[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>

1 files changed, 1 insertions, 38 deletions

diff --git a/include/asm-xtensa/system.h b/include/asm-xtensa/system.h
index e0cb9116d8ab..62b1e8f3c13c 100644
--- a/include/asm-xtensa/system.h
+++ b/include/asm-xtensa/system.h
@@ -46,42 +46,6 @@ static inline int irqs_disabled(void)
         return flags & 0xf;
 }
 
-#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);
-
-#define clear_cpenable() __clear_cpenable()
-
-static inline void __clear_cpenable(void)
-{
-#if XCHAL_HAVE_CP
-        unsigned long i = 0;
-        WSR_CPENABLE(i);
-#endif
-}
-
-static inline void enable_coprocessor(int i)
-{
-#if XCHAL_HAVE_CP
-        int cp;
-        RSR_CPENABLE(cp);
-        cp |= 1 << i;
-        WSR_CPENABLE(cp);
-#endif
-}
-
-static inline void disable_coprocessor(int i)
-{
-#if XCHAL_HAVE_CP
-        int cp;
-        RSR_CPENABLE(cp);
-        cp &= ~(1 << i);
-        WSR_CPENABLE(cp);
-#endif
-}
 
 #define smp_read_barrier_depends() do { } while(0)
 #define read_barrier_depends() do { } while(0)
@@ -111,7 +75,6 @@ extern void *_switch_to(void *last, void *next);
 
 #define switch_to(prev,next,last)               \
 do {                                            \
-        clear_cpenable();                       \
         (last) = _switch_to(prev, next);        \
 } while(0)
 
@@ -244,7 +207,7 @@ static inline void spill_registers(void)
                 "wsr    a13," __stringify(SAR) "\n\t"
                 "wsr    a14," __stringify(PS) "\n\t"
                 :: "a" (&a0), "a" (&ps)
-                : "a2", "a3", "a12", "a13", "a14", "a15", "memory");
+                : "a2", "a3", "a4", "a7", "a11", "a12", "a13", "a14", "a15", "memory");
 }
 
 #define arch_align_stack(x) (x)