Commit 9d86719f authored by Tony Lindgren's avatar Tony Lindgren Committed by Greg Kroah-Hartman
Browse files

serial: 8250: Allow using ports higher than SERIAL_8250_RUNTIME_UARTS 



We already allocate CONFIG_SERIAL_8250_NR_UARTS, but only allow using
CONFIG_SERIAL_8250_RUNTIME_UARTS uarts unless nr_uarts module params
is set. This causes issues for using distro kernels on SoCs with a
large number of serial ports.

Let's allow up to CONFIG_SERIAL_8250_NR_UARTS instead. To do this, we init
the ports as needed if the initial uarts was too low. This way there's no
need to set the value for CONFIG_SERIAL_8250_RUNTIME_UARTS to some SoC
specific higher value. Typically the default value of 4 can be used as
set for legacy reasons.

Note that limiting the number of intial uarts still works as before
unless a serial console on a higher port is specified. In this case we
will increase the nr_ports up to the console port specified.

Suggested-by: default avatarAndrew Davis <afd@ti.com>
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20230508111903.39339-1-tony@atomide.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent db86bb6e

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

+63 −23
Original line number Diff line number Diff line
@@ -488,28 +488,20 @@ static inline void serial8250_apply_quirks(struct uart_8250_port *up) 
	up->port.quirks |= skip_txen_test ? UPQ_NO_TXEN_TEST : 0;

}



static void __init serial8250_isa_init_ports(void)

static struct uart_8250_port *serial8250_setup_port(int index)

{

	struct uart_8250_port *up;

	static int first = 1;

	int i, irqflag = 0;



	if (!first)

		return;

	first = 0;



	if (nr_uarts > UART_NR)

		nr_uarts = UART_NR;

	if (index >= UART_NR)

		return NULL;



	for (i = 0; i < nr_uarts; i++) {

		struct uart_8250_port *up = &serial8250_ports[i];

		struct uart_port *port = &up->port;

	up = &serial8250_ports[index];

	up->port.line = index;



		port->line = i;

	serial8250_init_port(up);

	if (!base_ops)

			base_ops = port->ops;

		port->ops = &univ8250_port_ops;

		base_ops = up->port.ops;

	up->port.ops = &univ8250_port_ops;



	timer_setup(&up->timer, serial8250_timeout, 0);
@@ -517,11 +509,34 @@ static void __init serial8250_isa_init_ports(void) 


	if (IS_ENABLED(CONFIG_ALPHA_JENSEN) ||

	    (IS_ENABLED(CONFIG_ALPHA_GENERIC) && alpha_jensen()))

			port->set_mctrl = alpha_jensen_set_mctrl;

		up->port.set_mctrl = alpha_jensen_set_mctrl;



	serial8250_set_defaults(up);



	return up;

}



static void __init serial8250_isa_init_ports(void)

{

	struct uart_8250_port *up;

	static int first = 1;

	int i, irqflag = 0;



	if (!first)

		return;

	first = 0;



	if (nr_uarts > UART_NR)

		nr_uarts = UART_NR;



	/*

	 * Set up initial isa ports based on nr_uart module param, or else

	 * default to CONFIG_SERIAL_8250_RUNTIME_UARTS. Note that we do not

	 * need to increase nr_uarts when setting up the initial isa ports.

	 */

	for (i = 0; i < nr_uarts; i++)

		serial8250_setup_port(i);



	/* chain base port ops to support Remote Supervisor Adapter */

	univ8250_port_ops = *base_ops;

	univ8250_rsa_support(&univ8250_port_ops);
@@ -586,16 +601,29 @@ static void univ8250_console_write(struct console *co, const char *s, 


static int univ8250_console_setup(struct console *co, char *options)

{

	struct uart_8250_port *up;

	struct uart_port *port;

	int retval;

	int retval, i;



	/*

	 * Check whether an invalid uart number has been specified, and

	 * if so, search for the first available port that does have

	 * console support.

	 */

	if (co->index >= nr_uarts)

	if (co->index >= UART_NR)

		co->index = 0;



	/*

	 * If the console is past the initial isa ports, init more ports up to

	 * co->index as needed and increment nr_uarts accordingly.

	 */

	for (i = nr_uarts; i <= co->index; i++) {

		up = serial8250_setup_port(i);

		if (!up)

			return -ENODEV;

		nr_uarts++;

	}



	port = &serial8250_ports[co->index].port;

	/* link port to console */

	port->cons = co;
@@ -990,7 +1018,18 @@ int serial8250_register_8250_port(const struct uart_8250_port *up) 
	mutex_lock(&serial_mutex);



	uart = serial8250_find_match_or_unused(&up->port);

	if (uart && uart->port.type != PORT_8250_CIR) {

	if (!uart) {

		/*

		 * If the port is past the initial isa ports, initialize a new

		 * port and increment nr_uarts accordingly.

		 */

		uart = serial8250_setup_port(nr_uarts);

		if (!uart)

			goto unlock;

		nr_uarts++;

	}



	if (uart->port.type != PORT_8250_CIR) {

		struct mctrl_gpios *gpios;



		if (uart->port.dev)
@@ -1120,6 +1159,7 @@ int serial8250_register_8250_port(const struct uart_8250_port *up) 
		}

	}



unlock:

	mutex_unlock(&serial_mutex);



	return ret;