serial: core: Fix serial core port id, including multiport devices

We want to fix the serial core port DEVNAME to use a port id of the
hardware specific controller port instance instead of the port->line.

For example, the 8250 driver sets up a number of serial8250 ports
initially that can be inherited by the hardware specific driver. At that
the port->line no longer decribes the port's relation to the serial core
controller instance.

Let's fix the issue by assigning port->port_id for each serial core
controller port instance.

Fixes: 7d695d83767c ("serial: core: Fix serial_base_match() after fixing controller port name")
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230811103648.2826-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/serial_base.h b/drivers/tty/serial/serial_base.h
index 9faac0f..c74c548 100644 (file)
--- a/drivers/tty/serial/serial_base.h
+++ b/drivers/tty/serial/serial_base.h
@@ -16,6 +16,7 @@ struct device;
 
 struct serial_ctrl_device {
        struct device dev;
+       struct ida port_ida;
 };
 
 struct serial_port_device {

diff --git a/drivers/tty/serial/serial_base_bus.c b/drivers/tty/serial/serial_base_bus.c
index e446c57..3dfcf20 100644 (file)
--- a/drivers/tty/serial/serial_base_bus.c
+++ b/drivers/tty/serial/serial_base_bus.c
@@ -10,6 +10,7 @@
 
 #include <linux/container_of.h>
 #include <linux/device.h>
+#include <linux/idr.h>
 #include <linux/module.h>
 #include <linux/serial_core.h>
 #include <linux/slab.h>
@@ -112,6 +113,8 @@ struct serial_ctrl_device *serial_base_ctrl_add(struct uart_port *port,
        if (!ctrl_dev)
                return ERR_PTR(-ENOMEM);
 
+       ida_init(&ctrl_dev->port_ida);
+
        err = serial_base_device_init(port, &ctrl_dev->dev,
                                      parent, &serial_ctrl_type,
                                      serial_base_ctrl_release,
@@ -142,16 +145,31 @@ struct serial_port_device *serial_base_port_add(struct uart_port *port,
                                                struct serial_ctrl_device *ctrl_dev)
 {
        struct serial_port_device *port_dev;
+       int min = 0, max = -1;  /* Use -1 for max to apply IDA defaults */
        int err;
 
        port_dev = kzalloc(sizeof(*port_dev), GFP_KERNEL);
        if (!port_dev)
                return ERR_PTR(-ENOMEM);
 
+       /* Device driver specified port_id vs automatic assignment? */
+       if (port->port_id) {
+               min = port->port_id;
+               max = port->port_id;
+       }
+
+       err = ida_alloc_range(&ctrl_dev->port_ida, min, max, GFP_KERNEL);
+       if (err < 0) {
+               kfree(port_dev);
+               return ERR_PTR(err);
+       }
+
+       port->port_id = err;
+
        err = serial_base_device_init(port, &port_dev->dev,
                                      &ctrl_dev->dev, &serial_port_type,
                                      serial_base_port_release,
-                                     port->ctrl_id, port->line);
+                                     port->ctrl_id, port->port_id);
        if (err)
                goto err_put_device;
 
@@ -165,16 +183,24 @@ struct serial_port_device *serial_base_port_add(struct uart_port *port,
 
 err_put_device:
        put_device(&port_dev->dev);
+       ida_free(&ctrl_dev->port_ida, port->port_id);
 
        return ERR_PTR(err);
 }
 
 void serial_base_port_device_remove(struct serial_port_device *port_dev)
 {
+       struct serial_ctrl_device *ctrl_dev;
+       struct device *parent;
+
        if (!port_dev)
                return;
 
+       parent = port_dev->dev.parent;
+       ctrl_dev = to_serial_base_ctrl_device(parent);
+
        device_del(&port_dev->dev);
+       ida_free(&ctrl_dev->port_ida, port_dev->port->port_id);
        put_device(&port_dev->dev);
 }