[PATCH 2/4] xen/arm: its: add platform match callback for ITS quirks

[Mykola Kvach <xakep.amatop@xxxxxxxxx>]

From: Mykola Kvach <mykola_kvach@xxxxxxxx>

Extend ITS quirk lookup with an optional match callback so that
platforms sharing the same IIDR can still be distinguished.

Use the board compatible string to positively identify Renesas R-Car
Gen4 before applying ITS workaround flags, preventing false matches
on other SoCs that happen to use the same GIC IP block.

Signed-off-by: Mykola Kvach <mykola_kvach@xxxxxxxx>
---
 xen/arch/arm/gic-v3-its.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
index 00524b43a3..c40629731f 100644
--- a/xen/arch/arm/gic-v3-its.c
+++ b/xen/arch/arm/gic-v3-its.c
@@ -57,6 +57,7 @@ struct its_device {
  */
 struct its_quirk {
     const char *desc;
+    bool (*match)(const struct host_its *hw_its);
     uint32_t iidr;
     uint32_t mask;
     uint32_t flags;
@@ -64,11 +65,24 @@ struct its_quirk {
 
 static uint32_t __ro_after_init its_quirk_flags;
 
+static bool gicv3_its_match_quirk_gen4(const struct host_its *hw_its)
+{
+    if ( !hw_its->dt_node )
+        return false;
+
+    if ( !dt_machine_is_compatible("renesas,r8a779f0") &&
+         !dt_machine_is_compatible("renesas,r8a779g0") )
+        return false;
+
+    return true;
+}
+
 static const struct its_quirk its_quirks[] = {
     {
         .desc  = "R-Car Gen4",
         .iidr  = 0x0201743b,
         .mask  = 0xffffffffU,
+        .match = gicv3_its_match_quirk_gen4,
         .flags = HOST_ITS_WORKAROUND_NC_NS |
                  HOST_ITS_WORKAROUND_32BIT_ADDR,
     },
@@ -77,7 +91,8 @@ static const struct its_quirk its_quirks[] = {
     }
 };
 
-static const struct its_quirk *gicv3_its_find_quirk(uint32_t iidr)
+static const struct its_quirk *gicv3_its_find_quirk(
+    const struct host_its *hw_its, uint32_t iidr)
 {
     const struct its_quirk *quirk = its_quirks;
 
@@ -86,7 +101,8 @@ static const struct its_quirk *gicv3_its_find_quirk(uint32_t 
iidr)
         if ( quirk->iidr != (quirk->mask & iidr) )
             continue;
 
-        return quirk;
+        if ( !quirk->match || quirk->match(hw_its) )
+            return quirk;
     }
 
     return NULL;
@@ -99,7 +115,7 @@ static uint32_t gicv3_its_collect_quirks(const struct 
host_its *hw_its,
     uint32_t flags = 0;
     uint32_t iidr = readl_relaxed(hw_its->its_base + GITS_IIDR);
 
-    quirk = gicv3_its_find_quirk(iidr);
+    quirk = gicv3_its_find_quirk(hw_its, iidr);
     if ( quirk )
         flags |= quirk->flags;
 
-- 
2.43.0