diff options
Diffstat (limited to 'Documentation/driver-api')
21 files changed, 176 insertions, 517 deletions
diff --git a/Documentation/driver-api/aperture.rst b/Documentation/driver-api/aperture.rst new file mode 100644 index 000000000000..d173f4e7a7d9 --- /dev/null +++ b/Documentation/driver-api/aperture.rst @@ -0,0 +1,13 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Managing Ownership of the Framebuffer Aperture +============================================== + +.. kernel-doc:: drivers/video/aperture.c + :doc: overview + +.. kernel-doc:: include/linux/aperture.h + :internal: + +.. kernel-doc:: drivers/video/aperture.c + :export: diff --git a/Documentation/driver-api/dmaengine/provider.rst b/Documentation/driver-api/dmaengine/provider.rst index 1e0f1f85d10e..ceac2a300e32 100644 --- a/Documentation/driver-api/dmaengine/provider.rst +++ b/Documentation/driver-api/dmaengine/provider.rst @@ -162,16 +162,6 @@ Currently, the types available are: - The device is able to do memory to memory copies -- - DMA_MEMCPY_SG - - - The device supports memory to memory scatter-gather transfers. - - - Even though a plain memcpy can look like a particular case of a - scatter-gather transfer, with a single chunk to copy, it's a distinct - transaction type in the mem2mem transfer case. This is because some very - simple devices might be able to do contiguous single-chunk memory copies, - but have no support for more complex SG transfers. - - No matter what the overall size of the combined chunks for source and destination is, only as many bytes as the smallest of the two will be transmitted. That means the number and size of the scatter-gather buffers in diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst index 2d39967bafcc..55272942e721 100644 --- a/Documentation/driver-api/driver-model/devres.rst +++ b/Documentation/driver-api/driver-model/devres.rst @@ -277,7 +277,6 @@ GPIO devm_gpiochip_add_data() devm_gpio_request() devm_gpio_request_one() - devm_gpio_free() I2C devm_i2c_new_dummy_device() diff --git a/Documentation/driver-api/firmware/core.rst b/Documentation/driver-api/firmware/core.rst index 1d1688cbc078..803cd574bbd7 100644 --- a/Documentation/driver-api/firmware/core.rst +++ b/Documentation/driver-api/firmware/core.rst @@ -13,4 +13,5 @@ documents these features. direct-fs-lookup fallback-mechanisms lookup-order + firmware-usage-guidelines diff --git a/Documentation/driver-api/firmware/firmware-usage-guidelines.rst b/Documentation/driver-api/firmware/firmware-usage-guidelines.rst new file mode 100644 index 000000000000..fdcfce42c6d2 --- /dev/null +++ b/Documentation/driver-api/firmware/firmware-usage-guidelines.rst @@ -0,0 +1,44 @@ +=================== +Firmware Guidelines +=================== + +Users switching to a newer kernel should *not* have to install newer +firmware files to keep their hardware working. At the same time updated +firmware files must not cause any regressions for users of older kernel +releases. + +Drivers that use firmware from linux-firmware should follow the rules in +this guide. (Where there is limited control of the firmware, +i.e. company doesn't support Linux, firmwares sourced from misc places, +then of course these rules will not apply strictly.) + +* Firmware files shall be designed in a way that it allows checking for + firmware ABI version changes. It is recommended that firmware files be + versioned with at least a major/minor version. It is suggested that + the firmware files in linux-firmware be named with some device + specific name, and just the major version. The firmware version should + be stored in the firmware header, or as an exception, as part of the + firmware file name, in order to let the driver detact any non-ABI + fixes/changes. The firmware files in linux-firmware should be + overwritten with the newest compatible major version. Newer major + version firmware shall remain compatible with all kernels that load + that major number. + +* If the kernel support for the hardware is normally inactive, or the + hardware isn't available for public consumption, this can + be ignored, until the first kernel release that enables that hardware. + This means no major version bumps without the kernel retaining + backwards compatibility for the older major versions. Minor version + bumps should not introduce new features that newer kernels depend on + non-optionally. + +* If a security fix needs lockstep firmware and kernel fixes in order to + be successful, then all supported major versions in the linux-firmware + repo that are required by currently supported stable/LTS kernels, + should be updated with the security fix. The kernel patches should + detect if the firmware is new enough to declare if the security issue + is fixed. All communications around security fixes should point at + both the firmware and kernel fixes. If a security fix requires + deprecating old major versions, then this should only be done as a + last option, and be stated clearly in