[v14,04/15] irqchip/gic-v3-its: Add support for device tree msi-map and msi-mask

Commit Message

Frank Li Feb. 7, 2025, 7:39 p.m. UTC

Some platform devices create child devices dynamically and require the
parent device's msi-map to map device IDs to actual sideband information.

A typical use case is using ITS as a PCIe Endpoint Controller(EPC)'s
doorbell function, where PCI hosts send TLP memory writes to the EP
controller. The EP controller converts these writes to AXI transactions
and appends platform-specific sideband information.  See below figure.

               ┌────────────────────────────────┐
               │                                │
               │     PCI Endpoint Controller    │
               │                                │
               │  ┌─────┐   ┌─────┐     ┌─────┐ │
    PCI Bus    │  │     │   │     │     │     │ │
    ─────────► │  │Func1│   │Func2│ ... │Func │ │
    TLP Memory │  │     │   │     │     │<n>  │ │
    Write Push │  │     │   │     │     │     │ │
    DoorBell   │  └─┬─┬─┘   └──┬──┘     └──┬──┘ │
               │    │ │        │           │    │
               └────┼─┼────────┼───────────┼────┘
        sideband    │ │ Address│           │
        information ▼ ▼ /Data  ▼           ▼
                   ┌────────────────────────┐
                   │    MSI Controller      │
                   └────────────────────────┘

EPC's DTS will provide such information by msi-map and msi-mask. A
simplified dts as

pcie-ep@10000000 {
	...
	msi-map = <0 &its 0xc 8>;
                          ^^^ 0xc is implement defined sideband information,
			      which append to AXI write transaction.
	           ^ 0 is function index.

	msi-mask = <0x7>
}

Check msi-map if msi-parent missed to keep compatility with existed system.

Signed-off-by: Frank Li <[e-mail]>
---
 drivers/irqchip/irq-gic-v3-its-msi-parent.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Patch

diff --git a/drivers/irqchip/irq-gic-v3-its-msi-parent.c b/drivers/irqchip/irq-gic-v3-its-msi-parent.c
index e150365fbe892..6c7389bb84a4a 100644
--- a/drivers/irqchip/irq-gic-v3-its-msi-parent.c
+++ b/drivers/irqchip/irq-gic-v3-its-msi-parent.c
@@ -118,6 +118,14 @@  static int of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev,
 		index++;
 	} while (!ret);
 
+	if (ret) {
+		struct device_node *np = NULL;
+
+		ret = of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &np, dev_id);
+		if (np)
+			of_node_put(np);
+	}
+
 	return ret;
 }