diff options
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/basics.rst | 21 | ||||
| -rw-r--r-- | Documentation/driver-api/dmaengine/provider.rst | 38 | ||||
| -rw-r--r-- | Documentation/driver-api/firmware/built-in-fw.rst | 7 | ||||
| -rw-r--r-- | Documentation/driver-api/firmware/fallback-mechanisms.rst | 2 | ||||
| -rw-r--r-- | Documentation/driver-api/iio/hw-consumer.rst | 51 | ||||
| -rw-r--r-- | Documentation/driver-api/iio/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/driver-api/index.rst | 2 | ||||
| -rw-r--r-- | Documentation/driver-api/pm/devices.rst | 54 | ||||
| -rw-r--r-- | Documentation/driver-api/s390-drivers.rst | 32 | ||||
| -rw-r--r-- | Documentation/driver-api/scsi.rst | 10 | ||||
| -rw-r--r-- | Documentation/driver-api/slimbus.rst | 127 | ||||
| -rw-r--r-- | Documentation/driver-api/soundwire/index.rst | 15 | ||||
| -rw-r--r-- | Documentation/driver-api/soundwire/summary.rst | 207 | ||||
| -rw-r--r-- | Documentation/driver-api/uio-howto.rst | 26 | ||||
| -rw-r--r-- | Documentation/driver-api/usb/usb3-debug-port.rst | 52 | ||||
| -rw-r--r-- | Documentation/driver-api/usb/writing_usb_driver.rst | 2 |
16 files changed, 590 insertions, 57 deletions
diff --git a/Documentation/driver-api/basics.rst b/Documentation/driver-api/basics.rst index 73fa7d42bbba..826e85d50a16 100644 --- a/Documentation/driver-api/basics.rst +++ b/Documentation/driver-api/basics.rst @@ -13,12 +13,6 @@ Driver device table .. kernel-doc:: include/linux/mod_devicetable.h :internal: -Atomic and pointer manipulation -------------------------------- - -.. kernel-doc:: arch/x86/include/asm/atomic.h - :internal: - Delaying, scheduling, and timer routines ---------------------------------------- @@ -85,6 +79,21 @@ Internal Functions .. kernel-doc:: kernel/kthread.c :export: +Reference counting +------------------ + +.. kernel-doc:: include/linux/refcount.h + :internal: + +.. kernel-doc:: lib/refcount.c + :export: + +Atomics +------- + +.. kernel-doc:: arch/x86/include/asm/atomic.h + :internal: + Kernel objects manipulation --------------------------- diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst index 814acb4d2294..dfc4486b5743 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -111,40 +111,36 @@ The first thing you need to do in your driver is to allocate this structure. Any of the usual memory allocators will do, but you'll also need to initialize a few fields in there: -- channels: should be initialized as a list using the +- ``channels``: should be initialized as a list using the INIT_LIST_HEAD macro for example -- src_addr_widths: +- ``src_addr_widths``: should contain a bitmask of the supported source transfer width -- dst_addr_widths: +- ``dst_addr_widths``: should contain a bitmask of the supported destination transfer width -- directions: +- ``directions``: should contain a bitmask of the supported slave directions (i.e. excluding mem2mem transfers) -- residue_granularity: +- ``residue_granularity``: + granularity of the transfer residue reported to dma_set_residue. + This can be either: - - Granularity of the transfer residue reported to dma_set_residue. - This can be either: + - Descriptor: + your device doesn't support any kind of residue + reporting. The framework will only know that a particular + transaction descriptor is done. - - Descriptor + - Segment: + your device is able to report which chunks have been transferred - - Your device doesn't support any kind of residue - reporting. The framework will only know that a particular - transaction descriptor is done. + - Burst: + your device is able to report which burst have been transferred - - Segment - - - Your device is able to report which chunks have been transferred - - - Burst - - - Your device is able to report which burst have been transferred - - - dev: should hold the pointer to the ``struct device`` associated - to your current driver instance. +- ``dev``: should hold the pointer to the ``struct device`` associated + to your current driver instance. Supported transaction types --------------------------- diff --git a/Documentation/driver-api/firmware/built-in-fw.rst b/Documentation/driver-api/firmware/built-in-fw.rst index 7300e66857f8..396cdf591ac5 100644 --- a/Documentation/driver-api/firmware/built-in-fw.rst +++ b/Documentation/driver-api/firmware/built-in-fw.rst @@ -11,13 +11,8 @@ options: * CONFIG_EXTRA_FIRMWARE * CONFIG_EXTRA_FIRMWARE_DIR -This should not be confused with CONFIG_FIRMWARE_IN_KERNEL, this