irqchip/gicv3-its: Add a new function for parsing device table BASERn

Only the device table BASERn needs to be handled differently as
compared to all other tables. So, adding a separate function for
easy code maintenance and improved code readability.

Signed-off-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 26 insertions, 23 deletions

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index a8a1144205e6..5cfa29991eed 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -840,6 +840,30 @@ static void its_write_baser(struct its_node *its, struct its_baser *baser,
         baser->val = its_read_baser(its, baser);
 }
 
+static void its_parse_baser_device(struct its_node *its, struct its_baser *baser,
+                                   u32 *order)
+{
+        u64 esz = GITS_BASER_ENTRY_SIZE(its_read_baser(its, baser));
+        u32 ids = its->device_ids;
+        u32 new_order = *order;
+
+        /*
+         * Allocate as many entries as required to fit the
+         * range of device IDs that the ITS can grok... The ID
+         * space being incredibly sparse, this results in a
+         * massive waste of memory.
+         */
+        new_order = max_t(u32, get_order(esz << ids), new_order);
+        if (new_order >= MAX_ORDER) {
+                new_order = MAX_ORDER - 1;
+                ids = ilog2(PAGE_ORDER_TO_SIZE(new_order) / esz);
+                pr_warn("ITS@%pa: Device Table too large, reduce ids %u->%u\n",
+                        &its->phys_base, its->device_ids, ids);
+        }
+
+        *order = new_order;
+}
+
 static void its_free_tables(struct its_node *its)
 {
         int i;
@@ -891,29 +915,8 @@ static int its_alloc_tables(const char *node_name, struct its_node *its)
                 if (type == GITS_BASER_TYPE_NONE)
                         continue;
 
-                /*
-                 * Allocate as many entries as required to fit the
-                 * range of device IDs that the ITS can grok... The ID
-                 * space being incredibly sparse, this results in a
-                 * massive waste of memory.
-                 *
-                 * For other tables, only allocate a single page.
-                 */
-                if (type == GITS_BASER_TYPE_DEVICE) {
-                        /*
-                         * 'order' was initialized earlier to the default page
-                         * granule of the the ITS.  We can't have an allocation
-                         * smaller than that.  If the requested allocation
-                         * is smaller, round up to the default page granule.
-                         */
-                        order = max(get_order((1UL << ids) * entry_size),
-                                    order);
-                        if (order >= MAX_ORDER) {
-                                order = MAX_ORDER - 1;
-                                pr_warn("%s: Device Table too large, reduce its page order to %u\n",
-                                        node_name, order);
-                        }
-                }
+                if (type == GITS_BASER_TYPE_DEVICE)
+                        its_parse_baser_device(its, baser, &order);
 
 retry_alloc_baser:
                 alloc_pages = (PAGE_ORDER_TO_SIZE(order) / psz);