tty: switch tty_port::xmit_* to u8

Both xmit_buf and xmit_fifo of struct tty_port should be u8. To conform
to characters in the rest of the tty layer.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@

tty: switch tty_port::xmit_* to u8

Both xmit_buf and xmit_fifo of struct tty_port should be u8. To conform
to characters in the rest of the tty layer.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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serial: core: Move tty and serdev to be children of serial core port device

Let's move tty and serdev controller to be children of the serial core port
device. This way the runtime PM usage count of

serial: core: Move tty and serdev to be children of serial core port device

Let's move tty and serdev controller to be children of the serial core port
device. This way the runtime PM usage count of a child device propagates
to the serial hardware device.

The tty and serdev devices are associated with a specific serial port of
a serial hardware controller device, and we now have serial core hierarchy
of controllers and ports.

The tty device moves happily with just a change of the parent device and
update of device_find_child() handling. The serdev device init needs some
changes to separate the serial hardware controller device from the parent
device.

With this change the tty devices move under sysfs similar to this x86_64
qemu example of a diff of "find /sys -name ttyS*":

/sys/class/tty/ttyS0
/sys/class/tty/ttyS3
/sys/class/tty/ttyS1
-/sys/devices/pnp0/00:04/tty/ttyS0
-/sys/devices/platform/serial8250/tty/ttyS2
-/sys/devices/platform/serial8250/tty/ttyS3
-/sys/devices/platform/serial8250/tty/ttyS1
+/sys/devices/pnp0/00:04/00:04:0/00:04:0.0/tty/ttyS0
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.3/tty/ttyS3
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.1/tty/ttyS1
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.2/tty/ttyS2

If a serdev device is used instead of a tty, it moves in a similar way.

Suggested-by: Johan Hovold <[email protected]>
Cc: Maximilian Luz <[email protected]>
Cc: Rob Herring <[email protected]>
Signed-off-by: Tony Lindgren <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: make counts in tty_port_client_operations hooks size_t

The counts in tty_port_client_operations hooks' are currently
represented by all 'int', 'unsigned int', and 'size_t'. Unify them all
to un

tty: make counts in tty_port_client_operations hooks size_t

The counts in tty_port_client_operations hooks' are currently
represented by all 'int', 'unsigned int', and 'size_t'. Unify them all
to unsigned 'size_t' for clarity. Note that size_t is used already in
tty_buffer.c. So, eventually, it is spread for counts everywhere and
this is the beginning.

So the two changes namely:
* ::receive_buf() is called from tty_ldisc_receive_buf(). And that
expects values ">= 0" from ::receive_buf(), so switch its rettype to
size_t is fine. tty_ldisc_receive_buf() types will be changed
separately.
* ::lookahead_buf()'s count comes from lookahead_bufs() and is already
'unsigned int'.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Cc: Rob Herring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: make tty_port_client_operations operate with u8

The parameters are already unsigned chars. So make them explicitly u8s,
as the rest is going to be unified to u8 eventually too.

Signed-off-by:

tty: make tty_port_client_operations operate with u8

The parameters are already unsigned chars. So make them explicitly u8s,
as the rest is going to be unified to u8 eventually too.

Signed-off-by: "Jiri Slaby (SUSE)" <[email protected]>
Cc: Rob Herring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: Call ->dtr_rts() parameter active consistently

Convert various parameter names for ->dtr_rts() and related functions
from onoff, on, and raise to active.

Reviewed-by: Jiri Slaby <jirislaby@ker

tty: Call ->dtr_rts() parameter active consistently

Convert various parameter names for ->dtr_rts() and related functions
from onoff, on, and raise to active.

Reviewed-by: Jiri Slaby <[email protected]>
Acked-by: Ulf Hansson <[email protected]> # For MMC
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: Convert ->dtr_rts() to take bool argument

Convert the raise/on parameter in ->dtr_rts() to bool through the
callchain. The parameter is used like bool. In USB serial, there
remains a few implic

tty: Convert ->dtr_rts() to take bool argument

Convert the raise/on parameter in ->dtr_rts() to bool through the
callchain. The parameter is used like bool. In USB serial, there
remains a few implicit bool -> larger type conversions because some
devices use u8 in their control messages.

In moxa_tiocmget(), dtr variable was reused for line status which
requires int so use a separate variable for status.

