[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>

10 files changed, 352 insertions, 144 deletions

diff --git a/include/asm-xtensa/coprocessor.h b/include/asm-xtensa/coprocessor.h
index aa212103455..e5849bb9f6c 100644
--- a/include/asm-xtensa/coprocessor.h
+++ b/include/asm-xtensa/coprocessor.h
@@ -5,81 +5,168 @@
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
- * Copyright (C) 2003 - 2005 Tensilica Inc.
+ * Copyright (C) 2003 - 2007 Tensilica Inc.
  */
 
+
 #ifndef _XTENSA_COPROCESSOR_H
 #define _XTENSA_COPROCESSOR_H
 
-#include <asm/variant/core.h>
+#include <linux/stringify.h>
 #include <asm/variant/tie.h>
+#include <asm/types.h>
+
+#ifdef __ASSEMBLY__
+# include <asm/variant/tie-asm.h>
+
+.macro  xchal_sa_start  a b
+        .set .Lxchal_pofs_, 0
+        .set .Lxchal_ofs_, 0
+.endm
+
+.macro  xchal_sa_align  ptr minofs maxofs ofsalign totalign
+        .set    .Lxchal_ofs_, .Lxchal_ofs_ + .Lxchal_pofs_ + \totalign - 1
+        .set    .Lxchal_ofs_, (.Lxchal_ofs_ & -\totalign) - .Lxchal_pofs_
+.endm
+
+#define _SELECT (  XTHAL_SAS_TIE | XTHAL_SAS_OPT \
+                 | XTHAL_SAS_CC \
+                 | XTHAL_SAS_CALR | XTHAL_SAS_CALE | XTHAL_SAS_GLOB )
+
+.macro save_xtregs_opt ptr clb at1 at2 at3 at4 offset
+        .if XTREGS_OPT_SIZE > 0
+                addi    \clb, \ptr, \offset
+                xchal_ncp_store \clb \at1 \at2 \at3 \at4 select=_SELECT
+        .endif
+.endm
+
+.macro load_xtregs_opt ptr clb at1 at2 at3 at4 offset
+        .if XTREGS_OPT_SIZE > 0
+                addi    \clb, \ptr, \offset
+                xchal_ncp_load \clb \at1 \at2 \at3 \at4 select=_SELECT
+        .endif
+.endm
+#undef _SELECT
+
+#define _SELECT (  XTHAL_SAS_TIE | XTHAL_SAS_OPT \
+                 | XTHAL_SAS_NOCC \
+                 | XTHAL_SAS_CALR | XTHAL_SAS_CALE | XTHAL_SAS_GLOB )
+
+.macro save_xtregs_user ptr clb at1 at2 at3 at4 offset
+        .if XTREGS_USER_SIZE > 0
+                addi    \clb, \ptr, \offset
+                xchal_ncp_store \clb \at1 \at2 \at3 \at4 select=_SELECT
+        .endif
+.endm
+
+.macro load_xtregs_user ptr clb at1 at2 at3 at4 offset
+        .if XTREGS_USER_SIZE > 0
+                addi    \clb, \ptr, \offset
+                xchal_ncp_load \clb \at1 \at2 \at3 \at4 select=_SELECT
+        .endif
+.endm
+#undef _SELECT
+
+
+
+#endif  /* __ASSEMBLY__ */
 
