[PATCH v3 05/12] PCI: qcom-ep: Expose link transition counts via debugfs

Manivannan Sadhasivam
2022-09-10T06:32:18Z

Qualcomm PCIe controllers have debug registers in the MMIO 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@linaro.org>
---
drivers/pci/controller/dwc/pcie-qcom-ep.c | 60 +++++++++++++++++++++++
1 file changed, 60 insertions(+)

diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
index 72eb6cacdb3a..2dc6d4e44aff 100644
--- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
+++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
@@ -10,6 +10,7 @@
*/

#include <linux/clk.h>
+#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/mfd/syscon.h>
@@ -45,6 +46,11 @@
#define PARF_ATU_BASE_ADDR 0x634
#define PARF_ATU_BASE_ADDR_HI 0x638
#define PARF_SRIS_MODE 0x644
+#define PARF_DEBUG_CNT_PM_LINKST_IN_L2 0xc04
+#define PARF_DEBUG_CNT_PM_LINKST_IN_L1 0xc0c
+#define PARF_DEBUG_CNT_PM_LINKST_IN_L0S 0xc10
+#define PARF_DEBUG_CNT_AUX_CLK_IN_L1SUB_L1 0xc84
+#define PARF_DEBUG_CNT_AUX_CLK_IN_L1SUB_L2 0xc88
#define PARF_DEVICE_TYPE 0x1000
#define PARF_BDF_TO_SID_CFG 0x2c00

@@ -135,12 +141,14 @@ enum qcom_pcie_ep_link_status {
* @pci: Designware PCIe controller struct
* @parf: Qualcomm PCIe specific PARF register base
* @elbi: Designware PCIe specific ELBI register base
+ * @mmio: MMIO register base
* @perst_map: PERST regmap
* @mmio_res: MMIO region resource
* @core_reset: PCIe Endpoint core reset
* @reset: PERST# GPIO
* @wake: WAKE# GPIO
* @phy: PHY controller block
+ * @debugfs: PCIe Endpoint Debugfs directory
* @clks: PCIe clocks
* @num_clks: PCIe clocks count
* @perst_en: Flag for PERST enable
@@ -154,6 +162,7 @@ struct qcom_pcie_ep {

void __iomem *parf;
void __iomem *elbi;
+ void __iomem *mmio;
struct regmap *perst_map;
struct resource *mmio_res;

@@ -161,6 +170,7 @@ struct qcom_pcie_ep {
struct gpio_desc *reset;
struct gpio_desc *wake;
struct phy *phy;
+ struct dentry *debugfs;

struct clk_bulk_data *clks;
int num_clks;
@@ -446,6 +456,9 @@ static int qcom_pcie_ep_get_io_resources(struct platform_device *pdev,

pcie_ep->mmio_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
"mmio");
+ pcie_ep->mmio = devm_pci_remap_cfg_resource(dev, pcie_ep->mmio_res);
+ if (IS_ERR(pcie_ep->mmio))
+ return PTR_ERR(pcie_ep->mmio);

syscon = of_parse_phandle(dev->of_node, "qcom,perst-regs", 0);
if (!syscon) {
@@ -629,6 +642,37 @@ static int qcom_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
}
}

+static int qcom_pcie_ep_link_transition_count(struct seq_file *s, void *data)
+{
+ struct qcom_pcie_ep *pcie_ep = (struct qcom_pcie_ep *)
+ dev_get_drvdata(s->private);
+
+ seq_printf(s, "L0s transition count: %u\n",
+ readl_relaxed(pcie_ep->mmio + PARF_DEBUG_CNT_PM_LINKST_IN_L0S));
+
+ seq_printf(s, "L1 transition count: %u\n",
+ readl_relaxed(pcie_ep->mmio + PARF_DEBUG_CNT_PM_LINKST_IN_L1));
+
+ seq_printf(s, "L1.1 transition count: %u\n",
+ readl_relaxed(pcie_ep->mmio + PARF_DEBUG_CNT_AUX_CLK_IN_L1SUB_L1));
+
+ seq_printf(s, "L1.2 transition count: %u\n",
+ readl_relaxed(pcie_ep->mmio + PARF_DEBUG_CNT_AUX_CLK_IN_L1SUB_L2));
+
+ seq_printf(s, "L2 transition count: %u\n",
+ readl_relaxed(pcie_ep->mmio + PARF_DEBUG_CNT_PM_LINKST_IN_L2));
+
+ return 0;
+}
+
+static void qcom_pcie_ep_init_debugfs(struct qcom_pcie_ep *pcie_ep)
+{
+ struct dw_pcie *pci = &pcie_ep->pci;
+
+ debugfs_create_devm_seqfile(pci->dev, "link_transition_count", pcie_ep->debugfs,
+ qcom_pcie_ep_link_transition_count);
+}
+
static const struct pci_epc_features qcom_pcie_epc_features = {
.linkup_notifier = true,
.core_init_notifier = true,
@@ -661,6 +705,7 @@ static int qcom_pcie_ep_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct qcom_pcie_ep *pcie_ep;
+ char *name;
int ret;

pcie_ep = devm_kzalloc(dev, sizeof(*pcie_ep), GFP_KERNEL);
@@ -686,8 +731,21 @@ static int qcom_pcie_ep_probe(struct platform_device *pdev)
if (ret)
goto err_disable_resources;

+ name = devm_kasprintf(dev, GFP_KERNEL, "%pOFP", dev->of_node);
+ if (!name) {
+ ret = -ENOMEM;
+ goto err_disable_irqs;
+ }
+
+ pcie_ep->debugfs = debugfs_create_dir(name, NULL);
+ qcom_pcie_ep_init_debugfs(pcie_ep);
+
return 0;

+err_disable_irqs:
+ disable_irq(pcie_ep->global_irq);
+ disable_irq(pcie_ep->perst_irq);
+
err_disable_resources:
qcom_pcie_disable_resources(pcie_ep);

@@ -701,6 +759,8 @@ static int qcom_pcie_ep_remove(struct platform_device *pdev)
disable_irq(pcie_ep->global_irq);
disable_irq(pcie_ep->perst_irq);

+ debugfs_remove_recursive(pcie_ep->debugfs);
+
if (pcie_ep->link_status == QCOM_PCIE_EP_LINK_DISABLED)
return 0;

--
2.25.1