no support for parsing delimiters.
......@@ -128,7 +128,7 @@ Description: Discover cpuidle policy and mechanism
What: /sys/devices/system/cpu/cpu#/cpufreq/*
Date: pre-git history
Contact: cpufreq@vger.kernel.org
Contact: linux-pm@vger.kernel.org
Description: Discover and change clock speed of CPUs
Clock scaling allows you to change the clock speed of the
......@@ -146,7 +146,7 @@ Description: Discover and change clock speed of CPUs
What: /sys/devices/system/cpu/cpu#/cpufreq/freqdomain_cpus
Date: June 2013
Contact: cpufreq@vger.kernel.org
Contact: linux-pm@vger.kernel.org
Description: Discover CPUs in the same CPU frequency coordination domain
freqdomain_cpus is the list of CPUs (online+offline) that share
......
What: /sys/class/leds/blink1::<serial>/rgb
Date: January 2013
Contact: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Description: The ThingM blink1 is an USB RGB LED. The color notation is
3-byte hexadecimal. Read this attribute to get the last set
color. Write the 24-bit hexadecimal color to change the current
LED color. The default color is full white (0xFFFFFF).
For instance, set the color to green with: echo 00FF00 > rgb
What: /sys/class/leds/blink1::<serial>/fade
Date: January 2013
Contact: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Description: This attribute allows to set a fade time in milliseconds for
the next color change. Read the attribute to know the current
fade time. The default value is set to 0 (no fade time). For
instance, set a fade time of 2 seconds with: echo 2000 > fade
What: /sys/class/leds/blink1::<serial>/play
Date: January 2013
Contact: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Description: This attribute is used to play/pause the light patterns. Write 1
to start playing, 0 to stop. Reading this attribute returns the
current playing status.
What: /sys/devices/../../gisb_arb_timeout
Date: May 2014
KernelVersion: 3.17
Contact: Florian Fainelli <f.fainelli@gmail.com>
Description:
Returns the currently configured raw timeout value of the
Broadcom Set Top Box internal GISB bus arbiter. Minimum value
is 1, and maximum value is 0xffffffff.
What: /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
Date: Feb 2014
Contact: Li Jun <b47624@freescale.com>
Description:
Can be set and read.
Set a_bus_req(A-device bus request) input to be 1 if
the application running on the A-device wants to use the bus,
and to be 0 when the application no longer wants to use
the bus(or wants to work as peripheral). a_bus_req can also
be set to 1 by kernel in response to remote wakeup signaling
from the B-device, the A-device should decide to resume the bus.
Valid values are "1" and "0".
Reading: returns 1 if the application running on the A-device
is using the bus as host role, otherwise 0.
What: /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
Date: Feb 2014
Contact: Li Jun <b47624@freescale.com>
Description:
Can be set and read
The a_bus_drop(A-device bus drop) input is 1 when the
application running on the A-device wants to power down
the bus, and is 0 otherwise, When a_bus_drop is 1, then
the a_bus_req shall be 0.
Valid values are "1" and "0".
Reading: returns 1 if the bus is off(vbus is turned off) by
A-device, otherwise 0.
What: /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
Date: Feb 2014
Contact: Li Jun <b47624@freescale.com>
Description:
Can be set and read.
The b_bus_req(B-device bus request) input is 1 during the time
that the application running on the B-device wants to use the
bus as host, and is 0 when the application no longer wants to
work as host and decides to switch back to be peripheral.
Valid values are "1" and "0".
Reading: returns if the application running on the B device
is using the bus as host role, otherwise 0.
What: /sys/bus/platform/devices/ci_hdrc.0/inputs/a_clr_err
Date: Feb 2014
Contact: Li Jun <b47624@freescale.com>
Description:
Only can be set.
The a_clr_err(A-device Vbus error clear) input is used to clear
vbus error, then A-device will power down the bus.
Valid value is "1"
......@@ -7,19 +7,30 @@ Description:
subsystem.
What: /sys/power/state
Date: August 2006
Date: May 2014
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
Description:
The /sys/power/state file controls the system power state.
Reading from this file returns what states are supported,
which is hard-coded to 'freeze' (Low-Power Idle), 'standby'
(Power-On Suspend), 'mem' (Suspend-to-RAM), and 'disk'
(Suspend-to-Disk).
The /sys/power/state file controls system sleep states.
