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!
> --- /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?
> +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?
> + }
> +
> + 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.
> + 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);
> +/* 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?
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
