ppc4xx: Add 44x cache locking to better support init-ram in d-cache

This patch adds support for locking the init-ram/stack in d-cache,
so that other regions may use d-cache as well

Note, that this current implementation locks exactly 4k of d-cache,
so please make sure that you don't define a bigger init-ram area. Take
a look at the lwmon5 440EPx implementation as a reference.

Signed-off-by: Stefan Roese <sr@denx.de>

diff --git a/cpu/ppc4xx/start.S b/cpu/ppc4xx/start.S
index 52601ed..a730604 100644 (file)
--- a/cpu/ppc4xx/start.S
+++ b/cpu/ppc4xx/start.S
@@ -636,6 +636,33 @@ _start:
        dcbz    r0,r3
        addi    r3,r3,32
        bdnz    ..d_ag
+
+       /*
+        * Lock the init-ram/stack in d-cache, so that other regions
+        * may use d-cache as well
+        * Note, that this current implementation locks exactly 4k
+        * of d-cache, so please make sure that you don't define a
+        * bigger init-ram area. Take a look at the lwmon5 440EPx
+        * implementation as a reference.
+        */
+       msync
+       isync
+       /* 8. set TFLOOR/NFLOOR to 8 (-> 8*16*32 bytes locked -> 4k) */
+       lis     r1,0x0201
+       ori     r1,r1,0xf808
+       mtspr   dvlim,r1
+       lis     r1,0x0808
+       ori     r1,r1,0x0808
+       mtspr   dnv0,r1
+       mtspr   dnv1,r1
+       mtspr   dnv2,r1
+       mtspr   dnv3,r1
+       mtspr   dtv0,r1
+       mtspr   dtv1,r1
+       mtspr   dtv2,r1
+       mtspr   dtv3,r1
+       msync
+       isync
 #endif /* CFG_INIT_RAM_DCACHE */
 
        /* 440EP & 440GR are only 440er PPC's without internal SRAM */
@@ -1345,6 +1372,31 @@ relocate_code:
        mr      r4,r10
        mr      r5,r11
 #endif
+
+#ifdef CFG_INIT_RAM_DCACHE
+       /*
+        * Unlock the previously locked d-cache
+        */
+       msync
+       isync
+       /* set TFLOOR/NFLOOR to 0 again */
+       lis     r6,0x0001
+       ori     r6,r6,0xf800
+       mtspr   dvlim,r6
+       lis     r6,0x0000
+       ori     r6,r6,0x0000
+       mtspr   dnv0,r6
+       mtspr   dnv1,r6
+       mtspr   dnv2,r6
+       mtspr   dnv3,r6
+       mtspr   dtv0,r6
+       mtspr   dtv1,r6
+       mtspr   dtv2,r6
+       mtspr   dtv3,r6
+       msync
+       isync
+#endif /* CFG_INIT_RAM_DCACHE */
+
 #if defined(CONFIG_440EP) || defined(CONFIG_440GR) || \
     defined(CONFIG_440EPX) || defined(CONFIG_440GRX) || \
     defined(CONFIG_440SP) || defined(CONFIG_440SPE)