video: tegra20: dsi: add ganged mode support

Implement ganged mode support for the Tegra DSI driver. The DSI host
controller to gang up with is specified via a phandle in the device tree
and the resolved DSI host controller used for the programming of the
ganged-mode registers.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>

drivers/video/tegra20/tegra-dsi.c

@@ -20,6 +20,7 @@
 #include <asm/gpio.h>
 #include <asm/io.h>
 #include <asm/arch/clock.h>
+#include <asm/arch-tegra/clk_rst.h>
 
 #include "tegra-dc.h"
 #include "tegra-dsi.h"
@@ -50,6 +51,10 @@ struct tegra_dsi_priv {
 	int host_fifo_depth;
 
 	u32 version;
+
+	/* for ganged-mode support */
+	struct udevice *master;
+	struct udevice *slave;
 };
 
 static void tegra_dc_enable_controller(struct udevice *dev)
@@ -595,6 +600,17 @@ static void tegra_dsi_set_phy_timing(struct dsi_timing_reg *ptiming,
 	writel(value, &ptiming->dsi_bta_timing);
 }
 
+static void tegra_dsi_ganged_enable(struct udevice *dev, unsigned int start,
+				    unsigned int size)
+{
+	struct tegra_dsi_priv *priv = dev_get_priv(dev);
+	struct dsi_ganged_mode_reg *ganged = &priv->dsi->ganged;
+
+	writel(start, &ganged->ganged_mode_start);
+	writel(size << 16 | size, &ganged->ganged_mode_size);
+	writel(DSI_GANGED_MODE_CONTROL_ENABLE, &ganged->ganged_mode_ctrl);
+}
+
 static void tegra_dsi_configure(struct udevice *dev,
 				unsigned long mode_flags)
 {
@@ -679,9 +695,19 @@ static void tegra_dsi_configure(struct udevice *dev,
 		writel(hact << 16 | hbp, &len->dsi_pkt_len_2_3);
 		writel(hfp, &len->dsi_pkt_len_4_5);
 		writel(0x0f0f << 16, &len->dsi_pkt_len_6_7);
+
+		/* set SOL delay (for non-burst mode only) */
+		writel(8 * mul / div, &misc->dsi_sol_delay);
+	} else {
+		if (priv->master || priv->slave) {
+			/*
+			 * For ganged mode, assume symmetric left-right mode.
+			 */
+			value = 1 + (timing->hactive.typ / 2) * mul / div;
 		} else {
 			/* 1 byte (DCS command) + pixel data */
 			value = 1 + timing->hactive.typ * mul / div;
+		}
 
 		writel(0, &len->dsi_pkt_len_0_1);
 		writel(value << 16, &len->dsi_pkt_len_2_3);
@@ -691,10 +717,40 @@ static void tegra_dsi_configure(struct udevice *dev,
 		value = MIPI_DCS_WRITE_MEMORY_START << 8 |
 			MIPI_DCS_WRITE_MEMORY_CONTINUE;
 		writel(value, &len->dsi_dcs_cmds);
+
+		/* set SOL delay */
+		if (priv->master || priv->slave) {
+			unsigned long delay, bclk, bclk_ganged;
+			unsigned int lanes = device->lanes;
+			unsigned long htotal = timing->hactive.typ + timing->hfront_porch.typ +
+					       timing->hback_porch.typ + timing->hsync_len.typ;
+
+			/* SOL to valid, valid to FIFO and FIFO write delay */
+			delay = 4 + 4 + 2;
+			delay = DIV_ROUND_UP(delay * mul, div * lanes);
+			/* FIFO read delay */
+			delay = delay + 6;
+
+			bclk = DIV_ROUND_UP(htotal * mul, div * lanes);
+			bclk_ganged = DIV_ROUND_UP(bclk * lanes / 2, lanes);
+			value = bclk - bclk_ganged + delay + 20;
+		} else {
+			/* TODO: revisit for non-ganged mode */
+			value = 8 * mul / div;
 		}
 
-	/* set SOL delay (for non-burst mode only) */
+		writel(value, &misc->dsi_sol_delay);
-	writel(8 * mul / div, &misc->dsi_sol_delay);
+	}
+
+	if (priv->slave) {
+		/*
+		 * TODO: Support modes other than symmetrical left-right
+		 * split.
+		 */
+		tegra_dsi_ganged_enable(dev, 0, timing->hactive.typ / 2);
+		tegra_dsi_ganged_enable(priv->slave, timing->hactive.typ / 2,
+					timing->hactive.typ / 2);
+	}
 }
 
 static int tegra_dsi_encoder_enable(struct udevice *dev)
@@ -774,6 +830,9 @@ static int tegra_dsi_encoder_enable(struct udevice *dev)
 	value |= DSI_POWER_CONTROL_ENABLE;
 	writel(value, &misc->dsi_pwr_ctrl);
 
