[ARM] Feroceon: speed up flushing of the entire cache

Flushing the L1 D cache with a test/clean/invalidate loop is very
easy in software, but it is not the quickest way of doing it, as
there is a lot of overhead involved in re-scanning the cache from
the beginning every time we hit a dirty line.

This patch makes proc-feroceon.S use "clean+invalidate by set/way"
loops according to possible cache configuration of Feroceon CPUs
(either direct-mapped or 4-way set associative).

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>

1 files changed, 48 insertions, 11 deletions

diff --git a/arch/arm/mm/proc-feroceon.S b/arch/arm/mm/proc-feroceon.S
index 12b46d7b7f5e..00eadb5995c7 100644
--- a/arch/arm/mm/proc-feroceon.S
+++ b/arch/arm/mm/proc-feroceon.S
@@ -44,11 +44,31 @@
  */
 #define CACHE_DLINESIZE 32
 
+        .bss
+        .align 3
+__cache_params_loc:
+        .space  8
+
         .text
+__cache_params:
+        .word   __cache_params_loc
+
 /*
  * cpu_feroceon_proc_init()
  */
 ENTRY(cpu_feroceon_proc_init)
+        mrc     p15, 0, r0, c0, c0, 1           @ read cache type register
+        ldr     r1, __cache_params
+        mov     r2, #(16 << 5)
+        tst     r0, #(1 << 16)                  @ get way
+        mov     r0, r0, lsr #18                 @ get cache size order
+        movne   r3, #((4 - 1) << 30)            @ 4-way
+        and     r0, r0, #0xf
+        moveq   r3, #0                          @ 1-way
+        mov     r2, r2, lsl r0                  @ actual cache size
+        movne   r2, r2, lsr #2                  @ turned into # of sets
+        sub     r2, r2, #(1 << 5)
+        stmia   r1, {r2, r3}
         mov     pc, lr
 
 /*
@@ -117,11 +137,19 @@ ENTRY(feroceon_flush_user_cache_all)
  */
 ENTRY(feroceon_flush_kern_cache_all)
         mov     r2, #VM_EXEC
-        mov     ip, #0
+
 __flush_whole_cache:
-1:      mrc     p15, 0, r15, c7, c14, 3         @ test,clean,invalidate
-        bne     1b
+        ldr     r1, __cache_params
+        ldmia   r1, {r1, r3}
+1:      orr     ip, r1, r3
+2:      mcr     p15, 0, ip, c7, c14, 2          @ clean + invalidate D set/way
+        subs    ip, ip, #(1 << 30)              @ next way
+        bcs     2b
+        subs    r1, r1, #(1 << 5)               @ next set
+        bcs     1b
+
         tst     r2, #VM_EXEC
+        mov     ip, #0
         mcrne   p15, 0, ip, c7, c5, 0           @ invalidate I cache
         mcrne   p15, 0, ip, c7, c10, 4          @ drain WB
         mov     pc, lr
@@ -138,7 +166,6 @@ __flush_whole_cache:
  */
         .align  5
 ENTRY(feroceon_flush_user_cache_range)
-        mov     ip, #0
         sub     r3, r1, r0                      @ calculate total size
         cmp     r3, #CACHE_DLIMIT
         bgt     __flush_whole_cache
@@ -152,6 +179,7 @@ ENTRY(feroceon_flush_user_cache_range)
         cmp     r0, r1
         blo     1b
         tst     r2, #VM_EXEC
+        mov     ip, #0
         mcrne   p15, 0, ip, c7, c10, 4          @ drain WB
         mov     pc, lr
 
@@ -306,16 +334,25 @@ ENTRY(cpu_feroceon_dcache_clean_area)
         .align  5
 ENTRY(cpu_feroceon_switch_mm)
 #ifdef CONFIG_MMU
-        mov     ip, #0
-@ && 'Clean & Invalidate whole DCache'
-1:      mrc     p15, 0, r15, c7, c14, 3         @ test,clean,invalidate
-        bne     1b
-        mcr     p15, 0, ip, c7, c5, 0           @ invalidate I cache
-        mcr     p15, 0, ip, c7, c10, 4          @ drain WB
+        /*
+         * Note: we wish to call __flush_whole_cache but we need to preserve
+         * lr to do so.  The only way without touching main memory is to
+         * use r2 which is normally used to test the VM_EXEC flag, and
+         * compensate locally for the skipped ops if it is not set.
+         */
+        mov     r2, lr                          @ abuse r2 to preserve lr
+        bl      __flush_whole_cache
+        @ if r2 contains the VM_EXEC bit then the next 2 ops are done already
+        tst     r2, #VM_EXEC
+        mcreq   p15, 0, ip, c7, c5, 0           @ invalidate I cache
+        mcreq   p15, 0, ip, c7, c10, 4          @ drain WB
+
         mcr     p15, 0, r0, c2, c0, 0           @ load page table pointer
         mcr     p15, 0, ip, c8, c7, 0           @ invalidate I & D TLBs
-#endif
+        mov     pc, r2
+#else
         mov     pc, lr
+#endif
 
 /*
  * cpu_feroceon_set_pte_ext(ptep, pte, ext)