nb/intel/i440bx: Clean up register_values table

The table of initial i440BX register values has a bitmask that allows
preserving certain bits as they are programmed. This feature has been
unused since day one and probably will never be used. So drop it.

Drop DRB, RPS, PGPOL registers from the table as they will be
programmed during RAM init. These two reductions combined saved ~104
bytes.

Drop unneeded SDRAMC "+0".

Slightly compact a comment block.

TEST=Boot tested on asus/p2b-ls, i440bx config did not change

Change-Id: I020f616455bb671fe284993a488beb6386a03d0d
Signed-off-by: Keith Hui <buurin@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40391
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

1 files changed, 42 insertions, 59 deletions

diff --git a/src/northbridge/intel/i440bx/raminit.c b/src/northbridge/intel/i440bx/raminit.c
index e2db5e70ea..dddcc217f4 100644
--- a/src/northbridge/intel/i440bx/raminit.c
+++ b/src/northbridge/intel/i440bx/raminit.c
@@ -60,7 +60,7 @@ static const uint32_t refresh_rate_map[] = {
 	1, 5, 5, 2, 3, 4
 };
 
-/* Table format: register, bitmask, value. */
+/* Table format: register, value. */
 static const u8 register_values[] = {
 	/* NBXCFG - NBX Configuration Register
 	 * 0x50 - 0x53
@@ -122,11 +122,11 @@ static const u8 register_values[] = {
 	 *         0 = A7# is sampled asserted (i.e., 0)
 	 * [01:00] Reserved
 	 */
-	NBXCFG + 0, 0x00, 0x0c,
+	NBXCFG + 0, 0x0c,
 	// TODO: Bit 15 should be 0 for multiprocessor boards
-	NBXCFG + 1, 0x00, 0x80,
-	NBXCFG + 2, 0x00, 0x00,
-	NBXCFG + 3, 0x00, 0xff,
+	NBXCFG + 1, 0x80,
+	NBXCFG + 2, 0x00,
+	NBXCFG + 3, 0xff,
 
 	/* DRAMC - DRAM Control Register
 	 * 0x57
@@ -156,7 +156,7 @@ static const u8 register_values[] = {
 	 *       111 = Reserved
 	 */
 	/* Choose SDRAM (not registered), and disable refresh for now. */
-	DRAMC, 0x00, 0x08,
+	DRAMC, 0x08,
 
 	/*
 	 * PAM[6:0] - Programmable Attribute Map Registers
@@ -190,13 +190,13 @@ static const u8 register_values[] = {
 	 * registers are not set here appropriately, the RAM in that region
 	 * will not be accessible, thus a RAM check of it will also fail.
 	 */
-	PAM0, 0x00, 0x30,
-	PAM1, 0x00, 0x33,
-	PAM2, 0x00, 0x33,
-	PAM3, 0x00, 0x33,
-	PAM4, 0x00, 0x33,
-	PAM5, 0x00, 0x33,
-	PAM6, 0x00, 0x33,
+	PAM0, 0x30,
+	PAM1, 0x33,
+	PAM2, 0x33,
+	PAM3, 0x33,
+	PAM4, 0x33,
+	PAM5, 0x33,
+	PAM6, 0x33,
 
 	/* DRB[0:7] - DRAM Row Boundary Registers
 	 * 0x60 - 0x67
@@ -214,14 +214,6 @@ static const u8 register_values[] = {
 	 * 0x67 DRB7 = Total memory in row0+1+2+3+4+5+6+7 (in 8 MB)
 	 */
 	/* DRBs will be set later. */
-	DRB0, 0x00, 0x00,
-	DRB1, 0x00, 0x00,
-	DRB2, 0x00, 0x00,
-	DRB3, 0x00, 0x00,
-	DRB4, 0x00, 0x00,
-	DRB5, 0x00, 0x00,
-	DRB6, 0x00, 0x00,
-	DRB7, 0x00, 0x00,
 
 	/* FDHC - Fixed DRAM Hole Control Register
 	 * 0x68
@@ -236,7 +228,7 @@ static const u8 register_values[] = {
 	 * [5:0] Reserved
 	 */
 	/* No memory holes. */
-	FDHC, 0x00, 0x00,
+	FDHC, 0x00,
 
 	/* RPS - SDRAM Row Page Size Register
 	 * 0x74 - 0x75
@@ -261,8 +253,6 @@ static const u8 register_values[] = {
 	 * [15:14]  DRB[7], row 7
 	 */
 	/* Power on defaults to 2KB. Will be set later. */
-	// RPS + 0, 0x00, 0x00,
-	// RPS + 1, 0x00, 0x00,
 
