ppc4xx: Add remove_tlb() function to remove a mem area from TLB setup

The new function remove_tlb() can be used to remove the TLB's used to
map a specific memory region. This is especially useful for the DDR(2)
setup routines which configure the SDRAM area temporarily as a cached
area (for speedup on auto-calibration and ECC generation) and later
need this area uncached for normal usage.

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

diff --git a/cpu/ppc4xx/tlb.c b/cpu/ppc4xx/tlb.c
index 049a78549505272e37f6de874d15752c12331527..098694caf4946704aed9344e808897b955064848 100644 (file)
--- a/cpu/ppc4xx/tlb.c
+++ b/cpu/ppc4xx/tlb.c
@@ -25,7 +25,6 @@
 
 #if defined(CONFIG_440)
 
-#include <ppc4xx.h>
 #include <ppc440.h>
 #include <asm/io.h>
 #include <asm/mmu.h>
@@ -36,6 +35,67 @@ typedef struct region {
        unsigned long tlb_word2_i_value;
 } region_t;
 
+void remove_tlb(u32 vaddr, u32 size)
+{
+       int i;
+       u32 tlb_word0_value;
+       u32 tlb_vaddr;
+       u32 tlb_size = 0;
+
+       /* First, find the index of a TLB entry not being used */
+       for (i=0; i<PPC4XX_TLB_SIZE; i++) {
+               tlb_word0_value = mftlb1(i);
+               tlb_vaddr = TLB_WORD0_EPN_DECODE(tlb_word0_value);
+               if (((tlb_word0_value & TLB_WORD0_V_MASK) == TLB_WORD0_V_ENABLE) &&
+                   (tlb_vaddr >= vaddr)) {
+                       /*
+                        * TLB is enabled and start address is lower or equal
+                        * than the area we are looking for. Now we only have
+                        * to check the size/end address for a match.
+                        */
+                       switch (tlb_word0_value & TLB_WORD0_SIZE_MASK) {
+                       case TLB_WORD0_SIZE_1KB:
+                               tlb_size = 1 << 10;
+                               break;
+                       case TLB_WORD0_SIZE_4KB:
+                               tlb_size = 4 << 10;
+                               break;
+                       case TLB_WORD0_SIZE_16KB:
+                               tlb_size = 16 << 10;
+                               break;
+                       case TLB_WORD0_SIZE_64KB:
+                               tlb_size = 64 << 10;
+                               break;
+                       case TLB_WORD0_SIZE_256KB:
+                               tlb_size = 256 << 10;
+                               break;
+                       case TLB_WORD0_SIZE_1MB:
+                               tlb_size = 1 << 20;
+                               break;
+                       case TLB_WORD0_SIZE_16MB:
+                               tlb_size = 16 << 20;
+                               break;
+                       case TLB_WORD0_SIZE_256MB:
+                               tlb_size = 256 << 20;
+                               break;
+                       }
+
+                       /*
+                        * Now check the end-address if it's in the range
+                        */
+                       if ((tlb_vaddr + tlb_size - 1) <= (vaddr + size - 1))
+                               /*
+                                * Found a TLB in the range.
+                                * Disable it by writing 0 to tlb0 word.
+                                */
+                               mttlb1(i, 0);
+               }
+       }
+
+       /* Execute an ISYNC instruction so that the new TLB entry takes effect */
+       asm("isync");
+}
+
 static int add_tlb_entry(unsigned long phys_addr,
                         unsigned long virt_addr,
                         unsigned long tlb_word0_size_value,

diff --git a/include/asm-ppc/mmu.h b/include/asm-ppc/mmu.h
index 48fd9829506992bcd95da0fe8eaabbdd3d701933..b3cfa9b37268dde73f6a5cd70b04e327e01f63c7 100644 (file)
--- a/include/asm-ppc/mmu.h
+++ b/include/asm-ppc/mmu.h
@@ -645,6 +645,9 @@ void mttlb3(unsigned long index, unsigned long value);
 unsigned long mftlb1(unsigned long index);
 unsigned long mftlb2(unsigned long index);
 unsigned long mftlb3(unsigned long index);
+
+void program_tlb(u32 phys_addr, u32 virt_addr, u32 size, u32 tlb_word2_i_value);
+void remove_tlb(u32 vaddr, u32 size);
 #endif /* __ASSEMBLY__ */
 
 #endif /* CONFIG_440 */