all communications. + diff --git a/Documentation/driver-api/firmware/other_interfaces.rst b/Documentation/driver-api/firmware/other_interfaces.rst index b81794e0cfbb..06ac89adaafb 100644 --- a/Documentation/driver-api/firmware/other_interfaces.rst +++ b/Documentation/driver-api/firmware/other_interfaces.rst @@ -13,6 +13,12 @@ EDD Interfaces .. kernel-doc:: drivers/firmware/edd.c :internal: +Generic System Framebuffers Interface +------------------------------------- + +.. kernel-doc:: drivers/firmware/sysfb.c + :export: + Intel Stratix10 SoC Service Layer --------------------------------- Some features of the Intel Stratix10 SoC require a level of privilege diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst index 42c01f396dce..49c0a9512653 100644 --- a/Documentation/driver-api/fpga/fpga-mgr.rst +++ b/Documentation/driver-api/fpga/fpga-mgr.rst @@ -79,12 +79,27 @@ do the programming sequence for this particular FPGA. These ops return 0 for success or negative error codes otherwise. The programming sequence is:: - 1. .write_init - 2. .write or .write_sg (may be called once or multiple times) - 3. .write_complete - -The .write_init function will prepare the FPGA to receive the image data. The -buffer passed into .write_init will be at most .initial_header_size bytes long; + 1. .parse_header (optional, may be called once or multiple times) + 2. .write_init + 3. .write or .write_sg (may be called once or multiple times) + 4. .write_complete + +The .parse_header function will set header_size and data_size to +struct fpga_image_info. Before parse_header call, header_size is initialized +with initial_header_size. If flag skip_header of fpga_manager_ops is true, +.write function will get image buffer starting at header_size offset from the +beginning. If data_size is set, .write function will get data_size bytes of +the image buffer, otherwise .write will get data up to the end of image buffer. +This will not affect .write_sg, .write_sg will still get whole image in +sg_table form. If FPGA image is already mapped as a single contiguous buffer, +whole buffer will be passed into .parse_header. If image is in scatter-gather +form, core code will buffer up at least .initial_header_size before the first +call of .parse_header, if it is not enough, .parse_header should set desired +size into info->header_size and return -EAGAIN, then it will be called again +with greater part of image buffer on the input. + +The .write_init function will prepare the FPGA to receive the image data. The +buffer passed into .write_init will be at least info->header_size bytes long; if the whole bitstream is not immediately available then the core code will buffer up at least this much before starting. diff --git a/Documentation/driver-api/gpio/board.rst b/Documentation/driver-api/gpio/board.rst index 4e3adf31c8d1..b33aa04f213f 100644 --- a/Documentation/driver-api/gpio/board.rst +++ b/Documentation/driver-api/gpio/board.rst @@ -6,7 +6,7 @@ This document explains how GPIOs can be assigned to given devices and functions. Note that it only applies to the new descriptor-based interface. For a description of the deprecated integer-based GPIO interface please refer to -gpio-legacy.txt (actually, there is no real mapping possible with the old +legacy.rst (actually, there is no real mapping possible with the old interface; you just fetch an integer from somewhere and request the corresponding GPIO). diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst index 47869ca8ccf0..de6fc79ad6f0 100644 --- a/Documentation/driver-api/gpio/consumer.rst +++ b/Documentation/driver-api/gpio/consumer.rst @@ -4,7 +4,7 @@ GPIO Descriptor Consumer Interface This document describes the consumer interface of the GPIO framework. Note that it describes the new descriptor-based interface. For a description of the -deprecated integer-based GPIO interface please refer to gpio-legacy.txt. +deprecated integer-based GPIO interface please refer to legacy.rst. Guidelines for GPIOs consumers @@ -78,7 +78,7 @@ whether the line is configured active high or active low (see The two last flags are used for use cases where open drain is mandatory, such as I2C: if the line is not already configured as open drain in the mappings -(see board.txt), then open drain will be enforced anyway and a warning will be +(see board.rst), then open drain will be enforced anyway and a warning will be printed that the board configuration needs to be updated to match the use case. Both functions return either a valid GPIO descriptor, or an error code checkable @@ -114,7 +114,7 @@ For a function using multiple GPIOs all of those can be obtained with one call:: This function returns a struct gpio_descs which contains an array of descriptors. It also contains a pointer to a gpiolib private structure which, -if passed back to get/set array functions, may speed up I/O proocessing:: +if passed back to get/set array functions, may speed up I/O processing:: struct gpio_descs { struct gpio_array *info; @@ -270,7 +270,7 @@ driven. The same is applicable for open drain or open source output lines: those do not actively drive their output high (open drain) or low (open source), they just switch their output to a high impedance value. The consumer should not need to -care. (For details read about open drain in driver.txt.) +care. (For details read about open drain in driver.rst.) With this, all the gpiod_set_(array)_value_xxx() functions interpret the parameter "value" as "asserted" ("1") or "de-asserted" ("0"). The physical line diff --git a/Documentation/driver-api/gpio/driver.rst b/Documentation/driver-api/gpio/driver.rst index 70ff43ac4fcc..6baaeab79534 100644 --- a/Documentation/driver-api/gpio/driver.rst +++ b/Documentation/driver-api/gpio/driver.rst @@ -119,7 +119,7 @@ GPIO lines with debounce support Debouncing is a configuration set to a pin indicating that it is connected to a mechanical switch or button, or similar that may bounce. Bouncing means the line is pulled high/low quickly at very short intervals for mechanical -reasons. This can result in the value being unstable or irqs fireing repeatedly +reasons. This can result in the value being unstable or irqs firing repeatedly unless the line is debounced. Debouncing in practice involves setting up a timer when something happens on @@ -219,7 +219,7 @@ use a trick: when a line is set as output, if the line is flagged as open drain, and the IN output value is low, it will be driven low as usual. But if the IN output value is set to high, it will instead *NOT* be driven high, instead it will be switched to input, as input mode is high impedance, thus -achieveing an "open drain emulation" of sorts: electrically the behaviour will +achieving an "open drain emulation" of sorts: electrically the behaviour will be identical, with the exception of possible hardware glitches when switching the mode of the line. @@ -642,7 +642,7 @@ In this case the typical set-up will look like this: As you can see pretty similar, but you do not supply a parent handler for the IRQ, instead a parent irqdomain, an fwnode for the hardware and -a funcion .child_to_parent_hwirq() that has the purpose of looking up +a function .child_to_parent_hwirq() that has the purpose of looking up the parent hardware irq from a child (i.e. this gpio chip) hardware irq. As always it is good to look at examples in the kernel tree for advice on how to find the required pieces. diff --git a/Documentation/driver-api/gpio/intro.rst b/Documentation/driver-api/gpio/intro.rst index 2e924fb5b3d5..c9c19243b97f 100644 --- a/Documentation/driver-api/gpio/intro.rst +++ b/Documentation/driver-api/gpio/intro.rst @@ -14,12 +14,12 @@ Due to the history of GPIO interfaces in the kernel, there are two different ways to obtain and use GPIOs: - The descriptor-based interface is the preferred way to manipulate GPIOs, - and is described by all the files in this directory excepted gpio-legacy.txt. + and is described by all the files in this directory excepted legacy.rst. - The legacy integer-based interface which is considered deprecated (but still - usable for compatibility reasons) is documented in gpio-legacy.txt. + usable for compatibility reasons) is documented in legacy.rst. The remainder of this document applies to the new descriptor-based interface. -gpio-legacy.txt contains the same information applied to the legacy +legacy.rst contains the same information applied to the legacy integer-based interface. diff --git a/Documentation/driver-api/gpio/using-gpio.rst b/Documentation/driver-api/gpio/using-gpio.rst index 64c8d3f76c3a..894d88855d73 100644 --- a/Documentation/driver-api/gpio/using-gpio.rst +++ b/Documentation/driver-api/gpio/using-gpio.rst @@ -44,7 +44,7 @@ These devices will appear on the system as ``/dev/gpiochip0`` thru found in the kernel tree ``tools/gpio`` subdirectory. For structured and managed applications, we recommend that you make use of the -libgpiod_ library. This provides helper abstractions, command line utlities +libgpiod_ library. This provides helper abstractions, command line utilities and arbitration for multiple simultaneous consumers on the same GPIO chip. .. _libgpiod: https://git.kernel.org/pub/scm/libs/libgpiod/libgpiod.git/ diff --git a/Documentation/driver-api/hte/tegra194-hte.rst b/Documentation/driver-api/hte/tegra194-hte.rst index 41983e04d2a0..f2d617265546 100644 --- a/Documentation/driver-api/hte/tegra194-hte.rst +++ b/Documentation/driver-api/hte/tegra194-hte.rst @@ -25,8 +25,7 @@ and userspace consumers. The kernel space consumers can directly talk to HTE subsystem while userspace consumers timestamp requests go through GPIOLIB CDEV framework to HTE subsystem. -.. kernel-doc:: drivers/gpio/gpiolib.c - :functions: gpiod_enable_hw_timestamp_ns gpiod_disable_hw_timestamp_ns +See gpiod_enable_hw_timestamp_ns() and gpiod_disable_hw_timestamp_ns(). For userspace consumers, GPIO_V2_LINE_FLAG_EVENT_CLOCK_HTE flag must be specified during IOCTL calls. Refer