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Message-Id: <20230508111903.39339-1-tony@atomide.com>
Date: Mon, 8 May 2023 14:19:02 +0300
From: Tony Lindgren <tony@...mide.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>
Cc: Andy Shevchenko <andriy.shevchenko@...el.com>,
Dhruva Gole <d-gole@...com>,
Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
Johan Hovold <johan@...nel.org>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Vignesh Raghavendra <vigneshr@...com>,
linux-omap@...r.kernel.org, Andrew Davis <afd@...com>,
linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] 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: Andrew Davis <afd@...com>
Signed-off-by: Tony Lindgren <tony@...mide.com>
---
drivers/tty/serial/8250/8250_core.c | 86 +++++++++++++++++++++--------
1 file changed, 63 insertions(+), 23 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -488,6 +488,34 @@ static inline void serial8250_apply_quirks(struct uart_8250_port *up)
up->port.quirks |= skip_txen_test ? UPQ_NO_TXEN_TEST : 0;
}
+static struct uart_8250_port *serial8250_setup_port(int index)
+{
+ struct uart_8250_port *up;
+
+ if (index >= UART_NR)
+ return NULL;
+
+ up = &serial8250_ports[index];
+ up->port.line = index;
+
+ serial8250_init_port(up);
+ if (!base_ops)
+ base_ops = up->port.ops;
+ up->port.ops = &univ8250_port_ops;
+
+ timer_setup(&up->timer, serial8250_timeout, 0);
+
+ up->ops = &univ8250_driver_ops;
+
+ if (IS_ENABLED(CONFIG_ALPHA_JENSEN) ||
+ (IS_ENABLED(CONFIG_ALPHA_GENERIC) && alpha_jensen()))
+ 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;
@@ -501,26 +529,13 @@ static void __init serial8250_isa_init_ports(void)
if (nr_uarts > UART_NR)
nr_uarts = UART_NR;
- for (i = 0; i < nr_uarts; i++) {
- struct uart_8250_port *up = &serial8250_ports[i];
- struct uart_port *port = &up->port;
-
- port->line = i;
- serial8250_init_port(up);
- if (!base_ops)
- base_ops = port->ops;
- port->ops = &univ8250_port_ops;
-
- timer_setup(&up->timer, serial8250_timeout, 0);
-
- up->ops = &univ8250_driver_ops;
-
- if (IS_ENABLED(CONFIG_ALPHA_JENSEN) ||
- (IS_ENABLED(CONFIG_ALPHA_GENERIC) && alpha_jensen()))
- port->set_mctrl = alpha_jensen_set_mctrl;
-
- serial8250_set_defaults(up);
- }
+ /*
+ * 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;
@@ -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;
--
2.40.1
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