ACPI: scan: Define weak function to populate dependencies

Some architectures like RISC-V need to add dependencies without explicit
_DEP. Define a weak function which can be implemented by the architecture.

Signed-off-by: Sunil V L <[email protected]>
Tested-by: Björn Töpel <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: vlsunil

drivers/acpi/scan.c

@@ -2077,11 +2077,22 @@ static void acpi_scan_init_hotplug(struct acpi_device *adev)
 	}
 }
 
+u32 __weak arch_acpi_add_auto_dep(acpi_handle handle) { return 0; }
+
 static u32 acpi_scan_check_dep(acpi_handle handle)
 {
 	struct acpi_handle_list dep_devices;
 	u32 count = 0;
 
+	/*
+	 * Some architectures like RISC-V need to add dependencies for
+	 * all devices which use GSI to the interrupt controller so that
+	 * interrupt controller is probed before any of those devices.
+	 * Instead of mandating _DEP on all the devices, detect the
+	 * dependency and add automatically.
+	 */
+	count += arch_acpi_add_auto_dep(handle);
+
 	/*
 	 * Check for _HID here to avoid deferring the enumeration of:
 	 * 1. PCI devices.

include/acpi/acpi_bus.h

@@ -994,6 +994,7 @@ static inline void acpi_put_acpi_dev(struct acpi_device *adev)
 int acpi_wait_for_acpi_ipmi(void);
 
 int acpi_scan_add_dep(acpi_handle handle, struct acpi_handle_list *dep_devices);
+u32 arch_acpi_add_auto_dep(acpi_handle handle);
 #else	/* CONFIG_ACPI */
 
 static inline int register_acpi_bus_type(void *bus) { return 0; }