to ``tools/gpio/gpio-event-mon.c``, which @@ -37,7 +36,7 @@ LIC (Legacy Interrupt Controller) IRQ GTE This GTE instance timestamps LIC IRQ lines in real time. There are 352 IRQ lines which this instance can add timestamps to in real time. The hte -devicetree binding described at ``Documentation/devicetree/bindings/hte/`` +devicetree binding described at ``Documentation/devicetree/bindings/timestamp`` provides an example of how a consumer can request an IRQ line. Since it is a one-to-one mapping with IRQ GTE provider, consumers can simply specify the IRQ number that they are interested in. There is no userspace consumer support for diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index a6d525cd9fc4..d3a58f77328e 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -27,6 +27,7 @@ available subsections can be seen below. component message-based infiniband + aperture frame-buffer regulator reset diff --git a/Documentation/driver-api/media/mc-core.rst b/Documentation/driver-api/media/mc-core.rst index 02481a2513b9..84aa7cdb5341 100644 --- a/Documentation/driver-api/media/mc-core.rst +++ b/Documentation/driver-api/media/mc-core.rst @@ -186,8 +186,9 @@ is required and the graph structure can be freed normally. Helper functions can be used to find a link between two given pads, or a pad connected to another pad through an enabled link -:c:func:`media_entity_find_link()` and -:c:func:`media_entity_remote_pad()`. +(:c:func:`media_entity_find_link()`, :c:func:`media_pad_remote_pad_first()`, +:c:func:`media_entity_remote_source_pad_unique()` and +:c:func:`media_pad_remote_pad_unique()`). Use count and power handling ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/Documentation/driver-api/media/v4l2-subdev.rst b/Documentation/driver-api/media/v4l2-subdev.rst index cf3b52bdbfb9..6f8d79926aa5 100644 --- a/Documentation/driver-api/media/v4l2-subdev.rst +++ b/Documentation/driver-api/media/v4l2-subdev.rst @@ -243,6 +243,12 @@ notifier callback is called. After all subdevices have been located the .complete() callback is called. When a subdevice is removed from the system the .unbind() method is called. All three callbacks are optional. +Drivers can store any type of custom data in their driver-specific +:c:type:`v4l2_async_subdev` wrapper. If any of that data requires special +handling when the structure is freed, drivers must implement the ``.destroy()`` +notifier callback. The framework will call it right before freeing the +:c:type:`v4l2_async_subdev`. + Calling subdev operations ~~~~~~~~~~~~~~~~~~~~~~~~~ diff --git a/Documentation/driver-api/serial/driver.rst b/Documentation/driver-api/serial/driver.rst index 7ef83fd3917b..23c6b956cd90 100644 --- a/Documentation/driver-api/serial/driver.rst +++ b/Documentation/driver-api/serial/driver.rst @@ -25,10 +25,10 @@ Console Support --------------- The serial core provides a few helper functions. This includes identifing -the correct port structure (via uart_get_console) and decoding command line -arguments (uart_parse_options). +the correct port structure (via uart_get_console()) and decoding command line +arguments (uart_parse_options()). -There is also a helper function (uart_console_write) which performs a +There is also a helper function (uart_console_write()) which performs a character by character write, translating newlines to CRLF sequences. Driver writers are recommended to use this function rather than implementing their own version. @@ -39,7 +39,7 @@ Locking It is the responsibility of the low level hardware driver to perform the necessary locking using port->lock. There are some exceptions (which -are described in the uart_ops listing below.) +are described in the struct uart_ops listing below.) There are two locks. A per-port spinlock, and an overall semaphore. @@ -63,442 +63,20 @@ commonly referred to as the port mutex. uart_ops -------- -The uart_ops structure is the main interface between serial_core and the -hardware specific driver. It contains all the methods to control the -hardware. - - tx_empty(port) - This function tests whether the transmitter fifo and shifter - for the port described by 'port' is empty. If it is empty, - this function should return TIOCSER_TEMT, otherwise return 0. - If the port does not support this operation, then it should - return TIOCSER_TEMT. - - Locking: none. - - Interrupts: caller dependent. - - This call must not sleep - - set_mctrl(port, mctrl) - This function sets the modem control lines for port described - by 'port' to the state described by mctrl. The relevant bits - of mctrl are: - - - TIOCM_RTS RTS signal. - - TIOCM_DTR DTR signal. - - TIOCM_OUT1 OUT1 signal. - - TIOCM_OUT2 OUT2 signal. - - TIOCM_LOOP Set the port into loopback mode. - - If the appropriate bit is set, the signal should be driven - active. If the bit is clear, the signal should be driven - inactive. - - Locking: port->lock taken. - - Interrupts: locally disabled. - - This call must not sleep - - get_mctrl(port) - Returns the