Reading from this file returns the available sleep state
labels, which may be "mem", "standby", "freeze" and "disk"
(hibernation). The meanings of the first three labels depend on
the relative_sleep_states command line argument as follows:
1) relative_sleep_states = 1
"mem", "standby", "freeze" represent non-hibernation sleep
states from the deepest ("mem", always present) to the
shallowest ("freeze"). "standby" and "freeze" may or may
not be present depending on the capabilities of the
platform. "freeze" can only be present if "standby" is
present.
2) relative_sleep_states = 0 (default)
"mem" - "suspend-to-RAM", present if supported.
"standby" - "power-on suspend", present if supported.
"freeze" - "suspend-to-idle", always present.
Writing to this file one of these strings causes the system to
transition into that state. Please see the file
Documentation/power/states.txt for a description of each of
these states.
transition into the corresponding state, if available. See
Documentation/power/states.txt for a description of what
"suspend-to-RAM", "power-on suspend" and "suspend-to-idle" mean.
What: /sys/power/disk
Date: September 2006
......
......@@ -73,6 +73,11 @@ Perl
You will need perl 5 and the following modules: Getopt::Long, Getopt::Std,
File::Basename, and File::Find to build the kernel.
BC
--
You will need bc to build kernels 3.10 and higher
System utilities
================
......
......@@ -660,15 +660,23 @@ There are a number of driver model diagnostic macros in <linux/device.h>
which you should use to make sure messages are matched to the right device
and driver, and are tagged with the right level: dev_err(), dev_warn(),
dev_info(), and so forth. For messages that aren't associated with a
particular device, <linux/printk.h> defines pr_debug() and pr_info().
particular device, <linux/printk.h> defines pr_notice(), pr_info(),
pr_warn(), pr_err(), etc.
Coming up with good debugging messages can be quite a challenge; and once
you have them, they can be a huge help for remote troubleshooting. Such
messages should be compiled out when the DEBUG symbol is not defined (that
is, by default they are not included). When you use dev_dbg() or pr_debug(),
that's automatic. Many subsystems have Kconfig options to turn on -DDEBUG.
A related convention uses VERBOSE_DEBUG to add dev_vdbg() messages to the
ones already enabled by DEBUG.
you have them, they can be a huge help for remote troubleshooting. However
debug message printing is handled differently than printing other non-debug
messages. While the other pr_XXX() functions print unconditionally,
pr_debug() does not; it is compiled out by default, unless either DEBUG is
defined or CONFIG_DYNAMIC_DEBUG is set. That is true for dev_dbg() also,
and a related convention uses VERBOSE_DEBUG to add dev_vdbg() messages to
the ones already enabled by DEBUG.
Many subsystems have Kconfig debug options to turn on -DDEBUG in the
corresponding Makefile; in other cases specific files #define DEBUG. And
when a debug message should be unconditionally printed, such as if it is
already inside a debug-related #ifdef secton, printk(KERN_DEBUG ...) can be
used.
Chapter 14: Allocating memory
......
This diff is collapsed.
......@@ -4,22 +4,26 @@
James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
This document describes the DMA API. For a more gentle introduction
of the API (and actual examples) see
Documentation/DMA-API-HOWTO.txt.
of the API (and actual examples), see Documentation/DMA-API-HOWTO.txt.
This API is split into two pieces. Part I describes the API. Part II
describes the extensions to the API for supporting non-consistent
memory machines. Unless you know that your driver absolutely has to
support non-consistent platforms (this is usually only legacy
platforms) you should only use the API described in part I.
This API is split into two pieces. Part I describes the basic API.
Part II describes extensions for supporting non-consistent memory
machines. Unless you know that your driver absolutely has to support
non-consistent platforms (this is usually only legacy platforms) you
should only use the API described in part I.
Part I - dma_ API
-------------------------------------
To get the dma_ API, you must #include <linux/dma-mapping.h>
To get the dma_ API, you must #include <linux/dma-mapping.h>. This
provides dma_addr_t and the interfaces described below.
A dma_addr_t can hold any valid DMA or bus address for the platform. It
can be given to a device to use as a DMA source or target. A CPU cannot
reference a dma_addr_t directly because there may be translation between
its physical address space and the bus address space.
Part Ia - Using large dma-coherent buffers
Part Ia - Using large DMA-coherent buffers
------------------------------------------
void *
......@@ -33,20 +37,21 @@ to make sure to flush the processor's write buffers before telling
devices to read that memory.)
This routine allocates a region of <size> bytes of consistent memory.
It also returns a <dma_handle> which may be cast to an unsigned
integer the same width as the bus and used as the physical address
base of the region.
