serial: core: Add UPIO_UNKNOWN constant for unknown port type

[ Upstream commit 79d713baf63c8f23cc58b304c40be33d64a12aaf ]

In some APIs we would like to assign the special value to iotype
and compare against it in another places. Introduce UPIO_UNKNOWN
for this purpose.

Note, we can't use 0, because it's a valid value for IO port access.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240304123035.758700-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 87d80bfbd577 ("serial: 8250_dw: Don't use struct dw8250_data outside of 8250_dw")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Andy Shevchenko 2024-03-04 14:27:03 +02:00 committed by Greg Kroah-Hartman
parent 1006d1b5eb
commit 68a53d1212

View File

@ -470,6 +470,7 @@ struct uart_port {
unsigned char iotype; /* io access style */
unsigned char quirks; /* internal quirks */
#define UPIO_UNKNOWN ((unsigned char)~0U) /* UCHAR_MAX */
#define UPIO_PORT (SERIAL_IO_PORT) /* 8b I/O port access */
#define UPIO_HUB6 (SERIAL_IO_HUB6) /* Hub6 ISA card */
#define UPIO_MEM (SERIAL_IO_MEM) /* driver-specific */