Fix/enhance ECC POST for 440EPx/GRx

This patch allows the ECC POST to be used for different boards with the
PPC440 Denali SDRAM controller.  Modifications include skipping the test
if ECC is not enabled (as for non-ECC DIMMs) and adding synchronization
to prevent timing errors.

Signed-off-by: Larry Johnson <lrj@acm.org>

post/cpu/ppc4xx/Makefile

@@ -24,6 +24,6 @@
 LIB	= libpostppc4xx.a
 
 AOBJS   = cache_4xx.o
-COBJS	= cache.o ether.o fpu.o spr.o uart.o watchdog.o
+COBJS	= cache.o denali_ecc.o ether.o fpu.o spr.o uart.o watchdog.o
 
 include $(TOPDIR)/post/rules.mk

post/cpu/ppc4xx/denali_ecc.c

@@ -31,7 +31,7 @@
 #include <common.h>
 #include <watchdog.h>
 
-#ifdef CONFIG_POST
+#if defined(CONFIG_POST) && (defined(CONFIG_440EPX) || defined(CONFIG_440GRX))
 
 #include <post.h>
 
@@ -47,8 +47,6 @@
 #include <asm/io.h>
 #include <ppc440.h>
 
-#include "../../../board/lwmon5/sdram.h"
-
 DECLARE_GLOBAL_DATA_PTR;
 
 const static unsigned char syndrome_codes[] = {
@@ -65,9 +63,9 @@ const static unsigned char syndrome_codes[] = {
 
 #define ECC_START_ADDR		0x10
 #define ECC_STOP_ADDR		0x2000
-#define ECC_PATTERN		0x0101010101010101ull
-#define ECC_PATTERN_CORR	0x0101010101010100ull
-#define ECC_PATTERN_UNCORR	0x010101010101010Full
+#define ECC_PATTERN		0x01010101
+#define ECC_PATTERN_CORR	0x11010101
+#define ECC_PATTERN_UNCORR	0xF1010101
 
 static int test_ecc_error(void)
 {
@@ -152,68 +150,78 @@ static int test_ecc_error(void)
 
 static int test_ecc(unsigned long ecc_addr)
 {
-	volatile unsigned long long *ecc_mem;
 	unsigned long value;
-	unsigned long ecc_data;
-	volatile unsigned long *lecc_mem;
-	int pret, ret = 0;
+	volatile unsigned *const ecc_mem = (volatile unsigned *) ecc_addr;
+	int pret;
+	int ret = 0;
 
 	sync();
 	eieio();
 	WATCHDOG_RESET();
 
-	ecc_mem = (unsigned long long *)ecc_addr;
-	lecc_mem = (ulong *)ecc_addr;
-	*ecc_mem = ECC_PATTERN;
+	debug("Entering test_ecc(0x%08lX)\n", ecc_addr);
+	out_be32(ecc_mem, ECC_PATTERN);
+	out_be32(ecc_mem + 1, ECC_PATTERN);
+	in_be32(ecc_mem);
 	pret = test_ecc_error();
-	if (pret != 0)
+	if (pret != 0) {
+		debug("pret: expected 0, got %d\n", pret);
 		ret = 1;
-
-	/* disconnect ecc */
+	}
+	/* test for correctable error */
+	/* disconnect from ecc storage */
 	mfsdram(DDR0_22, value);
 	mtsdram(DDR0_22, (value &~ DDR0_22_CTRL_RAW_MASK)
 		| DDR0_22_CTRL_RAW_ECC_DISABLE);
 
-	/* injecting error */
-	*ecc_mem = ECC_PATTERN_CORR;
+	/* creating (correctable) single-bit error */
+	out_be32(ecc_mem, ECC_PATTERN_CORR);
 
 	/* enable ecc */
 	mfsdram(DDR0_22, value);
 	mtsdram(DDR0_22, (value &~ DDR0_22_CTRL_RAW_MASK)
 		| DDR0_22_CTRL_RAW_ECC_ENABLE);
+	sync();
+	eieio();
 
