[PATCH 2/4] serial: Allow port type to be specified when calling serial8250_register_port.

[David Daney <ddaney@xxxxxxxxxxxxxxxxxx>]

Allow port type to be specified when calling serial8250_register_port.

Add flag value UPF_FIXED_TYPE which specifies that the UART type is
known and should not be probed.  For this case the UARTs properties
are just copied out of the uart_config entry.

Signed-off-by: David Daney <ddaney@xxxxxxxxxxxxxxxxxx>
---
drivers/serial/8250.c        |    8 ++++++++
drivers/serial/serial_core.c |    7 +++++--
include/linux/serial_core.h  |    2 ++
3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 02771d6..c575b61 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2975,6 +2975,14 @@ int serial8250_register_port(struct uart_port *port)
		uart->port.private_data = port->private_data;
		if (port->dev)
			uart->port.dev = port->dev;
+
+		if (port->flags & UPF_FIXED_TYPE) {
+			uart->port.type = port->type;
+			uart->port.fifosize = uart_config[port->type].fifo_size;
+			uart->capabilities = uart_config[port->type].flags;
+			uart->tx_loadsz = uart_config[port->type].tx_loadsz;
+		}
+
		set_io_fns_from_upio(&uart->port);
		/* Possibly override default I/O functions.  */
		if (port->serial_in_fn)
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index f977c98..65b8a74 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -2196,11 +2196,14 @@ uart_configure_port(struct uart_driver *drv, struct uart_state *state,
	 * Now do the auto configuration stuff.  Note that config_port
	 * is expected to claim the resources and map the port for us.
	 */
-	flags = UART_CONFIG_TYPE;
+	flags = 0;
	if (port->flags & UPF_AUTO_IRQ)
		flags |= UART_CONFIG_IRQ;
	if (port->flags & UPF_BOOT_AUTOCONF) {
-		port->type = PORT_UNKNOWN;
+		if (!(port->flags & UPF_FIXED_TYPE)) {
+			port->type = PORT_UNKNOWN;
+			flags |= UART_CONFIG_TYPE;
+		}
		port->ops->config_port(port, flags);
	}

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 3a4afcf..c68dc94 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -290,6 +290,8 @@ struct uart_port {
#define UPF_MAGIC_MULTIPLIER	((__force upf_t) (1 << 16))
#define UPF_CONS_FLOW		((__force upf_t) (1 << 23))
#define UPF_SHARE_IRQ		((__force upf_t) (1 << 24))
+/* The exact UART type is known and should not be probed.  */
+#define UPF_FIXED_TYPE		((__force upf_t) (1 << 27))
#define UPF_BOOT_AUTOCONF	((__force upf_t) (1 << 28))
#define UPF_FIXED_PORT		((__force upf_t) (1 << 29))
#define UPF_DEAD		((__force upf_t) (1 << 30))