irqchip/gic-v3-its: Make LPI allocation optional on device creation

The normal course of action when allocating the ITS' view of a
device is to allocate the corresponding LPIs. But we're about
to introduce devices that borrow their interrupts from
some other entities.

So let's make the allocation optional.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 9040fb4..017a6ef 100644 (file)
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1978,10 +1978,10 @@ static bool its_alloc_vpe_table(u32 vpe_id)
 }
 
 static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
-                                           int nvecs)
+                                           int nvecs, bool alloc_lpis)
 {
        struct its_device *dev;
-       unsigned long *lpi_map;
+       unsigned long *lpi_map = NULL;
        unsigned long flags;
        u16 *col_map = NULL;
        void *itt;
@@ -2003,11 +2003,18 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
        sz = nr_ites * its->ite_size;
        sz = max(sz, ITS_ITT_ALIGN) + ITS_ITT_ALIGN - 1;
        itt = kzalloc(sz, GFP_KERNEL);
-       lpi_map = its_lpi_alloc_chunks(nvecs, &lpi_base, &nr_lpis);
-       if (lpi_map)
-               col_map = kzalloc(sizeof(*col_map) * nr_lpis, GFP_KERNEL);
+       if (alloc_lpis) {
+               lpi_map = its_lpi_alloc_chunks(nvecs, &lpi_base, &nr_lpis);
+               if (lpi_map)
+                       col_map = kzalloc(sizeof(*col_map) * nr_lpis,
+                                         GFP_KERNEL);
+       } else {
+               col_map = kzalloc(sizeof(*col_map) * nr_ites, GFP_KERNEL);
+               nr_lpis = 0;
+               lpi_base = 0;
+       }
 
-       if (!dev || !itt || !lpi_map || !col_map) {
+       if (!dev || !itt ||  !col_map || (!lpi_map && alloc_lpis)) {
                kfree(dev);
                kfree(itt);
                kfree(lpi_map);
@@ -2094,7 +2101,7 @@ static int its_msi_prepare(struct irq_domain *domain, struct device *dev,
                goto out;
        }
 
-       its_dev = its_create_device(its, dev_id, nvec);
+       its_dev = its_create_device(its, dev_id, nvec, true);
        if (!its_dev)
                return -ENOMEM;