-	ecc_data = *lecc_mem;
+	in_be32(ecc_mem);
 	pret = test_ecc_error();
 	/* if read data ok, 1 correctable error must be fixed */
-	if (pret != 3)
+	if (pret != 3) {
+		debug("pret: expected 3, got %d\n", pret);
 		ret = 1;
-
+	}
 	/* test for uncorrectable error */
 	/* disconnect from ecc storage */
 	mfsdram(DDR0_22, value);
 	mtsdram(DDR0_22, (value &~ DDR0_22_CTRL_RAW_MASK)
 		| DDR0_22_CTRL_RAW_NO_ECC_RAM);
 
-	/* injecting multiply bit error */
-
-	*ecc_mem = ECC_PATTERN_UNCORR;
+	/* creating (uncorrectable) multiple-bit error */
+	out_be32(ecc_mem, ECC_PATTERN_UNCORR);
 
 	/* enable ecc */
 	mfsdram(DDR0_22, value);
 	mtsdram(DDR0_22, (value &~ DDR0_22_CTRL_RAW_MASK)
 		| DDR0_22_CTRL_RAW_ECC_ENABLE);
+	sync();
+	eieio();
 
-	ecc_data = *lecc_mem;
-	/* what the data should be read? */
-
+	in_be32(ecc_mem);
 	pret = test_ecc_error();
 	/* info about uncorrectable error must appear */
-	if (pret != 5)
+	if (pret != 5) {
+		debug("pret: expected 5, got %d\n", pret);
 		ret = 1;
+	}
+	/* remove error from SDRAM */
+	out_be32(ecc_mem, ECC_PATTERN);
+	/* clear error caused by read-modify-write */
+	mfsdram(DDR0_00, value);
+	mtsdram(DDR0_00, value | DDR0_00_INT_ACK_ALL);
 
 	sync();
 	eieio();
-
 	return ret;
 }
 
@@ -223,10 +231,15 @@ int ecc_post_test (int flags)
 	unsigned long value;
 	unsigned long iaddr;
 
-#if CONFIG_DDR_ECC
 	sync();
 	eieio();
 
+	mfsdram(DDR0_22, value);
+	if (0x3 != DDR0_22_CTRL_RAW_DECODE(value)) {
+		debug("SDRAM ECC not enabled, skipping ECC POST.\n");
+		return 0;
+	}
+
 	/* mask all int */
 	mfsdram(DDR0_01, value);
 	mtsdram(DDR0_01, (value &~ DDR0_01_INT_MASK_MASK)
@@ -236,32 +249,19 @@ int ecc_post_test (int flags)
 	mfsdram(DDR0_00, value);
 	mtsdram(DDR0_00, value | DDR0_00_INT_ACK_ALL);
 
-	/* enable full support of ECC */
-	mfsdram(DDR0_22, value);
-	mtsdram(DDR0_22, (value &~ DDR0_22_CTRL_RAW_MASK)
-		| DDR0_22_CTRL_RAW_ECC_ENABLE);
-
-	for (iaddr = ECC_START_ADDR; iaddr < ECC_STOP_ADDR; iaddr += iaddr) {
+	for (iaddr = ECC_START_ADDR; iaddr <= ECC_STOP_ADDR; iaddr += iaddr) {
 		ret = test_ecc(iaddr);
 		if (ret)
 			break;
 	}
-
-	/* clear error status */
-	mfsdram(DDR0_00, value);
-	mtsdram(DDR0_00, value | DDR0_00_INT_ACK_ALL);
-
 	/*
 	 * Clear possible errors resulting from ECC testing.
 	 * If not done, then we could get an interrupt later on when
 	 * exceptions are enabled.
 	 */
 	set_mcsr(get_mcsr());
-#endif
-
 	return ret;
 
 }
-
 #endif /* CONFIG_POST & CFG_POST_ECC */
-#endif /* CONFIG_POST */
+#endif /* defined(CONFIG_POST) && ... */