-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
projects / linux-2.6-microblaze.git / blobdiff