[PATCH v2 2/3] PCI: j721e: Add PCI legacy interrupt support for J721E

Kishon Vijay Abraham I
2021-08-04T13:29:37Z

Add PCI legacy interrupt support for J721E. J721E has a single HW
interrupt line for all the four legacy interrupts INTA/INTB/INTC/INTD.
The HW interrupt line connected to GIC is a pulse interrupt whereas
the legacy interrupts by definition is level interrupt. In order to
provide level interrupt functionality to edge interrupt line, PCIe
in J721E has provided IRQ_EOI register.

However due to Errata ID #i2094 ([1]), EOI feature is not enabled in HW
and only a single pulse interrupt will be generated for every
ASSERT_INTx/DEASSERT_INTx.

[1] -> J721E DRA829/TDA4VM Processors Silicon Revision 1.1/1.0 SPRZ455A –
DECEMBER 2020 – REVISED AUGUST 2021
(https://www.ti.com/lit/er/sprz455a/sprz455a.pdf)

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
---
drivers/pci/controller/cadence/pci-j721e.c | 85 ++++++++++++++++++++++
1 file changed, 85 insertions(+)

diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
index 2ec037c43bd5..c2e7a78dc31f 100644
--- a/drivers/pci/controller/cadence/pci-j721e.c
+++ b/drivers/pci/controller/cadence/pci-j721e.c
@@ -29,6 +29,13 @@
#define LINK_DOWN BIT(1)
#define J7200_LINK_DOWN BIT(10)

+#define EOI_REG 0x10
+
+#define ENABLE_REG_SYS_0 0x100
+#define STATUS_REG_SYS_0 0x500
+#define STATUS_CLR_REG_SYS_0 0x700
+#define INTx_EN(num) (1 << (num))
+
#define J721E_PCIE_USER_CMD_STATUS 0x4
#define LINK_TRAINING_ENABLE BIT(0)

@@ -59,6 +66,7 @@ struct j721e_pcie {
void __iomem *user_cfg_base;
void __iomem *intd_cfg_base;
u32 linkdown_irq_regfield;
+ struct irq_domain *legacy_irq_domain;
};

enum j721e_pcie_mode {
@@ -121,6 +129,79 @@ static void j721e_pcie_config_link_irq(struct j721e_pcie *pcie)
j721e_pcie_intd_writel(pcie, ENABLE_REG_SYS_2, reg);
}

+static void j721e_pcie_v1_legacy_irq_handler(struct irq_desc *desc)
+{
+ struct j721e_pcie *pcie = irq_desc_get_handler_data(desc);
+ struct irq_chip *chip = irq_desc_get_chip(desc);
+ int i, virq;
+ u32 reg;
+
+ chained_irq_enter(chip, desc);
+
+ for (i = 0; i < PCI_NUM_INTX; i++) {
+ reg = j721e_pcie_intd_readl(pcie, STATUS_REG_SYS_0);
+ if (!(reg & INTx_EN(i)))
+ continue;
+
+ virq = irq_find_mapping(pcie->legacy_irq_domain, 3 - i);
+ generic_handle_irq(virq);
+ j721e_pcie_intd_writel(pcie, STATUS_CLR_REG_SYS_0, INTx_EN(i));
+ }
+
+ chained_irq_exit(chip, desc);
+}
+
+static int j721e_pcie_intx_map(struct irq_domain *domain, unsigned int irq, irq_hw_number_t hwirq)
+{
+ irq_set_chip_and_handler(irq, &dummy_irq_chip, handle_simple_irq);
+ irq_set_chip_data(irq, domain->host_data);
+
+ return 0;
+}
+
+static const struct irq_domain_ops j721e_pcie_intx_domain_ops = {
+ .map = j721e_pcie_intx_map,
+};
+
+static int j721e_pcie_config_legacy_irq(struct j721e_pcie *pcie)
+{
+ struct irq_domain *legacy_irq_domain;
+ struct device *dev = pcie->dev;
+ struct device_node *node = dev->of_node;
+ struct device_node *intc_node;
+ int irq, i;
+ u32 reg;
+
+ intc_node = of_get_child_by_name(node, "interrupt-controller");
+ if (!intc_node) {
+ dev_dbg(dev, "interrupt-controller node is absent. Legacy INTR not supported\n");
+ return 0;
+ }
+
+ irq = irq_of_parse_and_map(intc_node, 0);
+ if (!irq) {
+ dev_err(dev, "Failed to parse and map legacy irq\n");
+ return -EINVAL;
+ }
+ irq_set_chained_handler_and_data(irq, j721e_pcie_v1_legacy_irq_handler, pcie);
+
+ legacy_irq_domain = irq_domain_add_linear(intc_node, PCI_NUM_INTX,
+ &j721e_pcie_intx_domain_ops, pcie);
+ if (!legacy_irq_domain) {
+ dev_err(dev, "Failed to add irq domain for legacy irqs\n");
+ return -EINVAL;
+ }
+ pcie->legacy_irq_domain = legacy_irq_domain;
+
+ for (i = 0; i < PCI_NUM_INTX; i++) {
+ reg = j721e_pcie_intd_readl(pcie, ENABLE_REG_SYS_0);
+ reg |= INTx_EN(i);
+ j721e_pcie_intd_writel(pcie, ENABLE_REG_SYS_0, reg);
+ }
+
+ return 0;
+}
+
static int j721e_pcie_start_link(struct cdns_pcie *cdns_pcie)
{
struct j721e_pcie *pcie = dev_get_drvdata(cdns_pcie->dev);
@@ -433,6 +514,10 @@ static int j721e_pcie_probe(struct platform_device *pdev)
goto err_get_sync;
}

+ ret = j721e_pcie_config_legacy_irq(pcie);
+ if (ret < 0)
+ goto err_get_sync;
+
bridge = devm_pci_alloc_host_bridge(dev, sizeof(*rc));
if (!bridge) {
ret = -ENOMEM;
--
2.17.1