current state of modem control inputs. The state - of the outputs should not be returned, since the core keeps - track of their state. The state information should include: - - - TIOCM_CAR state of DCD signal - - TIOCM_CTS state of CTS signal - - TIOCM_DSR state of DSR signal - - TIOCM_RI state of RI signal - - The bit is set if the signal is currently driven active. If - the port does not support CTS, DCD or DSR, the driver should - indicate that the signal is permanently active. If RI is - not available, the signal should not be indicated as active. - - Locking: port->lock taken. - - Interrupts: locally disabled. - - This call must not sleep - - stop_tx(port) - Stop transmitting characters. This might be due to the CTS - line becoming inactive or the tty layer indicating we want - to stop transmission due to an XOFF character. - - The driver should stop transmitting characters as soon as - possible. - - Locking: port->lock taken. - - Interrupts: locally disabled. - - This call must not sleep - - start_tx(port) - Start transmitting characters. - - Locking: port->lock taken. - - Interrupts: locally disabled. - - This call must not sleep - - throttle(port) - Notify the serial driver that input buffers for the line discipline are - close to full, and it should somehow signal that no more characters - should be sent to the serial port. - This will be called only if hardware assisted flow control is enabled. - - Locking: serialized with .unthrottle() and termios modification by the - tty layer. - - unthrottle(port) - Notify the serial driver that characters can now be sent to the serial - port without fear of overrunning the input buffers of the line - disciplines. - - This will be called only if hardware assisted flow control is enabled. - - Locking: serialized with .throttle() and termios modification by the - tty layer. - - send_xchar(port,ch) - Transmit a high priority character, even if the port is stopped. - This is used to implement XON/XOFF flow control and tcflow(). If - the serial driver does not implement this function, the tty core - will append the character to the circular buffer and then call - start_tx() / stop_tx() to flush the data out. - - Do not transmit if ch == '\0' (__DISABLED_CHAR). - - Locking: none. - - Interrupts: caller dependent. - - stop_rx(port) - Stop receiving characters; the port is in the process of - being closed. - - Locking: port->lock taken. - - Interrupts: locally disabled. - - This call must not sleep - - enable_ms(port) - Enable the modem status interrupts. - - This method may be called multiple times. Modem status - interrupts should be disabled when the shutdown method is - called. - - Locking: port->lock taken. - - Interrupts: locally disabled. - - This call must not sleep - - break_ctl(port,ctl) - Control the transmission of a break signal. If ctl is - nonzero, the break signal should be transmitted. The signal - should be terminated when another call is made with a zero - ctl. - - Locking: caller holds tty_port->mutex - - startup(port) - Grab any interrupt resources and initialise any low level driver - state. Enable the port for reception. It should not activate - RTS nor DTR; this will be done via a separate call to set_mctrl. - - This method will only be called when the port is initially opened. - - Locking: port_sem taken. - - Interrupts: globally disabled. - - shutdown(port) - Disable the port, disable any break condition that may be in - effect, and free any interrupt resources. It should not disable - RTS nor DTR; this will have already been done via a separate - call to set_mctrl. - - Drivers must not access port->state once this call has completed. - - This method will only be called when there are no more users of - this port. - - Locking: port_sem taken. - - Interrupts: caller dependent. - - flush_buffer(port) - Flush any write buffers, reset any DMA state and stop any - ongoing DMA transfers. - - This will be called whenever the port->state->xmit circular - buffer is cleared. - - Locking: port->lock taken. - - Interrupts: locally disabled. - - This call must not sleep - - set_termios(port,termios,oldtermios) - Change the port parameters, including word length, parity, stop - bits. Update read_status_mask and ignore_status_mask to indicate - the types of events we are interested in receiving. Relevant - termios->c_cflag bits are: - - CSIZE - - word size - CSTOPB - - 2 stop bits - PARENB - - parity enable - PARODD - - odd parity (when PARENB is in force) - CREAD - - enable reception of characters (if not set, - still receive characters from the port, but - throw them away. - CRTSCTS - - if set, enable CTS status change reporting - CLOCAL - - if not set, enable modem status change - reporting. - - Relevant termios->c_iflag bits are: - - INPCK - - enable frame and parity error events to be - passed to the TTY layer. - BRKINT / PARMRK - - both of these enable break events to be - passed to the TTY layer. - - IGNPAR - - ignore parity and framing