is for drivers -which enables firmware to be built as part of the kernel build process. This -option, CONFIG_FIRMWARE_IN_KERNEL, will build all firmware for all drivers -enabled which ship its firmware inside the Linux kernel source tree. - There are a few reasons why you might want to consider building your firmware -into the kernel with CONFIG_EXTRA_FIRMWARE though: +into the kernel with CONFIG_EXTRA_FIRMWARE: * Speed * Firmware is needed for accessing the boot device, and the user doesn't diff --git a/Documentation/driver-api/firmware/fallback-mechanisms.rst b/Documentation/driver-api/firmware/fallback-mechanisms.rst index d19354794e67..4055ac76b288 100644 --- a/Documentation/driver-api/firmware/fallback-mechanisms.rst +++ b/Documentation/driver-api/firmware/fallback-mechanisms.rst @@ -71,7 +71,7 @@ via fw_create_instance(). This call creates a new struct device named after the firmware requested, and establishes it in the device hierarchy by associating the device used to make the request as the device's parent. The sysfs directory's file attributes are defined and controlled through -the new device's class (firmare_class) and group (fw_dev_attr_groups). +the new device's class (firmware_class) and group (fw_dev_attr_groups). This is actually where the original firmware_class.c file name comes from, as originally the only firmware loading mechanism available was the mechanism we now use as a fallback mechanism. diff --git a/Documentation/driver-api/iio/hw-consumer.rst b/Documentation/driver-api/iio/hw-consumer.rst new file mode 100644 index 000000000000..8facce6a6733 --- /dev/null +++ b/Documentation/driver-api/iio/hw-consumer.rst @@ -0,0 +1,51 @@ +=========== +HW consumer +=========== +An IIO device can be directly connected to another device in hardware. in this +case the buffers between IIO provider and IIO consumer are handled by hardware. +The Industrial I/O HW consumer offers a way to bond these IIO devices without +software buffer for data. The implementation can be found under +:file:`drivers/iio/buffer/hw-consumer.c` + + +* struct :c:type:`iio_hw_consumer` — Hardware consumer structure +* :c:func:`iio_hw_consumer_alloc` — Allocate IIO hardware consumer +* :c:func:`iio_hw_consumer_free` — Free IIO hardware consumer +* :c:func:`iio_hw_consumer_enable` — Enable IIO hardware consumer +* :c:func:`iio_hw_consumer_disable` — Disable IIO hardware consumer + + +HW consumer setup +================= + +As standard IIO device the implementation is based on IIO provider/consumer. +A typical IIO HW consumer setup looks like this:: + + static struct iio_hw_consumer *hwc; + + static const struct iio_info adc_info = { + .read_raw = adc_read_raw, + }; + + static int adc_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int *val, + int *val2, long mask) + { + ret = iio_hw_consumer_enable(hwc); + + /* Acquire data */ + + ret = iio_hw_consumer_disable(hwc); + } + + static int adc_probe(struct platform_device *pdev) + { + hwc = devm_iio_hw_consumer_alloc(&iio->dev); + } + +More details +============ +.. kernel-doc:: include/linux/iio/hw-consumer.h +.. kernel-doc:: drivers/iio/buffer/industrialio-hw-consumer.c + :export: + diff --git a/Documentation/driver-api/iio/index.rst b/Documentation/driver-api/iio/index.rst index e5c3922d1b6f..7fba341bd8b2 100644 --- a/Documentation/driver-api/iio/index.rst +++ b/Documentation/driver-api/iio/index.rst @@ -15,3 +15,4 @@ Contents: buffers triggers triggered-buffers + hw-consumer diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index d17a9876b473..e9b41b1634f3 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -47,6 +47,8 @@ available subsections can be seen below. gpio misc_devices dmaengine/index + slimbus + soundwire/index .. only:: subproject and html diff --git a/Documentation/driver-api/pm/devices.rst b/Documentation/driver-api/pm/devices.rst index 53c1b0b06da5..1128705a5731 100644 --- a/Documentation/driver-api/pm/devices.rst +++ b/Documentation/driver-api/pm/devices.rst @@ -777,17 +777,51 @@ The driver can indicate that by setting ``DPM_FLAG_SMART_SUSPEND`` in runtime suspend at the beginning of the ``suspend_late`` phase of system-wide suspend (or in the ``poweroff_late`` phase of hibernation), when runtime PM has been disabled for it, under the assumption that its state should not change -after that point until the system-wide transition is over. If that happens, the -driver's system-wide resume callbacks, if present, may still be invoked during -the subsequent system-wide resume transition and the device's runtime power -management status may be set to "active" before enabling runtime PM for it, -so the driver must be prepared to cope with the invocation of its system-wide -resume callbacks back-to-back with its ``->runtime_suspend`` one (without the -intervening ``->runtime_resume`` and so on) and the final state of the device -must reflect the "active" status for runtime PM in that case. +after that point until the system-wide transition is over (the PM core itself +does that for devices whose "noirq", "late" and "early" system-wide PM callbacks +are executed directly by it). If that happens, the driver's system-wide resume +callbacks, if present, may still be invoked during the subsequent system-wide +resume transition and the device's runtime power management status may be set +to "active" before enabling runtime PM for it, so the driver must be prepared to +cope with the invocation of its system-wide resume callbacks back-to-back with +its ``->runtime_suspend`` one (without the intervening ``->runtime_resume`` and +so on) and the final state of the device must reflect the "active" runtime PM +status in that case. During system-wide resume from a sleep state it's easiest to put devices into the full-power state, as explained in :file:`Documentation/power/runtime_pm.txt`. -Refer to that document for more information regarding this particular issue as +[Refer to that document for more information regarding this particular issue as well as for information on the device runtime power management framework in -general. +general.] + +However, it often is desirable to leave devices in suspend after system +transitions to the working state, especially if those devices had been in +runtime suspend before the preceding system-wide suspend (or analogous) +transition. Device drivers can use the ``DPM_FLAG_LEAVE_SUSPENDED`` flag to +indicate to the PM core (and middle-layer code) that they prefer the specific +devices handled by them to be left suspended and they have no problems with +skipping their system-wide resume callbacks for this reason. Whether or not the +devices will actually be left in suspend may depend on their state before the +given system suspend-resume cycle and on the type of the system transition under +way. In particular, devices are not left suspended if that transition is a +restore from hibernation, as device states are not guaranteed to be reflected +by the information stored in the hibernation image in that case. + +The middle-layer code involved in the handling of the device is expected to +indicate to the PM core if the device may be left in suspend by setting its +:c:member:`power.may_skip_resume` status bit which is checked by the PM core +during the "noirq" phase of the preceding system-wide suspend (or analogous) +transition. The middle layer is then responsible for handling the device as +appropriate in its "noirq" resume callback, which is executed regardless of +whether or not the device is left suspended, but the other resume callbacks +(except for ``->complete``) will be skipped automatically by the PM core if the +device really can be left in suspend. + +For devices whose "noirq", "late" and "early" driver callbacks are invoked +directly by the PM core, all of the system-wide resume callbacks are skipped if +``DPM_FLAG_LEAVE_SUSPENDED`` is set and the device is in runtime suspend during +the ``suspend_noirq`` (or analogous) phase or the transition under way is a +proper system suspend (rather than anything related to hibernation) and the +device's wakeup settings are suitable for runtime PM (that is, it cannot +generate wakeup signals at all or it is allowed to wake up the system from +sleep). diff --git a/Documentation/driver-api/s390-drivers.rst b/Documentation/driver-api/s390-drivers.rst index ecf8851d3565..30e6aa7e160b 100644 --- a/Documentation/driver-api/s390-drivers.rst +++ b/Documentation/driver-api/s390-drivers.rst @@ -22,9 +22,28 @@ While most I/O devices on a s390 system are typically driven through the channel I/O mechanism described here, there are various other methods (like the diag interface). These are out of the scope of this document. +The s390 common I/O layer also provides access to some devices that are +not strictly considered I/O devices. They are considered here as well, +although they are not the focus of this document. + Some additional information can also be found in the