linux-kernel - [PATCH v3 19/19] PCI: qcom: Expose link transition counts via debugfs for v2.4.0

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Date:   Fri, 10 Mar 2023 09:38:16 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     andersson@...nel.org, lpieralisi@...nel.org, kw@...ux.com,
        krzysztof.kozlowski+dt@...aro.org, robh@...nel.org
Cc:     konrad.dybcio@...aro.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_srichara@...cinc.com,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Subject: [PATCH v3 19/19] PCI: qcom: Expose link transition counts via debugfs for v2.4.0

Qualcomm PCIe controllers of version v2.4.0 have debug registers in the
PARF region that count PCIe link transitions. Expose them over debugfs to
userspace to help debug the low power issues.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 33 ++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index f99b7e7f3f73..0b41f007fa90 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -37,6 +37,7 @@
 /* PARF registers */
 #define PARF_SYS_CTRL				0x00
 #define PARF_PM_CTRL				0x20
+#define PARF_PM_STTS				0x24
 #define PARF_PCS_DEEMPH				0x34
 #define PARF_PCS_SWING				0x38
 #define PARF_PHY_CTRL				0x40
@@ -84,6 +85,12 @@
 /* PARF_PM_CTRL register fields */
 #define REQ_NOT_ENTR_L1				BIT(5)
 
+/* PARF_PM_STTS register fields */
+#define PM_LINKST_IN_L1SUB			BIT(8)
+#define PM_LINKST_IN_L0S			BIT(7)
+#define PM_LINKST_IN_L2				BIT(5)
+#define PM_LINKST_IN_L1				BIT(4)
+
 /* PARF_PCS_DEEMPH register fields */
 #define PCS_DEEMPH_TX_DEEMPH_GEN1(x)		FIELD_PREP(GENMASK(21, 16), x)
 #define PCS_DEEMPH_TX_DEEMPH_GEN2_3_5DB(x)	FIELD_PREP(GENMASK(13, 8), x)
@@ -737,6 +744,31 @@ static int qcom_pcie_post_init_2_4_0(struct qcom_pcie *pcie)
 	return 0;
 }
 
+static int qcom_pcie_debugfs_func_2_4_0(struct seq_file *s, void *data)
+{
+	struct qcom_pcie *pcie = (struct qcom_pcie *) dev_get_drvdata(s->private);
+
+	seq_printf(s, "L0s transition count: %u\n",
+		   readl_relaxed(pcie->parf + PM_LINKST_IN_L0S));
+
+	seq_printf(s, "L1 transition count: %u\n",
+		   readl_relaxed(pcie->parf + PM_LINKST_IN_L1));
+
+	seq_printf(s, "L1.1 transition count: %u\n",
+		   readl_relaxed(pcie->parf + PM_LINKST_IN_L1SUB));
+
+	seq_printf(s, "L2 transition count: %u\n",
+		   readl_relaxed(pcie->parf + PM_LINKST_IN_L2));
+
+	return 0;
+}
+
+
+static void qcom_pcie_init_debugfs_2_4_0(struct qcom_pcie *pcie)
+{
+	qcom_pcie_init_debugfs(pcie, qcom_pcie_debugfs_func_2_4_0);
+}
+
 static int qcom_pcie_get_resources_2_3_3(struct qcom_pcie *pcie)
 {
 	struct qcom_pcie_resources_2_3_3 *res = &pcie->res.v2_3_3;
@@ -1300,6 +1332,7 @@ static const struct qcom_pcie_ops ops_2_4_0 = {
 	.post_init = qcom_pcie_post_init_2_4_0,
 	.deinit = qcom_pcie_deinit_2_4_0,
 	.ltssm_enable = qcom_pcie_2_3_2_ltssm_enable,
+	.init_debugfs = qcom_pcie_init_debugfs_2_4_0,
 };
 
 /* Qcom IP rev.: 2.3.3	Synopsys IP rev.: 4.30a */
-- 
2.25.1