libflash: Provide an internal parity implementation, to remove libgcc dependency

In commit 8f5b8616, we introduced a dependency on libgcc, for the
__builtin_parityl() function in commit 6cfaa3ba.

However, if we're building with a biarch compiler, we may not have a
libgcc available.

This commit removes the __builtin_parityl() call, and replaces with the
equivalent instructions, and removes the dependency on libgcc.

Although this is untested, I have confirmed that the __builtin_parityl()
functions emits the same instructions (on power7 and power8, with
gcc-4.9) as we're using in the parity() function.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
[stewart@linux.vnet.ibm.com: only use inline asm for skiboot build]
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 17 insertions, 1 deletions

diff --git a/libflash/ecc.c b/libflash/ecc.c
index 05c0e14..9cd6ad2 100644
--- a/libflash/ecc.c
+++ b/libflash/ecc.c
@@ -108,6 +108,22 @@ static enum eccbitfields syndromematrix[] = {
         UE, UE, UE, UE,  4, UE, UE, UE, UE, UE, UE, UE, UE, UE, UE, UE,
 };
 
+static uint8_t parity(uint64_t data)
+{
+#ifdef __SKIBOOT__
+	uint8_t p;
+
+	asm volatile(
+		"popcntb %1,%0\n"
+		"prtyd   %1,%1\n"
+		: "=r"(p) : "r"(data));
+
+	return p;
+#else
+	return __builtin_parityl(data);
+#endif
+}
+
 /**
  * Create the ECC field corresponding to a 8-byte data field
  *
@@ -120,7 +136,7 @@ static uint8_t eccgenerate(uint64_t data)
 	uint8_t result = 0;
 
 	for (i = 0; i < 8; i++)
-		result |= __builtin_parityl(eccmatrix[i] & data) << i;
+		result |= parity(eccmatrix[i] & data) << i;
 
 	return result;
 }