Documentation: serial: move uart_ops documentation to the struct

While it's a lot of text, it always helps to keep it up to date when
it's by the source. (And not in a separate file.)

The documentation tooling also makes sure that all members of the
structure are documented. (If not, it complains loudly.)

Finally, there needs to be no comments inlined in the structure, so they
are dropped as they are superfluous now.

The compilation time of this header (tested with serial_core.c) didn't
change in my testing at all.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2022-07-28 08:10:51 +02:00 committed by Greg Kroah-Hartman
parent 0f42d7f23f
commit e60a723368
2 changed files with 331 additions and 372 deletions

View file

@ -63,362 +63,8 @@ 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)
ADDRB
- address bit (changed through .rs485_config()).
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
---------------

View file

@ -31,9 +31,336 @@ struct serial_struct;
struct device;
struct gpio_desc;
/*
/**
* struct uart_ops -- interface between serial_core and the driver
*
* This structure describes all the operations that can be done on the
* physical hardware. See Documentation/driver-api/serial/driver.rst for details.
* physical hardware.
*
* @tx_empty: ``unsigned int ()(struct uart_port *port)``
*
* This function tests whether the transmitter fifo and shifter for the
* @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: ``void ()(struct uart_port *port, unsigned int mctrl)``
*
* This function sets the modem control lines for @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: ``unsigned int ()(struct uart_port *port)``
*
* Returns the current state of modem control inputs of @port. 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: ``void ()(struct uart_port *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: ``void ()(struct uart_port *port)``
*
* Start transmitting characters.
*
* Locking: @port->lock taken.
* Interrupts: locally disabled.
* This call must not sleep
*
* @throttle: ``void ()(struct uart_port *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: ``void ()(struct uart_port *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: ``void ()(struct uart_port *port, char 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: ``void ()(struct uart_port *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: ``void ()(struct uart_port *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: ``void ()(struct uart_port *port, int 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: ``int ()(struct uart_port *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: ``void ()(struct uart_port *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: ``void ()(struct uart_port *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: ``void ()(struct uart_port *port, struct ktermios *new,
* struct ktermios *old)``
*
* Change the @port parameters, including word length, parity, stop bits.
* Update @port->read_status_mask and @port->ignore_status_mask to
* indicate the types of events we are interested in receiving. Relevant
* ktermios::c_cflag bits are:
*
* - %CSIZE - word size
* - %CSTOPB - 2 stop bits
* - %PARENB - parity enable
* - %PARODD - odd parity (when %PARENB is in force)
* - %ADDRB - address bit (changed through uart_port::rs485_config()).
* - %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 ktermios::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 ktermios::c_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: ``void ()(struct uart_port *port, struct ktermios *termios)``
*
* Notifier for discipline change. See
* Documentation/driver-api/tty/tty_ldisc.rst.
*
* Locking: caller holds tty_port->mutex
*
* @pm: ``void ()(struct uart_port *port, unsigned int state,
* unsigned int 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: ``const char *()(struct uart_port *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: ``void ()(struct uart_port *port)``
*
* Release any memory and IO region resources currently in use by the
* @port.
*
* Locking: none.
* Interrupts: caller dependent.
*
* @request_port: ``int ()(struct uart_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: ``void ()(struct uart_port *port, int 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: ``int ()(struct uart_port *port,
* struct serial_struct *serinfo)``
*
* Verify the new serial port information contained within @serinfo is
* suitable for this port type.
*
* Locking: none.
* Interrupts: caller dependent.
*
* @ioctl: ``int ()(struct uart_port *port, unsigned int cmd,
* unsigned long 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: ``int ()(struct uart_port *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: ``void ()(struct uart_port *port, unsigned char ch)``
*
* Called by kgdb to write a single character @ch 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: ``int ()(struct uart_port *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
*/
struct uart_ops {
unsigned int (*tx_empty)(struct uart_port *);
@ -56,22 +383,8 @@ struct uart_ops {
void (*set_ldisc)(struct uart_port *, struct ktermios *);
void (*pm)(struct uart_port *, unsigned int state,
unsigned int oldstate);
/*
* Return a string describing the type of the port
*/
const char *(*type)(struct uart_port *);
/*
* Release IO and memory resources used by the port.
* This includes iounmap if necessary.
*/
void (*release_port)(struct uart_port *);
/*
* Request IO and memory resources used by the port.
* This includes iomapping the port if necessary.
*/
int (*request_port)(struct uart_port *);
void (*config_port)(struct uart_port *, int);
int (*verify_port)(struct uart_port *, struct serial_struct *);