-#if !XCHAL_HAVE_CP
-
-#define XTENSA_CP_EXTRA_OFFSET  0
-#define XTENSA_CP_EXTRA_ALIGN   1       /* must be a power of 2 */
-#define XTENSA_CP_EXTRA_SIZE    0
-
-#else
-
-#define XTOFS(last_start,last_size,align) \
-        ((last_start+last_size+align-1) & -align)
-
-#define XTENSA_CP_EXTRA_OFFSET  0
-#define XTENSA_CP_EXTRA_ALIGN   XCHAL_EXTRA_SA_ALIGN
-
-#define XTENSA_CPE_CP0_OFFSET   \
-        XTOFS(XTENSA_CP_EXTRA_OFFSET, XCHAL_EXTRA_SA_SIZE, XCHAL_CP0_SA_ALIGN)
-#define XTENSA_CPE_CP1_OFFSET   \
-        XTOFS(XTENSA_CPE_CP0_OFFSET, XCHAL_CP0_SA_SIZE, XCHAL_CP1_SA_ALIGN)
-#define XTENSA_CPE_CP2_OFFSET   \
-        XTOFS(XTENSA_CPE_CP1_OFFSET, XCHAL_CP1_SA_SIZE, XCHAL_CP2_SA_ALIGN)
-#define XTENSA_CPE_CP3_OFFSET   \
-        XTOFS(XTENSA_CPE_CP2_OFFSET, XCHAL_CP2_SA_SIZE, XCHAL_CP3_SA_ALIGN)
-#define XTENSA_CPE_CP4_OFFSET   \
-        XTOFS(XTENSA_CPE_CP3_OFFSET, XCHAL_CP3_SA_SIZE, XCHAL_CP4_SA_ALIGN)
-#define XTENSA_CPE_CP5_OFFSET   \
-        XTOFS(XTENSA_CPE_CP4_OFFSET, XCHAL_CP4_SA_SIZE, XCHAL_CP5_SA_ALIGN)
-#define XTENSA_CPE_CP6_OFFSET   \
-        XTOFS(XTENSA_CPE_CP5_OFFSET, XCHAL_CP5_SA_SIZE, XCHAL_CP6_SA_ALIGN)
-#define XTENSA_CPE_CP7_OFFSET   \
-        XTOFS(XTENSA_CPE_CP6_OFFSET, XCHAL_CP6_SA_SIZE, XCHAL_CP7_SA_ALIGN)
-#define XTENSA_CP_EXTRA_SIZE    \
-        XTOFS(XTENSA_CPE_CP7_OFFSET, XCHAL_CP7_SA_SIZE, 16)
-
-#if XCHAL_CP_NUM > 0
-# ifndef __ASSEMBLY__
 /*
- * Tasks that own contents of (last user) each coprocessor.
- * Entries are 0 for not-owned or non-existent coprocessors.
- * Note: The size of this structure is fixed to 8 bytes in entry.S
+ * XTENSA_HAVE_COPROCESSOR(x) returns 1 if coprocessor x is configured.
+ *
+ * XTENSA_HAVE_IO_PORT(x) returns 1 if io-port x is configured.
+ *
  */
-typedef struct {
-        struct task_struct *owner;      /* owner */
-        int offset;                     /* offset in cpextra space. */
-} coprocessor_info_t;
-# else
-#  define COPROCESSOR_INFO_OWNER 0
-#  define COPROCESSOR_INFO_OFFSET 4
-#  define COPROCESSOR_INFO_SIZE 8
-# endif
-#endif
-#endif  /* XCHAL_HAVE_CP */
 
+#define XTENSA_HAVE_COPROCESSOR(x)                                      \
+        ((XCHAL_CP_MASK ^ XCHAL_CP_PORT_MASK) & (1 << (x)))
+#define XTENSA_HAVE_COPROCESSORS                                        \
+        (XCHAL_CP_MASK ^ XCHAL_CP_PORT_MASK)
+#define XTENSA_HAVE_IO_PORT(x)                                          \
+        (XCHAL_CP_PORT_MASK & (1 << (x)))
+#define XTENSA_HAVE_IO_PORTS                                            \
+        XCHAL_CP_PORT_MASK
 
 #ifndef __ASSEMBLY__
-# if XCHAL_CP_NUM > 0
-struct task_struct;
-extern void release_coprocessors (struct task_struct*);
-extern void save_coprocessor_registers(void*, int);
-# else
-#  define release_coprocessors(task)
-# endif
 
-typedef unsigned char cp_state_t[XTENSA_CP_EXTRA_SIZE]
-        __attribute__ ((aligned (XTENSA_CP_EXTRA_ALIGN)));
 
-#endif  /* !__ASSEMBLY__ */
+#if XCHAL_HAVE_CP
 
+#define RSR_CPENABLE(x) do {                                              \
+        __asm__ __volatile__("rsr %0," __stringify(CPENABLE) : "=a" (x)); \
+        } while(0);
+#define WSR_CPENABLE(x) do {                                              \
+        __asm__ __volatile__("wsr %0," __stringify(CPENABLE) "; rsync"    \
+                             :: "a" (x));                                 \
+        } while(0);
 
+#endif /* XCHAL_HAVE_CP */
+
+
+/*
+ * Additional registers.
+ * We define three types of additional registers:
+ *  ext: extra registers that are used by the compiler
+ *  cpn: optional registers that can be used by a user application
+ *  cpX: coprocessor registers that can only be used if the corresponding
+ *       CPENABLE bit is set.
+ */
+
+#define XCHAL_SA_REG(list,compiler,x,type,y,name,z,align,size,...)      \
+        __REG ## list (compiler, type, name, size, align)
+
+#define __REG0(compiler,t,name,s,a)     __REG0_ ## compiler (name)
+#define __REG1(compiler,t,name,s,a)     __REG1_ ## compiler (name)
+#define __REG2(c,type,...)              __REG2_ ## type (__VA_ARGS__)
+