ppc4xx: Add change_tlb function to modify I attribute of TLB(s)

This function is used to either turn cache on or off in a specific
memory area.

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

cpu/ppc4xx/tlb.c

@@ -26,6 +26,7 @@
 #if defined(CONFIG_440)
 
 #include <ppc440.h>
+#include <asm/cache.h>
 #include <asm/io.h>
 #include <asm/mmu.h>
 
@@ -42,7 +43,6 @@ void remove_tlb(u32 vaddr, u32 size)
 	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);
@@ -96,6 +96,92 @@ void remove_tlb(u32 vaddr, u32 size)
 	asm("isync");
 }
 
+/*
+ * Change the I attribute (cache inhibited) of a TLB or multiple TLB's.
+ * This function is used to either turn cache on or off in a specific
+ * memory area.
+ */
+void change_tlb(u32 vaddr, u32 size, u32 tlb_word2_i_value)
+{
+	int i;
+	u32 tlb_word0_value;
+	u32 tlb_word2_value;
+	u32 tlb_vaddr;
+	u32 tlb_size = 0;
+
+	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.
+				 * Change cache attribute in tlb2 word.
+				 */
+				tlb_word2_value =
+					TLB_WORD2_U0_DISABLE | TLB_WORD2_U1_DISABLE |
+					TLB_WORD2_U2_DISABLE | TLB_WORD2_U3_DISABLE |
+					TLB_WORD2_W_DISABLE | tlb_word2_i_value |
+					TLB_WORD2_M_DISABLE | TLB_WORD2_G_DISABLE |
+					TLB_WORD2_E_DISABLE | TLB_WORD2_UX_ENABLE |
+					TLB_WORD2_UW_ENABLE | TLB_WORD2_UR_ENABLE |
+					TLB_WORD2_SX_ENABLE | TLB_WORD2_SW_ENABLE |
+					TLB_WORD2_SR_ENABLE;
+
+				/*
+				 * Now either flush or invalidate the dcache
+				 */
+				if (tlb_word2_i_value)
+					flush_dcache();
+				else
+					invalidate_dcache();
+
+				mttlb3(i, tlb_word2_value);
+				asm("iccci 0,0");
+			}
+		}
+	}
+
+	/* 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,

include/asm-ppc/mmu.h

@@ -648,6 +648,7 @@ 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);
+void change_tlb(u32 vaddr, u32 size, u32 tlb_word2_i_value);
 #endif /* __ASSEMBLY__ */
 
 #endif /* CONFIG_440 */