On Fri, Jun 19, 2015 at 09:46:06AM +0100, Hanjun Guo wrote:
[...]
+
+static int __init
+match_gic_redist(struct acpi_subtable_header *header, const unsigned long end)
+{
+ return 0;
+}
+static bool __init acpi_gic_redist_is_present(void)
+{
+ int count;
+
+ /* scan MADT table to find if we have redistributor entries */
+ count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR,
+ match_gic_redist, 0);
+
+ /* has at least one GIC redistributor entry */
+ if (count > 0)
+ return true;
+ else
+ return false;
+}
return count > 0;
What about systems where the redistributor data is in the GICC subtable ? Do
you treat them as GIC V2 :) ?
On a side note, having to define an empty function like match_gic_redist is
horrible.
I wonder whether it is not better to refactor map_madt_entry(), create
a MADT subtable iterator out of it and make that code generic, instead
of being forced to add these useless MADT handlers just to count
entries, it is not the first I noticed.
+static int __init acpi_gic_version_init(void)
+{
+ int count;
+ void __iomem *dist_base;
+ u32 reg;
+
+ count = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR,
+ acpi_gic_parse_distributor, 0);
+
+ if (count <= 0) {
+ pr_err("No valid GIC distributor entry exists\n");
+ return -ENODEV;
+ }
+
+ if (gic_version >= ACPI_MADT_GIC_VERSION_RESERVED) {
+ pr_err("Invalid GIC version %d in MADT\n", gic_version);
+ return -EINVAL;
+ }
+
+ /*
+ * when the GIC version is 0, we fallback to hardware discovery.
+ * this is also needed to keep compatiable with ACPI 5.1,
+ * which has no gic_version field in distributor structure and
+ * reserved as 0.
+ *
+ * For hardware discovery, the offset for GICv1/2 and GICv3/4 to
+ * get the GIC version is different (0xFE8 for GICv1/2 and 0xFFE8
+ * for GICv3/4), so we need to handle it separately.
+ */
+ if (gic_version == ACPI_MADT_GIC_VERSION_NONE) {
+ /* it's GICv3/v4 if redistributor is present */
+ if (acpi_gic_redist_is_present()) {
See above, IIUC you might have systems with GIC v3 where this call
would fail, and we do not want to fall back to GIC v2.