genirq: Add IRQ_SET_MASK_OK_DONE to support stacked irqchip

Add IRQ_SET_MASK_OK_DONE in addition to IRQ_SET_MASK_OK and
IRQ_SET_MASK_OK_NOCOPY to support stacked irqchip. IRQ_SET_MASK_OK_DONE
is the same as IRQ_SET_MASK_OK to irq core. To stacked irqchip, it means
that ascendant irqchips have done all the work and no more handling
needed in descendant irqchips.

Signed-off-by: Jiang Liu <[e-mail]>
Cc: Bjorn Helgaas <[e-mail]>
Cc: Grant Likely <[e-mail]>
Cc: Marc Zyngier <[e-mail]>
Cc: Yingjoe Chen <[e-mail]>
Cc: Yijing Wang <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>

include/linux/irq.h

···
  *
  * IRQ_SET_MASK_OK	- OK, core updates irq_data.affinity
  * IRQ_SET_MASK_NOCPY	- OK, chip did update irq_data.affinity
+ * IRQ_SET_MASK_OK_DONE	- Same as IRQ_SET_MASK_OK for core. Special code to
+ *			  support stacked irqchips, which indicates skipping
+ *			  all descendent irqchips.
  */
 enum {
 	IRQ_SET_MASK_OK = 0,
 	IRQ_SET_MASK_OK_NOCOPY,
+	IRQ_SET_MASK_OK_DONE,
 };
 
 struct msi_desc;

kernel/irq/manage.c

···
 	ret = chip->irq_set_affinity(data, mask, force);
 	switch (ret) {
 	case IRQ_SET_MASK_OK:
+	case IRQ_SET_MASK_OK_DONE:
 		cpumask_copy(data->affinity, mask);
 	case IRQ_SET_MASK_OK_NOCOPY:
 		irq_set_thread_affinity(desc);
···
 
 	switch (ret) {
 	case IRQ_SET_MASK_OK:
+	case IRQ_SET_MASK_OK_DONE:
 		irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
 		irqd_set(&desc->irq_data, flags);