kernel source under Documentation/s390/driver-model.txt. +The css bus +=========== + +The css bus contains the subchannels available on the system. They fall +into several categories: + +* Standard I/O subchannels, for use by the system. They have a child + device on the ccw bus and are described below. +* I/O subchannels bound to the vfio-ccw driver. See + Documentation/s390/vfio-ccw.txt. +* Message subchannels. No Linux driver currently exists. +* CHSC subchannels (at most one). The chsc subchannel driver can be used + to send asynchronous chsc commands. +* eADM subchannels. Used for talking to storage class memory. + The ccw bus =========== @@ -102,10 +121,15 @@ ccw group devices Generic interfaces ================== -Some interfaces are available to other drivers that do not necessarily -have anything to do with the busses described above, but still are -indirectly using basic infrastructure in the common I/O layer. One -example is the support for adapter interrupts. +The following section contains interfaces in use not only by drivers +dealing with ccw devices, but drivers for various other s390 hardware +as well. + +Adapter interrupts +------------------ + +The common I/O layer provides helper functions for dealing with adapter +interrupts and interrupt vectors. .. kernel-doc:: drivers/s390/cio/airq.c :export: diff --git a/Documentation/driver-api/scsi.rst b/Documentation/driver-api/scsi.rst index 9ae03171daca..3ae337929721 100644 --- a/Documentation/driver-api/scsi.rst +++ b/Documentation/driver-api/scsi.rst @@ -224,6 +224,14 @@ mid to lowlevel SCSI driver interface .. kernel-doc:: drivers/scsi/hosts.c :export: +drivers/scsi/scsi_common.c +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +general support functions + +.. kernel-doc:: drivers/scsi/scsi_common.c + :export: + Transport classes ----------------- @@ -332,5 +340,5 @@ todo ~~~~ Parallel (fast/wide/ultra) SCSI, USB, SATA, SAS, Fibre Channel, -FireWire, ATAPI devices, Infiniband, I20, iSCSI, Parallel ports, +FireWire, ATAPI devices, Infiniband, I2O, iSCSI, Parallel ports, netlink... diff --git a/Documentation/driver-api/slimbus.rst b/Documentation/driver-api/slimbus.rst new file mode 100644 index 000000000000..7555ecd538de --- /dev/null +++ b/Documentation/driver-api/slimbus.rst @@ -0,0 +1,127 @@ +============================ +Linux kernel SLIMbus support +============================ + +Overview +======== + +What is SLIMbus? +---------------- +SLIMbus (Serial Low Power Interchip Media Bus) is a specification developed by +MIPI (Mobile Industry Processor Interface) alliance. The bus uses master/slave +configuration, and is a 2-wire multi-drop implementation (clock, and data). + +Currently, SLIMbus is used to interface between application processors of SoCs +(System-on-Chip) and peripheral components (typically codec). SLIMbus uses +Time-Division-Multiplexing to accommodate multiple data channels, and +a control channel. + +The control channel is used for various control functions such as bus +management, configuration and status updates. These messages can be unicast (e.g. +reading/writing device specific values), or multicast (e.g. data channel +reconfiguration sequence is a broadcast message announced to all devices) + +A data channel is used for data-transfer between 2 SLIMbus devices. Data +channel uses dedicated ports on the device. + +Hardware description: +--------------------- +SLIMbus specification has different types of device classifications based on +their capabilities. +A manager device is responsible for enumeration, configuration, and dynamic +channel allocation. Every bus has 1 active manager. + +A generic device is a device providing application functionality (e.g. codec). + +Framer device is responsible for clocking the bus, and transmitting frame-sync +and framing information on the bus. + +Each SLIMbus component has an interface device for monitoring physical layer. + +Typically each SoC contains SLIMbus component having 1 manager, 1 framer device, +1 generic device (for data channel support), and 1 interface device. +External peripheral SLIMbus component usually has 1 generic device (for +functionality/data channel support), and an associated interface device. +The generic device's registers are mapped as 'value elements' so that they can +be written/read using SLIMbus control channel exchanging control/status type of +information. +In case there are multiple framer devices on the same bus, manager device is +responsible to select the active-framer for clocking the bus. + +Per specification, SLIMbus uses "clock gears" to do power management based on +current frequency and bandwidth requirements. There are 10 clock gears and each +gear changes the SLIMbus frequency to be twice its previous gear. + +Each device has a 6-byte enumeration-address and the manager assigns every +device with a 1-byte logical address after the devices report presence on the +bus. + +Software description: +--------------------- +There are 2 types of SLIMbus drivers: + +slim_controller represents a 'controller' for SLIMbus. This driver should +implement duties needed by the SoC (manager device, associated +interface device for monitoring the layers and reporting errors, default +framer device). + +slim_device represents the 'generic device/component' for SLIMbus, and a +slim_driver should implement driver for that slim_device. + +Device notifications to the driver: +----------------------------------- +Since SLIMbus devices have mechanisms for reporting their presence, the +framework allows drivers to bind when corresponding devices report their +presence on the bus. +However, it is possible that the driver needs to be probed +first so that it can enable corresponding SLIMbus device (e.g. power it up and/or +take it out of reset). To support that behavior, the framework allows drivers +to probe first as well (e.g. using standard DeviceTree compatibility field). +This creates the necessity for the driver to know when the device is functional +(i.e. reported present). device_up callback is used for that reason when the +device reports present and is assigned a logical address by the controller. + +Similarly, SLIMbus devices 'report absent' when they go down. A 'device_down' +callback notifies the driver when the device reports absent and its logical +address assignment is invalidated by the controller. + +Another notification "boot_device" is used to notify the slim_driver when +controller resets the bus. This notification allows the driver to take necessary +steps to boot the device so that it's functional after the bus has been reset. + +Driver and Controller APIs: +-------------------------- +.. kernel-doc:: include/linux/slimbus.h + :internal: + +.. kernel-doc:: drivers/slimbus/slimbus.h + :internal: + +.. kernel-doc:: drivers/slimbus/core.c + :export: + +Clock-pause: +------------ +SLIMbus mandates that a reconfiguration sequence (known as clock-pause) be +broadcast to all active devices on the bus before the bus can enter low-power +mode. Controller uses this sequence when it decides to enter low-power mode so +that corresponding clocks and/or power-rails can be turned off to save power. +Clock-pause is exited by waking up framer device (if controller driver initiates +exiting low power mode), or by toggling the data line (if a slave device wants +to initiate it). + +Clock-pause APIs: +~~~~~~~~~~~~~~~~~ +.. kernel-doc:: drivers/slimbus/sched.c + :export: + +Messaging: +---------- +The framework supports regmap and read/write apis to exchange control-information +with a SLIMbus device. APIs can be synchronous or asynchronous. +The header file <linux/slimbus.h> has more documentation about messaging APIs. + +Messaging APIs: +~~~~~~~~~~~~~~~ +.. kernel-doc:: drivers/slimbus/messaging.c + :export: diff --git a/Documentation/driver-api/soundwire/index.rst b/Documentation/driver-api/soundwire/index.rst new file mode 100644 index 000000000000..647e94654752 --- /dev/null +++ b/Documentation/driver-api/soundwire/index.rst @@ -0,0 +1,15 @@ +======================= +SoundWire Documentation +======================= + +.. toctree:: + :maxdepth: 1 + + summary + +.. only:: subproject + + Indices + ======= + + * :ref:`genindex` diff --git a/Documentation/driver-api/soundwire/summary.rst b/Documentation/driver-api/soundwire/summary.rst new file mode 100644 index 000000000000..8193125a2bfb --- /dev/null +++ b/Documentation/driver-api/soundwire/summary.rst @@ -0,0 +1,207 @@ +=========================== +SoundWire Subsystem Summary +=========================== + +SoundWire is a new interface ratified in 2015 by the MIPI Alliance. +SoundWire is used for transporting data typically related to audio +functions. SoundWire interface is optimized to integrate audio devices in +mobile or mobile inspired systems. + +SoundWire is a 2-pin multi-drop interface with data and clock line. It +facilitates development of low cost, efficient, high performance