Re: [Xen-devel] [RFC 01/24] xen/char: dt-uart: Allow the user to give a path to the node

[Andre Przywara <andre.przywara@xxxxxxxxxx>]

On 08/16/2013 11:05 PM, Julien Grall wrote:
> On some board, there is no alias to the UART. To avoid modification in
> the device tree, dt-uart should also search device by path.
Funny, it wrote almost the same patch two days ago (including the 
variable renaming, minus the "/" check). Thanks for saving me the 
cleanup and send-out ;-)
It is really useful for Midway!

> To distinguish an alias from a path, dt-uart will check the first character.
> If it's a / then it's path, otherwise it's an alias.
Is that really needed? In my patch I just try it as an alias first, if 
there is no match (dev == NULL), I try the full path.
Are there any ambiguities expected between an alias and a full path?

Regards,
Andre.

> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> ---
>   xen/drivers/char/dt-uart.c |   16 ++++++++++------
>   1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/xen/drivers/char/dt-uart.c b/xen/drivers/char/dt-uart.c
> index 93bb0f5..d7204fb 100644
> --- a/xen/drivers/char/dt-uart.c
> +++ b/xen/drivers/char/dt-uart.c
> @@ -26,9 +26,10 @@
>
>   /*
>    * Configure UART port with a string:
> - * alias,options
> + * path,options
>    *
> - * @alias: alias used in the device tree for the UART
> + * @path: full path used in the device tree for the UART. If the path
> + * doesn't start with '/', we assuming that it's an alias.
>    * @options: UART speficic options (see in each UART driver)
>    */
>   static char __initdata opt_dtuart[30] = "";
> @@ -38,7 +39,7 @@ void __init dt_uart_init(void)
>   {
>       struct dt_device_node *dev;
>       int ret;
> -    const char *devalias = opt_dtuart;
> +    const char *devpath = opt_dtuart;
>       char *options;
>
>       if ( !console_has("dtuart") || !strcmp(opt_dtuart, "") )
> @@ -53,12 +54,15 @@ void __init dt_uart_init(void)
>       else
>           options = "";
>
> -    early_printk("Looking for UART console %s\n", devalias);
> -    dev = dt_find_node_by_alias(devalias);
> +    early_printk("Looking for UART console %s\n", devpath);
> +    if ( *devpath == '/' )
> +        dev = dt_find_node_by_path(devpath);
> +    else
> +        dev = dt_find_node_by_alias(devpath);
>
>       if ( !dev )
>       {
> -        early_printk("Unable to find device \"%s\"\n", devalias);
> +        early_printk("Unable to find device \"%s\"\n", devpath);
>           return;
>       }

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