linux-kernel - [PATCH v2 3/3] PCI: qcom: Add OPP support for speed based performance state of RPMH

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Date:   Wed, 16 Aug 2023 18:54:24 +0530
From:   Krishna chaitanya chundru <quic_krichai@...cinc.com>
To:     manivannan.sadhasivam@...aro.org
Cc:     helgaas@...nel.org, linux-pci@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        quic_vbadigan@...cinc.com, quic_nitegupt@...cinc.com,
        quic_skananth@...cinc.com, quic_ramkri@...cinc.com,
        quic_parass@...cinc.com, krzysztof.kozlowski@...aro.org,
        Krishna chaitanya chundru <quic_krichai@...cinc.com>,
        Manivannan Sadhasivam <mani@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v2 3/3] PCI: qcom: Add OPP support for speed based performance state of RPMH

Before link training vote for the maximum performance state of RPMH
and once link is up, vote for the performance state based upon the link
speed.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@...cinc.com>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 65 ++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 7a87a47..831d158 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -22,6 +22,7 @@
 #include <linux/of_device.h>
 #include <linux/of_gpio.h>
 #include <linux/pci.h>
+#include <linux/pm_opp.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_device.h>
 #include <linux/phy/pcie.h>
@@ -1357,6 +1358,51 @@ static int qcom_pcie_icc_init(struct qcom_pcie *pcie)
 	return 0;
 }
 
+static void qcom_pcie_opp_update(struct qcom_pcie *pcie)
+{
+	struct dw_pcie *pci = pcie->pci;
+	struct dev_pm_opp *opp;
+	u32 offset, status;
+	int speed, ret = 0;
+	uint32_t freq;
+
+	offset = dw_pcie_find_capability(pci, PCI_CAP_ID_EXP);
+	status = readw(pci->dbi_base + offset + PCI_EXP_LNKSTA);
+
+	/* Only update constraints if link is up. */
+	if (!(status & PCI_EXP_LNKSTA_DLLLA))
+		return;
+
+	speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, status);
+
+	switch (speed) {
+	case 1:
+		freq = 2500000;
+		break;
+	case 2:
+		freq = 5000000;
+		break;
+	case 3:
+		freq = 8000000;
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		fallthrough;
+	case 4:
+		freq = 16000000;
+		break;
+	}
+
+	opp = dev_pm_opp_find_freq_exact(pci->dev, freq, true);
+	if (!IS_ERR(opp)) {
+		ret = dev_pm_opp_set_opp(pci->dev, opp);
+		if (ret)
+			dev_err(pci->dev, "Failed to set opp: %d\n", ret);
+		dev_pm_opp_put(opp);
+	}
+
+}
+
 static void qcom_pcie_icc_update(struct qcom_pcie *pcie)
 {
 	struct dw_pcie *pci = pcie->pci;
@@ -1439,8 +1485,10 @@ static void qcom_pcie_init_debugfs(struct qcom_pcie *pcie)
 static int qcom_pcie_probe(struct platform_device *pdev)
 {
 	const struct qcom_pcie_cfg *pcie_cfg;
+	unsigned long max_freq = INT_MAX;
 	struct device *dev = &pdev->dev;
 	struct qcom_pcie *pcie;
+	struct dev_pm_opp *opp;
 	struct dw_pcie_rp *pp;
 	struct resource *res;
 	struct dw_pcie *pci;
@@ -1511,6 +1559,21 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_pm_runtime_put;
 
+	/* OPP table is optional */
+	ret = devm_pm_opp_of_add_table(dev);
+	if (ret && ret != -ENODEV) {
+		dev_err(dev, "Invalid OPP table in Device tree\n");
+		goto err_pm_runtime_put;
+	}
+
+	opp = dev_pm_opp_find_freq_floor(dev, &max_freq);
+	if (!IS_ERR(opp)) {
+		ret = dev_pm_opp_set_opp(dev, opp);
+		if (ret)
+			dev_err(pci->dev, "Failed to set opp: %d\n", ret);
+		dev_pm_opp_put(opp);
+	}
+
 	ret = pcie->cfg->ops->get_resources(pcie);
 	if (ret)
 		goto err_pm_runtime_put;
@@ -1531,6 +1594,8 @@ static int qcom_pcie_probe(struct platform_device *pdev)
 
 	qcom_pcie_icc_update(pcie);
 
+	qcom_pcie_opp_update(pcie);
+
 	if (pcie->mhi)
 		qcom_pcie_init_debugfs(pcie);
 
-- 
2.7.4