systems. +Broad level key features of SoundWire interface include: + + (1) Transporting all of payload data channels, control information, and setup + commands over a single two-pin interface. + + (2) Lower clock frequency, and hence lower power consumption, by use of DDR + (Dual Data Rate) data transmission. + + (3) Clock scaling and optional multiple data lanes to give wide flexibility + in data rate to match system requirements. + + (4) Device status monitoring, including interrupt-style alerts to the Master. + +The SoundWire protocol supports up to eleven Slave interfaces. All the +interfaces share the common Bus containing data and clock line. Each of the +Slaves can support up to 14 Data Ports. 13 Data Ports are dedicated to audio +transport. Data Port0 is dedicated to transport of Bulk control information, +each of the audio Data Ports (1..14) can support up to 8 Channels in +transmit or receiving mode (typically fixed direction but configurable +direction is enabled by the specification). Bandwidth restrictions to +~19.2..24.576Mbits/s don't however allow for 11*13*8 channels to be +transmitted simultaneously. + +Below figure shows an example of connectivity between a SoundWire Master and +two Slave devices. :: + + +---------------+ +---------------+ + | | Clock Signal | | + | Master |-------+-------------------------------| Slave | + | Interface | | Data Signal | Interface 1 | + | |-------|-------+-----------------------| | + +---------------+ | | +---------------+ + | | + | | + | | + +--+-------+--+ + | | + | Slave | + | Interface 2 | + | | + +-------------+ + + +Terminology +=========== + +The MIPI SoundWire specification uses the term 'device' to refer to a Master +or Slave interface, which of course can be confusing. In this summary and +code we use the term interface only to refer to the hardware. We follow the +Linux device model by mapping each Slave interface connected on the bus as a +device managed by a specific driver. The Linux SoundWire subsystem provides +a framework to implement a SoundWire Slave driver with an API allowing +3rd-party vendors to enable implementation-defined functionality while +common setup/configuration tasks are handled by the bus. + +Bus: +Implements SoundWire Linux Bus which handles the SoundWire protocol. +Programs all the MIPI-defined Slave registers. Represents a SoundWire +Master. Multiple instances of Bus may be present in a system. + +Slave: +Registers as SoundWire Slave device (Linux Device). Multiple Slave devices +can register to a Bus instance. + +Slave driver: +Driver controlling the Slave device. MIPI-specified registers are controlled +directly by the Bus (and transmitted through the Master driver/interface). +Any implementation-defined Slave register is controlled by Slave driver. In +practice, it is expected that the Slave driver relies on regmap and does not +request direct register access. + +Programming interfaces (SoundWire Master interface Driver) +========================================================== + +SoundWire Bus supports programming interfaces for the SoundWire Master +implementation and SoundWire Slave devices. All the code uses the "sdw" +prefix commonly used by SoC designers and 3rd party vendors. + +Each of the SoundWire Master interfaces needs to be registered to the Bus. +Bus implements API to read standard Master MIPI properties and also provides +callback in Master ops for Master driver to implement its own functions that +provides capabilities information. DT support is not implemented at this +time but should be trivial to add since capabilities are enabled with the +``device_property_`` API. + +The Master interface along with the Master interface capabilities are +registered based on board file, DT or ACPI. + +Following is the Bus API to register the SoundWire Bus: + +.. code-block:: c + + int sdw_add_bus_master(struct sdw_bus *bus) + { + if (!bus->dev) + return -ENODEV; + + mutex_init(&bus->lock); + INIT_LIST_HEAD(&bus->slaves); + + /* Check ACPI for Slave devices */ + sdw_acpi_find_slaves(bus); + + /* Check DT for Slave devices */ + sdw_of_find_slaves(bus); + + return 0; + } + +This will initialize sdw_bus object for Master device. "sdw_master_ops" and +"sdw_master_port_ops" callback functions are provided to the Bus. + +"sdw_master_ops" is used by Bus to control the Bus in the hardware specific +way. It includes Bus control functions such as sending the SoundWire +read/write messages on Bus, setting