drm/tegra: Add Tegra186 display hub support

The display architecture has changed in several significant ways with
the new Tegra186 SoC. Shared between all display controllers is a set
of common resources referred to as the display hub. The hub generates
accesses to memory and feeds them into various composition pipelines,
each of which being a window that can be assigned to arbitrary heads.

Atomic state is subclassed in order to track the global bandwidth
requirements and select and adjust the hub clocks appropriately. The
plane code is shared to a large degree with earlier SoC generations,
except where the programming differs.

Signed-off-by: Thierry Reding <treding@nvidia.com>

1 files changed, 790 insertions, 0 deletions

diff --git a/drivers/gpu/drm/tegra/hub.c b/drivers/gpu/drm/tegra/hub.c
new file mode 100644
index 000000000000..33d008fb8745
--- /dev/null
+++ b/drivers/gpu/drm/tegra/hub.c
@@ -0,0 +1,790 @@
+/*
+ * Copyright (C) 2017 NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/host1x.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_graph.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+
+#include <drm/drmP.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc_helper.h>
+
+#include "drm.h"
+#include "dc.h"
+#include "plane.h"
+
+static const u32 tegra_shared_plane_formats[] = {
+	DRM_FORMAT_XBGR8888,
+	DRM_FORMAT_XRGB8888,
+	DRM_FORMAT_RGB565,
+};
+
+static inline unsigned int tegra_plane_offset(struct tegra_shared_plane *plane,
+					      unsigned int offset)
+{
+	struct tegra_plane *p = &plane->base;
+
+	if (offset >= 0x500 && offset <= 0x581) {
+		offset = 0x000 + (offset - 0x500);
+		return p->offset + offset;
+	}
+
+	if (offset >= 0x700 && offset <= 0x73c) {
+		offset = 0x180 + (offset - 0x700);
+		return p->offset + offset;
+	}
+
+	if (offset >= 0x800 && offset <= 0x83e) {
+		offset = 0x1c0 + (offset - 0x800);
+		return p->offset + offset;
+	}
+
+	dev_WARN(plane->dc->dev, "invalid offset: %x\n", offset);
+
+	return p->offset + offset;
+}
+
+static inline u32 tegra_plane_readl(struct tegra_shared_plane *plane,
+				    unsigned int offset)
+{
+	return tegra_dc_readl(plane->dc, tegra_plane_offset(plane, offset));
+}
+
+static inline void tegra_plane_writel(struct tegra_shared_plane *plane,
+				      u32 value, unsigned int offset)
+{
+	tegra_dc_writel(plane->dc, value, tegra_plane_offset(plane, offset));
+}
+
+static int tegra_windowgroup_enable(struct tegra_windowgroup *wgrp)
+{
+	mutex_lock(&wgrp->lock);
+
+	if (wgrp->usecount == 0) {
+		pm_runtime_get_sync(wgrp->parent);
+		reset_control_deassert(wgrp->rst);
+	}
+
+	wgrp->usecount++;
+	mutex_unlock(&wgrp->lock);
+
+	return 0;
+}
+
+static void tegra_windowgroup_disable(struct tegra_windowgroup *wgrp)
+{
+	int err;
+
+	mutex_lock(&wgrp->lock);
+
+	if (wgrp->usecount == 1) {
+		err = reset_control_assert(wgrp->rst);
+		if (err < 0) {
+			pr_err("failed to assert reset for window group %u\n",
+			       wgrp->index);
+		}
+
+		pm_runtime_put(wgrp->parent);
+	}
+
+	wgrp->usecount--;
+	mutex_unlock(&wgrp->lock);
+}
+
+int tegra_display_hub_prepare(struct tegra_display_hub *hub)
+{
+	unsigned int i;
+
+	/*
+	 * XXX Enabling/disabling windowgroups needs to happen when the owner
+	 * display controller is disabled. There's currently no good point at
+	 * which this could be executed, so unconditionally enable all window
+	 * groups for now.
+	 */
+	for (i = 0; i < hub->soc->num_wgrps; i++) {
+		struct tegra_windowgroup *wgrp = &hub->wgrps[i];
+
+		tegra_windowgroup_enable(wgrp);
+	}
+
+	return 0;
+}
+
+void tegra_display_hub_cleanup(struct tegra_display_hub *hub)
+{
+	unsigned int i;
+
+	/*
+	 * XXX Remove this once window groups can be more fine-grainedly
+	 * enabled and disabled.
