powerpc: Convert some mftb/mftbu into mfspr

Some CPUs (such as e500v1/v2) don't implement mftb and will take a
trap.  mfspr should work on everything that has a timebase, and is the
preferred instruction according to ISA v2.06.

Currently we get away with mftb on 85xx because the assembler converts
it to mfspr due to -Wa,-me500.  However, that flag has other effects
that are undesireable for certain targets (e.g.  lwsync is converted to
sync), and is hostile to multiplatform kernels.  Thus we would like to
stop setting it for all e500-family builds.

mftb/mftbu instances which are in 85xx code or common code are
converted.  Instances which will never run on 85xx are left alone.

Signed-off-by: Scott Wood <scottwood@freescale.com>

7 files changed, 29 insertions, 19 deletions

diff --git a/arch/powerpc/boot/ppc_asm.h b/arch/powerpc/boot/ppc_asm.h
index 1c2c2817f9b7..eb0e98be69e0 100644
--- a/arch/powerpc/boot/ppc_asm.h
+++ b/arch/powerpc/boot/ppc_asm.h
@@ -59,4 +59,7 @@
 #define r30     30
 #define r31     31
 
+#define SPRN_TBRL       268
+#define SPRN_TBRU       269
+
 #endif /* _PPC64_PPC_ASM_H */
diff --git a/arch/powerpc/boot/util.S b/arch/powerpc/boot/util.S
index 427ddfc11991..5143228e3e5f 100644
--- a/arch/powerpc/boot/util.S
+++ b/arch/powerpc/boot/util.S
@@ -71,18 +71,18 @@ udelay:
         add     r4,r4,r5
         addi    r4,r4,-1
         divw    r4,r4,r5        /* BUS ticks */
-1:      mftbu   r5
-        mftb    r6
-        mftbu   r7
+1:      mfspr   r5, SPRN_TBRU
+        mfspr   r6, SPRN_TBRL
+        mfspr   r7, SPRN_TBRU
         cmpw    0,r5,r7
         bne     1b              /* Get [synced] base time */
         addc    r9,r6,r4        /* Compute end time */
         addze   r8,r5
-2:      mftbu   r5
+2:      mfspr   r5, SPRN_TBRU
         cmpw    0,r5,r8
         blt     2b
         bgt     3f
-        mftb    r6
+        mfspr   r6, SPRN_TBRL
         cmpw    0,r6,r9
         blt     2b
 3:      blr
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 8fdd3da134e0..599545738af3 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -433,13 +433,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_601)
 
 #if defined(CONFIG_PPC_CELL) || defined(CONFIG_PPC_FSL_BOOK3E)
 #define MFTB(dest)                      \
-90:     mftb  dest;                     \
+90:     mfspr dest, SPRN_TBRL;          \
 BEGIN_FTR_SECTION_NESTED(96);           \
         cmpwi dest,0;                   \
         beq-  90b;                      \
 END_FTR_SECTION_NESTED(CPU_FTR_CELL_TB_BUG, CPU_FTR_CELL_TB_BUG, 96)
 #else
-#define MFTB(dest)                      mftb dest
+#define MFTB(dest)                      mfspr dest, SPRN_TBRL
 #endif
 
 #ifndef CONFIG_SMP
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index 55b03079d197..64264bf601f5 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -1120,7 +1120,7 @@
 #if defined(CONFIG_PPC_CELL) || defined(CONFIG_PPC_FSL_BOOK3E)
 #define mftb()          ({unsigned long rval;                           \
                         asm volatile(                                   \
-                                "90:    mftb %0;\n"                     \
+                                "90:    mfspr %0, %2;\n"                \
                                 "97:    cmpwi %0,0;\n"                  \
                                 "       beq- 90b;\n"                    \
                                 "99:\n"                                 \
@@ -1134,18 +1134,23 @@
                                 "       .llong 0\n"                     \
                                 "       .llong 0\n"                     \
                                 ".previous"                             \
-                        : "=r" (rval) : "i" (CPU_FTR_CELL_TB_BUG)); rval;})
+                        : "=r" (rval) \
+                        : "i" (CPU_FTR_CELL_TB_BUG), "i" (SPRN_TBRL)); \
+                        rval;})
 #else
 #define mftb()          ({unsigned long rval;   \
-                        asm volatile("mftb %0" : "=r" (rval)); rval;})
+                        asm volatile("mfspr %0, %1" : \
+                                     "=r" (rval) : "i" (SPRN_TBRL)); rval;})
 #endif /* !CONFIG_PPC_CELL */
 
 #else /* __powerpc64__ */
 
 #define mftbl()         ({unsigned long rval;   \
-                        asm volatile("mftbl %0" : "=r" (rval)); rval;})
+                        asm volatile("mfspr %0, %1" : "=r" (rval) : \
+                                "i" (SPRN_TBRL)); rval;})
 #define mftbu()         ({unsigned long rval;   \
-                        asm volatile("mftbu %0" : "=r" (rval)); rval;})
+                        asm volatile("mfspr %0, %1" : "=r" (rval) : \
+                                "i" (SPRN_TBRU)); rval;})
 #endif /* !__powerpc64__ */
 
 #define mttbl(v)        asm volatile("mttbl %0":: "r"(v))
diff --git a/arch/powerpc/include/asm/timex.h b/arch/powerpc/include/asm/timex.h
index c55e14f7ef44..18908caa1f3b 100644
--- a/arch/powerpc/include/asm/timex.h
+++ b/arch/powerpc/include/asm/timex.h
@@ -29,7 +29,7 @@ static inline cycles_t get_cycles(void)
         ret = 0;
 
         __asm__ __volatile__(
-                "97:    mftb %0\n"
+                "97:    mfspr %0, %2\n"
                 "99:\n"
                 ".section __ftr_fixup,\"a\"\n"
                 ".align 2\n"
@@ -41,7 +41,7 @@ static inline cycles_t get_cycles(void)
                 "       .long 0\n"
                 "       .long 0\n"
                 ".previous"
-                : "=r" (ret) : "i" (CPU_FTR_601));
+                : "=r" (ret) : "i" (CPU_FTR_601), "i" (SPRN_TBRL));
         return ret;
 #endif
 }
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index 27e2f623210b..6b1f2a6d5517 100644
--- a/arch/powerpc/kernel/vdso32/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -232,9 +232,9 @@ __do_get_tspec:
         lwz     r6,(CFG_TB_ORIG_STAMP+4)(r9)
 
         /* Get a stable TB value */
-2:      mftbu   r3
-        mftbl   r4
-        mftbu   r0
+2:      mfspr   r3, SPRN_TBRU
+        mfspr   r4, SPRN_TBRL
+        mfspr   r0, SPRN_TBRU
         cmplw   cr0,r3,r0
         bne-    2b
 
diff --git a/arch/powerpc/platforms/85xx/smp.c b/arch/powerpc/platforms/85xx/smp.c
index ea7e62910891..281b7f01df63 100644
--- a/arch/powerpc/platforms/85xx/smp.c
+++ b/arch/powerpc/platforms/85xx/smp.c
@@ -83,11 +83,13 @@ static void mpc85xx_give_timebase(void)
         {
                 u64 prev;
 
-                asm volatile("mftb %0" : "=r" (timebase));
+                asm volatile("mfspr %0, %1" : "=r" (timebase) :
+                             "i" (SPRN_TBRL));
 
                 do {
                         prev = timebase;
-                        asm volatile("mftb %0" : "=r" (timebase));
+                        asm volatile("mfspr %0, %1" : "=r" (timebase) :
+                                     "i" (SPRN_TBRL));
                 } while (prev != timebase);
         }
 #else