[PATCH v9 2/6] serial: 8250: create lsr_save_mask

[Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>]

Allow drivers to alter LSR save mask.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
 drivers/tty/serial/8250/8250.h      | 2 +-
 drivers/tty/serial/8250/8250_core.c | 4 ++++
 drivers/tty/serial/8250/8250_dw.c   | 2 +-
 include/linux/serial_8250.h         | 1 +
 4 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 0ff5688ba90c..5cc967fe3b59 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -138,7 +138,7 @@ static inline u16 serial_lsr_in(struct uart_8250_port *up)
 	u16 lsr = up->lsr_saved_flags;
 
 	lsr |= serial_in(up, UART_LSR);
-	up->lsr_saved_flags = lsr & LSR_SAVE_FLAGS;
+	up->lsr_saved_flags = lsr & up->lsr_save_mask;
 
 	return lsr;
 }
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 90ddc8924811..57e86133af4f 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1007,6 +1007,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
 		uart->port.rs485	= up->port.rs485;
 		uart->rs485_start_tx	= up->rs485_start_tx;
 		uart->rs485_stop_tx	= up->rs485_stop_tx;
+		uart->lsr_save_mask	= up->lsr_save_mask;
 		uart->dma		= up->dma;
 
 		/* Take tx_loadsz from fifosize if it wasn't set separately */
@@ -1094,6 +1095,9 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
 			ret = 0;
 		}
 
+		if (!uart->lsr_save_mask)
+			uart->lsr_save_mask = LSR_SAVE_FLAGS;	/* Use default LSR mask */
+
 		/* Initialise interrupt backoff work if required */
 		if (up->overrun_backoff_time_ms > 0) {
 			uart->overrun_backoff_time_ms =
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 4cc69bb612ab..167a691c7b19 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -129,7 +129,7 @@ static void dw8250_tx_wait_empty(struct uart_port *p)
 
 	while (tries--) {
 		lsr = readb (p->membase + (UART_LSR << p->regshift));
-		up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
+		up->lsr_saved_flags |= lsr & up->lsr_save_mask;
 
 		if (lsr & UART_LSR_TEMT)
 			break;
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 4565f25ba9a2..8c7b793aa4d7 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -120,6 +120,7 @@ struct uart_8250_port {
 	 */
 #define LSR_SAVE_FLAGS UART_LSR_BRK_ERROR_BITS
 	u16			lsr_saved_flags;
+	u16			lsr_save_mask;
 #define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
 	unsigned char		msr_saved_flags;
 
-- 
2.30.2