xen: arm: X-Gene Storm check GIC DIST address for EOI quirk

In old X-Gene Storm firmware and DT, secure mode addresses have been
mentioned in GICv2 node. In this case maintenance interrupt is used
instead of EOI HW method.

This patch checks the GIC Distributor Base Address to enable EOI quirk
for old firmware.

Ref:
http://lists.xen.org/archives/html/xen-devel/2014-07/msg01263.html

Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Tested-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Julien Grall <julien.grall@citrix.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

xen/arch/arm/platforms/xgene-storm.c

@@ -22,6 +22,7 @@
 #include <asm/platform.h>
 #include <xen/stdbool.h>
 #include <xen/vmap.h>
+#include <xen/device_tree.h>
 #include <asm/io.h>
 #include <asm/gic.h>
 
@@ -35,9 +36,44 @@ static u64 reset_addr, reset_size;
 static u32 reset_mask;
 static bool reset_vals_valid = false;
 
+#define XGENE_SEC_GICV2_DIST_ADDR    0x78010000
+static u32 __read_mostly xgene_quirks = PLATFORM_QUIRK_GIC_64K_STRIDE;
+
+static void __init xgene_check_pirq_eoi(void)
+{
+    const struct dt_device_node *node;
+    int res;
+    paddr_t dbase;
+    const struct dt_device_match xgene_dt_int_ctrl_match[] =
+    {
+        DT_MATCH_COMPATIBLE("arm,cortex-a15-gic"),
+        { /*sentinel*/ },
+    };
+
+    node = dt_find_interrupt_controller(xgene_dt_int_ctrl_match);
+    if ( !node )
+        panic("%s: Can not find interrupt controller node", __func__);
+
+    res = dt_device_get_address(node, 0, &dbase, NULL);
+    if ( !dbase )
+        panic("%s: Cannot find a valid address for the distributor", __func__);
+
+    /*
+     * In old X-Gene Storm firmware and DT, secure mode addresses have
+     * been mentioned in GICv2 node. We have to use maintenance interrupt
+     * instead of EOI HW in this case. We check the GIC Distributor Base
+     * Address to maintain compatibility with older firmware.
+     */
+    if ( dbase == XGENE_SEC_GICV2_DIST_ADDR )
+    {
+        xgene_quirks |= PLATFORM_QUIRK_GUEST_PIRQ_NEED_EOI;
+        printk("Xen: WARNING: OLD X-Gene Firmware, disabling PIRQ EOI mode\n");
+    }
+}
+
 static uint32_t xgene_storm_quirks(void)
 {
-    return PLATFORM_QUIRK_GIC_64K_STRIDE|PLATFORM_QUIRK_GUEST_PIRQ_NEED_EOI;
+    return xgene_quirks;
 }
 
 static int map_one_mmio(struct domain *d, const char *what,
@@ -216,6 +252,8 @@ static int xgene_storm_init(void)
     reset_mask = XGENE_RESET_MASK;
 
     reset_vals_valid = true;
+    xgene_check_pirq_eoi();
+
     return 0;
 }