Hi Geert-san,
> From: Geert Uytterhoeven
> Sent: Wednesday, July 5, 2017 7:09 PM
>
> Hi Simoda-san,
>
> On Wed, Jun 28, 2017 at 8:28 AM, Yoshihiro Shimoda
> <[email protected]> wrote:
> > R-Car USB 2.0 controller can change the clock source from an oscillator
> > to an external clock via a register. So, this patch adds support
> > the clock source selector as a clock driver.
> >
> > Signed-off-by: Yoshihiro Shimoda <[email protected]>
>
> Thanks for your patch!
Thank you very much for the comments!
> > --- /dev/null
> > +++ b/drivers/clk/renesas/rcar-usb2-clock-sel.c
>
> > +static void usb2_clock_sel_enable_extal_only(struct usb2_clock_sel_priv
> > *priv)
> > +{
> > + u16 val = readw(priv->base + USB20_CLKSET0);
> > +
> > + pr_debug("%s: enter %d %d %x\n", __func__,
> > + priv->extal, priv->xtal, val);
> > +
> > + if (priv->extal && !priv->xtal && val != CLKSET0_EXTAL_ONLY)
> > + writew(CLKSET0_EXTAL_ONLY, priv->base + USB20_CLKSET0);
> > +}
> > +
> > +static void usb2_clock_sel_disable_extal_only(struct usb2_clock_sel_priv
> > *priv)
> > +{
> > + if (priv->extal && !priv->xtal)
> > + writew(CLKSET0_PRIVATE, priv->base + USB20_CLKSET0);
> > +}
> > +
> > +static int usb2_clock_sel_enable(struct clk_hw *hw)
> > +{
> > + usb2_clock_sel_enable_extal_only(to_priv(hw));
> > +
> > + return 0;
> > +}
> > +
> > +static void usb2_clock_sel_disable(struct clk_hw *hw)
> > +{
> > + usb2_clock_sel_disable_extal_only(to_priv(hw));
> > +}
> > +
> > +/*
> > + * This module seems a mux, but this driver assumes a gate because
> > + * ehci/ohci platform drivers don't support clk_set_parent() for now.
> > + * If this driver acts as a gate, ehci/ohci-platform drivers don't need
> > + * any modification.
> > + */
> > +static const struct clk_ops usb2_clock_sel_clock_ops = {
> > + .enable = usb2_clock_sel_enable,
> > + .disable = usb2_clock_sel_disable,
> > +};
>
> So you do "smart muxing" in the enable routine above?
Yes.
> > +static int __init rcar_usb2_clock_sel_probe(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct device_node *np = dev->of_node;
> > + struct usb2_clock_sel_priv *priv;
> > + struct resource *res;
> > + struct clk *clk;
> > + struct clk_init_data init;
> > + int error;
> > +
> > + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > + if (!priv)
> > + return -ENOMEM;
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + priv->base = devm_ioremap_resource(dev, res);
> > + if (IS_ERR(priv->base))
> > + return PTR_ERR(priv->base);
> > +
> > + priv->ehci_clk = devm_clk_get(dev, "ehci_ohci");
> > + if (!IS_ERR(priv->ehci_clk)) {
> > + error = clk_prepare_enable(priv->ehci_clk);
> > + if (error)
> > + return error;
> > + }
> > +
> > + clk = devm_clk_get(dev, "usb_extal");
> > + if (!IS_ERR(clk) && !clk_prepare_enable(clk)) {
> > + priv->extal = !!clk_get_rate(clk);
> > + clk_disable_unprepare(clk);
> > + }
> > + clk = devm_clk_get(dev, "usb_xtal");
> > + if (!IS_ERR(clk) && !clk_prepare_enable(clk)) {
> > + priv->xtal = !!clk_get_rate(clk);
> > + clk_disable_unprepare(clk);
> > + }
> > +
> > + if (!priv->extal && !priv->extal) {
> > + dev_err(dev, "This driver needs usb_extal or usb_xtal\n");
> > + return -ENOENT;
>
> Perhaps enabled clocks should be disabled on error?
Oops! I should call clk_disable_unprepare(priv->ehci_clk) here.
I will fix it.
> > + }
> > +
> > + platform_set_drvdata(pdev, priv);
> > + dev_set_drvdata(dev, priv);
> > +
> > + init.name = "rcar_usb2_clock_sel";
> > + init.ops = &usb2_clock_sel_clock_ops;
> > + init.flags = CLK_IS_BASIC;
> > + init.parent_names = NULL;
> > + init.num_parents = 0;
> > + priv->hw.init = &init;
> > +
> > + clk = clk_register(NULL, &priv->hw);
> > + if (IS_ERR(clk))
> > + return PTR_ERR(clk);
>
> Likewise.
Same here. So, I will use "goto" for it.
> > + error = of_clk_add_provider(np, of_clk_src_simple_get, clk);
> > + if (error)
> > + return error;
> > +
> > + return 0;
>
> return of_clk_add_provider(np, of_clk_src_simple_get, clk);
Thanks. I will fix it.
> > +/* Since this driver needs other ccf drivers, this uses
> > subsys_initcall_sync */
> > +subsys_initcall_sync(rcar_usb2_clock_sel_init);
>
> I suppose this is a workaround for the lack of probe deferral support in the
> USB subsystem?
This is my fault. I added "power-domains" property into this device's node.
After I remove the power-domains like the cpg node, this driver can use
subsys_initcall()
instead of subsys_initcall_sync().
Best regards,
Yoshihiro Shimoda
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 --
> [email protected]
>
> 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