+	 */
+	for (i = 0; i < hub->soc->num_wgrps; i++) {
+		struct tegra_windowgroup *wgrp = &hub->wgrps[i];
+
+		tegra_windowgroup_disable(wgrp);
+	}
+}
+
+static void tegra_shared_plane_update(struct tegra_shared_plane *plane)
+{
+	struct tegra_dc *dc = plane->dc;
+	unsigned long timeout;
+	u32 mask, value;
+
+	mask = COMMON_UPDATE | WIN_A_UPDATE << plane->base.index;
+	tegra_dc_writel(dc, mask, DC_CMD_STATE_CONTROL);
+
+	timeout = jiffies + msecs_to_jiffies(1000);
+
+	while (time_before(jiffies, timeout)) {
+		value = tegra_dc_readl(dc, DC_CMD_STATE_CONTROL);
+		if ((value & mask) == 0)
+			break;
+
+		usleep_range(100, 400);
+	}
+}
+
+static void tegra_shared_plane_activate(struct tegra_shared_plane *plane)
+{
+	struct tegra_dc *dc = plane->dc;
+	unsigned long timeout;
+	u32 mask, value;
+
+	mask = COMMON_ACTREQ | WIN_A_ACT_REQ << plane->base.index;
+	tegra_dc_writel(dc, mask, DC_CMD_STATE_CONTROL);
+
+	timeout = jiffies + msecs_to_jiffies(1000);
+
+	while (time_before(jiffies, timeout)) {
+		value = tegra_dc_readl(dc, DC_CMD_STATE_CONTROL);
+		if ((value & mask) == 0)
+			break;
+
+		usleep_range(100, 400);
+	}
+}
+
+static unsigned int
+tegra_shared_plane_get_owner(struct tegra_shared_plane *plane,
+			     struct tegra_dc *dc)
+{
+	unsigned int offset =
+		tegra_plane_offset(plane, DC_WIN_CORE_WINDOWGROUP_SET_CONTROL);
+
+	return tegra_dc_readl(dc, offset) & OWNER_MASK;
+}
+
+static bool tegra_dc_owns_shared_plane(struct tegra_dc *dc,
+				       struct tegra_shared_plane *plane)
+{
+	struct device *dev = dc->dev;
+
+	if (tegra_shared_plane_get_owner(plane, dc) == dc->pipe) {
+		if (plane->dc == dc)
+			return true;
+
+		dev_WARN(dev, "head %u owns window %u but is not attached\n",
+			 dc->pipe, plane->base.index);
+	}
+
+	return false;
+}
+
+static int tegra_shared_plane_set_owner(struct tegra_shared_plane *plane,
+					struct tegra_dc *new)
+{
+	unsigned int offset =
+		tegra_plane_offset(plane, DC_WIN_CORE_WINDOWGROUP_SET_CONTROL);
+	struct tegra_dc *old = plane->dc, *dc = new ? new : old;
+	struct device *dev = new ? new->dev : old->dev;
+	unsigned int owner, index = plane->base.index;
+	u32 value;
+
+	value = tegra_dc_readl(dc, offset);
+	owner = value & OWNER_MASK;
+
+	if (new && (owner != OWNER_MASK && owner != new->pipe)) {
+		dev_WARN(dev, "window %u owned by head %u\n", index, owner);
+		return -EBUSY;
+	}
+
+	/*
+	 * This seems to happen whenever the head has been disabled with one
+	 * or more windows being active. This is harmless because we'll just
+	 * reassign the window to the new head anyway.
