serial: core: Fix serial core port id to not use port->line

The serial core port id should be serial core controller specific port
instance, which is not always the port->line index.

For example, 8250 driver maps a number of legacy ports, and when a
hardware specific device driver takes over, we typically have one
driver instance for each port. Let's instead add port->port_id to
keep track serial ports mapped to each serial core controller instance.

Currently this is only a cosmetic issue for the serial core port device
names. The issue can be noticed looking at /sys/bus/serial-base/devices
for example though. Let's fix the issue to avoid port addressing issues
later on.

Fixes: 84a9582 ("serial: core: Start managing serial controllers to enable runtime PM")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20230725054216.45696-3-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_core.c

@@ -497,6 +497,7 @@ static struct uart_8250_port *serial8250_setup_port(int index)
 
 	up = &serial8250_ports[index];
 	up->port.line = index;
+	up->port.port_id = index;
 
 	serial8250_init_port(up);
 	if (!base_ops)
@@ -1040,6 +1041,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up)
 			uart_remove_one_port(&serial8250_reg, &uart->port);
 
 		uart->port.ctrl_id	= up->port.ctrl_id;
+		uart->port.port_id	= up->port.port_id;
 		uart->port.iobase       = up->port.iobase;
 		uart->port.membase      = up->port.membase;
 		uart->port.irq          = up->port.irq;

drivers/tty/serial/serial_base_bus.c

@@ -136,7 +136,7 @@ struct serial_port_device *serial_base_port_add(struct uart_port *port,
 	err = serial_base_device_init(port, &port_dev->dev,
 				      &ctrl_dev->dev, &serial_port_type,
 				      serial_base_port_release,
-				      port->line);
+				      port->port_id);
 	if (err)
 		goto err_put_device;
 

include/linux/serial_core.h

@@ -460,6 +460,7 @@ struct uart_port {
 	int			(*iso7816_config)(struct uart_port *,
 						  struct serial_iso7816 *iso7816);
 	unsigned int		ctrl_id;		/* optional serial core controller id */
+	unsigned int		port_id;		/* optional serial core port id */
 	unsigned int		irq;			/* irq number */
 	unsigned long		irqflags;		/* irq flags  */
 	unsigned int		uartclk;		/* base uart clock */