errors - IGNBRK - - ignore break errors, If IGNPAR is also - set, ignore overrun errors as well. - - The interaction of the iflag bits is as follows (parity error - given as an example): - - =============== ======= ====== ============================= - Parity error INPCK IGNPAR - =============== ======= ====== ============================= - n/a 0 n/a character received, marked as - TTY_NORMAL - None 1 n/a character received, marked as - TTY_NORMAL - Yes 1 0 character received, marked as - TTY_PARITY - Yes 1 1 character discarded - =============== ======= ====== ============================= - - Other flags may be used (eg, xon/xoff characters) if your - hardware supports hardware "soft" flow control. - - Locking: caller holds tty_port->mutex - - Interrupts: caller dependent. - - This call must not sleep - - set_ldisc(port,termios) - Notifier for discipline change. See ../tty/tty_ldisc.rst. - - Locking: caller holds tty_port->mutex - - pm(port,state,oldstate) - Perform any power management related activities on the specified - port. State indicates the new state (defined by - enum uart_pm_state), oldstate indicates the previous state. - - This function should not be used to grab any resources. - - This will be called when the port is initially opened and finally - closed, except when the port is also the system console. This - will occur even if CONFIG_PM is not set. - - Locking: none. - - Interrupts: caller dependent. - - type(port) - Return a pointer to a string constant describing the specified - port, or return NULL, in which case the string 'unknown' is - substituted. - - Locking: none. - - Interrupts: caller dependent. - - release_port(port) - Release any memory and IO region resources currently in use by - the port. - - Locking: none. - - Interrupts: caller dependent. - - request_port(port) - Request any memory and IO region resources required by the port. - If any fail, no resources should be registered when this function - returns, and it should return -EBUSY on failure. - - Locking: none. - - Interrupts: caller dependent. - - config_port(port,type) - Perform any autoconfiguration steps required for the port. `type` - contains a bit mask of the required configuration. UART_CONFIG_TYPE - indicates that the port requires detection and identification. - port->type should be set to the type found, or PORT_UNKNOWN if - no port was detected. - - UART_CONFIG_IRQ indicates autoconfiguration of the interrupt signal, - which should be probed using standard kernel autoprobing techniques. - This is not necessary on platforms where ports have interrupts - internally hard wired (eg, system on a chip implementations). - - Locking: none. - - Interrupts: caller dependent. - - verify_port(port,serinfo) - Verify the new serial port information contained within serinfo is - suitable for this port type. - - Locking: none. - - Interrupts: caller dependent. - - ioctl(port,cmd,arg) - Perform any port specific IOCTLs. IOCTL commands must be defined - using the standard numbering system found in <asm/ioctl.h> - - Locking: none. - - Interrupts: caller dependent. - - poll_init(port) - Called by kgdb to perform the minimal hardware initialization needed - to support poll_put_char() and poll_get_char(). Unlike ->startup() - this should not request interrupts. - - Locking: tty_mutex and tty_port->mutex taken. - - Interrupts: n/a. - - poll_put_char(port,ch) - Called by kgdb to write a single character directly to the serial - port. It can and should block until there is space in the TX FIFO. - - Locking: none. - - Interrupts: caller dependent. - - This call must not sleep - - poll_get_char(port) - Called by kgdb to read a single character directly from the serial - port. If data is available, it should be returned; otherwise - the function should return NO_POLL_CHAR immediately. - - Locking: none. - - Interrupts: caller dependent. - - This call must not sleep +.. kernel-doc:: include/linux/serial_core.h + :identifiers: uart_ops Other functions --------------- -uart_update_timeout(port,cflag,baud) - Update the FIFO drain timeout, port->timeout, according to the - number of bits, parity, stop bits and baud rate. - - Locking: caller is expected to take port->lock - - Interrupts: n/a - -uart_get_baud_rate(port,termios,old,min,max) - Return the numeric baud rate for the specified termios, taking - account of the special 38400 baud "kludge". The B0 baud rate - is mapped to 9600 baud. - - If the baud rate is not within min..max, then if old is non-NULL, - the original baud rate will be tried. If that exceeds the - min..max constraint, 9600 baud will be returned. termios will - be updated to the baud rate in use. - - Note: min..max must always allow 9600 baud to be selected. - - Locking: caller dependent. - - Interrupts: n/a - -uart_get_divisor(port,baud) - Return the divisor (baud_base / baud) for the specified baud - rate, appropriately rounded. - - If 38400 baud and custom divisor is selected, return the - custom divisor