[PATCH V6 2/5] irqchip/gicv3-its: Add a new function for parsing device table BASERn

From: Shanker Donthineni
Date: Tue Jun 14 2016 - 10:45:31 EST


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@xxxxxxxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
drivers/irqchip/irq-gic-v3-its.c | 49 +++++++++++++++++++++-------------------
1 file changed, 26 insertions(+), 23 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 924f836..254085a 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);
--
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a Linux Foundation Collaborative Project