up clock frequency & Stream +Synchronization Point (SSP). The "sdw_master_ops" structure abstracts the +hardware details of the Master from the Bus. + +"sdw_master_port_ops" is used by Bus to setup the Port parameters of the +Master interface Port. Master interface Port register map is not defined by +MIPI specification, so Bus calls the "sdw_master_port_ops" callback +function to do Port operations like "Port Prepare", "Port Transport params +set", "Port enable and disable". The implementation of the Master driver can +then perform hardware-specific configurations. + +Programming interfaces (SoundWire Slave Driver) +=============================================== + +The MIPI specification requires each Slave interface to expose a unique +48-bit identifier, stored in 6 read-only dev_id registers. This dev_id +identifier contains vendor and part information, as well as a field enabling +to differentiate between identical components. An additional class field is +currently unused. Slave driver is written for a specific vendor and part +identifier, Bus enumerates the Slave device based on these two ids. +Slave device and driver match is done based on these two ids . Probe +of the Slave driver is called by Bus on successful match between device and +driver id. A parent/child relationship is enforced between Master and Slave +devices (the logical representation is aligned with the physical +connectivity). + +The information on Master/Slave dependencies is stored in platform data, +board-file, ACPI or DT. The MIPI Software specification defines additional +link_id parameters for controllers that have multiple Master interfaces. The +dev_id registers are only unique in the scope of a link, and the link_id +unique in the scope of a controller. Both dev_id and link_id are not +necessarily unique at the system level but the parent/child information is +used to avoid ambiguity. + +.. code-block:: c + + static const struct sdw_device_id slave_id[] = { + SDW_SLAVE_ENTRY(0x025d, 0x700, 0), + {}, + }; + MODULE_DEVICE_TABLE(sdw, slave_id); + + static struct sdw_driver slave_sdw_driver = { + .driver = { + .name = "slave_xxx", + .pm = &slave_runtime_pm, + }, + .probe = slave_sdw_probe, + .remove = slave_sdw_remove, + .ops = &slave_slave_ops, + .id_table = slave_id, + }; + + +For capabilities, Bus implements API to read standard Slave MIPI properties +and also provides callback in Slave ops for Slave driver to implement own +function that provides capabilities information. Bus needs to know a set of +Slave capabilities to program Slave registers and to control the Bus +reconfigurations. + +Future enhancements to be done +============================== + + (1) Bulk Register Access (BRA) transfers. + + + (2) Multiple data lane support. + +Links +===== + +SoundWire MIPI specification 1.1 is available at: +https://members.mipi.org/wg/All-Members/document/70290 + +SoundWire MIPI DisCo (Discovery and Configuration) specification is +available at: +https://www.mipi.org/specifications/mipi-disco-soundwire + +(publicly accessible with registration or directly accessible to MIPI +members) + +MIPI Alliance Manufacturer ID Page: mid.mipi.org diff --git a/Documentation/driver-api/uio-howto.rst b/Documentation/driver-api/uio-howto.rst index f73d660b2956..693e3bd84e79 100644 --- a/Documentation/driver-api/uio-howto.rst +++ b/Documentation/driver-api/uio-howto.rst @@ -667,27 +667,28 @@ Making the driver recognize the device Since the driver does not declare any device GUID's, it will not get loaded automatically and will not automatically bind to any devices, you must load it and allocate id to the driver yourself. For example, to use -the network device GUID:: +the network device class GUID:: modprobe uio_hv_generic echo "f8615163-df3e-46c5-913f-f2d2f965ed0e" > /sys/bus/vmbus/drivers/uio_hv_generic/new_id If there already is a hardware specific kernel driver for the device, the generic driver still won't bind to it, in this case if you want to -use the generic driver (why would you?) you'll have to manually unbind -the hardware specific driver and bind the generic driver, like this:: +use the generic driver for a userspace library you'll have to manually unbind +the hardware specific driver and bind the generic driver, using the device specific GUID +like this:: - echo -n vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3 > /sys/bus/vmbus/drivers/hv_netvsc/unbind - echo -n vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3 > /sys/bus/vmbus/drivers/uio_hv_generic/bind + echo -n ed963694-e847-4b2a-85af-bc9cfc11d6f3 > /sys/bus/vmbus/drivers/hv_netvsc/unbind + echo -n ed963694-e847-4b2a-85af-bc9cfc11d6f3 > /sys/bus/vmbus/drivers/uio_hv_generic/bind You can verify that the device has been bound to the driver by looking for it in sysfs, for example like the following:: - ls -l /sys/bus/vmbus/devices/vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver + ls -l /sys/bus/vmbus/devices/ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver Which if successful should print:: - .../vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver -> ../../../bus/vmbus/drivers/uio_hv_generic + .../ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver -> ../../../bus/vmbus/drivers/uio_hv_generic Things to know about uio_hv_generic ----------------------------------- @@ -697,6 +698,17 @@ prevents the device from generating further interrupts until the bit is cleared. The userspace driver should clear this bit before blocking and waiting for more interrupts. +When host rescinds a device, the interrupt file descriptor is marked down +and any reads of the interrupt file descriptor will return -EIO. Similar +to a closed socket or disconnected serial device. + +The vmbus device regions are mapped into uio device resources: + 0) Channel ring buffers: guest to host and host to guest + 1) Guest to host interrupt signalling pages + 2) Guest to host monitor page + 3) Network receive buffer region + 4) Network send buffer region + Further information =================== diff --git a/Documentation/driver-api/usb/usb3-debug-port.rst b/Documentation/driver-api/usb/usb3-debug-port.rst index feb1a36a65b7..b9fd131f4723 100644 --- a/Documentation/driver-api/usb/usb3-debug-port.rst +++ b/Documentation/driver-api/usb/usb3-debug-port.rst @@ -98,3 +98,55 @@ you to check the sanity of the setup. cat /dev/ttyUSB0 done ===== end of bash scripts =============== + +Serial TTY +========== + +The DbC support has been added to the xHCI driver. You can get a +debug device provided by the DbC at runtime. + +In order to use this, you need to make sure your kernel has been +configured to support USB_XHCI_DBGCAP. A sysfs attribute under +the xHCI device node is used to enable or disable DbC. By default, +DbC is disabled:: + + root@target:/sys/bus/pci/devices/0000:00:14.0# cat dbc + disabled + +Enable DbC with the following command:: + + root@target:/sys/bus/pci/devices/0000:00:14.0# echo enable > dbc + +You can check the DbC state at anytime:: + + root@target:/sys/bus/pci/devices/0000:00:14.0# cat dbc + enabled + +Connect the debug target to the debug host with a USB 3.0 super- +speed A-to-A debugging cable. You can see /dev/ttyDBC0 created +on the debug target. You will see below kernel message lines:: + + root@target: tail -f /var/log/kern.log + [ 182.730103] xhci_hcd 0000:00:14.0: DbC connected + [ 191.169420] xhci_hcd 0000:00:14.0: DbC configured + [ 191.169597] xhci_hcd 0000:00:14.0: DbC now attached to /dev/ttyDBC0 + +Accordingly, the DbC state has been brought up to:: + + root@target:/sys/bus/pci/devices/0000:00:14.0# cat dbc + configured + +On the debug host, you will see the debug device has been enumerated. +You will see below kernel message lines:: + + root@host: tail -f /var/log/kern.log + [ 79.454780] usb 2-2.1: new SuperSpeed USB device number 3 using xhci_hcd + [ 79.475003] usb 2-2.1: LPM exit latency is zeroed, disabling LPM. + [ 79.475389] usb 2-2.1: New USB device found, idVendor=1d6b, idProduct=0010 + [ 79.475390] usb 2-2.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 + [ 79.475391] usb 2-2.1: Product: Linux USB Debug Target + [ 79.475392] usb 2-2.1: Manufacturer: Linux Foundation + [ 79.475393] usb 2-2.1: SerialNumber: 0001 + +The debug device works now. You can use any communication or debugging +program to talk between the host and the target. diff --git a/Documentation/driver-api/usb/writing_usb_driver.rst b/Documentation/driver-api/usb/writing_usb_driver.rst index 69f077dcdb78..4fe1c06b6a13 100644 --- a/Documentation/driver-api/usb/writing_usb_driver.rst +++ b/Documentation/driver-api/usb/writing_usb_driver.rst @@ -321,6 +321,6 @@ linux-usb-devel Mailing List Archives: http://marc.theaimsgroup.com/?l=linux-usb-devel Programming Guide for Linux USB Device Drivers: -http://usb.cs.tum.edu/usbdoc +http://lmu.web.psi.ch/docu/manuals/software_manuals/linux_sl/usb_linux_programming_guide.pdf USB Home Page: http://www.usb.org |