instead. - - Locking: caller dependent. - - Interrupts: n/a - -uart_match_port(port1,port2) - This utility function can be used to determine whether two - uart_port structures describe the same port. - - Locking: n/a - - Interrupts: n/a - -uart_write_wakeup(port) - A driver is expected to call this function when the number of - characters in the transmit buffer have dropped below a threshold. - - Locking: port->lock should be held. - - Interrupts: n/a - -uart_register_driver(drv) - Register a uart driver with the core driver. We in turn register - with the tty layer, and initialise the core driver per-port state. - - drv->port should be NULL, and the per-port structures should be - registered using uart_add_one_port after this call has succeeded. - - Locking: none - - Interrupts: enabled - -uart_unregister_driver() - Remove all references to a driver from the core driver. The low - level driver must have removed all its ports via the - uart_remove_one_port() if it registered them with uart_add_one_port(). - - Locking: none - - Interrupts: enabled - -**uart_suspend_port()** - -**uart_resume_port()** - -**uart_add_one_port()** - -**uart_remove_one_port()** +.. kernel-doc:: drivers/tty/serial/serial_core.c + :identifiers: uart_update_timeout uart_get_baud_rate uart_get_divisor + uart_match_port uart_write_wakeup uart_register_driver + uart_unregister_driver uart_suspend_port uart_resume_port + uart_add_one_port uart_remove_one_port uart_console_write + uart_parse_earlycon uart_parse_options uart_set_options + uart_get_lsr_info uart_handle_dcd_change uart_handle_cts_change + uart_try_toggle_sysrq uart_get_console Other notes ----------- @@ -519,31 +97,7 @@ Modem control lines via GPIO Some helpers are provided in order to set/get modem control lines via GPIO. -mctrl_gpio_init(port, idx): - This will get the {cts,rts,...}-gpios from device tree if they are - present and request them, set direction etc, and return an - allocated structure. `devm_*` functions are used, so there's no need - to call mctrl_gpio_free(). - As this sets up the irq handling make sure to not handle changes to the - gpio input lines in your driver, too. - -mctrl_gpio_free(dev, gpios): - This will free the requested gpios in mctrl_gpio_init(). - As `devm_*` functions are used, there's generally no need to call - this function. - -mctrl_gpio_to_gpiod(gpios, gidx) - This returns the gpio_desc structure associated to the modem line - index. - -mctrl_gpio_set(gpios, mctrl): - This will sets the gpios according to the mctrl state. - -mctrl_gpio_get(gpios, mctrl): - This will update mctrl with the gpios values. - -mctrl_gpio_enable_ms(gpios): - Enables irqs and handling of changes to the ms lines. - -mctrl_gpio_disable_ms(gpios): - Disables irqs and handling of changes to the ms lines. +.. kernel-doc:: drivers/tty/serial/serial_mctrl_gpio.c + :identifiers: mctrl_gpio_init mctrl_gpio_free mctrl_gpio_to_gpiod + mctrl_gpio_set mctrl_gpio_get mctrl_gpio_enable_ms + mctrl_gpio_disable_ms diff --git a/Documentation/driver-api/serial/serial-rs485.rst b/Documentation/driver-api/serial/serial-rs485.rst index 6bc824f948f9..6ebad75c74ed 100644 --- a/Documentation/driver-api/serial/serial-rs485.rst +++ b/Documentation/driver-api/serial/serial-rs485.rst @@ -38,10 +38,14 @@ RS485 Serial Communications the values given by the device tree. Any driver for devices capable of working both as RS232 and RS485 should - implement the rs485_config callback in the uart_port structure. The - serial_core calls rs485_config to do the device specific part in response - to TIOCSRS485 and TIOCGRS485 ioctls (see below). The rs485_config callback - receives a pointer to struct serial_rs485. + implement the rs485_config callback and provide rs485_supported in the + uart_port structure. The serial core calls rs485_config to do the device + specific part in response to TIOCSRS485 ioctl (see below). The rs485_config + callback receives a pointer to a sanitizated serial_rs485 structure. The + serial_rs485 userspace provides is sanitized before calling rs485_config + using rs485_supported that indicates what RS485 features the driver supports + for the uart_port. TIOCGRS485 ioctl can be used to read back the + serial_rs485 structure matching to the current configuration. 