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| author | Maciej W. Rozycki <macro@orcam.me.uk> | 2022-04-18 18:27:27 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-05 23:36:46 +0300 |
| commit | cb5a40e3143bc64437858b337273fd63cc42e9c2 (patch) | |
| tree | 96e8941237d08cd2bb837b5e72ac81518c55f906 /drivers/tty/serial/8250/8250.h | |
| parent | 1f32c65bad24b9787d3e52843de375430e3df822 (diff) | |
| download | linux-cb5a40e3143bc64437858b337273fd63cc42e9c2.tar.xz | |
serial: 8250: Export ICR access helpers for internal use
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@orcam.me.uk>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2204181517500.9383@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/8250/8250.h')
| -rw-r--r-- | drivers/tty/serial/8250/8250.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 5a4e05c0e552..d70adaa3b117 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -123,6 +123,28 @@ 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) |