 	/* SDRAMC - SDRAM Control Register
 	 * 0x76 - 0x77
@@ -298,9 +288,9 @@ static const u8 register_values[] = {
 	 *         1 = 2 clocks of RAS# precharge
 	 */
 #if CONFIG(SDRAMPWR_4DIMM)
-	SDRAMC + 0, 0x00, 0x10, /* The board has 4 DIMM slots. */
+	SDRAMC, 0x10, /* The board has 4 DIMM slots. */
 #else
-	SDRAMC + 0, 0x00, 0x00, /* The board has 3 DIMM slots. */
+	SDRAMC, 0x00, /* The board has 3 DIMM slots. */
 #endif
 
 	/* PGPOL - Paging Policy Register
@@ -325,40 +315,38 @@ static const u8 register_values[] = {
 	 *         0111 = 32 clocks
 	 *         1xxx = Infinite (pages are not closed for idle condition)
 	 */
-	PGPOL + 0, 0x00, 0x00,
-	PGPOL + 1, 0x00, 0xff,
+	/* PGPOL will be set later. */
 
 	/* PMCR - Power Management Control Register
 	 * 0x7a
 	 *
-	 * [07:07] Power Down SDRAM Enable (PDSE)
-	 *         1 = Enable
-	 *         0 = Disable
-	 * [06:06] ACPI Control Register Enable (SCRE)
-	 *         1 = Enable
-	 *         0 = Disable (default)
-	 * [05:05] Suspend Refresh Type (SRT)
-	 *         1 = Self refresh mode
-	 *         0 = CBR fresh mode
-	 * [04:04] Normal Refresh Enable (NREF_EN)
-	 *         1 = Enable
-	 *         0 = Disable
-	 * [03:03] Quick Start Mode (QSTART)
-	 *         1 = Quick start mode for the processor is enabled
-	 * [02:02] Gated Clock Enable (GCLKEN)
-	 *         1 = Enable
-	 *         0 = Disable
-	 * [01:01] AGP Disable (AGP_DIS)
-	 *         1 = Disable
-	 *         0 = Enable
-	 * [00:00] CPU reset without PCIRST enable (CRst_En)
-	 *         1 = Enable
-	 *         0 = Disable
+	 * [7] Power Down SDRAM Enable (PDSE)
+	 *     1 = Enable
+	 *     0 = Disable
+	 * [6] ACPI Control Register Enable (SCRE)
+	 *     1 = Enable
+	 *     0 = Disable (default)
+	 * [5] Suspend Refresh Type (SRT)
+	 *     1 = Self refresh mode
+	 *     0 = CBR fresh mode
+	 * [4] Normal Refresh Enable (NREF_EN)
+	 *     1 = Enable
+	 *     0 = Disable
+	 * [3] Quick Start Mode (QSTART)
+	 *     1 = Quick start mode for the processor is enabled
+	 * [2] Gated Clock Enable (GCLKEN)
+	 *     1 = Enable
+	 *     0 = Disable
+	 * [1] AGP Disable (AGP_DIS)
+	 *     1 = AGP disabled (Hardware strap)
+	 * [0] CPU reset without PCIRST enable (CRst_En)
+	 *     1 = Enable
+	 *     0 = Disable
 	 */
 	/* PMCR will be set later. */
 
 	/* Enable SCRR.SRRAEN and let BX choose the SRR. */
-	SCRR + 1, 0x00, 0x10,
+	SCRR + 1, 0x10,
 };
 
 /*-----------------------------------------------------------------------------
@@ -666,7 +654,6 @@ Public interface.
 static void sdram_set_registers(void)
 {
 	int i, max;
-	uint8_t reg;
 
 	PRINT_DEBUG("Northbridge prior to SDRAM init:\n");
 	DUMPNORTH();
@@ -674,12 +661,8 @@ static void sdram_set_registers(void)
 	max = ARRAY_SIZE(register_values);
 
 	/* Set registers as specified in the register_values[] array. */
-	for (i = 0; i < max; i += 3) {
-		reg = pci_read_config8(NB, register_values[i]);
-		reg &= register_values[i + 1];
-		reg |= register_values[i + 2] & ~(register_values[i + 1]);
-		pci_write_config8(NB, register_values[i], reg);
-	}
+	for (i = 0; i < max; i += 2)
+		pci_write_config8(NB, register_values[i], register_values[i + 1]);
 }
 
 struct dimm_size {