4. Usage from user-level ======================== @@ -95,7 +99,31 @@ RS485 Serial Communications /* Error handling. See errno. */ } -5. References +5. Multipoint Addressing +======================== + + The Linux kernel provides addressing mode for multipoint RS-485 serial + communications line. The addressing mode is enabled with SER_RS485_ADDRB + flag in serial_rs485. Struct serial_rs485 has two additional flags and + fields for enabling receive and destination addresses. + + Address mode flags: + - SER_RS485_ADDRB: Enabled addressing mode (sets also ADDRB in termios). + - SER_RS485_ADDR_RECV: Receive (filter) address enabled. + - SER_RS485_ADDR_DEST: Set destination address. + + Address fields (enabled with corresponding SER_RS485_ADDR_* flag): + - addr_recv: Receive address. + - addr_dest: Destination address. + + Once a receive address is set, the communication can occur only with the + particular device and other peers are filtered out. It is left up to the + receiver side to enforce the filtering. Receive address will be cleared + if SER_RS485_ADDR_RECV is not set. + + Note: not all devices supporting RS485 support multipoint addressing. + +6. References ============= [1] include/uapi/linux/serial.h diff --git a/Documentation/driver-api/surface_aggregator/client.rst b/Documentation/driver-api/surface_aggregator/client.rst index e519d374c378..27f95abdbe99 100644 --- a/Documentation/driver-api/surface_aggregator/client.rst +++ b/Documentation/driver-api/surface_aggregator/client.rst @@ -17,6 +17,8 @@ .. |SSAM_DEVICE| replace:: :c:func:`SSAM_DEVICE` .. |ssam_notifier_register| replace:: :c:func:`ssam_notifier_register` .. |ssam_notifier_unregister| replace:: :c:func:`ssam_notifier_unregister` +.. |ssam_device_notifier_register| replace:: :c:func:`ssam_device_notifier_register` +.. |ssam_device_notifier_unregister| replace:: :c:func:`ssam_device_notifier_unregister` .. |ssam_request_sync| replace:: :c:func:`ssam_request_sync` .. |ssam_event_mask| replace:: :c:type:`enum ssam_event_mask <ssam_event_mask>` @@ -312,7 +314,9 @@ Handling Events To receive events from the SAM EC, an event notifier must be registered for the desired event via |ssam_notifier_register|. The notifier must be unregistered via |ssam_notifier_unregister| once it is not required any -more. +more. For |ssam_device| type clients, the |ssam_device_notifier_register| and +|ssam_device_notifier_unregister| wrappers should be preferred as they properly +handle hot-removal of client devices. Event notifiers are registered by providing (at minimum) a callback to call in case an event has been received, the registry specifying how the event diff --git a/Documentation/driver-api/vfio-mediated-device.rst b/Documentation/driver-api/vfio-mediated-device.rst index eded8719180f..f47dca6645aa 100644 --- a/Documentation/driver-api/vfio-mediated-device.rst +++ b/Documentation/driver-api/vfio-mediated-device.rst @@ -1,3 +1,4 @@ +.. SPDX-License-Identifier: GPL-2.0-only .. include:: <isonum.txt> ===================== @@ -8,9 +9,6 @@ VFIO Mediated devices :Author: Neo Jia <[email protected]> :Author: Kirti Wankhede <[email protected]> -This program is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License version 2 as -published by the Free Software Foundation. Virtual Function I/O (VFIO) Mediated devices[1] @@ -114,11 +112,11 @@ to register and unregister itself with the core driver: * Register:: - extern int mdev_register_driver(struct mdev_driver *drv); + int mdev_register_driver(struct mdev_driver *drv); * Unregister:: - extern void mdev_unregister_driver(struct mdev_driver *drv); + void mdev_unregister_driver(struct mdev_driver *drv); The mediated bus driver's probe function should create a vfio_device on top of the mdev_device and connect it to an appropriate implementation of @@ -127,8 +125,8 @@ vfio_device_ops. When a driver wants to add the GUID creation sysfs to an existing device it has probe'd to then it should call:: - extern int mdev_register_device(struct device *dev, - struct mdev_driver *mdev_driver); + int mdev_register_device(struct device *dev, + struct mdev_driver *mdev_driver); This will provide the 'mdev_supported_types/XX/create' files which can then be used to trigger the creation of a mdev_device. The created mdev_device will be @@ -136,7 +134,7 @@ attached to the specified driver. When the driver needs to remove itself it calls:: - extern void mdev_unregister_device(struct device *dev); + void mdev_unregister_device(struct device *dev); Which will unbind and destroy all the created mdevs and remove the sysfs files. @@ -262,10 +260,10 @@ Translation APIs for Mediated Devices The following APIs are provided for translating user pfn to host pfn in a VFIO driver:: - int vfio_pin_pages(struct vfio_device *device, unsigned long *user_pfn, - int npage, int prot, unsigned long *phys_pfn); + int vfio_pin_pages(struct vfio_device *device, dma_addr_t iova, + int npage, int prot, struct page **pages); - int vfio_unpin_pages(struct vfio_device *device, unsigned long *user_pfn, + void vfio_unpin_pages(struct vfio_device *device, dma_addr_t iova, int npage); These functions call back into the back-end IOMMU module by using the pin_pages diff --git a/Documentation/driver-api/vme.rst b/Documentation/driver-api/vme.rst index def139c13410..c0b475369de0 100644 --- a/Documentation/driver-api/vme.rst +++ b/Documentation/driver-api/vme.rst @@ -290,8 +290,8 @@ The function :c:func:`vme_bus_num` returns the bus ID of the provided bridge. VME API ------- -.. kernel-doc:: include/linux/vme.h +.. kernel-doc:: drivers/staging/vme_user/vme.h :internal: -.. kernel-doc:: drivers/vme/vme.c +.. kernel-doc:: drivers/staging/vme_user/vme.c :export: |