+	 */
+	if (old && owner == OWNER_MASK)
+		dev_dbg(dev, "window %u not owned by head %u but %u\n", index,
+			 old->pipe, owner);
+
+	value &= ~OWNER_MASK;
+
+	if (new)
+		value |= OWNER(new->pipe);
+	else
+		value |= OWNER_MASK;
+
+	tegra_dc_writel(dc, value, offset);
+
+	plane->dc = new;
+
+	return 0;
+}
+
+static void tegra_dc_assign_shared_plane(struct tegra_dc *dc,
+					 struct tegra_shared_plane *plane)
+{
+	u32 value;
+	int err;
+
+	if (!tegra_dc_owns_shared_plane(dc, plane)) {
+		err = tegra_shared_plane_set_owner(plane, dc);
+		if (err < 0)
+			return;
+	}
+
+	value = tegra_plane_readl(plane, DC_WIN_CORE_IHUB_LINEBUF_CONFIG);
+	value |= MODE_FOUR_LINES;
+	tegra_plane_writel(plane, value, DC_WIN_CORE_IHUB_LINEBUF_CONFIG);
+
+	value = tegra_plane_readl(plane, DC_WIN_CORE_IHUB_WGRP_FETCH_METER);
+	value = SLOTS(1);
+	tegra_plane_writel(plane, value, DC_WIN_CORE_IHUB_WGRP_FETCH_METER);
+
+	/* disable watermark */
+	value = tegra_plane_readl(plane, DC_WIN_CORE_IHUB_WGRP_LATENCY_CTLA);
+	value &= ~LATENCY_CTL_MODE_ENABLE;
+	tegra_plane_writel(plane, value, DC_WIN_CORE_IHUB_WGRP_LATENCY_CTLA);
+
+	value = tegra_plane_readl(plane, DC_WIN_CORE_IHUB_WGRP_LATENCY_CTLB);
+	value |= WATERMARK_MASK;
+	tegra_plane_writel(plane, value, DC_WIN_CORE_IHUB_WGRP_LATENCY_CTLB);
+
+	/* pipe meter */
+	value = tegra_plane_readl(plane, DC_WIN_CORE_PRECOMP_WGRP_PIPE_METER);
+	value = PIPE_METER_INT(0) | PIPE_METER_FRAC(0);
+	tegra_plane_writel(plane, value, DC_WIN_CORE_PRECOMP_WGRP_PIPE_METER);
+
+	/* mempool entries */
+	value = tegra_plane_readl(plane, DC_WIN_CORE_IHUB_WGRP_POOL_CONFIG);
+	value = MEMPOOL_ENTRIES(0x331);
+	tegra_plane_writel(plane, value, DC_WIN_CORE_IHUB_WGRP_POOL_CONFIG);
+
+	value = tegra_plane_readl(plane, DC_WIN_CORE_IHUB_THREAD_GROUP);
+	value &= ~THREAD_NUM_MASK;
+	value |= THREAD_NUM(plane->base.index);
+	value |= THREAD_GROUP_ENABLE;
+	tegra_plane_writel(plane, value, DC_WIN_CORE_IHUB_THREAD_GROUP);
+
+	tegra_shared_plane_update(plane);
+	tegra_shared_plane_activate(plane);
+}
+
+static void tegra_dc_remove_shared_plane(struct tegra_dc *dc,
+					 struct tegra_shared_plane *plane)
+{
+	tegra_shared_plane_set_owner(plane, NULL);
+}
+
+static int tegra_shared_plane_atomic_check(struct drm_plane *plane,
+					   struct drm_plane_state *state)
+{
+	struct tegra_plane_state *plane_state = to_tegra_plane_state(state);
+	struct tegra_shared_plane *tegra = to_tegra_shared_plane(plane);
+	struct tegra_bo_tiling *tiling = &plane_state->tiling;
+	struct tegra_dc *dc = to_tegra_dc(state->crtc);
+	int err;
+
+	/* no need for further checks if the plane is being disabled */
+	if (!state->crtc || !state->fb)
+		return 0;
+
+	err = tegra_plane_format(state->fb->format->format,
+				 &plane_state->format,
+				 &plane_state->swap);
+	if (err < 0)
+		return err;
+
+	err = tegra_fb_get_tiling(state->fb, tiling);
+	if (err < 0)
+		return err;
+
+	if (tiling->mode == TEGRA_BO_TILING_MODE_BLOCK &&
+	    !dc->soc->supports_block_linear) {
+		DRM_ERROR("hardware doesn't support block linear mode\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * Tegra doesn't support different strides for U and V planes so we
+	 * error out if the user tries to display a framebuffer with such a
+	 * configuration.
+	 */
+	if (state->fb->format->num_planes > 2) {
+		if (state->fb->pitches[2] != state->fb->pitches[1]) {
+			DRM_ERROR("unsupported UV-plane configuration\n");
+			return -EINVAL;
+		}
+	}
+
+	/* XXX scaling is not yet supported, add a check here */
+
+	err = tegra_plane_state_add(&tegra->base, state);
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static void tegra_shared_plane_atomic_disable(struct drm_plane *plane,
+					      struct drm_plane_state *old_state)
+{
+	struct tegra_shared_plane *p = to_tegra_shared_plane(plane);
+	struct tegra_dc *dc = to_tegra_dc(old_state->crtc);
+	u32 value;
+
+	/* rien ne va plus */
+	if (!old_state || !old_state->crtc)
+		return;
+
+	/*
+	 * XXX Legacy helpers seem to sometimes call ->atomic_disable() even
+	 * on planes that are already disabled. Make sure we fallback to the
+	 * head for this particular state instead of crashing.
