On 08/05/2015 11:43 AM, Maciej S. Szmigiero wrote:
> CIR type serial ports aren't real serial ports.
>
> This is just a way to prevent legacy 8250 serial
> driver from probing and eventually binding some
> resources.
>
> Since in current state such ports aren't providing
> any real functionality and it is not possible
> to change their type via setserial/ioctl(TIOCSSERIAL)
> (due to UPF_FIXED_PORT flag set on them)
> it is simpler and cleaner to not register them at all
> with serial core.
The only thing I think this patch is missing is either a comment
or specific code in serial8250_register_ports() regarding not
adding PORT_8250_CIR-type ports.
Like either:
static void __init
serial8250_register_ports(struct uart_driver *drv, struct device *dev)
{
int i;
for (i = 0; i < nr_uarts; i++) {
struct uart_8250_port *up = &serial8250_ports[i];
+ /* PORT_8250_CIR-type ports must have non-NULL dev */
if (up->port.dev)
continue;
up->port.dev = dev;
or:
static void __init
serial8250_register_ports(struct uart_driver *drv, struct device *dev)
{
int i;
for (i = 0; i < nr_uarts; i++) {
struct uart_8250_port *up = &serial8250_ports[i];
+ if (up->port.type == PORT_8250_CIR)
+ continue;
if (up->port.dev)
continue;
up->port.dev = dev;
Regards,
Peter Hurley
> Print a short message in this case so it is known
> to user what has happened.
>
> This way checks for PORT_8250_CIR in serial port
> callbacks can be removed too, since they won't
> ever be called.
>
> Signed-off-by: Maciej Szmigiero <m...@maciej.szmigiero.name>
> ---
> This replaces "serial: don't announce CIR serial ports"
> submission.
>
> Changes from v1: print message using dev_info()
>
> drivers/tty/serial/8250/8250_core.c | 37
> +++++++++++++++++------------------
> 1 files changed, 18 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_core.c
> b/drivers/tty/serial/8250/8250_core.c
> index 37fff12..145b0b37 100644
> --- a/drivers/tty/serial/8250/8250_core.c
> +++ b/drivers/tty/serial/8250/8250_core.c
> @@ -2129,9 +2129,6 @@ int serial8250_do_startup(struct uart_port *port)
> unsigned char lsr, iir;
> int retval;
>
> - if (port->type == PORT_8250_CIR)
> - return -ENODEV;
> -
> if (!port->fifosize)
> port->fifosize = uart_config[port->type].fifo_size;
> if (!up->tx_loadsz)
> @@ -2858,14 +2855,8 @@ static void serial8250_release_port(struct uart_port
> *port)
> static int serial8250_request_port(struct uart_port *port)
> {
> struct uart_8250_port *up = up_to_u8250p(port);
> - int ret;
> -
> - if (port->type == PORT_8250_CIR)
> - return -ENODEV;
> -
> - ret = serial8250_request_std_resource(up);
>
> - return ret;
> + return serial8250_request_std_resource(up);
> }
>
> static int fcr_get_rxtrig_bytes(struct uart_8250_port *up)
> @@ -3013,9 +3004,6 @@ static void serial8250_config_port(struct uart_port
> *port, int flags)
> struct uart_8250_port *up = up_to_u8250p(port);
> int ret;
>
> - if (port->type == PORT_8250_CIR)
> - return;
> -
> /*
> * Find the region that we can probe for. This in turn
> * tells us whether we can probe for the type of port.
> @@ -3889,13 +3877,24 @@ int serial8250_register_8250_port(struct
> uart_8250_port *up)
> if (up->dl_write)
> uart->dl_write = up->dl_write;
>
> - if (serial8250_isa_config != NULL)
> - serial8250_isa_config(0, &uart->port,
> - &uart->capabilities);
> + if (uart->port.type != PORT_8250_CIR) {
> + if (serial8250_isa_config != NULL)
> + serial8250_isa_config(0, &uart->port,
> + &uart->capabilities);
>
> - ret = uart_add_one_port(&serial8250_reg, &uart->port);
> - if (ret == 0)
> - ret = uart->port.line;
> + ret = uart_add_one_port(&serial8250_reg,
> + &uart->port);
> + if (ret == 0)
> + ret = uart->port.line;
> + } else {
> + dev_info(uart->port.dev,
> + "skipping CIR port at 0x%lx / 0x%llx, IRQ %d\n",
> + uart->port.iobase,
> + (unsigned long long)uart->port.mapbase,
> + uart->port.irq);
> +
> + ret = 0;
> + }
> }
> mutex_unlock(&serial_mutex);
>
>
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