PCI: rockchip-dwc: Add legacy interrupt support

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.

Link: https://lore.kernel.org/r/20220429123832.2376381-4-pgwipeout@gmail.com
Signed-off-by: Peter Geis <pgwipeout@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>

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>
@@ -26,6 +29,7 @@
  */
 #define HIWORD_UPDATE(mask, val) (((mask) << 16) | (val))
 #define HIWORD_UPDATE_BIT(val)	HIWORD_UPDATE(val, val)
+#define HIWORD_DISABLE_BIT(val)	HIWORD_UPDATE(val, ~val)
 
 #define to_rockchip_pcie(x) dev_get_drvdata((x)->dev)
 
@@ -36,10 +40,12 @@
 #define PCIE_LINKUP			(PCIE_SMLH_LINKUP | PCIE_RDLH_LINKUP)
 #define PCIE_L0S_ENTRY			0x11
 #define PCIE_CLIENT_GENERAL_CONTROL	0x0
+#define PCIE_CLIENT_INTR_STATUS_LEGACY	0x8
+#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_LTSSM_ENABLE_ENHANCE	BIT(4)
 #define PCIE_LTSSM_STATUS_MASK		GENMASK(5, 0)
 
 struct rockchip_pcie {
@@ -51,6 +57,7 @@ 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 +72,78 @@ 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);
+	unsigned long reg, hwirq;
+
+	chained_irq_enter(chip, desc);
+
+	reg = rockchip_pcie_readl_apb(rockchip, PCIE_CLIENT_INTR_STATUS_LEGACY);
+
+	for_each_set_bit(hwirq, &reg, 4)
+		generic_handle_domain_irq(rockchip->irq_domain, hwirq);
+
+	chained_irq_exit(chip, desc);
+}
+
+static void rockchip_intx_mask(struct irq_data *data)
+{
+	rockchip_pcie_writel_apb(irq_data_get_irq_chip_data(data),
+				 HIWORD_UPDATE_BIT(BIT(data->hwirq)),
+				 PCIE_CLIENT_INTR_MASK_LEGACY);
+};
+
+static void rockchip_intx_unmask(struct irq_data *data)
+{
+	rockchip_pcie_writel_apb(irq_data_get_irq_chip_data(data),
+				 HIWORD_DISABLE_BIT(BIT(data->hwirq)),
+				 PCIE_CLIENT_INTR_MASK_LEGACY);
+};
+
+static struct irq_chip rockchip_intx_irq_chip = {
+	.name			= "INTx",
+	.irq_mask		= rockchip_intx_mask,
+	.irq_unmask		= rockchip_intx_unmask,
+	.flags			= IRQCHIP_SKIP_SET_WAKE | IRQCHIP_MASK_ON_SUSPEND,
+};
+
+static int rockchip_pcie_intx_map(struct irq_domain *domain, unsigned int irq,
+				  irq_hw_number_t hwirq)
+{
+	irq_set_chip_and_handler(irq, &rockchip_intx_irq_chip, handle_level_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,
@@ -111,7 +190,20 @@ 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);
+	struct device *dev = rockchip->pci.dev;
 	u32 val = HIWORD_UPDATE_BIT(PCIE_LTSSM_ENABLE_ENHANCE);
+	int irq, ret;
+
+	irq = of_irq_get_byname(dev->of_node, "legacy");
+	if (irq < 0)
+		return irq;
+
+	ret = rockchip_pcie_init_irq_domain(rockchip);
+	if (ret < 0)
+		dev_err(dev, "failed to init irq domain\n");
+
+	irq_set_chained_handler_and_data(irq, rockchip_pcie_legacy_int_handler,
+					 rockchip);
 
 	/* LTSSM enable control mode */
 	rockchip_pcie_writel_apb(rockchip, val, PCIE_CLIENT_HOT_RESET_CTRL);