From f6fd357f7afbeb34a633e5688a23b9d7eb49d558 Mon Sep 17 00:00:00 2001 From: Krishna Chaitanya Chundru Date: Tue, 23 Sep 2025 16:56:52 +0530 Subject: PCI: dwc: Prepare the driver for enabling ECAM mechanism using iATU 'CFG Shift Feature' In order to enable PCIe ECAM mechanism in DWC driver as per the 'CFG Shift Feature' documented in Designware databook r5.20a, sec 3.10.10.3, prepare the driver to handle the one time iATU setup and creating ECAM window. Signed-off-by: Krishna Chaitanya Chundru [mani: splitted the preparatory code into a separate commit for bisectability] Signed-off-by: Manivannan Sadhasivam Link: https://patch.msgid.link/20250923-controller-dwc-ecam-v10-2-e84390ba75fa@kernel.org --- drivers/pci/controller/dwc/pcie-designware-host.c | 116 +++++++++++++++++++--- 1 file changed, 102 insertions(+), 14 deletions(-) (limited to 'drivers/pci/controller/dwc/pcie-designware-host.c') diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c index 952f8594b501..94e0fe11a0b0 100644 --- a/drivers/pci/controller/dwc/pcie-designware-host.c +++ b/drivers/pci/controller/dwc/pcie-designware-host.c @@ -413,6 +413,67 @@ static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp) } } +static int dw_pcie_config_ecam_iatu(struct dw_pcie_rp *pp) +{ + struct dw_pcie *pci = to_dw_pcie_from_pp(pp); + struct dw_pcie_ob_atu_cfg atu = {0}; + resource_size_t bus_range_max; + struct resource_entry *bus; + int ret; + + bus = resource_list_first_type(&pp->bridge->windows, IORESOURCE_BUS); + + /* + * Root bus under the host bridge doesn't require any iATU configuration + * as DBI region will be used to access root bus config space. + * Immediate bus under Root Bus, needs type 0 iATU configuration and + * remaining buses need type 1 iATU configuration. + */ + atu.index = 0; + atu.type = PCIE_ATU_TYPE_CFG0; + atu.parent_bus_addr = pp->cfg0_base + SZ_1M; + /* 1MiB is to cover 1 (bus) * 32 (devices) * 8 (functions) */ + atu.size = SZ_1M; + atu.ctrl2 = PCIE_ATU_CFG_SHIFT_MODE_ENABLE; + ret = dw_pcie_prog_outbound_atu(pci, &atu); + if (ret) + return ret; + + bus_range_max = resource_size(bus->res); + + if (bus_range_max < 2) + return 0; + + /* Configure remaining buses in type 1 iATU configuration */ + atu.index = 1; + atu.type = PCIE_ATU_TYPE_CFG1; + atu.parent_bus_addr = pp->cfg0_base + SZ_2M; + atu.size = (SZ_1M * bus_range_max) - SZ_2M; + atu.ctrl2 = PCIE_ATU_CFG_SHIFT_MODE_ENABLE; + + return dw_pcie_prog_outbound_atu(pci, &atu); +} + +static int dw_pcie_create_ecam_window(struct dw_pcie_rp *pp, struct resource *res) +{ + struct dw_pcie *pci = to_dw_pcie_from_pp(pp); + struct device *dev = pci->dev; + struct resource_entry *bus; + + bus = resource_list_first_type(&pp->bridge->windows, IORESOURCE_BUS); + if (!bus) + return -ENODEV; + + pp->cfg = pci_ecam_create(dev, res, bus->res, &pci_generic_ecam_ops); + if (IS_ERR(pp->cfg)) + return PTR_ERR(pp->cfg); + + pci->dbi_base = pp->cfg->win; + pci->dbi_phys_addr = res->start; + + return 0; +} + static int dw_pcie_host_get_resources(struct dw_pcie_rp *pp) { struct dw_pcie *pci = to_dw_pcie_from_pp(pp); @@ -422,10 +483,6 @@ static int dw_pcie_host_get_resources(struct dw_pcie_rp *pp) struct resource *res; int ret; - ret = dw_pcie_get_resources(pci); - if (ret) - return ret; - res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "config"); if (!res) { dev_err(dev, "Missing \"config\" reg space\n"); @@ -435,9 +492,31 @@ static int dw_pcie_host_get_resources(struct dw_pcie_rp *pp) pp->cfg0_size = resource_size(res); pp->cfg0_base = res->start; - pp->va_cfg0_base = devm_pci_remap_cfg_resource(dev, res); - if (IS_ERR(pp->va_cfg0_base)) - return PTR_ERR(pp->va_cfg0_base); + if (pp->ecam_enabled) { + ret = dw_pcie_create_ecam_window(pp, res); + if (ret) + return ret; + + pp->bridge->ops = (struct pci_ops *)&pci_generic_ecam_ops.pci_ops; + pp->bridge->sysdata = pp->cfg; + pp->cfg->priv = pp; + } else { + pp->va_cfg0_base = devm_pci_remap_cfg_resource(dev, res); + if (IS_ERR(pp->va_cfg0_base)) + return PTR_ERR(pp->va_cfg0_base); + + /* Set default bus ops */ + pp->bridge->ops = &dw_pcie_ops; + pp->bridge->child_ops = &dw_child_pcie_ops; + pp->bridge->sysdata = pp; + } + + ret = dw_pcie_get_resources(pci); + if (ret) { + if (pp->cfg) + pci_ecam_free(pp->cfg); + return ret; + } /* Get the I/O range from DT */ win = resource_list_first_type(&pp->bridge->windows, IORESOURCE_IO); @@ -476,14 +555,10 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp) if (ret) return ret; - /* Set default bus ops */ - bridge->ops = &dw_pcie_ops; - bridge->child_ops = &dw_child_pcie_ops; - if (pp->ops->init) { ret = pp->ops->init(pp); if (ret) - return ret; + goto err_free_ecam; } if (pci_msi_enabled()) { @@ -525,6 +600,14 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp) if (ret) goto err_free_msi; + if (pp->ecam_enabled) { + ret = dw_pcie_config_ecam_iatu(pp); + if (ret) { + dev_err(dev, "Failed to configure iATU in ECAM mode\n"); + goto err_free_msi; + } + } + /* * Allocate the resource for MSG TLP before programming the iATU * outbound window in dw_pcie_setup_rc(). Since the allocation depends @@ -560,8 +643,6 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp) /* Ignore errors, the link may come up later */ dw_pcie_wait_for_link(pci); - bridge->sysdata = pp; - ret = pci_host_probe(bridge); if (ret) goto err_stop_link; @@ -587,6 +668,10 @@ err_deinit_host: if (pp->ops->deinit) pp->ops->deinit(pp); +err_free_ecam: + if (pp->cfg) + pci_ecam_free(pp->cfg); + return ret; } EXPORT_SYMBOL_GPL(dw_pcie_host_init); @@ -609,6 +694,9 @@ void dw_pcie_host_deinit(struct dw_pcie_rp *pp) if (pp->ops->deinit) pp->ops->deinit(pp); + + if (pp->cfg) + pci_ecam_free(pp->cfg); } EXPORT_SYMBOL_GPL(dw_pcie_host_deinit); -- cgit v1.2.3 From 0da48c5b2fa731b21bc523c82d927399a1e508b0 Mon Sep 17 00:00:00 2001 From: Krishna Chaitanya Chundru Date: Tue, 23 Sep 2025 16:56:54 +0530 Subject: PCI: dwc: Support ECAM mechanism by enabling iATU 'CFG Shift Feature' Designware databook r5.20a, sec 3.10.10.3 documents the 'CFG Shift Feature' of the internal Address Translation Unit (iATU). When this feature is enabled, it shifts/maps the BDF contained in the bits [27:12] of the target address in MEM TLP to become BDF of the CFG TLP. This essentially implements the Enhanced Configuration Address Mapping (ECAM) mechanism as defined in PCIe r6.0, sec 7.2.2. Currently, the driver is not making use of this CFG shift feature, thereby creating the iATU outbound map for each config access to the devices, causing latency and wasting CPU cycles. So to avoid this, configure the controller to enable CFG shift feature by enabling the 'CFG Shift' bit of the 'iATU Control 2 Register'. As a result of enabling CFG shift (ECAM), there is no longer a need to map the DBI register space separately as the DBI region falls under the 'config' space used for ECAM (as DBI is used to access the Root Port). For enabling ECAM using CFG shift, the platform has to satisfy following requirements: 1. Size of the 'config' memory space to be used as ECAM memory should be able to accommodate the number of buses defined in the 'bus-range' property of the host bridge DT node. 2. The 'config' memory space should be 256 MiB aligned. This requirement comes from PCIe r6.0, sec 7.2.2, which says the base address of ECAM memory should be aligned to a 2^(n+20) byte address boundary. For the DWC cores, n is 8, so this results in 2^28 byte alignment requirement. It should be noted that some DWC vendor glue drivers like pcie-al may use their own ECAM mechanism. For those controllers, set 'dw_pcie_rp::native_ecam' flag and skip enabling the CFG Shift feature in the DWC core. Signed-off-by: Krishna Chaitanya Chundru [mani: code split, reworded subject/description, comment, native_ecam flag] Signed-off-by: Manivannan Sadhasivam Link: https://patch.msgid.link/20250923-controller-dwc-ecam-v10-4-e84390ba75fa@kernel.org --- drivers/pci/controller/dwc/pcie-designware-host.c | 32 +++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'drivers/pci/controller/dwc/pcie-designware-host.c') diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c index 94e0fe11a0b0..20c9333bcb1c 100644 --- a/drivers/pci/controller/dwc/pcie-designware-host.c +++ b/drivers/pci/controller/dwc/pcie-designware-host.c @@ -8,6 +8,7 @@ * Author: Jingoo Han */ +#include #include #include #include @@ -32,6 +33,8 @@ static struct pci_ops dw_child_pcie_ops; MSI_FLAG_PCI_MSIX | \ MSI_GENERIC_FLAGS_MASK) +#define IS_256MB_ALIGNED(x) IS_ALIGNED(x, SZ_256M) + static const struct msi_parent_ops dw_pcie_msi_parent_ops = { .required_flags = DW_PCIE_MSI_FLAGS_REQUIRED, .supported_flags = DW_PCIE_MSI_FLAGS_SUPPORTED, @@ -474,6 +477,34 @@ static int dw_pcie_create_ecam_window(struct dw_pcie_rp *pp, struct resource *re return 0; } +static bool dw_pcie_ecam_enabled(struct dw_pcie_rp *pp, struct resource *config_res) +{ + struct resource *bus_range; + u64 nr_buses; + + /* Vendor glue drivers may implement their own ECAM mechanism */ + if (pp->native_ecam) + return false; + + /* + * PCIe spec r6.0, sec 7.2.2 mandates the base address used for ECAM to + * be aligned on a 2^(n+20) byte boundary, where n is the number of bits + * used for representing 'bus' in BDF. Since the DWC cores always use 8 + * bits for representing 'bus', the base address has to be aligned to + * 2^28 byte boundary, which is 256 MiB. + */ + if (!IS_256MB_ALIGNED(config_res->start)) + return false; + + bus_range = resource_list_first_type(&pp->bridge->windows, IORESOURCE_BUS)->res; + if (!bus_range) + return false; + + nr_buses = resource_size(config_res) >> PCIE_ECAM_BUS_SHIFT; + + return nr_buses >= resource_size(bus_range); +} + static int dw_pcie_host_get_resources(struct dw_pcie_rp *pp) { struct dw_pcie *pci = to_dw_pcie_from_pp(pp); @@ -492,6 +523,7 @@ static int dw_pcie_host_get_resources(struct dw_pcie_rp *pp) pp->cfg0_size = resource_size(res); pp->cfg0_base = res->start; + pp->ecam_enabled = dw_pcie_ecam_enabled(pp, res); if (pp->ecam_enabled) { ret = dw_pcie_create_ecam_window(pp, res); if (ret) -- cgit v1.2.3