RE: [PATCH v2] clk: renesas: rcar-usb2-clock-sel: Add R-Car USB 2.0 clock selector PHY

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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
> <yoshihiro.shimoda.uh@xxxxxxxxxxx> 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 <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> 
> 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 -- 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




[Index of Archives]     [Linux Samsung SOC]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Samba]     [Device Mapper]

  Powered by Linux