Re: [PATCH v2 1/1] serial: core: Fix serial core port id, including multiport devices

[Andy Shevchenko]

On Fri, Aug 11, 2023 at 01:36:45PM +0300, Tony Lindgren wrote:
> 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.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

> Fixes: 7d695d83767c ("serial: core: Fix serial_base_match() after fixing controller port name")
> Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> Reviewed-by: Dhruva Gole <d-gole@xxxxxx>
> Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx>
> ---
> 
> Changes since v1:
> - Generated with --base as suggested by Andy, this is against tty-linus
> 
> - Initialized ida_alloc_range() values as suggested by Andy
> 
> - Added Reviewed-by from Dhruva
> 
> - Kept Guenter's Tested-by
> 
> ---
>  drivers/tty/serial/serial_base.h     |  1 +
>  drivers/tty/serial/serial_base_bus.c | 28 +++++++++++++++++++++++++++-
>  2 files changed, 28 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/serial_base.h b/drivers/tty/serial/serial_base.h
> --- 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
> --- 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);
>  }
>  
> 
> base-commit: a4a79e03bab57729bd8046d22bf3666912e586fb
> -- 
> 2.41.0

-- 
With Best Regards,
Andy Shevchenko