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authorKim Phillips <kim.phillips@freescale.com>2006-12-08 02:43:30 -0600
committerKumar Gala <galak@kernel.crashing.org>2006-12-08 02:43:30 -0600
commitaa42c69c67f82e88f0726258efe7306708e1cf14 (patch)
treed5305de3285d504e1bd1e955155e5e06b5b9ef76
parentc99767974ebd2a719d849fdeaaa1674456f5283f (diff)
[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>
-rw-r--r--arch/powerpc/Kconfig2
-rw-r--r--arch/powerpc/kernel/cputable.c2
-rw-r--r--arch/powerpc/kernel/head_32.S7
-rw-r--r--arch/powerpc/kernel/traps.c2
-rw-r--r--include/asm-powerpc/cputable.h10
5 files changed, 19 insertions, 4 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 291c95ac4b31..0b2d05da89d7 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -706,7 +706,7 @@ config FORCE_MAX_ZONEORDER
config MATH_EMULATION
bool "Math emulation"
- depends on 4xx || 8xx || E200 || E500
+ depends on 4xx || 8xx || E200 || PPC_83xx || E500
---help---
Some PowerPC chips designed for embedded applications do not have
a floating-point unit and therefore do not implement the
diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c
index 9d1614c3ce67..11bfbaf655b5 100644
--- a/arch/powerpc/kernel/cputable.c
+++ b/arch/powerpc/kernel/cputable.c
@@ -833,7 +833,7 @@ static struct cpu_spec cpu_specs[] = {
.pvr_mask = 0x7fff0000,
.pvr_value = 0x00840000,
.cpu_name = "e300c2",
- .cpu_features = CPU_FTRS_E300,
+ .cpu_features = CPU_FTRS_E300C2,
.cpu_user_features = PPC_FEATURE_32 | PPC_FEATURE_HAS_MMU,
.icache_bsize = 32,
.dcache_bsize = 32,
diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index d88e182e40b3..9417cf5b4b7e 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -437,6 +437,13 @@ Alignment:
/* Floating-point unavailable */
. = 0x800
FPUnavailable:
+BEGIN_FTR_SECTION
+/*
+ * Certain Freescale cores don't have a FPU and treat fp instructions
+ * as a FP Unavailable exception. Redirect to illegal/emulation handling.
+ */
+ b ProgramCheck
+END_FTR_SECTION_IFSET(CPU_FTR_FPU_UNAVAILABLE)
EXCEPTION_PROLOG
bne load_up_fpu /* if from user, just load it up */
addi r3,r1,STACK_FRAME_OVERHEAD
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 0d4e203fa7a0..fde820e52d03 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -782,6 +782,8 @@ void __kprobes program_check_exception(struct pt_regs *regs)
unsigned int reason = get_reason(regs);
extern int do_mathemu(struct pt_regs *regs);
+ /* We can now get here via a FP Unavailable exception if the core
+ * has no FPU, in that case no reason flags will be set */
#ifdef CONFIG_MATH_EMULATION
/* (reason & REASON_ILLEGAL) would be the obvious thing here,
* but there seems to be a hardware bug on the 405GP (RevD)
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