[PATCH v1 2/4] PCI: dwc: rockchip: add legacy interrupt support

[Peter Geis <pgwipeout@gmail.com>]

The legacy interrupts on the rk356x pcie controller are handled by a
single muxed interrupt. Add irq domain support to the pcie-dw-rockchip
driver to support the virtual domain.

Signed-off-by: Peter Geis <pgwipeout@gmail.com>
---
 drivers/pci/controller/dwc/pcie-dw-rockchip.c | 92 ++++++++++++++++++-
 1 file changed, 89 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index c9b341e55cbb..d14518039674 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -10,9 +10,12 @@
 
 #include <linux/clk.h>
 #include <linux/gpio/consumer.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/of_irq.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
@@ -36,10 +39,12 @@
 #define PCIE_LINKUP			(PCIE_SMLH_LINKUP | PCIE_RDLH_LINKUP)
 #define PCIE_L0S_ENTRY			0x11
 #define PCIE_CLIENT_GENERAL_CONTROL	0x0
+#define PCIE_CLIENT_INTR_MASK_LEGACY	0x1c
 #define PCIE_CLIENT_GENERAL_DEBUG	0x104
-#define PCIE_CLIENT_HOT_RESET_CTRL      0x180
+#define PCIE_CLIENT_HOT_RESET_CTRL	0x180
 #define PCIE_CLIENT_LTSSM_STATUS	0x300
-#define PCIE_LTSSM_ENABLE_ENHANCE       BIT(4)
+#define PCIE_LEGACY_INT_ENABLE		GENMASK(7, 0)
+#define PCIE_LTSSM_ENABLE_ENHANCE	BIT(4)
 #define PCIE_LTSSM_STATUS_MASK		GENMASK(5, 0)
 
 struct rockchip_pcie {
@@ -51,6 +56,7 @@ struct rockchip_pcie {
 	struct reset_control		*rst;
 	struct gpio_desc		*rst_gpio;
 	struct regulator                *vpcie3v3;
+	struct irq_domain		*irq_domain;
 };
 
 static int rockchip_pcie_readl_apb(struct rockchip_pcie *rockchip,
@@ -65,6 +71,68 @@ static void rockchip_pcie_writel_apb(struct rockchip_pcie *rockchip,
 	writel_relaxed(val, rockchip->apb_base + reg);
 }
 
+static void rockchip_pcie_legacy_int_handler(struct irq_desc *desc)
+{
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	struct rockchip_pcie *rockchip = irq_desc_get_handler_data(desc);
+	struct device *dev = rockchip->pci.dev;
+	u32 reg;
+	u32 hwirq;
+	u32 virq;
+
+	chained_irq_enter(chip, desc);
+
+	reg = rockchip_pcie_readl_apb(rockchip, 0x8);
+
+	while (reg) {
+		hwirq = ffs(reg) - 1;
+		reg &= ~BIT(hwirq);
+
+		virq = irq_find_mapping(rockchip->irq_domain, hwirq);
+		if (virq)
+			generic_handle_irq(virq);
+		else
+			dev_err(dev, "unexpected IRQ, INT%d\n", hwirq);
+	}
+
+	chained_irq_exit(chip, desc);
+}
+
+static int rockchip_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 intx_domain_ops = {
+	.map = rockchip_pcie_intx_map,
+};
+
+static int rockchip_pcie_init_irq_domain(struct rockchip_pcie *rockchip)
+{
+	struct device *dev = rockchip->pci.dev;
+	struct device_node *intc;
+
+	intc = of_get_child_by_name(dev->of_node, "legacy-interrupt-controller");
+	if (!intc) {
+		dev_err(dev, "missing child interrupt-controller node\n");
+		return -EINVAL;
+	}
+
+	rockchip->irq_domain = irq_domain_add_linear(intc, PCI_NUM_INTX,
+						    &intx_domain_ops, rockchip);
+	of_node_put(intc);
+	if (!rockchip->irq_domain) {
+		dev_err(dev, "failed to get a INTx IRQ domain\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static void rockchip_pcie_enable_ltssm(struct rockchip_pcie *rockchip)
 {
 	rockchip_pcie_writel_apb(rockchip, PCIE_CLIENT_ENABLE_LTSSM,
@@ -111,9 +179,27 @@ static int rockchip_pcie_host_init(struct pcie_port *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 	struct rockchip_pcie *rockchip = to_rockchip_pcie(pci);
-	u32 val = HIWORD_UPDATE_BIT(PCIE_LTSSM_ENABLE_ENHANCE);
+	struct device *dev = rockchip->pci.dev;
+	int irq, ret;
+	u32 val;
+
+	irq = of_irq_get_byname(dev->of_node, "legacy");
+	if (irq < 0)
+		return irq;
+
+	irq_set_chained_handler_and_data(irq, rockchip_pcie_legacy_int_handler, rockchip);
+
+	ret = rockchip_pcie_init_irq_domain(rockchip);
+	if (ret < 0)
+		dev_err(dev, "failed to init irq domain\n");
+
+	/* enable legacy interrupts */
+	val = HIWORD_UPDATE_BIT(PCIE_LEGACY_INT_ENABLE);
+	val &= ~PCIE_LEGACY_INT_ENABLE;
+	rockchip_pcie_writel_apb(rockchip, val, PCIE_CLIENT_INTR_MASK_LEGACY);
 
 	/* LTSSM enable control mode */
+	val = HIWORD_UPDATE_BIT(PCIE_LTSSM_ENABLE_ENHANCE);
 	rockchip_pcie_writel_apb(rockchip, val, PCIE_CLIENT_HOT_RESET_CTRL);
 
 	rockchip_pcie_writel_apb(rockchip, PCIE_CLIENT_RC_MODE,
-- 
2.25.1