Hi Geert,
> On May 8, 2015, at 16:20 , Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
>
> Kalimera Pantelis,
>
> I'm trying to use an overlay to enable an additional serial port on an
> expansion port. The serial driver relies on of_alias_get_id() to find the
> serial index, so I have to update /aliases.
>
Ugh, yeah, aliases are ‘special’.
> My first naive try:
>
> fragment@0 {
> target-path = "/aliases";
>
> __overlay__ {
> serial3 = <&scif3>;
> };
> };
>
> didn't work, as now /aliases/serial3 is a phandle, not a string.
>
> Next try:
>
> serial3 = &scif3;
>
> That one isn't liked by dtc:
>
> ERROR (path_references): Reference to non-existent node or label "scif3"
>
> Am I correct in assuming that fixup_path_references() needs updating to
> support this, cfr. fixup_phandle_references()?
>
> Finally, let's hardcode the path:
>
> serial3 = "/serial@e6ea8000";
>
> Now /sys/firmware/devicetree/base/aliases/serial3 is correct, but it
> still doesn't
> work, as the list of aliases is created only once (by of_alias_scan_aliases()),
> after unpacking the device tree. I guess of_alias_add() should be called when
> adding a property to /aliases.
>
Yes, you should be updating the aliases when adding something there.
I’ve run into the same problem with the omap-serial driver but I’ve handled it differently.
Here’s how I’ve handled it.
> commit cc9d3f8406c8058dd5d0bd254d2452189365aac3
> Author: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
> Date: Thu Nov 6 14:12:14 2014 +0200
>
> serial: omap: Fix port line number without aliases
>
> Having an omap serial device without a serial aliases doesn't
> work. For now fallback to using the hwmod instance.
>
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
>
> diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
> index 211479a..d839418 100644
> --- a/drivers/tty/serial/omap-serial.c
> +++ b/drivers/tty/serial/omap-serial.c
> @@ -1616,6 +1616,31 @@ static int serial_omap_probe_rs485(struct uart_omap_port *up,
> return 0;
> }
>
> +static int serial_omap_of_get_port_line(struct device_node *np)
> +{
> + unsigned long val;
> + const char *hwmod;
> + int ret;
> +
> + /* first try the serial alias */
> + ret = of_alias_get_id(np, "serial");
> + if (ret >= 0)
> + return ret;
> +
> + /* no? calculate it from hwmods */
> + ret = of_property_read_string(np, "ti,hwmods", &hwmod);
> + if (ret != 0 || strncmp(hwmod, "uart", 4) ||
> + kstrtoul(hwmod + 4, 10, &val))
> + return -ENODEV;
> +
> + /* numbering of hwmods is +1 */
> + ret = (int)val - 1;
> + if (ret < 0)
> + return -ENODEV;
> +
> + return ret;
> +}
> +
> static int serial_omap_probe(struct platform_device *pdev)
> {
> struct omap_uart_port_info *omap_up_info = dev_get_platdata(&pdev->dev);
> @@ -1659,7 +1684,7 @@ static int serial_omap_probe(struct platform_device *pdev)
> up->port.ops = &serial_omap_pops;
>
> if (pdev->dev.of_node)
> - ret = of_alias_get_id(pdev->dev.of_node, "serial");
> + ret = serial_omap_of_get_port_line(pdev->dev.of_node);
> else
> ret = pdev->id;
>
>
It is possible for this to be fixed when adding something under aliases; give it a shot!
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
Regards
— Pantelis
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