Returns: a pointer to the allocated region (in the processor's virtual
It returns a pointer to the allocated region (in the processor's virtual
address space) or NULL if the allocation failed.
It also returns a <dma_handle> which may be cast to an unsigned integer the
same width as the bus and given to the device as the bus address base of
the region.
Note: consistent memory can be expensive on some platforms, and the
minimum allocation length may be as big as a page, so you should
consolidate your requests for consistent memory as much as possible.
The simplest way to do that is to use the dma_pool calls (see below).
The flag parameter (dma_alloc_coherent only) allows the caller to
specify the GFP_ flags (see kmalloc) for the allocation (the
The flag parameter (dma_alloc_coherent() only) allows the caller to
specify the GFP_ flags (see kmalloc()) for the allocation (the
implementation may choose to ignore flags that affect the location of
the returned memory, like GFP_DMA).
......@@ -61,24 +66,24 @@ void
dma_free_coherent(struct device *dev, size_t size, void *cpu_addr,
dma_addr_t dma_handle)
Free the region of consistent memory you previously allocated. dev,
size and dma_handle must all be the same as those passed into the
consistent allocate. cpu_addr must be the virtual address returned by
the consistent allocate.
Free a region of consistent memory you previously allocated. dev,
size and dma_handle must all be the same as those passed into
dma_alloc_coherent(). cpu_addr must be the virtual address returned by
the dma_alloc_coherent().
Note that unlike their sibling allocation calls, these routines
may only be called with IRQs enabled.
Part Ib - Using small dma-coherent buffers
Part Ib - Using small DMA-coherent buffers
------------------------------------------
To get this part of the dma_ API, you must #include <linux/dmapool.h>
Many drivers need lots of small dma-coherent memory regions for DMA
Many drivers need lots of small DMA-coherent memory regions for DMA
descriptors or I/O buffers. Rather than allocating in units of a page
or more using dma_alloc_coherent(), you can use DMA pools. These work
much like a struct kmem_cache, except that they use the dma-coherent allocator,
much like a struct kmem_cache, except that they use the DMA-coherent allocator,
not __get_free_pages(). Also, they understand common hardware constraints
for alignment, like queue heads needing to be aligned on N-byte boundaries.
......@@ -87,7 +92,7 @@ for alignment, like queue heads needing to be aligned on N-byte boundaries.
dma_pool_create(const char *name, struct device *dev,
size_t size, size_t align, size_t alloc);
The pool create() routines initialize a pool of dma-coherent buffers
dma_pool_create() initializes a pool of DMA-coherent buffers
for use with a given device. It must be called in a context which
can sleep.
......@@ -102,25 +107,26 @@ from this pool must not cross 4KByte boundaries.
void *dma_pool_alloc(struct dma_pool *pool, gfp_t gfp_flags,
dma_addr_t *dma_handle);
This allocates memory from the pool; the returned memory will meet the size
and alignment requirements specified at creation time. Pass GFP_ATOMIC to
prevent blocking, or if it's permitted (not in_interrupt, not holding SMP locks),
pass GFP_KERNEL to allow blocking. Like dma_alloc_coherent(), this returns
two values: an address usable by the cpu, and the dma address usable by the
pool's device.
This allocates memory from the pool; the returned memory will meet the
size and alignment requirements specified at creation time. Pass
GFP_ATOMIC to prevent blocking, or if it's permitted (not
in_interrupt, not holding SMP locks), pass GFP_KERNEL to allow
blocking. Like dma_alloc_coherent(), this returns two values: an
address usable by the CPU, and the DMA address usable by the pool's
device.
void dma_pool_free(struct dma_pool *pool, void *vaddr,
dma_addr_t addr);
This puts memory back into the pool. The pool is what was passed to
the pool allocation routine; the cpu (vaddr) and dma addresses are what
dma_pool_alloc(); the CPU (vaddr) and DMA addresses are what
were returned when that routine allocated the memory being freed.
void dma_pool_destroy(struct dma_pool *pool);
The pool destroy() routines free the resources of the pool. They must be
dma_pool_destroy() frees the resources of the pool. It must be
called in a context which can sleep. Make sure you've freed all allocated
memory back to the pool before you destroy it.
......@@ -187,9 +193,9 @@ dma_map_single(struct device *dev, void *cpu_addr, size_t size,
enum dma_data_direction direction)
Maps a piece of processor virtual memory so it can be accessed by the
device and returns the physical handle of the memory.
device and returns the bus address of the memory.
The direction for both api's may be converted freely by casting.
The direction for both APIs may be converted freely by casting.
