[Patch V4 37/42] x86, irq: introduce helper functions to release IOAPIC pin

[Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>]

Introduce function mp_unmap_irq() to release IOAPIC IRQ when IRQ is not
used any more, which will typically called by pcibios_disabled_irq.

And function mp_irqdomain_unmap() is a common implementation of
irq_domain_ops.unmap for IOAPIC.

Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/io_apic.h |    3 ++
 arch/x86/kernel/apic/io_apic.c |   61 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index af6f9d4309bf..0aeed5ca356e 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -187,10 +187,12 @@ 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, unsigned int flags);
+extern void mp_unmap_irq(int irq);
 extern void __init mp_register_ioapic(int id, u32 address, u32 gsi_base,
 				      struct ioapic_domain_cfg *cfg);
 extern int mp_irqdomain_map(struct irq_domain *domain, unsigned int virq,
 			    irq_hw_number_t hwirq);
+extern void mp_irqdomain_unmap(struct irq_domain *domain, unsigned int virq);
 extern int mp_set_gsi_attr(u32 gsi, int trigger, int polarity, int node);
 extern void __init pre_init_apic_IRQ0(void);
 
@@ -234,6 +236,7 @@ static inline void ioapic_insert_resources(void) { }
 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, unsigned int flags) { return gsi; }
+static inline void mp_unmap_irq(int irq) { }
 
 static inline int save_ioapic_entries(void)
 {
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 5fc76cf51e44..60555354b331 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -467,6 +467,21 @@ static int __add_pin_to_irq_node(struct irq_cfg *cfg, int node, int apic, int pi
 	return 0;
 }
 
+static void __remove_pin_from_irq(struct irq_cfg *cfg, int apic, int pin)
+{
+	struct irq_pin_list **last, *entry;
+
+	last = &cfg->irq_2_pin;
+	for_each_irq_pin(entry, cfg->irq_2_pin)
+		if (entry->apic == apic && entry->pin == pin) {
+			*last = entry->next;
+			kfree(entry);
+			return;
+		} else {
+			last = &entry->next;
+		}
+}
+
 static void add_pin_to_irq_node(struct irq_cfg *cfg, int node, int apic, int pin)
 {
 	if (__add_pin_to_irq_node(cfg, node, apic, pin))
@@ -1119,6 +1134,31 @@ int mp_map_gsi_to_irq(u32 gsi, unsigned int flags)
 	return mp_map_pin_to_irq(gsi, idx, ioapic, pin, flags);
 }
 
+void mp_unmap_irq(int irq)
+{
+	struct irq_data *data = irq_get_irq_data(irq);
+	struct mp_pin_info *info;
+	int ioapic, pin;
+
+	if (!data || !data->domain)
+		return;
+
+	ioapic = (int)(long)data->domain->host_data;
+	pin = (int)data->hwirq;
+	info = mp_pin_info(ioapic, pin);
+
+	mutex_lock(&ioapic_mutex);
+	if (--info->count == 0) {
+		info->set = 0;
+		if (irq < nr_legacy_irqs() &&
+		    ioapics[ioapic].irqdomain_cfg.type == IOAPIC_DOMAIN_LEGACY)
+			mp_irqdomain_unmap(data->domain, irq);
+		else
+			irq_dispose_mapping(irq);
+	}
+	mutex_unlock(&ioapic_mutex);
+}
+
 /*
  * Find a specific PCI IRQ entry.
  * Not an __init, possibly needed by modules
@@ -3874,6 +3914,27 @@ int mp_irqdomain_map(struct irq_domain *domain, unsigned int virq,
 	return io_apic_setup_irq_pin(virq, info->node, &attr);
 }
 
+void mp_irqdomain_unmap(struct irq_domain *domain, unsigned int virq)
+{
+	struct irq_data *data = irq_get_irq_data(virq);
+	struct irq_cfg *cfg = irq_cfg(virq);
+	int ioapic = (int)(long)domain->host_data;
+	int pin = (int)data->hwirq;
+
+	/*
+	 * Skip the timer IRQ if there's a quirk handler installed and if it
+	 * returns 1:
+	 */
+	if (apic->multi_timer_check &&
+	    apic->multi_timer_check(ioapic, virq))
+		return;
+
+	ioapic_mask_entry(ioapic, pin);
+	__remove_pin_from_irq(cfg, ioapic, pin);
+	WARN_ON(cfg->irq_2_pin != NULL);
+	arch_teardown_hwirq(virq);
+}
+
 int mp_set_gsi_attr(u32 gsi, int trigger, int polarity, int node)
 {
 	int ret = 0;
-- 
1.7.10.4

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