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Message-Id: <20250712-ecam_v4-v6-4-d820f912e354@qti.qualcomm.com>
Date: Sat, 12 Jul 2025 05:12:40 +0530
From: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
To: cros-qcom-dts-watchers@...omium.org,
Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Manivannan Sadhasivam <mani@...nel.org>,
Krzysztof Wilczyński <kwilczynski@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>, Jingoo Han <jingoohan1@...il.com>
Cc: linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
quic_vbadigan@...cinc.com, quic_mrana@...cinc.com,
quic_vpernami@...cinc.com, mmareddy@...cinc.com,
Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Subject: [PATCH v6 4/5] PCI: dwc: Add ECAM support with iATU configuration
The current implementation requires iATU for every configuration
space access which increases latency & cpu utilization.
Designware databook 5.20a, section 3.10.10.3 says about CFG Shift Feature,
which shifts/maps the BDF (bits [31:16] of the third header DWORD, which
would be matched against the Base and Limit addresses) of the incoming
CfgRd0/CfgWr0 down to bits[27:12]of the translated address.
Configuring iATU in config shift feature enables ECAM feature to access the
config space, which avoids iATU configuration for every config access.
Add "ctrl2" into struct dw_pcie_ob_atu_cfg to enable config shift feature.
As DBI comes under config space, this avoids remapping of DBI space
separately. Instead, it uses the mapped config space address returned from
ECAM initialization. Change the order of dw_pcie_get_resources() execution
to achieve this.
Enable the ECAM feature if the config space size is equal to size required
to represent number of buses in the bus range property.
Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
---
drivers/pci/controller/dwc/Kconfig | 1 +
drivers/pci/controller/dwc/pcie-designware-host.c | 131 +++++++++++++++++++---
drivers/pci/controller/dwc/pcie-designware.c | 2 +-
drivers/pci/controller/dwc/pcie-designware.h | 5 +
4 files changed, 124 insertions(+), 15 deletions(-)
diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
index d9f0386396edf66ad0e514a0f545ed24d89fcb6c..9fe9a7756139450819c6db14eb7f67b0a07b6aa8 100644
--- a/drivers/pci/controller/dwc/Kconfig
+++ b/drivers/pci/controller/dwc/Kconfig
@@ -19,6 +19,7 @@ config PCIE_DW_DEBUGFS
config PCIE_DW_HOST
bool
select PCIE_DW
+ select PCI_HOST_COMMON
config PCIE_DW_EP
bool
diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 906277f9ffaf79f2c5c3c76f1941556bebdba38f..169e890a5992783bed9480fa841e83d4d93898f1 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -418,6 +418,81 @@ 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 bool dw_pcie_ecam_supported(struct dw_pcie_rp *pp, struct resource *config_res)
+{
+ struct resource *bus_range;
+ u64 nr_buses;
+
+ 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);
@@ -427,10 +502,6 @@ 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");
@@ -440,9 +511,32 @@ 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);
+ pp->ecam_mode = dw_pcie_ecam_supported(pp, res);
+ if (pp->ecam_mode) {
+ 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);
@@ -481,14 +575,10 @@ 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()) {
@@ -530,6 +620,14 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
if (ret)
goto err_free_msi;
+ if (pp->ecam_mode) {
+ 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
@@ -565,8 +663,6 @@ 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;
@@ -592,6 +688,10 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
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);
@@ -614,6 +714,9 @@ 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);
diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index f7bbfd91b03b5e18031983ff4ebd829f450b8154..87527e09e392072c09b240d05f3cba4865ec8e9f 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -576,7 +576,7 @@ int dw_pcie_prog_outbound_atu(struct dw_pcie *pci,
val = dw_pcie_enable_ecrc(val);
dw_pcie_writel_atu_ob(pci, atu->index, PCIE_ATU_REGION_CTRL1, val);
- val = PCIE_ATU_ENABLE;
+ val = PCIE_ATU_ENABLE | atu->ctrl2;
if (atu->type == PCIE_ATU_TYPE_MSG) {
/* The data-less messages only for now */
val |= PCIE_ATU_INHIBIT_PAYLOAD | atu->code;
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 31b2a7e9dafa4ab481434068bde0775837babb4f..a8e25fb53a46a71063fafdf5665b88d106709413 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -20,6 +20,7 @@
#include <linux/irq.h>
#include <linux/msi.h>
#include <linux/pci.h>
+#include <linux/pci-ecam.h>
#include <linux/reset.h>
#include <linux/pci-epc.h>
@@ -173,6 +174,7 @@
#define PCIE_ATU_REGION_CTRL2 0x004
#define PCIE_ATU_ENABLE BIT(31)
#define PCIE_ATU_BAR_MODE_ENABLE BIT(30)
+#define PCIE_ATU_CFG_SHIFT_MODE_ENABLE BIT(28)
#define PCIE_ATU_INHIBIT_PAYLOAD BIT(22)
#define PCIE_ATU_FUNC_NUM_MATCH_EN BIT(19)
#define PCIE_ATU_LOWER_BASE 0x008
@@ -391,6 +393,7 @@ struct dw_pcie_ob_atu_cfg {
u8 func_no;
u8 code;
u8 routing;
+ u32 ctrl2;
u64 parent_bus_addr;
u64 pci_addr;
u64 size;
@@ -430,6 +433,8 @@ struct dw_pcie_rp {
struct resource *msg_res;
bool use_linkup_irq;
struct pci_eq_presets presets;
+ bool ecam_mode;
+ struct pci_config_window *cfg;
};
struct dw_pcie_ep_ops {
--
2.34.1
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