[PATCH v2 3/3] PCI: qcom-ep: Add ICC bandwidth voting support

[Krishna chaitanya chundru]

Add support to vote for ICC bandwidth based on the link
speed and width.

This patch is inspired from pcie-qcom driver to add basic
interconnect support.

Link:https://patchwork.kernel.org/project/linux-pci/patch/20221102090705.23634-3-johan+linaro@xxxxxxxxxx/
Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-qcom-ep.c | 68 +++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 19b3283..5f9139d 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -13,6 +13,7 @@
 #include <linux/debugfs.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
+#include <linux/interconnect.h>
 #include <linux/mfd/syscon.h>
 #include <linux/phy/pcie.h>
 #include <linux/phy/phy.h>
@@ -28,6 +29,7 @@
 #define PARF_SYS_CTRL				0x00
 #define PARF_DB_CTRL				0x10
 #define PARF_PM_CTRL				0x20
+#define PARF_PM_STTS				0x24
 #define PARF_MHI_CLOCK_RESET_CTRL		0x174
 #define PARF_MHI_BASE_ADDR_LOWER		0x178
 #define PARF_MHI_BASE_ADDR_UPPER		0x17c
@@ -128,6 +130,9 @@
 /* DBI register fields */
 #define DBI_CON_STATUS_POWER_STATE_MASK		GENMASK(1, 0)
 
+#define DBI_LINKCTRLSTATUS			0x80
+#define DBI_LINKCTRLSTATUS_SHIFT		16
+
 #define XMLH_LINK_UP				0x400
 #define CORE_RESET_TIME_US_MIN			1000
 #define CORE_RESET_TIME_US_MAX			1005
@@ -178,6 +183,8 @@ struct qcom_pcie_ep {
 	struct phy *phy;
 	struct dentry *debugfs;
 
+	struct icc_path *icc;
+
 	struct clk_bulk_data *clks;
 	int num_clks;
 
@@ -253,9 +260,51 @@ static void qcom_pcie_dw_stop_link(struct dw_pcie *pci)
 	disable_irq(pcie_ep->perst_irq);
 }
 
+static void qcom_pcie_ep_icc_update(struct qcom_pcie_ep *pcie_ep)
+{
+	struct dw_pcie *pci = &pcie_ep->pci;
+	int speed, width;
+	u32 val, bw;
+	int ret;
+
+	if (!pcie_ep->icc)
+		return;
+
+	val = dw_pcie_readl_dbi(pci, DBI_LINKCTRLSTATUS);
+	val = val >> DBI_LINKCTRLSTATUS_SHIFT;
+
+	speed = FIELD_GET(PCI_EXP_LNKSTA_CLS, val);
+	width = FIELD_GET(PCI_EXP_LNKSTA_NLW, val);
+
+	switch (speed) {
+	case 1:
+		bw = MBps_to_icc(250);	/* BW for GEN1 per lane: 250MBps */
+		break;
+	case 2:
+		bw = MBps_to_icc(500);	/* BW for GEN2 per lane: 500MBps */
+		break;
+	case 3:
+		bw = MBps_to_icc(985);	/* BW for GEN3 per lane: 985MBps */
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		fallthrough;
+	case 4:
+		bw = MBps_to_icc(1969);	/* BW for GEN4 per lane: 985MBps */
+		break;
+	}
+
+	ret = icc_set_bw(pcie_ep->icc, 0, width * bw);
+	if (ret) {
+		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
+			ret);
+	}
+}
+
 static int qcom_pcie_enable_resources(struct qcom_pcie_ep *pcie_ep)
 {
 	int ret;
+	struct dw_pcie *pci = &pcie_ep->pci;
 
 	ret = clk_bulk_prepare_enable(pcie_ep->num_clks, pcie_ep->clks);
 	if (ret)
@@ -277,6 +326,20 @@ static int qcom_pcie_enable_resources(struct qcom_pcie_ep *pcie_ep)
 	if (ret)
 		goto err_phy_exit;
 
+	/*
+	 * Some Qualcomm platforms require interconnect bandwidth constraints
+	 * to be set before enabling interconnect clocks.
+	 *
+	 * Set an initial average bandwidth corresponding to single-lane Gen 1
+	 * for the pcie to mem path.
+	 */
+	ret = icc_set_bw(pcie_ep->icc, 0, MBps_to_icc(250)); /* BW for GEN1 per lane: 250MBps */
+	if (ret) {
+		dev_err(pci->dev, "failed to set interconnect bandwidth: %d\n",
+			ret);
+		goto err_phy_exit;
+	}
+
 	return 0;
 
 err_phy_exit:
@@ -550,6 +613,10 @@ static int qcom_pcie_ep_get_resources(struct platform_device *pdev,
 	if (IS_ERR(pcie_ep->phy))
 		ret = PTR_ERR(pcie_ep->phy);
 
+	pcie_ep->icc = devm_of_icc_get(dev, "pcie-mem");
+	if (IS_ERR(pcie_ep->icc))
+		ret = PTR_ERR(pcie_ep->icc);
+
 	return ret;
 }
 
@@ -572,6 +639,7 @@ static irqreturn_t qcom_pcie_ep_global_irq_thread(int irq, void *data)
 	} else if (FIELD_GET(PARF_INT_ALL_BME, status)) {
 		dev_dbg(dev, "Received BME event. Link is enabled!\n");
 		pcie_ep->link_status = QCOM_PCIE_EP_LINK_ENABLED;
+		qcom_pcie_ep_icc_update(pcie_ep);
 	} else if (FIELD_GET(PARF_INT_ALL_PM_TURNOFF, status)) {
 		dev_dbg(dev, "Received PM Turn-off event! Entering L23\n");
 		val = readl_relaxed(pcie_ep->parf + PARF_PM_CTRL);
-- 
2.7.4