sunxi: H6: DRAM: Add support for half DQ

Half DQ configuration seems to be very rare for H6 based boards/STBs,
but exists nevertheless. Currently the only known product which needs
this support is Tanix TX6 mini.

This commit adds support for half DQ configuration. Code was tested
for regressions on other configurations (OrangePi 3 1 GiB/LPDDR3, Tanix
TX6 4 GiB/DDR3) and none were found.

Thanks to Icenowy Zheng for help with this code.

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: thomas graichen <thomas.graichen@gmail.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Maxime Ripard <mripard@kernel.org>

2 files changed, 54 insertions, 25 deletions

diff --git a/arch/arm/include/asm/arch-sunxi/dram_sun50i_h6.h b/arch/arm/include/asm/arch-sunxi/dram_sun50i_h6.h
index 0a1da02..49a8a66 100644
--- a/arch/arm/include/asm/arch-sunxi/dram_sun50i_h6.h
+++ b/arch/arm/include/asm/arch-sunxi/dram_sun50i_h6.h
@@ -315,6 +315,7 @@ struct dram_para {
 	u8 cols;
 	u8 rows;
 	u8 ranks;
+	u8 bus_full_width;
 	const u8 dx_read_delays[NR_OF_BYTE_LANES][RD_LINES_PER_BYTE_LANE];
 	const u8 dx_write_delays[NR_OF_BYTE_LANES][WR_LINES_PER_BYTE_LANE];
 };
diff --git a/arch/arm/mach-sunxi/dram_sun50i_h6.c b/arch/arm/mach-sunxi/dram_sun50i_h6.c
index 2a8275d..9375db7 100644
--- a/arch/arm/mach-sunxi/dram_sun50i_h6.c
+++ b/arch/arm/mach-sunxi/dram_sun50i_h6.c
@@ -201,6 +201,9 @@ static void mctl_set_addrmap(struct dram_para *para)
 	u8 rows = para->rows;
 	u8 ranks = para->ranks;
 
+	if (!para->bus_full_width)
+		cols -= 1;
+
 	/* Ranks */
 	if (ranks == 2)
 		mctl_ctl->addrmap[0] = rows + cols - 3;
@@ -213,6 +216,10 @@ static void mctl_set_addrmap(struct dram_para *para)
 	/* Columns */
 	mctl_ctl->addrmap[2] = 0;
 	switch (cols) {
+	case 7:
+		mctl_ctl->addrmap[3] = 0x1F1F1F00;
+		mctl_ctl->addrmap[4] = 0x1F1F;
+		break;
 	case 8:
 		mctl_ctl->addrmap[3] = 0x1F1F0000;
 		mctl_ctl->addrmap[4] = 0x1F1F;
@@ -300,13 +307,16 @@ static void mctl_com_init(struct dram_para *para)
 		reg_val = 0x3f00;
 	clrsetbits_le32(&mctl_com->unk_0x008, 0x3f00, reg_val);
 
-	/* TODO: half DQ, DDR4 */
-	reg_val = MSTR_BUSWIDTH_FULL | MSTR_BURST_LENGTH(8) |
-		  MSTR_ACTIVE_RANKS(para->ranks);
+	/* TODO: DDR4 */
+	reg_val = MSTR_BURST_LENGTH(8) | MSTR_ACTIVE_RANKS(para->ranks);
 	if (para->type == SUNXI_DRAM_TYPE_LPDDR3)
 		reg_val |= MSTR_DEVICETYPE_LPDDR3;
 	if (para->type == SUNXI_DRAM_TYPE_DDR3)
 		reg_val |= MSTR_DEVICETYPE_DDR3 | MSTR_2TMODE;
+	if (para->bus_full_width)
+		reg_val |= MSTR_BUSWIDTH_FULL;
+	else
+		reg_val |= MSTR_BUSWIDTH_HALF;
 	writel(reg_val | BIT(31), &mctl_ctl->mstr);
 
 	if (para->type == SUNXI_DRAM_TYPE_LPDDR3)
@@ -333,7 +343,10 @@ static void mctl_com_init(struct dram_para *para)
 	}
 	writel(reg_val, &mctl_ctl->odtcfg);
 
