Many serial drivers do the same thing:
* send x_char if set
* keep sending from the xmit circular buffer until either
- the loop reaches the end of the xmit buffer
- TX is stopped
- HW fifo is full
* check for pending characters and:
- wake up tty writers to fill for more data into xmit buffer
- stop TX if there is nothing in the xmit buffer
The only differences are:
* how to write the character to the HW fifo
* the check of the end condition:
- is the HW fifo full?
- is limit of the written characters reached?
So unify the above into two helpers:
* uart_port_tx_limited() -- it performs the above taking the written
characters limit into account, and
* uart_port_tx() -- the same as above, except it only checks the HW
readiness, not the characters limit.
The HW specific operations (as stated as "differences" above) are passed
as arguments to the macros. They are:
* tx_ready -- returns true if HW can accept more data.
* put_char -- write a character to the device.
* tx_done -- when the write loop is done, perform arbitrary action
before potential invocation of ops->stop_tx() happens.
Note that the above are macros. This means the code is generated in
place and the above 3 arguments are "inlined". I.e. no added penalty by
generating call instructions for every single character. Nor any
indirect calls. (As in some previous versions of this patchset.)
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20221004104927.14361-2-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The GPIO uart functions are documented in Documentation. Move and
transform this documentation into kernel-doc directly in the code and
reference it in Documentation using kernel-doc:.
This makes it easier to update, maintain and check by the build.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some of the serial (uart_*) functions are documented twice. Once as
kernel-doc along their sources and once in Documentation. So deduplicate
these texts, merge them into kernel-doc in the sources, and link them
using kernel-doc: from the Documentation.
To be properly linked and rendered, tabulators had to be removed from
the comments.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220728061056.20799-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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>
Add support for RS-485 multipoint addressing using 9th bit [*]. The
addressing mode is configured through ->rs485_config().
ADDRB in termios indicates 9th bit addressing mode is enabled. In this
mode, 9th bit is used to indicate an address (byte) within the
communication line. ADDRB can only be enabled/disabled through
->rs485_config() that is also responsible for setting the destination and
receiver (filter) addresses.
Add traps to detect unwanted changes to struct serial_rs485 layout using
static_assert().
[*] Technically, RS485 is just an electronic spec and does not itself
specify the 9th bit addressing mode but 9th bit seems at least
"semi-standard" way to do addressing with RS485.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220624204210.11112-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since commit 31f6bd7fad ("serial: Store character timing information
to uart_port"), per frame timing information is available on uart_port.
Uart port's timeout can be derived from frame_time by multiplying with
fifosize.
Most callers of uart_poll_timeout are not made under port's lock. To be
on the safe side, make sure frame_time is only accessed once. As
fifo_size is effectively a constant, it shouldn't cause any issues.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220613113905.22962-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Sanitize serial_rs485 struct before calling into rs485_setup. The
drivers provide supported_rs485 to help sanitization of the fields.
If neither of SER_RS485_RTS_ON_SEND or SER_RS485_RTS_AFTER_SEND
supported, don't pretend they can be set to sane settings but clear
them both instead. If only one of them is supported it may look
tempting to use the one driver supports to set the other, however, the
userspace does not have that information readily available so it
wouldn't be helpful.
While adjusting the documentation, remove also the claim that
TIOCGRS485 would call driver specific code. In reality, it does nothing
else than copies the stored serial_rs485 structure from uart_port to
userspace.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-23-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since b9e851cd4a ("tty: n_gsm: Add some instructions and code for requester") which
introduced a warning:
linux/Documentation/driver-api/serial/n_gsm.rst:23: WARNING: Definition list ends without a blank line; unexpected unindent.
linux/Documentation/driver-api/serial/n_gsm.rst💯 WARNING: Definition list ends without a blank line; unexpected unindent.
linux/Documentation/driver-api/serial/n_gsm.rst:115: WARNING: Inline emphasis start-string without end-string.
linux/Documentation/driver-api/serial/n_gsm.rst:118: WARNING: Inline emphasis start-string without end-string.
linux/Documentation/driver-api/serial/n_gsm.rst:120: WARNING: Inline emphasis start-string without end-string.
linux/Documentation/driver-api/serial/n_gsm.rst:122: WARNING: Inline emphasis start-string without end-string.
linux/Documentation/driver-api/serial/n_gsm.rst:125: WARNING: Inline emphasis start-string without end-string.
linux/Documentation/driver-api/serial/n_gsm.rst:139: WARNING: Inline emphasis start-string without end-string.
A paragraph consisting of two colons ("::") signifies that the following text block(s) comprise a literal block.
Add soome blank lines.
Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/20211209092439.562433-1-siyanteng@loongson.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Create a new directory in Documentation/ called tty. We will create more
documents in it in the next patches, so let's have this one in the very
same place.
Change title accordingly and all the headers. This is the way what other
documents look like in this directory in the next patches. So make this
unified.
And add a TOC.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211126081611.11001-20-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Move the partial tty_struct::flags documentation from tty_ldisc to the
tty.h header and combine it with the one-liners present there. Convert
all those to kernel-doc. This way, we can simply reference the
documentation in Documentation while the text is still along the
definitions.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211126081611.11001-10-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