+	if (priv->slave)
+		tegra_dsi_encoder_enable(priv->slave);
+
 	return 0;
 }
 
@@ -803,6 +862,14 @@ static void tegra_dsi_init_clocks(struct udevice *dev)
 	unsigned int mul, div;
 	unsigned long bclk, plld;
 
+	if (!priv->slave) {
+		/* Change DSIB clock parent to match DSIA */
+		struct clk_rst_ctlr *clkrst =
+			(struct clk_rst_ctlr *)NV_PA_CLK_RST_BASE;
+
+		clrbits_le32(&clkrst->plld2.pll_base, BIT(25)); /* DSIB_CLK_SRC */
+	}
+
 	tegra_dsi_get_muldiv(device->format, &mul, &div);
 
 	bclk = (priv->timing.pixelclock.typ * mul) /
@@ -854,6 +921,24 @@ static void tegra_dsi_init_clocks(struct udevice *dev)
 	reset_set_enable(priv->dsi_clk, 0);
 }
 
+static int tegra_dsi_ganged_probe(struct udevice *dev)
+{
+	struct tegra_dsi_priv *mpriv = dev_get_priv(dev);
+	struct udevice *gangster;
+
+	uclass_get_device_by_phandle(UCLASS_PANEL, dev,
+				     "nvidia,ganged-mode", &gangster);
+	if (gangster) {
+		/* Ganged mode is set */
+		struct tegra_dsi_priv *spriv = dev_get_priv(gangster);
+
+		mpriv->slave = gangster;
+		spriv->master = dev;
+	}
+
+	return 0;
+}
+
 static int tegra_dsi_bridge_probe(struct udevice *dev)
 {
 	struct tegra_dsi_priv *priv = dev_get_priv(dev);
@@ -873,6 +958,8 @@ static int tegra_dsi_bridge_probe(struct udevice *dev)
 	priv->video_fifo_depth = 1920;
 	priv->host_fifo_depth = 64;
 
+	tegra_dsi_ganged_probe(dev);
+
 	ret = reset_get_by_name(dev, "dsi", &reset_ctl);
 	if (ret) {
 		log_debug("%s: reset_get_by_name() failed: %d\n",

drivers/video/tegra20/tegra-dsi.h

@@ -98,9 +98,9 @@ struct dsi_timeout_reg {
 	uint dsi_to_tally;		/* _DSI_TO_TALLY_0 */
 };
 
-/* DSI PAD control register 0x04b ~ 0x04e */
+/* DSI PAD control register 0x04b ~ 0x052 */
 struct dsi_pad_ctrl_reg {
-	/* Address 0x04b ~ 0x04e */
+	/* Address 0x04b ~ 0x052 */
 	uint pad_ctrl;			/* _PAD_CONTROL_0 */
 	uint pad_ctrl_cd;		/* _PAD_CONTROL_CD_0 */
 	uint pad_cd_status;		/* _PAD_CD_STATUS_0 */
@@ -111,6 +111,14 @@ struct dsi_pad_ctrl_reg {
 	uint pad_ctrl_4;		/* _PAD_CONTROL_4 */
 };
 
+/* DSI ganged mode register 0x053 ~ 0x04e */
+struct dsi_ganged_mode_reg {
+	/* Address 0x053 ~ 0x055 */
+	uint ganged_mode_ctrl;		/* _DSI_GANGED_MODE_CONTROL_0 */
+	uint ganged_mode_start;		/* _DSI_GANGED_MODE_START_0 */
+	uint ganged_mode_size;		/* _DSI_GANGED_MODE_SIZE_0 */
+};
+
 /* Display Serial Interface (DSI_) regs */
 struct dsi_ctlr {
 	struct dsi_syncpt_reg syncpt;	/* SYNCPT register 0x000 ~ 0x002 */
@@ -133,6 +141,7 @@ struct dsi_ctlr {
 	uint reserved5[4];		/* reserved_5[4] */
 
 	struct dsi_pad_ctrl_reg pad;	/* PAD registers 0x04b ~ 0x04e */
+	struct dsi_ganged_mode_reg ganged; /* GANGED registers 0x053 ~ 0x055 */
 };
 
 #define DSI_POWER_CONTROL_ENABLE	BIT(0)
@@ -202,6 +211,8 @@ struct dsi_ctlr {
 #define DSI_PAD_PREEMP_PD(x)		(((x) & 0x3) << 4)
 #define DSI_PAD_PREEMP_PU(x)		(((x) & 0x3) << 0)
 
+#define DSI_GANGED_MODE_CONTROL_ENABLE	BIT(0)
+
 /*
  * pixel format as used in the DSI_CONTROL_FORMAT field
  */