Let's allow the userspace to find out the tty name for a serial core
controller id if a tty exists. This can be done with:
$ grep DEVNAME /sys/bus/serial-base/devices/port*/tty/uevent
/sys/bus/serial-base/devices/port.00:04.0/tty/uevent:DEVNAME=ttyS0
/sys/bus/serial-base/devices/port.serial8250.1/tty/uevent:DEVNAME=ttyS1
/sys/bus/serial-base/devices/port.serial8250.2/tty/uevent:DEVNAME=ttyS2
/sys/bus/serial-base/devices/port.serial8250.3/tty/uevent:DEVNAME=ttyS3
And with this, we can add /dev/serial/by-id symlinks to the serial port
device instances so we can start using serial core port addressing in
addition to the legacy ttyS naming.
The naming we can use is dev_name:0.0 where 0.0 are the serial core
controller id and port id, so for the ttyS0 example above the naming
would be 00:04.0:0.0.
Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
---
Note that this depends on fix for serial core port ids patch
"[PATCH] serial: core: Fix serial core port id to not use port->line"
---
drivers/tty/serial/serial_core.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -3371,6 +3371,8 @@ static int serial_core_add_preferred_console(struct uart_driver *drv,
int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
{
struct serial_ctrl_device *ctrl_dev, *new_ctrl_dev = NULL;
+ struct uart_match match = {port, drv};
+ struct device *tty_dev;
int ret;
mutex_lock(&port_mutex);
@@ -3411,10 +3413,21 @@ int serial_core_register_port(struct uart_driver *drv, struct uart_port *port)
port->flags &= ~UPF_DEAD;
+ tty_dev = device_find_child(port->dev, &match, serial_match_port);
+ if (tty_dev) {
+ ret = sysfs_create_link(&port->port_dev->dev.kobj, &tty_dev->kobj,
+ "tty");
+ if (ret)
+ goto err_remove_port;
+ }
+
mutex_unlock(&port_mutex);
return 0;
+err_remove_port:
+ serial_core_remove_one_port(drv, port);
+
err_unregister_port_dev:
serial_base_port_device_remove(port->port_dev);
@@ -3436,12 +3449,18 @@ void serial_core_unregister_port(struct uart_driver *drv, struct uart_port *port
struct device *phys_dev = port->dev;
struct serial_port_device *port_dev = port->port_dev;
struct serial_ctrl_device *ctrl_dev = serial_core_get_ctrl_dev(port_dev);
+ struct uart_match match = {port, drv};
int ctrl_id = port->ctrl_id;
+ struct device *tty_dev;
mutex_lock(&port_mutex);
port->flags |= UPF_DEAD;
+ tty_dev = device_find_child(port->dev, &match, serial_match_port);
+ if (tty_dev)
+ sysfs_remove_link(&port->port_dev->dev.kobj, "tty");
+
serial_core_remove_one_port(drv, port);
/* Note that struct uart_port *port is no longer valid at this point */
--
2.41.0
