[POWERPC] Add support for FP emulation for the e300c2 core

The e300c2 has no FPU.  Its MSR[FP] is grounded to zero.  If an attempt
is made to execute a floating point instruction (including floating-point
load, store, or move instructions), the e300c2 takes a floating-point
unavailable interrupt.

This patch adds support for FP emulation on the e300c2 by declaring a
new CPU_FTR_FP_TAKES_FPUNAVAIL, where FP unavail interrupts are
intercepted and redirected to the ProgramCheck exception path for
correct emulation handling.

(If we run out of CPU_FTR bits we could look to reclaim this bit by adding
support to test the cpu_user_features for PPC_FEATURE_HAS_FPU instead)

It adds a nop to the exception path for 32-bit processors with a FPU.

Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 8 insertions, 2 deletions

diff --git a/include/asm-powerpc/cputable.h b/include/asm-powerpc/cputable.h
index 6fe5c9d4ca3b..aca72f90849e 100644
--- a/include/asm-powerpc/cputable.h
+++ b/include/asm-powerpc/cputable.h
@@ -126,6 +126,7 @@ extern void do_feature_fixups(unsigned long value, void *fixup_start,
 #define CPU_FTR_NODSISRALIGN            ASM_CONST(0x0000000000100000)
 #define CPU_FTR_PPC_LE                  ASM_CONST(0x0000000000200000)
 #define CPU_FTR_REAL_LE                 ASM_CONST(0x0000000000400000)
+#define CPU_FTR_FPU_UNAVAILABLE         ASM_CONST(0x0000000000800000)
 
 /*
  * Add the 64-bit processor unique features in the top half of the word;
@@ -295,6 +296,9 @@ extern void do_feature_fixups(unsigned long value, void *fixup_start,
 #define CPU_FTRS_E300   (CPU_FTR_SPLIT_ID_CACHE | CPU_FTR_MAYBE_CAN_DOZE | \
             CPU_FTR_USE_TB | CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_HAS_HIGH_BATS | \
             CPU_FTR_COMMON)
+#define CPU_FTRS_E300C2 (CPU_FTR_SPLIT_ID_CACHE | CPU_FTR_MAYBE_CAN_DOZE | \
+            CPU_FTR_USE_TB | CPU_FTR_MAYBE_CAN_NAP | CPU_FTR_HAS_HIGH_BATS | \
+            CPU_FTR_COMMON | CPU_FTR_FPU_UNAVAILABLE)
 #define CPU_FTRS_CLASSIC32      (CPU_FTR_COMMON | CPU_FTR_SPLIT_ID_CACHE | \
             CPU_FTR_USE_TB | CPU_FTR_HPTE_TABLE)
 #define CPU_FTRS_8XX    (CPU_FTR_SPLIT_ID_CACHE | CPU_FTR_USE_TB)
@@ -364,7 +368,8 @@ enum {
             CPU_FTRS_7450_21 | CPU_FTRS_7450_23 | CPU_FTRS_7455_1 |
             CPU_FTRS_7455_20 | CPU_FTRS_7455 | CPU_FTRS_7447_10 |
             CPU_FTRS_7447 | CPU_FTRS_7447A | CPU_FTRS_82XX |
-            CPU_FTRS_G2_LE | CPU_FTRS_E300 | CPU_FTRS_CLASSIC32 |
+            CPU_FTRS_G2_LE | CPU_FTRS_E300 | CPU_FTRS_E300C2 |
+            CPU_FTRS_CLASSIC32 |
 #else
             CPU_FTRS_GENERIC_32 |
 #endif
@@ -403,7 +408,8 @@ enum {
             CPU_FTRS_7450_21 & CPU_FTRS_7450_23 & CPU_FTRS_7455_1 &
             CPU_FTRS_7455_20 & CPU_FTRS_7455 & CPU_FTRS_7447_10 &
             CPU_FTRS_7447 & CPU_FTRS_7447A & CPU_FTRS_82XX &
-            CPU_FTRS_G2_LE & CPU_FTRS_E300 & CPU_FTRS_CLASSIC32 &
+            CPU_FTRS_G2_LE & CPU_FTRS_E300 & CPU_FTRS_E300C2 &
+            CPU_FTRS_CLASSIC32 &
 #else
             CPU_FTRS_GENERIC_32 &
 #endif