[PATCH v1 3/3] PCI: qcom: Add OPP suuport for speed based performance state of RPMH

[Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>]

Before link training vote for the maximum performance state of RPMH
and once the link is up, vote for the performance state based upon
the link speed.
Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 61 ++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 7a87a47..e29a986 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;
+	uint32_t freq;
+	int speed;
+	int ret = 0;
+
+	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_get_voltage(opp);
+		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 +1559,17 @@ 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))
+		dev_pm_opp_put(opp);
+
 	ret = pcie->cfg->ops->get_resources(pcie);
 	if (ret)
 		goto err_pm_runtime_put;
@@ -1531,6 +1590,8 @@ 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