diff options
Diffstat (limited to 'Documentation/serial/driver')
| -rw-r--r-- | Documentation/serial/driver | 67 |
1 files changed, 63 insertions, 4 deletions
diff --git a/Documentation/serial/driver b/Documentation/serial/driver index 77ba0afbe4d..3bba1aeb799 100644 --- a/Documentation/serial/driver +++ b/Documentation/serial/driver @@ -101,7 +101,7 @@ hardware. 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_DCD state of DCD signal + - TIOCM_CAR state of DCD signal - TIOCM_CTS state of CTS signal - TIOCM_DSR state of DSR signal - TIOCM_RI state of RI signal @@ -133,6 +133,16 @@ hardware. Interrupts: locally disabled. This call must not sleep + 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. + + Locking: none. + Interrupts: caller dependent. + stop_rx(port) Stop receiving characters; the port is in the process of being closed. @@ -242,9 +252,8 @@ hardware. pm(port,state,oldstate) Perform any power management related activities on the specified - port. State indicates the new state (defined by ACPI D0-D3), - oldstate indicates the previous state. Essentially, D0 means - fully on, D3 means powered down. + 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. @@ -307,6 +316,31 @@ hardware. 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 + Other functions --------------- @@ -395,3 +429,28 @@ thus: struct uart_port port; int my_stuff; }; + +Modem control lines via GPIO +---------------------------- + +Some helpers are provided in order to set/get modem control lines via GPIO. + +mctrl_gpio_init(dev, 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(). + +mctrl_gpio_free(dev, gpios): + This will free the requested gpios in mctrl_gpio_init(). + As devm_* function are used, there's generally no need to call + this function. + +mctrl_gpio_to_gpiod(gpios, gidx) + This returns the gpio 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. |