Hi Laurent,
On Mon, Sep 14, 2015 at 2:14 PM, Laurent Pinchart
<laurent.pinchart+renesas@xxxxxxxxxxxxxxxx> wrote:
> As no platform defines an interface clock the SCI driver always fall
> back to a clock named "peripheral_clk". On SH platform that clock is the
> base clock for the SCI functional clock and has the same frequency. On
> ARM platforms that clock doesn't exist, and clk_get() will return the
> default clock for the device. We can thus make the functional clock
> mandatory and drop the interface clock.
>
> Cc: devicetree@xxxxxxxxxxxxxxx
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> ---
> .../bindings/serial/renesas,sci-serial.txt | 4 +-
> drivers/tty/serial/sh-sci.c | 60 +++++++++++++---------
> 2 files changed, 39 insertions(+), 25 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/serial/renesas,sci-serial.txt b/Documentation/devicetree/bindings/serial/renesas,sci-serial.txt
> index e84b13a8eda3..c390860bc23f 100644
> --- a/Documentation/devicetree/bindings/serial/renesas,sci-serial.txt
> +++ b/Documentation/devicetree/bindings/serial/renesas,sci-serial.txt
> @@ -2181,6 +2177,38 @@ static struct uart_ops sci_uart_ops = {
> #endif
> };
>
> +static int sci_init_clocks(struct sci_port *sci_port, struct device *dev)
> +{
> + /* Get the SCI functional clock. It's called "fck" on ARM. */
> + sci_port->fclk = clk_get(dev, "fck");
> + if (!IS_ERR(sci_port->fclk))
> + return 0;
> +
> + /*
> + * But it used to be called "sci_ick", and we need to maintain DT
> + * backward compatibility.
> + */
> + sci_port->fclk = clk_get(dev, "sci_ick");
> + if (!IS_ERR(sci_port->fclk))
> + return 0;
> +
> + /* SH has historically named the clock "sci_fck". */
> + sci_port->fclk = clk_get(dev, "sci_fck");
> + if (!IS_ERR(sci_port->fclk))
> + return 0;
> +
> + /*
> + * Not all SH platforms declare a clock lookup entry for SCI devices, in
> + * which case we need to get the global "peripheral_clk" clock.
> + */
> + sci_port->fclk = clk_get(dev, "peripheral_clk");
> + if (!IS_ERR(sci_port->fclk))
> + return 0;
> +
> + dev_err(dev, "failed to get functional clock\n");
> + return PTR_ERR(sci_port->fclk);
This doesn't handle probe deferral correctly.
-EPROBE_DEFER from an earlier clock will be overwritten by -ENOENT from a
later clock, and the driver will never be reprobed.
> +}
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
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