However the dma_ API uses a strongly typed enumerator for its
direction:
......@@ -198,31 +204,30 @@ DMA_TO_DEVICE data is going from the memory to the device
DMA_FROM_DEVICE data is coming from the device to the memory
DMA_BIDIRECTIONAL direction isn't known
Notes: Not all memory regions in a machine can be mapped by this
API. Further, regions that appear to be physically contiguous in
kernel virtual space may not be contiguous as physical memory. Since
this API does not provide any scatter/gather capability, it will fail
if the user tries to map a non-physically contiguous piece of memory.
For this reason, it is recommended that memory mapped by this API be
obtained only from sources which guarantee it to be physically contiguous
(like kmalloc).
Further, the physical address of the memory must be within the
dma_mask of the device (the dma_mask represents a bit mask of the
addressable region for the device. I.e., if the physical address of
the memory anded with the dma_mask is still equal to the physical
address, then the device can perform DMA to the memory). In order to
Notes: Not all memory regions in a machine can be mapped by this API.
Further, contiguous kernel virtual space may not be contiguous as
physical memory. Since this API does not provide any scatter/gather
capability, it will fail if the user tries to map a non-physically
contiguous piece of memory. For this reason, memory to be mapped by
this API should be obtained from sources which guarantee it to be
physically contiguous (like kmalloc).
Further, the bus address of the memory must be within the
dma_mask of the device (the dma_mask is a bit mask of the
addressable region for the device, i.e., if the bus address of
the memory ANDed with the dma_mask is still equal to the bus
address, then the device can perform DMA to the memory). To
ensure that the memory allocated by kmalloc is within the dma_mask,
the driver may specify various platform-dependent flags to restrict
the physical memory range of the allocation (e.g. on x86, GFP_DMA
guarantees to be within the first 16Mb of available physical memory,
the bus address range of the allocation (e.g., on x86, GFP_DMA
guarantees to be within the first 16MB of available bus addresses,
as required by ISA devices).
Note also that the above constraints on physical contiguity and
dma_mask may not apply if the platform has an IOMMU (a device which
supplies a physical to virtual mapping between the I/O memory bus and
the device). However, to be portable, device driver writers may *not*
assume that such an IOMMU exists.
maps an I/O bus address to a physical memory address). However, to be
portable, device driver writers may *not* assume that such an IOMMU
exists.
Warnings: Memory coherency operates at a granularity called the cache
line width. In order for memory mapped by this API to operate
......@@ -281,9 +286,9 @@ cache width is.
int
dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
In some circumstances dma_map_single and dma_map_page will fail to create
In some circumstances dma_map_single() and dma_map_page() will fail to create
a mapping. A driver can check for these errors by testing the returned
dma address with dma_mapping_error(). A non-zero return value means the mapping
DMA address with dma_mapping_error(). A non-zero return value means the mapping
could not be created and the driver should take appropriate action (e.g.
reduce current DMA mapping usage or delay and try again later).
......@@ -291,7 +296,7 @@ reduce current DMA mapping usage or delay and try again later).
dma_map_sg(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction direction)
Returns: the number of physical segments mapped (this may be shorter
Returns: the number of bus address segments mapped (this may be shorter
than <nents> passed in if some elements of the scatter/gather list are
physically or virtually adjacent and an IOMMU maps them with a single
entry).
......@@ -299,7 +304,7 @@ entry).
Please note that the sg cannot be mapped again if it has been mapped once.
The mapping process is allowed to destroy information in the sg.
As with the other mapping interfaces, dma_map_sg can fail. When it
As with the other mapping interfaces, dma_map_sg() can fail. When it
does, 0 is returned and a driver must take appropriate action. It is
critical that the driver do something, in the case of a block driver
aborting the request or even oopsing is better than doing nothing and
......@@ -335,7 +340,7 @@ must be the same as those and passed in to the scatter/gather mapping
API.
Note: <nents> must be the number you passed in, *not* the number of
physical entries returned.
bus address entries returned.
void
dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
......@@ -350,7 +355,7 @@ void
dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nelems,
enum dma_data_direction direction)
Synchronise a single contiguous or scatter/gather mapping for the cpu
Synchronise a single contiguous or scatter/gather mapping for the CPU
and device. With the sync_sg API, all the parameters must be the same
as those passed into the single mapping API. With the sync_single API,
you can use dma_handle and size parameters that aren't identical to
......@@ -391,10 +396,10 @@ The four functions above are just like the counterpart functions
without the _attrs suffixes, except that they pass an optional
struct dma_attrs*.