linux-kernel - Re: [PATCH 03/26] phy: qcom: add the SGMII SerDes PHY driver

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Date:   Wed, 14 Jun 2023 09:18:06 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     Vinod Koul <vkoul@...nel.org>,
        Bhupesh Sharma <bhupesh.sharma@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>, netdev@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-stm32@...md-mailman.stormreply.com,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH 03/26] phy: qcom: add the SGMII SerDes PHY driver

On Mon, Jun 12, 2023 at 11:45 AM Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
>
>
>
> On 12.06.2023 11:23, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > Implement support for the SGMII/SerDes PHY present on various Qualcomm
> > platforms.
> >
> > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> > ---
> > +static const struct regmap_config qcom_dwmac_sgmii_phy_regmap_cfg = {
> > +     .reg_bits               = 32,
> > +     .val_bits               = 32,
> > +     .reg_stride             = 4,
> > +     .use_relaxed_mmio       = true,
> > +     .disable_locking        = true,
> The last two are rather brave, no?
>

We don't need locking because all callbacks are already protected by
the phy subsystem with a mutex and I don't really see anything that
would make it dangerous to use relaxed semantics in this driver. It's
just basic configuration.

Bart

> Konrad
> > +};
> > +
> > +static int qcom_dwmac_sgmii_phy_probe(struct platform_device *pdev)
> > +{
> > +     struct qcom_dwmac_sgmii_phy_data *data;
> > +     struct device *dev = &pdev->dev;
> > +     struct phy_provider *provider;
> > +     struct clk *refclk;
> > +     void __iomem *base;
> > +     struct phy *phy;
> > +
> > +     data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> > +     if (!data)
> > +             return -ENOMEM;
> > +
> > +     base = devm_platform_ioremap_resource(pdev, 0);
> > +     if (IS_ERR(base))
> > +             return PTR_ERR(base);
> > +
> > +     data->regmap = devm_regmap_init_mmio(dev, base,
> > +                                          &qcom_dwmac_sgmii_phy_regmap_cfg);
> > +     if (IS_ERR(data->regmap))
> > +             return PTR_ERR(data->regmap);
> > +
> > +     phy = devm_phy_create(dev, NULL, &qcom_dwmac_sgmii_phy_ops);
> > +     if (IS_ERR(phy))
> > +             return PTR_ERR(phy);
> > +
> > +     refclk = devm_clk_get_enabled(dev, "sgmi_ref");
> > +     if (IS_ERR(refclk))
> > +             return PTR_ERR(refclk);
> > +
> > +     provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
> > +     if (IS_ERR(provider))
> > +             return PTR_ERR(provider);
> > +
> > +     phy_set_drvdata(phy, data);
> > +     platform_set_drvdata(pdev, data);
> > +
> > +     return 0;
> > +}
> > +
> > +static const struct of_device_id qcom_dwmac_sgmii_phy_of_match[] = {
> > +     { .compatible = "qcom,sa8775p-dwmac-sgmii-phy" },
> > +     { },
> > +};
> > +MODULE_DEVICE_TABLE(of, qcom_dwmac_sgmii_phy_of_match);
> > +
> > +static struct platform_driver qcom_dwmac_sgmii_phy_driver = {
> > +     .probe  = qcom_dwmac_sgmii_phy_probe,
> > +     .driver = {
> > +             .name   = "qcom-dwmac-sgmii-phy",
> > +             .of_match_table = qcom_dwmac_sgmii_phy_of_match,
> > +     }
> > +};
> > +
> > +module_platform_driver(qcom_dwmac_sgmii_phy_driver);
> > +
> > +MODULE_DESCRIPTION("Qualcomm DWMAC SGMII PHY driver");
> > +MODULE_LICENSE("GPL");