[PATCH v4 14/18] EDAC/synopsys: Simplify HIF/SDRAM column mapping get procedure

[Serge Semin]

What is currently implemented in the driver by means of the multiple
if-else-if-else statements in fact is described in the hardware reference
manual [1]. It says:
1. All of the column bits shift up 1 bit when only half of the data bus is
in use. (In this case, for instance, you need to look at
ADDRMAP3.addrmap_col_b6 instead to determine the value of column address
bit 7.)
2. All of the column bits shift up 2 bits when only a quarter of the data
bus is in use. (In this case, for instance, you need to look at
ADDRMAP2.addrmap_col_b5 instead to determine the value of column address
bit 7.)
3. In addition to the above, the column bit 10 is reserved for the
auto-precharge command in DDR2/3/4/mDDR. So the column bits must be
further shifted up 1 bit when one of these DDR protocols is enabled.

So taking into account all of the notes above and what the column bit 12
is always reserved, the SDRAM column bits mapping procedure can be
significantly simplified: initially read the mapping as if for the
LPDDR2/3/4 memory with Full DQ-bus utilized; then shift the column bits up
in accordance with the detected DQ-bus width mode. That's it. Simple,
canonical and scalable.

[1] DesignWare® Cores Enhanced Universal DDR Memory Controller (uMCTL2)
    Databook, Version 3.91a, October 2020, p.154

Signed-off-by: Serge Semin <fancer.lancer@xxxxxxxxx>
---
 drivers/edac/synopsys_edac.c | 83 ++++++++++++------------------------
 1 file changed, 27 insertions(+), 56 deletions(-)

diff --git a/drivers/edac/synopsys_edac.c b/drivers/edac/synopsys_edac.c
index 204d7f1fc7e2..a359018c261c 100644
--- a/drivers/edac/synopsys_edac.c
+++ b/drivers/edac/synopsys_edac.c
@@ -996,8 +996,22 @@ static void snps_get_hif_col_map(struct snps_edac_priv *priv, u32 *addrmap)
 	map->col[9] = map->col[9] == DDR_ADDRMAP_MAX_15 ?
 		      DDR_ADDRMAP_UNUSED : map->col[9] + COL_B9_BASE;
 
+	map->col[10] = FIELD_GET(DDR_ADDRMAP_B0_M15, addrmap[4]);
+	map->col[10] = map->col[10] == DDR_ADDRMAP_MAX_15 ?
+		      DDR_ADDRMAP_UNUSED : map->col[10] + COL_B10_BASE;
+
+	map->col[11] = FIELD_GET(DDR_ADDRMAP_B8_M15, addrmap[4]);
+	map->col[11] = map->col[11] == DDR_ADDRMAP_MAX_15 ?
+		      DDR_ADDRMAP_UNUSED : map->col[11] + COL_B11_BASE;
+
+	/*
+	 * In case of the non-Full DQ bus mode the lowest columns are
+	 * unmapped and used by the controller to read the full DQ word
+	 * in multiple cycles (col[0] for the Half bus mode, col[0:1] for
+	 * the Quarter bus mode).
+	 */
 	if (priv->info.dq_mode) {
-		for (i = 9; i > priv->info.dq_mode; i--) {
+		for (i = 11 + priv->info.dq_mode; i >= priv->info.dq_mode; i--) {
 			map->col[i] = map->col[i - priv->info.dq_mode];
 			map->col[i - priv->info.dq_mode] = DDR_ADDRMAP_UNUSED;
 		}
@@ -1007,65 +1021,22 @@ static void snps_get_hif_col_map(struct snps_edac_priv *priv, u32 *addrmap)
 	 * Per JEDEC DDR2/3/4/mDDR specification, column address bit 10 is
 	 * reserved for indicating auto-precharge, and hence no source
 	 * address bit can be mapped to col[10].
+	 */
+	if (priv->info.sdram_mode == MEM_LPDDR || priv->info.sdram_mode == MEM_DDR2 ||
+	    priv->info.sdram_mode == MEM_DDR3 || priv->info.sdram_mode == MEM_DDR4) {
+		for (i = 12 + priv->info.dq_mode; i > 10; i--) {
+			map->col[i] = map->col[i - 1];
+			map->col[i - 1] = DDR_ADDRMAP_UNUSED;
+		}
+	}
+
+	/*
 	 * Per JEDEC specification, column address bit 12 is reserved
 	 * for the Burst-chop status, so no source address bit mapping
 	 * for col[12] either.
 	 */
-	if (priv->info.dq_mode == SNPS_DQ_FULL) {
-		if (priv->info.sdram_mode == MEM_LPDDR3) {
-			map->col[10] = FIELD_GET(DDR_ADDRMAP_B0_M15, addrmap[4]);
-			map->col[10] = map->col[10] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[10] + COL_B10_BASE;
-
-			map->col[11] = FIELD_GET(DDR_ADDRMAP_B8_M15, addrmap[4]);
-			map->col[11] = map->col[11] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[11] + COL_B11_BASE;
-		} else {
-			map->col[11] = FIELD_GET(DDR_ADDRMAP_B0_M15, addrmap[4]);
-			map->col[11] = map->col[11] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[11] + COL_B10_BASE;
-
-			map->col[13] = FIELD_GET(DDR_ADDRMAP_B8_M15, addrmap[4]);
-			map->col[13] = map->col[13] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[13] + COL_B11_BASE;
-		}
-	} else if (priv->info.dq_mode == SNPS_DQ_HALF) {
-		if (priv->info.sdram_mode == MEM_LPDDR3) {
-			map->col[10] = FIELD_GET(DDR_ADDRMAP_B24_M15, addrmap[3]);
-			map->col[10] = map->col[10] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[10] + COL_B9_BASE;
-
-			map->col[11] = FIELD_GET(DDR_ADDRMAP_B0_M15, addrmap[4]);
-			map->col[11] = map->col[11] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[11] + COL_B10_BASE;
-		} else {
-			map->col[11] = FIELD_GET(DDR_ADDRMAP_B24_M15, addrmap[3]);
-			map->col[11] = map->col[11] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[11] + COL_B9_BASE;
-
-			map->col[13] = FIELD_GET(DDR_ADDRMAP_B0_M15, addrmap[4]);
-			map->col[13] = map->col[13] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[13] + COL_B10_BASE;
-		}
-	} else {
-		if (priv->info.sdram_mode == MEM_LPDDR3) {
-			map->col[10] = FIELD_GET(DDR_ADDRMAP_B16_M15, addrmap[3]);
-			map->col[10] = map->col[10] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[10] + COL_B8_BASE;
-
-			map->col[11] = FIELD_GET(DDR_ADDRMAP_B24_M15, addrmap[3]);
-			map->col[11] = map->col[11] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[11] + COL_B9_BASE;
-		} else {
-			map->col[11] = FIELD_GET(DDR_ADDRMAP_B16_M15, addrmap[3]);
-			map->col[11] = map->col[11] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[11] + COL_B8_BASE;
-
-			map->col[11] = FIELD_GET(DDR_ADDRMAP_B24_M15, addrmap[3]);
-			map->col[13] = map->col[13] == DDR_ADDRMAP_MAX_15 ?
-				       DDR_ADDRMAP_UNUSED : map->col[13] + COL_B9_BASE;
-		}
-	}
+	map->col[13] = map->col[12];
+	map->col[12] = DDR_ADDRMAP_UNUSED;
 }
 
 /**
-- 
2.41.0