On 3/9/2023 2:21 PM, Manivannan Sadhasivam wrote:
Qualcomm PCIe controllers have debug registers in the MHI region that
count PCIe link transitions. Expose them over debugfs to userspace to
help debug the low power issues.
Note that even though the registers are prefixed as PARF_, they don't
live under the "parf" register region. The register naming is following
the Qualcomm's internal documentation as like other registers.
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
drivers/pci/controller/dwc/pcie-qcom.c | 59 ++++++++++++++++++++++++++
1 file changed, 59 insertions(+)
diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index e1180c84f0fa..6d9bde64c9e9 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -10,6 +10,7 @@
#include <linux/clk.h>
#include <linux/crc8.h>
+#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/interconnect.h>
@@ -62,6 +63,13 @@
#define AXI_MSTR_RESP_COMP_CTRL1 0x81c
#define MISC_CONTROL_1_REG 0x8bc
+/* MHI registers */
+#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
+
/* PARF_SYS_CTRL register fields */
#define MAC_PHY_POWERDOWN_IN_P2_D_MUX_EN BIT(29)
#define MST_WAKEUP_EN BIT(13)
@@ -229,11 +237,13 @@ struct qcom_pcie {
struct dw_pcie *pci;
void __iomem *parf; /* DT parf */
void __iomem *elbi; /* DT elbi */
+ void __iomem *mhi;
union qcom_pcie_resources res;
struct phy *phy;
struct gpio_desc *reset;
struct icc_path *icc_mem;
const struct qcom_pcie_cfg *cfg;
+ struct dentry *debugfs;
};
#define to_qcom_pcie(x) dev_get_drvdata((x)->dev)
@@ -1385,6 +1395,37 @@ static void qcom_pcie_icc_update(struct qcom_pcie *pcie)
}
}
+static int qcom_pcie_link_transition_count(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->mhi + PARF_DEBUG_CNT_PM_LINKST_IN_L0S));
+
+ seq_printf(s, "L1 transition count: %u\n",
+ readl_relaxed(pcie->mhi + PARF_DEBUG_CNT_PM_LINKST_IN_L1));
+
+ seq_printf(s, "L1.1 transition count: %u\n",
+ readl_relaxed(pcie->mhi + PARF_DEBUG_CNT_AUX_CLK_IN_L1SUB_L1));
+
+ seq_printf(s, "L1.2 transition count: %u\n",
+ readl_relaxed(pcie->mhi + PARF_DEBUG_CNT_AUX_CLK_IN_L1SUB_L2));
+
+ seq_printf(s, "L2 transition count: %u\n",
+ readl_relaxed(pcie->mhi + PARF_DEBUG_CNT_PM_LINKST_IN_L2));
+
+ return 0;
+}
+
+static void qcom_pcie_init_debugfs(struct qcom_pcie *pcie)
+{
+ struct dw_pcie *pci = pcie->pci;
+
+ debugfs_create_devm_seqfile(pci->dev, "link_transition_count", pcie->debugfs,
+ qcom_pcie_link_transition_count);
+}
+
static int qcom_pcie_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
@@ -1392,6 +1433,7 @@ static int qcom_pcie_probe(struct platform_device *pdev)
struct dw_pcie *pci;
struct qcom_pcie *pcie;
const struct qcom_pcie_cfg *pcie_cfg;
+ char *name;
int ret;
pcie_cfg = of_device_get_match_data(dev);
@@ -1439,6 +1481,12 @@ static int qcom_pcie_probe(struct platform_device *pdev)
goto err_pm_runtime_put;
}
+ pcie->mhi = devm_platform_ioremap_resource_byname(pdev, "mhi");
+ if (IS_ERR(pcie->mhi)) {
+ ret = PTR_ERR(pcie->mhi);
+ goto err_pm_runtime_put;
+ }
+
Tested this series on ipq4019-ap.dk07.1-c1 board and the above hunk
breaks enumeration because there is no 'mhi' region. All the debug bits
used in the transition_count function is inside the PARF_STTS register
at offset 0x24 inside the PARF region.
Register: PCIE_0_PCIE20_PARF_PM_STTS | 0x80024
Offset: 0x24 Reset State: 0x00040000
Bits Field Name
31 LINK_REQ_RST_NOT
30 XMLH_LINK_UP
29 PM_DSTATE_0
0x0: D0
0x1: D3
28 PHYSTATUS
27:16 PM_DSTATE
15:12 PM_PME_EN
11 PHYCLK_REQ_N
10 L1SS_CLKREQN_OE
9 L1SS_CLKREQN_IN
8 PM_LINKST_IN_L1SUB
7 PM_LINKST_IN_L0S
6 PM_LINKST_L2_EXIT
5 PM_LINKST_IN_L2
4 PM_LINKST_IN_L1
3:0 PM_STATUS
Otherwise, with rest of the patches enumeration was fine.
Tested with a pcie ethernet adapter.
Regards,
Sricharan
