Re: [PATCH 1/2] serial: 8250: Allow port registration without UPF_BOOT_AUTOCONF

Andy Shevchenko
2019-04-26T14:39:54Z

On Fri, Apr 26, 2019 at 10:40:37AM +0200, Esben Haabendal wrote:
> With serial8250_register_8250_port() forcing UPF_BOOT_AUTOCONF bit on, it
> is not possible to register a port without having
> serial8250_request_std_resource() called.
>
> For adding a 8250 port to an MFD device, this is problematic, as the
> request_mem_region() call will fail, as the MFD device (and rightly so)
> has requested the region. For this case, the 8250 port should accept
> having passed mapbase and membase, and just use that.

You need to simple set port type and use UPF_FIXED_TYPE.
No need for this patch.

>
> Signed-off-by: Esben Haabendal <esben@geanix.com>
> ---
> drivers/tty/serial/8250/8250_core.c | 36 +++++++++++++++++++++---------------
> include/linux/serial_8250.h | 2 ++
> 2 files changed, 23 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
> index e441221..ddbb0a0 100644
> --- a/drivers/tty/serial/8250/8250_core.c
> +++ b/drivers/tty/serial/8250/8250_core.c
> @@ -957,20 +957,8 @@ static void serial_8250_overrun_backoff_work(struct work_struct *work)
> spin_unlock_irqrestore(&port->lock, flags);
> }
>
> -/**
> - * serial8250_register_8250_port - register a serial port
> - * @up: serial port template
> - *
> - * Configure the serial port specified by the request. If the
> - * port exists and is in use, it is hung up and unregistered
> - * first.
> - *
> - * The port is then probed and if necessary the IRQ is autodetected
> - * If this fails an error is returned.
> - *
> - * On success the port is ready to use and the line number is returned.
> - */
> -int serial8250_register_8250_port(struct uart_8250_port *up)
> +int __serial8250_register_8250_port(struct uart_8250_port *up,
> + unsigned int extra_flags)
> {
> struct uart_8250_port *uart;
> int ret = -ENOSPC;
> @@ -993,7 +981,7 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
> uart->port.fifosize = up->port.fifosize;
> uart->port.regshift = up->port.regshift;
> uart->port.iotype = up->port.iotype;
> - uart->port.flags = up->port.flags | UPF_BOOT_AUTOCONF;
> + uart->port.flags = up->port.flags | extra_flags;
> uart->bugs = up->bugs;
> uart->port.mapbase = up->port.mapbase;
> uart->port.mapsize = up->port.mapsize;
> @@ -1086,6 +1074,24 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
>
> return ret;
> }
> +
> +/**
> + * serial8250_register_8250_port - register a serial port
> + * @up: serial port template
> + *
> + * Configure the serial port specified by the request. If the
> + * port exists and is in use, it is hung up and unregistered
> + * first.
> + *
> + * The port is then probed and if necessary the IRQ is autodetected
> + * If this fails an error is returned.
> + *
> + * On success the port is ready to use and the line number is returned.
> + */
> +int serial8250_register_8250_port(struct uart_8250_port *up)
> +{
> + return __serial8250_register_8250_port(up, UPF_BOOT_AUTOCONF);
> +}
> EXPORT_SYMBOL(serial8250_register_8250_port);
>
> /**
> diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
> index 5a655ba..9d1fe2e 100644
> --- a/include/linux/serial_8250.h
> +++ b/include/linux/serial_8250.h
> @@ -145,6 +145,8 @@ static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up)
> return container_of(up, struct uart_8250_port, port);
> }
>
> +extern int __serial8250_register_8250_port(struct uart_8250_port *,
> + unsigned int);
> int serial8250_register_8250_port(struct uart_8250_port *);
> void serial8250_unregister_port(int line);
> void serial8250_suspend_port(int line);
> --
> 2.4.11
>

--
With Best Regards,
Andy Shevchenko