From: Krishna Chaitanya Chundru Date: Wed, 29 Apr 2026 06:42:24 +0000 (+0530) Subject: PCI: qcom: Add .get_ltssm() callback to query LTSSM status X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=131a93dbcb9546683384e31dc4057d4aaf38fa21;p=thirdparty%2Flinux.git PCI: qcom: Add .get_ltssm() callback to query LTSSM status For older SoCs like SC7280, reading DBI LTSSM register after sending PME_Turn_Off message causes NOC error. To avoid unsafe DBI accesses, introduce qcom_pcie_get_ltssm() to retrieve the LTSSM state without DBI. For newer platforms, read the LTSSM state from the PARF_LTSSM register; for older platforms continue to retrieve it from ELBI_SYS_STTS. This helper is used in place of direct DBI-based link state checks in the D3cold path after sending PME_Turn_Off message, ensuring the LTSSM state can be queried safely even after DBI access is no longer valid. Signed-off-by: Krishna Chaitanya Chundru [mani: commit log and fixed get_ltssm() check] Signed-off-by: Manivannan Sadhasivam Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20260429-d3cold-v5-2-89e9735b9df6@oss.qualcomm.com --- diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c index f21f3806fc1f..881746efe3b6 100644 --- a/drivers/pci/controller/dwc/pcie-qcom.c +++ b/drivers/pci/controller/dwc/pcie-qcom.c @@ -71,6 +71,7 @@ /* ELBI registers */ #define ELBI_SYS_CTRL 0x04 +#define ELBI_SYS_STTS 0x08 /* DBI registers */ #define AXI_MSTR_RESP_COMP_CTRL0 0x818 @@ -131,6 +132,7 @@ /* PARF_LTSSM register fields */ #define LTSSM_EN BIT(8) +#define PARF_LTSSM_STATE_MASK GENMASK(5, 0) /* PARF_NO_SNOOP_OVERRIDE register fields */ #define WR_NO_SNOOP_OVERRIDE_EN BIT(1) @@ -145,6 +147,9 @@ /* ELBI_SYS_CTRL register fields */ #define ELBI_SYS_CTRL_LT_ENABLE BIT(0) +/* ELBI_SYS_STTS register fields */ +#define ELBI_SYS_STTS_LTSSM_STATE_MASK GENMASK(17, 12) + /* AXI_MSTR_RESP_COMP_CTRL0 register fields */ #define CFG_REMOTE_RD_REQ_BRIDGE_SIZE_2K 0x4 #define CFG_REMOTE_RD_REQ_BRIDGE_SIZE_4K 0x5 @@ -245,6 +250,7 @@ struct qcom_pcie_ops { void (*deinit)(struct qcom_pcie *pcie); void (*ltssm_enable)(struct qcom_pcie *pcie); int (*config_sid)(struct qcom_pcie *pcie); + enum dw_pcie_ltssm (*get_ltssm)(struct qcom_pcie *pcie); }; /** @@ -428,6 +434,15 @@ static void qcom_pcie_2_1_0_ltssm_enable(struct qcom_pcie *pcie) writel(val, pci->elbi_base + ELBI_SYS_CTRL); } +static enum dw_pcie_ltssm qcom_pcie_2_1_0_get_ltssm(struct qcom_pcie *pcie) +{ + struct dw_pcie *pci = pcie->pci; + u32 val; + + val = readl(pci->elbi_base + ELBI_SYS_STTS); + return (enum dw_pcie_ltssm)FIELD_GET(ELBI_SYS_STTS_LTSSM_STATE_MASK, val); +} + static int qcom_pcie_get_resources_2_1_0(struct qcom_pcie *pcie) { struct qcom_pcie_resources_2_1_0 *res = &pcie->res.v2_1_0; @@ -1260,6 +1275,19 @@ static bool qcom_pcie_link_up(struct dw_pcie *pci) return val & PCI_EXP_LNKSTA_DLLLA; } +static enum dw_pcie_ltssm qcom_pcie_get_ltssm(struct dw_pcie *pci) +{ + struct qcom_pcie *pcie = to_qcom_pcie(pci); + u32 val; + + if (pcie->cfg->ops->get_ltssm) + return pcie->cfg->ops->get_ltssm(pcie); + + val = readl(pcie->parf + PARF_LTSSM); + + return (enum dw_pcie_ltssm)FIELD_GET(PARF_LTSSM_STATE_MASK, val); +} + static void qcom_pcie_phy_power_off(struct qcom_pcie *pcie) { struct qcom_pcie_port *port; @@ -1385,6 +1413,7 @@ static const struct qcom_pcie_ops ops_2_1_0 = { .post_init = qcom_pcie_post_init_2_1_0, .deinit = qcom_pcie_deinit_2_1_0, .ltssm_enable = qcom_pcie_2_1_0_ltssm_enable, + .get_ltssm = qcom_pcie_2_1_0_get_ltssm, }; /* Qcom IP rev.: 1.0.0 Synopsys IP rev.: 4.11a */ @@ -1394,6 +1423,7 @@ static const struct qcom_pcie_ops ops_1_0_0 = { .post_init = qcom_pcie_post_init_1_0_0, .deinit = qcom_pcie_deinit_1_0_0, .ltssm_enable = qcom_pcie_2_1_0_ltssm_enable, + .get_ltssm = qcom_pcie_2_1_0_get_ltssm, }; /* Qcom IP rev.: 2.3.2 Synopsys IP rev.: 4.21a */ @@ -1512,6 +1542,7 @@ static const struct qcom_pcie_cfg cfg_fw_managed = { static const struct dw_pcie_ops dw_pcie_ops = { .link_up = qcom_pcie_link_up, .start_link = qcom_pcie_start_link, + .get_ltssm = qcom_pcie_get_ltssm, }; static int qcom_pcie_icc_init(struct qcom_pcie *pcie)