x86, irq: Introduce mechanisms to support dynamically allocate IRQ for IOAPIC

Currently x86 support identity mapping between GSI(IOAPIC pin) and IRQ
number, so continous IRQs at low end are statically allocated to IOAPICs
at boot time. This design causes trouble to support IOAPIC hotplug.

This patch implements basic mechanism to dynamically allocate IRQ on
demand for IOAPIC pins by using irqdomain framework.

It first adds several fields into struct ioapic to support irqdomain.
Then it implements an algorithm to dynamically allocate IRQ number
for IOAPIC pins on demand.

Currently it supports three types of irqdomain:
1) LEGACY: used to support IOAPIC hosting legacy IRQs and building
   identity mapping for legacy IRQs. A speical case, we dynamically
   allocate IRQ number for IOAPIC pin which has GSI number below
   nr_legacy_irqs() but isn't legacy IRQ. This is for backward
   compatibility and avoid regression.
2) STRICT: build identity mapping between GSI and IRQ nubmer.
3) DYNAMIC: dynamically allocate IRQ number for IOAPIC pin on demand.

Legacy(ISA) IRQs is not managed by irqdomain because there may be
multiple pins sharing the same IRQ number and current irqdomain only
supports 1:1 mapping between pins and IRQ.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Link: http://lkml.kernel.org/r/1402302011-23642-24-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 19 insertions, 2 deletions

diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index 978e51fdcb59..64c6e344399b 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -98,6 +98,8 @@ struct IR_IO_APIC_route_entry {
 #define IOAPIC_AUTO     -1
 #define IOAPIC_EDGE     0
 #define IOAPIC_LEVEL    1
+#define	IOAPIC_MAP_ALLOC		0x1
+#define	IOAPIC_MAP_CHECK		0x2
 
 #ifdef CONFIG_X86_IO_APIC
 
@@ -163,6 +165,21 @@ extern int restore_ioapic_entries(void);
 extern void setup_ioapic_ids_from_mpc(void);
 extern void setup_ioapic_ids_from_mpc_nocheck(void);
 
+enum ioapic_domain_type {
+	IOAPIC_DOMAIN_INVALID,
+	IOAPIC_DOMAIN_LEGACY,
+	IOAPIC_DOMAIN_STRICT,
+	IOAPIC_DOMAIN_DYNAMIC,
+};
+
+struct device_node;
+struct irq_domain_ops;
+struct ioapic_domain_cfg {
+	enum ioapic_domain_type		type;
+	const struct irq_domain_ops	*ops;
+	struct device_node		*dev;
+};
+
 struct mp_ioapic_gsi{
 	u32 gsi_base;
 	u32 gsi_end;
@@ -172,7 +189,7 @@ extern u32 gsi_top;
 extern int mp_find_ioapic(u32 gsi);
 extern int mp_find_ioapic_pin(int ioapic, u32 gsi);
 extern u32 mp_pin_to_gsi(int ioapic, int pin);
-extern int mp_map_gsi_to_irq(u32 gsi);
+extern int mp_map_gsi_to_irq(u32 gsi, unsigned int flags);
 extern void __init mp_register_ioapic(int id, u32 address, u32 gsi_base);
 extern void __init pre_init_apic_IRQ0(void);
 
@@ -215,7 +232,7 @@ static inline void ioapic_insert_resources(void) { }
 #define gsi_top (NR_IRQS_LEGACY)
 static inline int mp_find_ioapic(u32 gsi) { return 0; }
 static inline u32 mp_pin_to_gsi(int ioapic, int pin) { return UINT_MAX; }
-static inline int mp_map_gsi_to_irq(u32 gsi) { return gsi; }
+static inline int mp_map_gsi_to_irq(u32 gsi, unsigned int flags) { return gsi; }
 
 struct io_apic_irq_attr;
 static inline int io_apic_set_pci_routing(struct device *dev, int irq,