linux-kernel - [PATCH 04/16] serial: 8250: introduce RPM guard()s

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Message-ID: <20250814072456.182853-5-jirislaby@kernel.org>
Date: Thu, 14 Aug 2025 09:24:44 +0200
From: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Jiri Slaby (SUSE)" <jirislaby@...nel.org>
Subject: [PATCH 04/16] serial: 8250: introduce RPM guard()s

Having this, guards like these work:
  guard(serial8250_rpm)(up);
or
  scoped_guard(serial8250_rpm, up) {
    ...
  }

See e.g. "serial: 8250: use guard()s" later in this series.

And make them available to anyone (EXPORT + put in 8250.h) as drivers
open code this anyway.

The _tx ones are not defined as they would have no user.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
---
 drivers/tty/serial/8250/8250.h      | 5 +++++
 drivers/tty/serial/8250/8250_port.c | 6 ++++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index cfe6ba286b45..58e64c4e1e3a 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -186,6 +186,11 @@ static unsigned int __maybe_unused serial_icr_read(struct uart_8250_port *up,
 
 void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p);
 
+void serial8250_rpm_get(struct uart_8250_port *p);
+void serial8250_rpm_put(struct uart_8250_port *p);
+DEFINE_GUARD(serial8250_rpm, struct uart_8250_port *,
+	     serial8250_rpm_get(_T), serial8250_rpm_put(_T));
+
 static inline u32 serial_dl_read(struct uart_8250_port *up)
 {
 	return up->dl_read(up);
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 2da9db960d09..5afae4025696 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -508,20 +508,22 @@ void serial8250_clear_and_reinit_fifos(struct uart_8250_port *p)
 }
 EXPORT_SYMBOL_GPL(serial8250_clear_and_reinit_fifos);
 
-static void serial8250_rpm_get(struct uart_8250_port *p)
+void serial8250_rpm_get(struct uart_8250_port *p)
 {
 	if (!(p->capabilities & UART_CAP_RPM))
 		return;
 	pm_runtime_get_sync(p->port.dev);
 }
+EXPORT_SYMBOL_GPL(serial8250_rpm_get);
 
-static void serial8250_rpm_put(struct uart_8250_port *p)
+void serial8250_rpm_put(struct uart_8250_port *p)
 {
 	if (!(p->capabilities & UART_CAP_RPM))
 		return;
 	pm_runtime_mark_last_busy(p->port.dev);
 	pm_runtime_put_autosuspend(p->port.dev);
 }
+EXPORT_SYMBOL_GPL(serial8250_rpm_put);
 
 /**
  *	serial8250_em485_init() - put uart_8250_port into rs485 emulating
-- 
2.50.1