serial: fix device name reporting when minor space is shared between drivers

The multiple drivers share the minor space occupied by a particular major
number, the actual index within the device name's space is indicated by
the tty_driver->name_base + uart_port->line

Another usable formula is (uart_driver->minor - MINOR_BASE) + port->line

Use those to print the device names properly in such situations in
serial_core.c and 8250.c

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/serial/8250.c

@@ -57,6 +57,13 @@ static unsigned int share_irqs = SERIAL8250_SHARE_IRQS;
 
 static unsigned int nr_uarts = CONFIG_SERIAL_8250_RUNTIME_UARTS;
 
+static struct uart_driver serial8250_reg;
+
+static int serial_index(struct uart_port *port)
+{
+	return (serial8250_reg.minor - 64) + port->line;
+}
+
 /*
  * Debugging.
  */
@@ -997,7 +1004,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
 		return;
 
 	DEBUG_AUTOCONF("ttyS%d: autoconf (0x%04x, 0x%p): ",
-			up->port.line, up->port.iobase, up->port.membase);
+		       serial_index(&up->port), up->port.iobase, up->port.membase);
 
 	/*
 	 * We really do need global IRQs disabled here - we're going to
@@ -1132,8 +1139,8 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
 	if (up->capabilities != uart_config[up->port.type].flags) {
 		printk(KERN_WARNING
 		       "ttyS%d: detected caps %08x should be %08x\n",
-			up->port.line, up->capabilities,
-			uart_config[up->port.type].flags);
+		       serial_index(&up->port), up->capabilities,
+		       uart_config[up->port.type].flags);
 	}
 
 	up->port.fifosize = uart_config[up->port.type].fifo_size;
@@ -1857,7 +1864,8 @@ static int serial8250_startup(struct uart_port *port)
 	 */
 	if (!(up->port.flags & UPF_BUGGY_UART) &&
 	    (serial_inp(up, UART_LSR) == 0xff)) {
-		printk("ttyS%d: LSR safety check engaged!\n", up->port.line);
+		printk(KERN_INFO "ttyS%d: LSR safety check engaged!\n",
+		       serial_index(&up->port));
 		return -ENODEV;
 	}
 
@@ -1912,7 +1920,8 @@ static int serial8250_startup(struct uart_port *port)
 		 */
 		if (!(iir1 & UART_IIR_NO_INT) && (iir & UART_IIR_NO_INT)) {
 			up->bugs |= UART_BUG_THRE;
-			pr_debug("ttyS%d - using backup timer\n", port->line);
+			pr_debug("ttyS%d - using backup timer\n",
+				 serial_index(port));
 		}
 	}
 
@@ -1972,7 +1981,7 @@ static int serial8250_startup(struct uart_port *port)
 		if (!(up->bugs & UART_BUG_TXEN)) {
 			up->bugs |= UART_BUG_TXEN;
 			pr_debug("ttyS%d - enabling bad tx status workarounds\n",
-				 port->line);
+				 serial_index(port));
 		}
 	} else {
 		up->bugs &= ~UART_BUG_TXEN;
@@ -2633,7 +2642,6 @@ static int serial8250_console_early_setup(void)
 	return serial8250_find_port_for_earlycon();
 }
 
-static struct uart_driver serial8250_reg;
 static struct console serial8250_console = {
 	.name		= "ttyS",
 	.write		= serial8250_console_write,

drivers/serial/serial_core.c

@@ -2051,7 +2051,8 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
 					"transmitter\n",
 			       port->dev ? port->dev->bus_id : "",
 			       port->dev ? ": " : "",
-			       drv->dev_name, port->line);
+			       drv->dev_name,
+			       drv->tty_driver->name_base + port->line);
 
 		ops->shutdown(port);
 	}
@@ -2176,7 +2177,9 @@ uart_report_port(struct uart_driver *drv, struct uart_port *port)
 	printk(KERN_INFO "%s%s%s%d at %s (irq = %d) is a %s\n",
 	       port->dev ? port->dev->bus_id : "",
 	       port->dev ? ": " : "",
-	       drv->dev_name, port->line, address, port->irq, uart_type(port));
+	       drv->dev_name,
+	       drv->tty_driver->name_base + port->line,
+	       address, port->irq, uart_type(port));
 }
 
 static void