Re: [PATCH 2/6] usb: cdns3-ti: move reg writes from probe into an init_hw helper

Roger Quadros
2023-11-15T11:34:03Z

Hi Théo,

On 13/11/2023 16:26, Théo Lebrun wrote:
> The hardware initialisation register write sequence is only used at
> probe. To support suspend/resume with a controller losing power, we
> must redo this sequence of writes.
>
> Extract the register write sequence to a new cdns_ti_init_hw function to
> reuse it later down the road, at resume.
>
> We keep the devicetree-parsing aspect of the sequence in probe & add a
> new field in the private struct to remember the USB2 refclk rate code
> computation result.
>
> Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
> ---
> drivers/usb/cdns3/cdns3-ti.c | 76 ++++++++++++++++++++++++--------------------
> 1 file changed, 41 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/usb/cdns3/cdns3-ti.c b/drivers/usb/cdns3/cdns3-ti.c
> index 5945c4b1e11f..c331bcd2faeb 100644
> --- a/drivers/usb/cdns3/cdns3-ti.c
> +++ b/drivers/usb/cdns3/cdns3-ti.c
> @@ -57,6 +57,7 @@ struct cdns_ti {
> unsigned vbus_divider:1;
> struct clk *usb2_refclk;
> struct clk *lpm_clk;
> + int usb2_refclk_rate_code;
> };
>
> static const int cdns_ti_rate_table[] = { /* in KHZ */
> @@ -85,15 +86,50 @@ static inline void cdns_ti_writel(struct cdns_ti *data, u32 offset, u32 value)
> writel(value, data->usbss + offset);
> }
>
> +static void cdns_ti_init_hw(struct cdns_ti *data)
> +{
> + u32 reg;
> +
> + /* assert RESET */
> + reg = cdns_ti_readl(data, USBSS_W1);
> + reg &= ~USBSS_W1_PWRUP_RST;
> + cdns_ti_writel(data, USBSS_W1, reg);
> +
> + /* set static config */
> + reg = cdns_ti_readl(data, USBSS_STATIC_CONFIG);
> + reg &= ~USBSS1_STATIC_PLL_REF_SEL_MASK;
> + reg |= data->usb2_refclk_rate_code << USBSS1_STATIC_PLL_REF_SEL_SHIFT;
> +
> + reg &= ~USBSS1_STATIC_VBUS_SEL_MASK;
> + if (data->vbus_divider)
> + reg |= 1 << USBSS1_STATIC_VBUS_SEL_SHIFT;
> +
> + cdns_ti_writel(data, USBSS_STATIC_CONFIG, reg);
> + reg = cdns_ti_readl(data, USBSS_STATIC_CONFIG);
> +
> + /* set USB2_ONLY mode if requested */
> + reg = cdns_ti_readl(data, USBSS_W1);
> + if (data->usb2_only)
> + reg |= USBSS_W1_USB2_ONLY;
> +
> + /* set default modestrap */
> + reg |= USBSS_W1_MODESTRAP_SEL;
> + reg &= ~USBSS_W1_MODESTRAP_MASK;
> + reg |= USBSS_MODESTRAP_MODE_NONE << USBSS_W1_MODESTRAP_SHIFT;
> + cdns_ti_writel(data, USBSS_W1, reg);
> +
> + /* de-assert RESET */
> + reg |= USBSS_W1_PWRUP_RST;
> + cdns_ti_writel(data, USBSS_W1, reg);
> +}
> +
> static int cdns_ti_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> struct device_node *node = pdev->dev.of_node;
> struct cdns_ti *data;
> - int error;
> - u32 reg;
> - int rate_code, i;
> unsigned long rate;
> + int error, i;

Should we leave rate_code and get rid of i?

>
> data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> if (!data)
> @@ -133,8 +169,6 @@ static int cdns_ti_probe(struct platform_device *pdev)
> return -EINVAL;
> }
>
> - rate_code = i;
> -
> pm_runtime_enable(dev);
> error = pm_runtime_get_sync(dev)> if (error < 0) {
> @@ -142,39 +176,11 @@ static int cdns_ti_probe(struct platform_device *pdev)
> goto err;
> }
>
> - /* assert RESET */
> - reg = cdns_ti_readl(data, USBSS_W1);
> - reg &= ~USBSS_W1_PWRUP_RST;
> - cdns_ti_writel(data, USBSS_W1, reg);
> -
> - /* set static config */
> - reg = cdns_ti_readl(data, USBSS_STATIC_CONFIG);
> - reg &= ~USBSS1_STATIC_PLL_REF_SEL_MASK;
> - reg |= rate_code << USBSS1_STATIC_PLL_REF_SEL_SHIFT;
> -
> - reg &= ~USBSS1_STATIC_VBUS_SEL_MASK;
> data->vbus_divider = device_property_read_bool(dev, "ti,vbus-divider");
> - if (data->vbus_divider)
> - reg |= 1 << USBSS1_STATIC_VBUS_SEL_SHIFT;
> -
> - cdns_ti_writel(data, USBSS_STATIC_CONFIG, reg);
> - reg = cdns_ti_readl(data, USBSS_STATIC_CONFIG);
> -
> - /* set USB2_ONLY mode if requested */
> - reg = cdns_ti_readl(data, USBSS_W1);
> data->usb2_only = device_property_read_bool(dev, "ti,usb2-only");
> - if (data->usb2_only)
> - reg |= USBSS_W1_USB2_ONLY;
> -
> - /* set default modestrap */
> - reg |= USBSS_W1_MODESTRAP_SEL;
> - reg &= ~USBSS_W1_MODESTRAP_MASK;
> - reg |= USBSS_MODESTRAP_MODE_NONE << USBSS_W1_MODESTRAP_SHIFT;
> - cdns_ti_writel(data, USBSS_W1, reg);
> + data->usb2_refclk_rate_code = i;

because 'i' seems temporary.

>
> - /* de-assert RESET */
> - reg |= USBSS_W1_PWRUP_RST;
> - cdns_ti_writel(data, USBSS_W1, reg);
> + cdns_ti_init_hw(data);
>
> error = of_platform_populate(node, NULL, NULL, dev);
> if (error) {
>

--
cheers,
-roger