serial: 8250: make port operations work on struct uart_8250_port

serial8250_register_8250_port() returns a line number and the other
port operations (serial8250_unregister_port(), serial8250_suspend_port(),
serial8250_resume_port()) accept it. Many drivers then convert the line
back to the port using serial8250_get_port() anyway.

Switch the interface to struct uart_8250_port:
* serial8250_register_8250_port() now returns the registered port, or
an ERR_PTR() on failure.
* serial8250_unregister_port(), serial8250_suspend_port() and
serial8250_resume_port() accept the port.

Convert all users accordingly. Drivers store the port pointer instead
of the line number. Several drivers kept a private struct only to hold
the line (airoha, dfl, em, fsl, ioc3); these are dropped and the port
is stored as drvdata directly.

This also fixes two latent issues:
* For a CIR port, serial8250_register_8250_port() used to return 0.
Callers stored this as the line, so a later unregister/suspend/resume
operated on ttyS0. Now the CIR port itself is returned.
* 8250_acorn checked ports[i] > 0 on removal, so a port registered as
line 0 was never unregistered.

There are no more users of serial8250_get_port() outside of the 8250
core, so drop its EXPORT.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: "Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>
Assisted-by: LLM
Link: https://patch.msgid.link/c59fa203f325e0fe7601ea0fbc0d222c8b37f9eb.1791873876.git.jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index eeb868e93e15..d91c0477be9d 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -186,10 +186,10 @@ static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up)
 	return container_of(up, struct uart_8250_port, port);
 }
 
-int serial8250_register_8250_port(const struct uart_8250_port *);
-void serial8250_unregister_port(int line);
-void serial8250_suspend_port(int line);
-void serial8250_resume_port(int line);
+struct uart_8250_port *serial8250_register_8250_port(const struct uart_8250_port *);
+void serial8250_unregister_port(struct uart_8250_port *);
+void serial8250_suspend_port(struct uart_8250_port *);
+void serial8250_resume_port(struct uart_8250_port *);
 
 int early_serial_setup(struct uart_port *port);
 int early_serial8250_setup(struct earlycon_device *device, const char *options);