This is a note to let you know that I've just added the patch titled
serial: 8250: Export ICR access helpers for internal use
to the 5.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-8250-export-icr-access-helpers-for-internal-u.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 34ca14884906041c60b540d3ca0d53aaf39b4ef8
Author: Maciej W. Rozycki <macro@xxxxxxxxxxx>
Date: Mon Apr 18 16:27:27 2022 +0100
serial: 8250: Export ICR access helpers for internal use
[ Upstream commit cb5a40e3143bc64437858b337273fd63cc42e9c2 ]
Make ICR access helpers available outside 8250_port.c, however retain
them as ordinary static functions so as not to regress code generation.
This is because `serial_icr_write' is currently automatically inlined by
GCC, however `serial_icr_read' is not. Making them both static inline
would grow code produced, e.g.:
$ i386-linux-gnu-size --format=gnu 8250_port-{old,new}.o
text data bss total filename
15065 3378 0 18443 8250_port-old.o
15289 3378 0 18667 8250_port-new.o
and:
$ riscv64-linux-gnu-size --format=gnu 8250_port-{old,new}.o
text data bss total filename
16980 5306 0 22286 8250_port-old.o
17124 5306 0 22430 8250_port-new.o
while making them external would needlessly add a new module interface
and lose the benefit from `serial_icr_write' getting inlined outside
8250_port.o.
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2204181517500.9383@xxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index db784ace25d8..467372534d1c 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -120,6 +120,28 @@ static inline void serial_out(struct uart_8250_port *up, int offset, int value)
up->port.serial_out(&up->port, offset, value);
}
+/*
+ * For the 16C950
+ */
+static void serial_icr_write(struct uart_8250_port *up, int offset, int value)
+{
+ serial_out(up, UART_SCR, offset);
+ serial_out(up, UART_ICR, value);
+}
+
+static unsigned int __maybe_unused serial_icr_read(struct uart_8250_port *up,
+ int offset)
+{
+ unsigned int value;
+
+ serial_icr_write(up, UART_ACR, up->acr | UART_ACR_ICRRD);
+ serial_out(up, UART_SCR, offset);
+ value = serial_in(up, UART_ICR);
+ serial_icr_write(up, UART_ACR, up->acr);
+
+ return value;
+}
+
void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p);
static inline int serial_dl_read(struct uart_8250_port *up)
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index ddaf35daf316..291fd99bd7f1 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -537,27 +537,6 @@ serial_port_out_sync(struct uart_port *p, int offset, int value)
}
}
-/*
- * For the 16C950
- */
-static void serial_icr_write(struct uart_8250_port *up, int offset, int value)
-{
- serial_out(up, UART_SCR, offset);
- serial_out(up, UART_ICR, value);
-}
-
-static unsigned int serial_icr_read(struct uart_8250_port *up, int offset)
-{
- unsigned int value;
-
- serial_icr_write(up, UART_ACR, up->acr | UART_ACR_ICRRD);
- serial_out(up, UART_SCR, offset);
- value = serial_in(up, UART_ICR);
- serial_icr_write(up, UART_ACR, up->acr);
-
- return value;
-}
-
/*
* FIFO support.
*/
