diff options
Diffstat (limited to 'drivers/tty/serial/8250/8250.h')
| -rw-r--r-- | drivers/tty/serial/8250/8250.h | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 696030cfcb09..c89cb881d9b0 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -123,6 +123,26 @@ static inline void serial_out(struct uart_8250_port *up, int offset, int value) up->port.serial_out(&up->port, offset, value); } +/** + * serial_lsr_in - Read LSR register and preserve flags across reads + * @up: uart 8250 port + * + * Read LSR register and handle saving non-preserved flags across reads. + * The flags that are not preserved across reads are stored into + * up->lsr_saved_flags. + * + * Returns LSR value or'ed with the preserved flags (if any). + */ +static inline unsigned int serial_lsr_in(struct uart_8250_port *up) +{ + unsigned int lsr = up->lsr_saved_flags; + + lsr |= serial_in(up, UART_LSR); + up->lsr_saved_flags = lsr & LSR_SAVE_FLAGS; + + return lsr; +} + /* * For the 16C950 */ |