-	/* TODO: half DQ */
+	if (!para->bus_full_width) {
+		writel(0x0, &mctl_phy->dx[2].gcr[0]);
+		writel(0x0, &mctl_phy->dx[3].gcr[0]);
+	}
 }
 
 static void mctl_bit_delay_set(struct dram_para *para)
@@ -514,22 +527,35 @@ static void mctl_channel_init(struct dram_para *para)
 
 	if (readl(&mctl_phy->pgsr[0]) & 0x400000)
 	{
-		/*
-		 * Detect single rank.
-		 * TODO: also detect half DQ.
-		 */
+		/* Check for single rank and optionally half DQ. */
 		if ((readl(&mctl_phy->dx[0].rsr[0]) & 0x3) == 2 &&
-		    (readl(&mctl_phy->dx[1].rsr[0]) & 0x3) == 2 &&
-		    (readl(&mctl_phy->dx[2].rsr[0]) & 0x3) == 2 &&
-		    (readl(&mctl_phy->dx[3].rsr[0]) & 0x3) == 2) {
+		    (readl(&mctl_phy->dx[1].rsr[0]) & 0x3) == 2) {
 			para->ranks = 1;
+
+			if ((readl(&mctl_phy->dx[2].rsr[0]) & 0x3) != 2 ||
+			    (readl(&mctl_phy->dx[3].rsr[0]) & 0x3) != 2)
+				para->bus_full_width = 0;
+
 			/* Restart DRAM initialization from scratch. */
 			mctl_core_init(para);
 			return;
 		}
-		else {
-			panic("This DRAM setup is currently not supported.\n");
+
+		/*
+		 * Check for dual rank and half DQ. NOTE: This combination
+		 * is highly unlikely and was not tested. Condition is the
+		 * same as in libdram, though.
+		 */
+		if ((readl(&mctl_phy->dx[0].rsr[0]) & 0x3) == 0 &&
+		    (readl(&mctl_phy->dx[1].rsr[0]) & 0x3) == 0) {
+			para->bus_full_width = 0;
+
+			/* Restart DRAM initialization from scratch. */
+			mctl_core_init(para);
+			return;
 		}
+
+		panic("This DRAM setup is currently not supported.\n");
 	}
 
 	if (readl(&mctl_phy->pgsr[0]) & 0xff00000) {
@@ -557,11 +583,8 @@ static void mctl_channel_init(struct dram_para *para)
 
 static void mctl_auto_detect_dram_size(struct dram_para *para)
 {
-	/* TODO: non-LPDDR3, half DQ */
-	/*
-	 * Detect rank number by the code in mctl_channel_init. Furtherly
-	 * when DQ detection is available it will also be executed there.
-	 */
+	/* TODO: non-(LP)DDR3 */
+	/* Detect rank number and half DQ by the code in mctl_channel_init. */
 	mctl_core_init(para);
 
 	/* detect row address bits */
@@ -570,8 +593,9 @@ static void mctl_auto_detect_dram_size(struct dram_para *para)
 	mctl_core_init(para);
 
 	for (para->rows = 13; para->rows < 18; para->rows++) {
-		/* 8 banks, 8 bit per byte and 32 bit width */
-		if (mctl_mem_matches((1 << (para->rows + para->cols + 5))))
+		/* 8 banks, 8 bit per byte and 16/32 bit width */
+		if (mctl_mem_matches((1 << (para->rows + para->cols +
+					    4 + para->bus_full_width))))
 			break;
 	}
 
@@ -580,18 +604,21 @@ static void mctl_auto_detect_dram_size(struct dram_para *para)
 	mctl_core_init(para);
 
 	for (para->cols = 8; para->cols < 11; para->cols++) {
-		/* 8 bits per byte and 32 bit width */
-		if (mctl_mem_matches(1 << (para->cols + 2)))
+		/* 8 bits per byte and 16/32 bit width */
+		if (mctl_mem_matches(1 << (para->cols + 1 +
+					   para->bus_full_width)))
 			break;
 	}
 }
 
 unsigned long mctl_calc_size(struct dram_para *para)
 {
-	/* TODO: non-LPDDR3, half DQ */
+	u8 width = para->bus_full_width ? 4 : 2;
+
+	/* TODO: non-(LP)DDR3 */
 
-	/* 8 banks, 32-bit (4 byte) data width */
-	return (1ULL << (para->cols + para->rows + 3)) * 4 * para->ranks;
+	/* 8 banks */
+	return (1ULL << (para->cols + para->rows + 3)) * width * para->ranks;
 }
 
 #define SUN50I_H6_LPDDR3_DX_WRITE_DELAYS			\
@@ -625,6 +652,7 @@ unsigned long sunxi_dram_init(void)
 		.ranks = 2,
 		.cols = 11,
 		.rows = 14,
+		.bus_full_width = 1,
 #ifdef CONFIG_SUNXI_DRAM_H6_LPDDR3
 		.type = SUNXI_DRAM_TYPE_LPDDR3,
 		.dx_read_delays  = SUN50I_H6_LPDDR3_DX_READ_DELAYS,