Double precision floating point unit is a FPU implementation different
from the FPU2000 in the following ways:
- it may be configured with only single or with both single and double
  precision operations support;
- it may be configured with division and square root opcodes;
- FSR register accumulates inValid, division by Zero, Overflow,
  Underflow and Inexact result flags of operations;
- QNaNs and SNaNs are handled properly;
- NaN propagation rules are different.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
Changes v3->v4:
- new patch split from the next one

 target/xtensa/cpu.h          |  2 ++
 target/xtensa/overlay_tool.h | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/target/xtensa/cpu.h b/target/xtensa/cpu.h
index 960f6573447f..6fc1565000b6 100644
--- a/target/xtensa/cpu.h
+++ b/target/xtensa/cpu.h
@@ -52,6 +52,8 @@ enum {
     XTENSA_OPTION_COPROCESSOR,
     XTENSA_OPTION_BOOLEAN,
     XTENSA_OPTION_FP_COPROCESSOR,
+    XTENSA_OPTION_DFP_COPROCESSOR,
+    XTENSA_OPTION_DFPU_SINGLE_ONLY,
     XTENSA_OPTION_MP_SYNCHRO,
     XTENSA_OPTION_CONDITIONAL_STORE,
     XTENSA_OPTION_ATOMCTL,
diff --git a/target/xtensa/overlay_tool.h b/target/xtensa/overlay_tool.h
index eb9f08af0bf6..9f0846c86b65 100644
--- a/target/xtensa/overlay_tool.h
+++ b/target/xtensa/overlay_tool.h
@@ -39,6 +39,26 @@
 #define XCHAL_HAVE_DEPBITS 0
 #endif
 
+#ifndef XCHAL_HAVE_DFP
+#define XCHAL_HAVE_DFP 0
+#endif
+
+#ifndef XCHAL_HAVE_DFPU_SINGLE_ONLY
+#define XCHAL_HAVE_DFPU_SINGLE_ONLY 0
+#endif
+
+#ifndef XCHAL_HAVE_DFPU_SINGLE_DOUBLE
+#define XCHAL_HAVE_DFPU_SINGLE_DOUBLE XCHAL_HAVE_DFP
+#endif
+
+/*
+ * We need to know the type of FP unit, not only its precision.
+ * Unfortunately XCHAL macros don't tell this explicitly.
+ */
+#define XCHAL_HAVE_DFPU (XCHAL_HAVE_DFP || \
+                         XCHAL_HAVE_DFPU_SINGLE_ONLY || \
+                         XCHAL_HAVE_DFPU_SINGLE_DOUBLE)
+
 #ifndef XCHAL_HAVE_DIV32
 #define XCHAL_HAVE_DIV32 0
 #endif
@@ -99,6 +119,9 @@
     XCHAL_OPTION(XCHAL_HAVE_CP, XTENSA_OPTION_COPROCESSOR) | \
     XCHAL_OPTION(XCHAL_HAVE_BOOLEANS, XTENSA_OPTION_BOOLEAN) | \
     XCHAL_OPTION(XCHAL_HAVE_FP, XTENSA_OPTION_FP_COPROCESSOR) | \
+    XCHAL_OPTION(XCHAL_HAVE_DFPU, XTENSA_OPTION_DFP_COPROCESSOR) | \
+    XCHAL_OPTION(XCHAL_HAVE_DFPU_SINGLE_ONLY, \
+                 XTENSA_OPTION_DFPU_SINGLE_ONLY) | \
     XCHAL_OPTION(XCHAL_HAVE_RELEASE_SYNC, XTENSA_OPTION_MP_SYNCHRO) | \
     XCHAL_OPTION(XCHAL_HAVE_S32C1I, XTENSA_OPTION_CONDITIONAL_STORE) | \
     XCHAL_OPTION(((XCHAL_HAVE_S32C1I && XCHAL_HW_VERSION >= 230000) || \
-- 
2.20.1