tty: serial_core: Add name field to uart_port struct

Introduce a field to store name of uart_port that can be used to easily
identify UART port instances on a system that has more than one UART
instance. The name is of the form ttyXN(eg. ttyS0, ttyAMA0,..) where N
is number that particular UART instance.
This field will be useful when printing debug info for a particular port
or in register IRQs with unique IRQ name. Port name is populated during
uart_add_one_port().
Signed-off-by: Vignesh R <vigneshr@ti.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/serial_core.c

@@ -2744,6 +2744,12 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport)
 	state->pm_state = UART_PM_STATE_UNDEFINED;
 	uport->cons = drv->cons;
 	uport->minor = drv->tty_driver->minor_start + uport->line;
+	uport->name = kasprintf(GFP_KERNEL, "%s%d", drv->dev_name,
+				drv->tty_driver->name_base + uport->line);
+	if (!uport->name) {
+		ret = -ENOMEM;
+		goto out;
+	}
 
 	/*
 	 * If this port is a console, then the spinlock is already
@@ -2861,6 +2867,7 @@ int uart_remove_one_port(struct uart_driver *drv, struct uart_port *uport)
 	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
 		uport->ops->release_port(uport);
 	kfree(uport->tty_groups);
+	kfree(uport->name);
 
 	/*
 	 * Indicate that there isn't a port here anymore.

include/linux/serial_core.h

@@ -247,6 +247,7 @@ struct uart_port {
 	unsigned char		suspended;
 	unsigned char		irq_wake;
 	unsigned char		unused[2];
+	char			*name;			/* port name */
 	struct attribute_group	*attr_group;		/* port specific attributes */
 	const struct attribute_group **tty_groups;	/* all attributes (serial core use only) */
 	struct serial_rs485     rs485;