serial: uniformize serial port I/O infos display

Uniformize serial port I/O infos display from three different functions
that display mostly the same information, but with some variations, by
adding a common function.

This make use of new functions uart_iotype_mmio() and
uart_iotype_legacy_io() to simplify and improve code readability.
This will prevent displaying irrelevant information for future IO types
(ex: UPIO_BUS), while also addressing the (eventually) invalid check for
"iotype >= UPIO_MEM".

This also allows us to remove the confusing cast to (unsigned long long)
for iobase which is defined as an unsigned long, and use %pa to display the
mapbase pointer, as it is done in earlycon_print_info().

Replace snprintf with more robust scnprintf so we could perhaps one day get
rid of snprintf() entirely.

Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://patch.msgid.link/20260521-tty-upio-v3-4-bf74567994a0@dimonoff.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/earlycon.c

@@ -75,19 +75,12 @@ static void __init earlycon_print_info(struct earlycon_device *device)
 {
 	struct console *earlycon = device->con;
 	struct uart_port *port = &device->port;
+	char ioinfos[64];
 
-	if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
+	uart_get_ioinfos(port, ioinfos, sizeof(ioinfos));
-	    port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
+
-		pr_info("%s%d at MMIO%s %pa (options '%s')\n",
+	pr_info("%s%d%s (options '%s')\n", earlycon->name, earlycon->index,
-			earlycon->name, earlycon->index,
+		ioinfos, device->options);
-			(port->iotype == UPIO_MEM) ? "" :
-			(port->iotype == UPIO_MEM16) ? "16" :
-			(port->iotype == UPIO_MEM32) ? "32" : "32be",
-			&port->mapbase, device->options);
-	else
-		pr_info("%s%d at I/O port 0x%lx (options '%s')\n",
-			earlycon->name, earlycon->index,
-			port->iobase, device->options);
 }
 
 static int __init parse_options(struct earlycon_device *device, char *options)

drivers/tty/serial/serial_core.c

@@ -1998,9 +1998,9 @@ static void uart_line_info(struct seq_file *m, struct uart_state *state)
 	struct tty_port *port = &state->port;
 	enum uart_pm_state pm_state;
 	struct uart_port *uport;
+	char ioinfos[64];
 	char stat_buf[32];
 	unsigned int status;
-	int mmio;
 
 	guard(mutex)(&port->mutex);
 
@@ -2008,13 +2008,10 @@ static void uart_line_info(struct seq_file *m, struct uart_state *state)
 	if (!uport)
 		return;
 
-	mmio = uport->iotype >= UPIO_MEM;
+	seq_printf(m, "%u: uart:%s", uport->line, uart_type(uport));
-	seq_printf(m, "%u: uart:%s %s%08llX irq:%u",
+	uart_get_ioinfos(uport, ioinfos, sizeof(ioinfos));
-			uport->line, uart_type(uport),
+	seq_printf(m, "%s", ioinfos);
-			mmio ? "mmio:0x" : "port:",
+	seq_printf(m, " irq:%u", uport->irq);
-			mmio ? (unsigned long long)uport->mapbase
-			     : (unsigned long long)uport->iobase,
-			uport->irq);
 
 	if (uport->type == PORT_UNKNOWN) {
 		seq_putc(m, '\n');
@@ -2488,38 +2485,47 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
 }
 EXPORT_SYMBOL(uart_resume_port);
 
+static const char *uart_get_mmio_width(struct uart_port *port)
+{
+	switch (port->iotype) {
+	case UPIO_MEM16:
+		return "16";
+	case UPIO_MEM32:
+	case UPIO_MEM32BE:
+		return "32be";
+	case UPIO_AU:
+	case UPIO_MEM:
+	default:
+		return "";
+	}
+}
+
+void uart_get_ioinfos(struct uart_port *port, char *buf, size_t size)
+{
+	buf[0] = '\0';
+
+	if (uart_iotype_mmio(port->iotype)) {
+		scnprintf(buf, size, " MMIO%s:%pa", uart_get_mmio_width(port), &port->mapbase);
+	} else if (uart_iotype_io(port->iotype)) {
+		if (port->iotype == UPIO_PORT)
+			scnprintf(buf, size, " I/O:0x%lx", port->iobase);
+		else if (port->iotype == UPIO_HUB6)
+			scnprintf(buf, size, " I/O:0x%lx, offset 0x%x", port->iobase, port->hub6);
+	}
+}
+EXPORT_SYMBOL(uart_get_ioinfos);
+
 static inline void
 uart_report_port(struct uart_driver *drv, struct uart_port *port)
 {
-	char address[64];
+	char ioinfos[64];
 
-	switch (port->iotype) {
+	uart_get_ioinfos(port, ioinfos, sizeof(ioinfos));
-	case UPIO_PORT:
-		snprintf(address, sizeof(address), "I/O 0x%lx", port->iobase);
-		break;
-	case UPIO_HUB6:
-		snprintf(address, sizeof(address),
-			 "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
-		break;
-	case UPIO_MEM:
-	case UPIO_MEM16:
-	case UPIO_MEM32:
-	case UPIO_MEM32BE:
-	case UPIO_AU:
-	case UPIO_TSI:
-		snprintf(address, sizeof(address),
-			 "MMIO 0x%llx", (unsigned long long)port->mapbase);
-		break;
-	default:
-		strscpy(address, "*unknown*", sizeof(address));
-		break;
-	}
 
-	pr_info("%s%s%s at %s (irq = %u, base_baud = %u) is a %s\n",
+	pr_info("%s%s%s%s (irq = %u, base_baud = %u) is a %s\n",
 		port->dev ? dev_name(port->dev) : "",
 		port->dev ? ": " : "",
-	       port->name,
+		port->name, ioinfos, port->irq, port->uartclk / 16, uart_type(port));
-	       address, port->irq, port->uartclk / 16, uart_type(port));
 
 	/* The magic multiplier feature is a bit obscure, so report it too.  */
 	if (port->flags & UPF_MAGIC_MULTIPLIER)

include/linux/serial_core.h

@@ -1339,6 +1339,7 @@ static inline int uart_handle_break(struct uart_port *port)
 
 int uart_get_rs485_mode(struct uart_port *port);
 
+void uart_get_ioinfos(struct uart_port *port, char *buf, size_t size);
 bool uart_iotype_mmio(enum uart_iotype iotype);
 bool uart_iotype_io(enum uart_iotype iotype);