[XTENSA] Add support for configurable registers and coprocessors
The Xtensa architecture allows to define custom instructions and
registers. Registers that are bound to a coprocessor are only
accessible if the corresponding enable bit is set, which allows
to implement a 'lazy' context switch mechanism. Other registers
needs to be saved and restore at the time of the context switch
or during interrupt handling.
This patch adds support for these additional states:
- save and restore registers that are used by the compiler upon
interrupt entry and exit.
- context switch additional registers unbound to any coprocessor
- 'lazy' context switch of registers bound to a coprocessor
- ptrace interface to provide access to additional registers
- update configuration files in include/asm-xtensa/variant-fsf
Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/include/asm-xtensa/variant-fsf/tie-asm.h b/include/asm-xtensa/variant-fsf/tie-asm.h
new file mode 100644
index 0000000..68a73bf
--- /dev/null
+++ b/include/asm-xtensa/variant-fsf/tie-asm.h
@@ -0,0 +1,70 @@
+/*
+ * This header file contains assembly-language definitions (assembly
+ * macros, etc.) for this specific Xtensa processor's TIE extensions
+ * and options. It is customized to this Xtensa processor configuration.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 1999-2008 Tensilica Inc.
+ */
+
+#ifndef _XTENSA_CORE_TIE_ASM_H
+#define _XTENSA_CORE_TIE_ASM_H
+
+/* Selection parameter values for save-area save/restore macros: */
+/* Option vs. TIE: */
+#define XTHAL_SAS_TIE 0x0001 /* custom extension or coprocessor */
+#define XTHAL_SAS_OPT 0x0002 /* optional (and not a coprocessor) */
+/* Whether used automatically by compiler: */
+#define XTHAL_SAS_NOCC 0x0004 /* not used by compiler w/o special opts/code */
+#define XTHAL_SAS_CC 0x0008 /* used by compiler without special opts/code */
+/* ABI handling across function calls: */
+#define XTHAL_SAS_CALR 0x0010 /* caller-saved */
+#define XTHAL_SAS_CALE 0x0020 /* callee-saved */
+#define XTHAL_SAS_GLOB 0x0040 /* global across function calls (in thread) */
+/* Misc */
+#define XTHAL_SAS_ALL 0xFFFF /* include all default NCP contents */
+
+
+
+/* Macro to save all non-coprocessor (extra) custom TIE and optional state
+ * (not including zero-overhead loop registers).
+ * Save area ptr (clobbered): ptr (1 byte aligned)
+ * Scratch regs (clobbered): at1..at4 (only first XCHAL_NCP_NUM_ATMPS needed)
+ */
+ .macro xchal_ncp_store ptr at1 at2 at3 at4 continue=0 ofs=-1 select=XTHAL_SAS_ALL
+ xchal_sa_start \continue, \ofs
+ .ifeq (XTHAL_SAS_OPT | XTHAL_SAS_CC | XTHAL_SAS_GLOB) & ~\select
+ xchal_sa_align \ptr, 0, 1024-4, 4, 4
+ rur \at1, THREADPTR // threadptr option
+ s32i \at1, \ptr, .Lxchal_ofs_ + 0
+ .set .Lxchal_ofs_, .Lxchal_ofs_ + 4
+ .endif
+ .endm // xchal_ncp_store
+
+/* Macro to save all non-coprocessor (extra) custom TIE and optional state
+ * (not including zero-overhead loop registers).
+ * Save area ptr (clobbered): ptr (1 byte aligned)
+ * Scratch regs (clobbered): at1..at4 (only first XCHAL_NCP_NUM_ATMPS needed)
+ */
+ .macro xchal_ncp_load ptr at1 at2 at3 at4 continue=0 ofs=-1 select=XTHAL_SAS_ALL
+ xchal_sa_start \continue, \ofs
+ .ifeq (XTHAL_SAS_OPT | XTHAL_SAS_CC | XTHAL_SAS_GLOB) & ~\select
+ xchal_sa_align \ptr, 0, 1024-4, 4, 4
+ l32i \at1, \ptr, .Lxchal_ofs_ + 0
+ wur \at1, THREADPTR // threadptr option
+ .set .Lxchal_ofs_, .Lxchal_ofs_ + 4
+ .endif
+ .endm // xchal_ncp_load
+
+
+
+#define XCHAL_NCP_NUM_ATMPS 1
+
+
+#define XCHAL_SA_NUM_ATMPS 1
+
+#endif /*_XTENSA_CORE_TIE_ASM_H*/
+