[PATCH 2/3] PCI: dwc: Add ECAM support with iATU configuration

Krishna chaitanya chundru
2024-11-16T22:01:06Z

The current implementation requires iATU for every configuration
space access which increases latency & cpu utilization.

Configuring iATU in config shift mode 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 mode.

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 acheive this.

Introduce new ecam_init() function op for the clients to configure after
ecam window creation has been done.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
---
drivers/pci/controller/dwc/pcie-designware-host.c | 114 ++++++++++++++++++----
drivers/pci/controller/dwc/pcie-designware.c | 2 +-
drivers/pci/controller/dwc/pcie-designware.h | 6 ++
3 files changed, 102 insertions(+), 20 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 3e41865c7290..e98cc841a2a9 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -418,6 +418,62 @@ 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};
+ struct resource_entry *bus;
+ int ret, bus_range_max;
+
+ bus = resource_list_first_type(&pp->bridge->windows, IORESOURCE_BUS);
+
+ /*
+ * Bus 1 config space needs type 0 atu configuration
+ * Remaining buses need type 1 atu configuration
+ */
+ atu.index = 0;
+ atu.type = PCIE_ATU_TYPE_CFG0;
+ atu.cpu_addr = pp->cfg0_base + SZ_1M;
+ 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 = bus->res->end - bus->res->start + 1;
+
+ /* Configure for bus 2 - bus_range_max in type 1 */
+ atu.index = 1;
+ atu.type = PCIE_ATU_TYPE_CFG1;
+ atu.cpu_addr = pp->cfg0_base + SZ_2M;
+ atu.size = (SZ_1M * (bus_range_max - 2));
+ 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;
+
+ if (pp->ops->ecam_init)
+ pp->ops->ecam_init(pci, pp->cfg);
+
+ return 0;
+}
+
int dw_pcie_host_init(struct dw_pcie_rp *pp)
{
struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -431,19 +487,8 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)

raw_spin_lock_init(&pp->lock);

- ret = dw_pcie_get_resources(pci);
- if (ret)
- return ret;
-
res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "config");
- if (res) {
- 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);
- } else {
+ if (!res) {
dev_err(dev, "Missing *config* reg space\n");
return -ENODEV;
}
@@ -454,6 +499,30 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)

pp->bridge = bridge;

+ pp->cfg0_size = resource_size(res);
+ pp->cfg0_base = res->start;
+
+ if (!pp->enable_ecam) {
+ 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 */
+ bridge->ops = &dw_pcie_ops;
+ bridge->child_ops = &dw_child_pcie_ops;
+ bridge->sysdata = pp;
+ } else {
+ ret = dw_pcie_create_ecam_window(pp, res);
+ if (ret)
+ return ret;
+ bridge->ops = (struct pci_ops *)&pci_generic_ecam_ops.pci_ops;
+ pp->bridge->sysdata = pp->cfg;
+ }
+
+ ret = dw_pcie_get_resources(pci);
+ if (ret)
+ goto err_free_ecam;
+
/* Get the I/O range from DT */
win = resource_list_first_type(&bridge->windows, IORESOURCE_IO);
if (win) {
@@ -462,14 +531,10 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
pp->io_base = pci_pio_to_address(win->res->start);
}

- /* 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()) {
@@ -504,6 +569,12 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)

dw_pcie_iatu_detect(pci);

+ if (pp->enable_ecam) {
+ ret = dw_pcie_config_ecam_iatu(pp);
+ if (ret)
+ 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
@@ -533,8 +604,6 @@ 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;
@@ -558,6 +627,10 @@ 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);
@@ -578,6 +651,9 @@ 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 6d6cbc8b5b2c..63d36676f858 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -509,7 +509,7 @@ 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 347ab74ac35a..33afa91b402c 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>
@@ -171,6 +172,7 @@
#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
@@ -342,6 +344,7 @@ struct dw_pcie_ob_atu_cfg {
u8 func_no;
u8 code;
u8 routing;
+ u32 ctrl2;
u64 cpu_addr;
u64 pci_addr;
u64 size;
@@ -353,6 +356,7 @@ struct dw_pcie_host_ops {
void (*post_init)(struct dw_pcie_rp *pp);
int (*msi_init)(struct dw_pcie_rp *pp);
void (*pme_turn_off)(struct dw_pcie_rp *pp);
+ int (*ecam_init)(struct dw_pcie *pcie, struct pci_config_window *cfg);
};

struct dw_pcie_rp {
@@ -379,6 +383,8 @@ struct dw_pcie_rp {
bool use_atu_msg;
int msg_atu_index;
struct resource *msg_res;
+ bool enable_ecam;
+ struct pci_config_window *cfg;
};

struct dw_pcie_ep_ops {

--
2.34.1