[PATCH v2 12/31] EDAC/amd64: Define function to dehash address

[Yazen Ghannam <yazen.ghannam@amd.com>]

Move the dehashing code into a separate helper function. Define a
DF2-specific function for the current code. Specific helper functions
will be added for future DF versions.

The dehashing code is tied to interleaving mode rather than Data Fabric
version, so save the function pointer in the ctx struct. The name
include "df2" because this mode only exists on DF2.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---
Link:
https://lkml.kernel.org/r/20210507190140.18854-9-Yazen.Ghannam@amd.com

v1->v2:
* Moved from arch/x86 to EDAC.
* Add new function pointer in ctx struct.

 drivers/edac/amd64_edac.c | 37 ++++++++++++++++++++-----------------
 1 file changed, 20 insertions(+), 17 deletions(-)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index 68c4aecd5e7a..46b0279a2e12 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -1098,7 +1098,7 @@ struct addr_ctx {
 	u8 map_num;
 	u8 intlv_addr_bit;
 	u8 cs_id;
-	bool hash_enabled;
+	int (*dehash_addr)(struct addr_ctx *ctx);
 };
 
 struct data_fabric_ops {
@@ -1111,13 +1111,29 @@ static u64 get_hi_addr_offset_df2(struct addr_ctx *ctx)
 	return (ctx->reg_dram_offset & GENMASK_ULL(31, 20)) << 8;
 }
 
+static int dehash_addr_df2(struct addr_ctx *ctx)
+{
+	u8 hashed_bit =	(ctx->ret_addr >> 12) ^
+			(ctx->ret_addr >> 18) ^
+			(ctx->ret_addr >> 21) ^
+			(ctx->ret_addr >> 30) ^
+			ctx->cs_id;
+
+	hashed_bit &= BIT(0);
+
+	if (hashed_bit != ((ctx->ret_addr >> ctx->intlv_addr_bit) & BIT(0)))
+		ctx->ret_addr ^= BIT(ctx->intlv_addr_bit);
+
+	return 0;
+}
+
 static int get_intlv_mode_df2(struct addr_ctx *ctx)
 {
 	ctx->intlv_mode = (ctx->reg_base_addr >> 4) & 0xF;
 
 	if (ctx->intlv_mode == 8) {
 		ctx->intlv_mode = DF2_HASH_2CH;
-		ctx->hash_enabled = true;
+		ctx->dehash_addr = &dehash_addr_df2;
 	}
 
 	if (ctx->intlv_mode != NONE &&
@@ -1347,8 +1363,6 @@ static int umc_normaddr_to_sysaddr(u64 norm_addr, u16 nid, u8 umc, u64 *sys_addr
 {
 	u64 dram_limit_addr;
 
-	u8 hashed_bit;
-
 	struct addr_ctx ctx;
 
 	memset(&ctx, 0, sizeof(ctx));
@@ -1379,19 +1393,8 @@ static int umc_normaddr_to_sysaddr(u64 norm_addr, u16 nid, u8 umc, u64 *sys_addr
 	if (add_base_and_hole(&ctx))
 		goto out_err;
 
-	if (ctx.hash_enabled) {
-		/* Save some parentheses and grab ls-bit at the end. */
-		hashed_bit =	(ctx.ret_addr >> 12) ^
-				(ctx.ret_addr >> 18) ^
-				(ctx.ret_addr >> 21) ^
-				(ctx.ret_addr >> 30) ^
-				ctx.cs_id;
-
-		hashed_bit &= BIT(0);
-
-		if (hashed_bit != ((ctx.ret_addr >> ctx.intlv_addr_bit) & BIT(0)))
-			ctx.ret_addr ^= BIT(ctx.intlv_addr_bit);
-	}
+	if (ctx.dehash_addr && ctx.dehash_addr(&ctx))
+		goto out_err;
 
 	/* Is calculated system address is above DRAM limit address? */
 	if (ctx.ret_addr > dram_limit_addr)
-- 
2.25.1