Reviewed-by: Jiri Slaby <[email protected]>
Acked-by: Ulf Hansson <[email protected]> # For MMC
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: Convert ->carrier_raised() and callchains to bool

Return boolean from ->carrier_raised() instead of 0 and 1. Make the
return type change also to tty_port_carrier_raised() that makes the
->carri

tty: Convert ->carrier_raised() and callchains to bool

Return boolean from ->carrier_raised() instead of 0 and 1. Make the
return type change also to tty_port_carrier_raised() that makes the
->carrier_raised() call (+ cd variable in moxa into which its return
value is stored).

Also cleans up a few unnecessary constructs related to this change:

return xx ? 1 : 0;
-> return xx;

if (xx)
return 1;
return 0;
-> return xx;

Reviewed-by: Jiri Slaby <[email protected]>
Acked-by: Ulf Hansson <[email protected]> # For MMC
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: Implement lookahead to process XON/XOFF timely

When tty is not read from, XON/XOFF may get stuck into an
intermediate buffer. As those characters are there to do software
flow-control, it is no

tty: Implement lookahead to process XON/XOFF timely

When tty is not read from, XON/XOFF may get stuck into an
intermediate buffer. As those characters are there to do software
flow-control, it is not very useful. In the case where neither end
reads from ttys, the receiving ends might not be able receive the
XOFF characters and just keep sending more data to the opposite
direction. This problem is almost guaranteed to occur with DMA
which sends data in large chunks.

If TTY is slow to process characters, that is, eats less than given
amount in receive_buf, invoke lookahead for the rest of the chars
to process potential XON/XOFF characters.

We need to keep track of how many characters have been processed by the
lookahead to avoid processing the flow control char again on the normal
path. Bookkeeping occurs parallel on two layers (tty_buffer and n_tty)
to avoid passing the lookahead_count through the whole call chain.

When a flow-control char is processed, two things must occur:
a) it must not be treated as normal char
b) if not yet processed, flow-control actions need to be taken
The return value of n_tty_receive_char_flow_ctrl() tells caller a), and
b) is kept internal to n_tty_receive_char_flow_ctrl().

If characters were previous looked ahead, __receive_buf() makes two
calls to the appropriate n_tty_receive_buf_* function. First call is
made with lookahead_done=true for the characters that were subject to
lookahead earlier and then with lookahead=false for the new characters.
Either of the calls might be skipped when it has no characters to
handle.

Reported-by: Gilles Buloz <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: add kfifo to tty_port

Define a kfifo inside struct tty_port. We use DECLARE_KFIFO_PTR and let
the preexisting tty_port::xmit_buf be also the buffer for the kfifo.
And handle the initialization/

tty: add kfifo to tty_port

Define a kfifo inside struct tty_port. We use DECLARE_KFIFO_PTR and let
the preexisting tty_port::xmit_buf be also the buffer for the kfifo.
And handle the initialization/decomissioning along with xmit_buf, i.e.
in tty_port_alloc_xmit_buf() and tty_port_free_xmit_buf(), respectively.

This allows for kfifo use in drivers which opt-in, while others still
may use the old xmit_buf. mxser will be the first user in the next
few patches.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: add kernel-doc for tty_port_operations

tty_port_operations used to have only comments along its members.
Convert them into proper kernel-doc comments in front of the structure.
And add some mor

tty: add kernel-doc for tty_port_operations

tty_port_operations used to have only comments along its members.
Convert them into proper kernel-doc comments in front of the structure.
And add some more explanation to them where needed.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: add kernel-doc for tty_port

tty_port used to have only short comments along its members. Convert
them into proper kernel-doc comments in front of the structure. And add
some more explanation to

tty: add kernel-doc for tty_port

tty_port used to have only short comments along its members. Convert
them into proper kernel-doc comments in front of the structure. And add
some more explanation to them where needed.

The whole structure purpose and handling is documented at the end too --
some pieces of preexisting text moved to this place.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: move tty_port to new tty_port.h

tty.h is long enough already. And I am slowly adding kernel-doc
documentation, so it grows to unmaintainable long mess. To avoid this,
split tty.h further into t

tty: move tty_port to new tty_port.h

tty.h is long enough already. And I am slowly adding kernel-doc
documentation, so it grows to unmaintainable long mess. To avoid this,
split tty.h further into tty_port.h and move there tty_port-related
declarations and function prototypes (those implemented in tty_port.c).

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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