linux-kernel - Re: [PATCH 2/6] usb: cdns3-ti: move reg writes from probe into an init

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Message-ID: <aabf618e-9352-4555-9059-f213cb16c84f@kernel.org>
Date:   Wed, 15 Nov 2023 13:33:57 +0200
From:   Roger Quadros <rogerq@...nel.org>
To:     Théo Lebrun <theo.lebrun@...tlin.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Peter Chen <peter.chen@...nel.org>,
        Pawel Laszczak <pawell@...ence.com>,
        Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Tero Kristo <kristo@...nel.org>
Cc:     linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/6] usb: cdns3-ti: move reg writes from probe into an
 init_hw helper

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@...tlin.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