+	 */
+	if (WARN_ON(p->dc == NULL))
+		p->dc = dc;
+
+	pm_runtime_get_sync(dc->dev);
+
+	value = tegra_plane_readl(p, DC_WIN_WIN_OPTIONS);
+	value &= ~WIN_ENABLE;
+	tegra_plane_writel(p, value, DC_WIN_WIN_OPTIONS);
+
+	tegra_dc_remove_shared_plane(dc, p);
+
+	pm_runtime_put(dc->dev);
+}
+
+static void tegra_shared_plane_atomic_update(struct drm_plane *plane,
+					     struct drm_plane_state *old_state)
+{
+	struct tegra_plane_state *state = to_tegra_plane_state(plane->state);
+	struct tegra_shared_plane *p = to_tegra_shared_plane(plane);
+	struct tegra_dc *dc = to_tegra_dc(plane->state->crtc);
+	struct drm_framebuffer *fb = plane->state->fb;
+	struct tegra_bo *bo;
+	dma_addr_t base;
+	u32 value;
+
+	/* rien ne va plus */
+	if (!plane->state->crtc || !plane->state->fb)
+		return;
+
+	if (!plane->state->visible) {
+		tegra_shared_plane_atomic_disable(plane, old_state);
+		return;
+	}
+
+	pm_runtime_get_sync(dc->dev);
+
+	tegra_dc_assign_shared_plane(dc, p);
+
+	tegra_plane_writel(p, VCOUNTER, DC_WIN_CORE_ACT_CONTROL);
+
+	/* blending */
+	value = BLEND_FACTOR_DST_ALPHA_ZERO | BLEND_FACTOR_SRC_ALPHA_K2 |
+		BLEND_FACTOR_DST_COLOR_NEG_K1_TIMES_SRC |
+		BLEND_FACTOR_SRC_COLOR_K1_TIMES_SRC;
+	tegra_plane_writel(p, value, DC_WIN_BLEND_MATCH_SELECT);
+
+	value = BLEND_FACTOR_DST_ALPHA_ZERO | BLEND_FACTOR_SRC_ALPHA_K2 |
+		BLEND_FACTOR_DST_COLOR_NEG_K1_TIMES_SRC |
+		BLEND_FACTOR_SRC_COLOR_K1_TIMES_SRC;
+	tegra_plane_writel(p, value, DC_WIN_BLEND_NOMATCH_SELECT);
+
+	value = K2(255) | K1(255) | WINDOW_LAYER_DEPTH(p->base.depth);
+	tegra_plane_writel(p, value, DC_WIN_BLEND_LAYER_CONTROL);
+
+	/* bypass scaling */
+	value = HORIZONTAL_TAPS_5 | VERTICAL_TAPS_5;
+	tegra_plane_writel(p, value, DC_WIN_WINDOWGROUP_SET_CONTROL_INPUT_SCALER);
+
+	value = INPUT_SCALER_VBYPASS | INPUT_SCALER_HBYPASS;
+	tegra_plane_writel(p, value, DC_WIN_WINDOWGROUP_SET_INPUT_SCALER_USAGE);
+
+	/* disable compression */
+	tegra_plane_writel(p, 0, DC_WINBUF_CDE_CONTROL);
+
+	bo = tegra_fb_get_plane(fb, 0);
+	base = bo->paddr;
+
+	tegra_plane_writel(p, state->format, DC_WIN_COLOR_DEPTH);
+	tegra_plane_writel(p, 0, DC_WIN_PRECOMP_WGRP_PARAMS);
+
+	value = V_POSITION(plane->state->crtc_y) |
+		H_POSITION(plane->state->crtc_x);
+	tegra_plane_writel(p, value, DC_WIN_POSITION);
+
+	value = V_SIZE(plane->state->crtc_h) | H_SIZE(plane->state->crtc_w);
+	tegra_plane_writel(p, value, DC_WIN_SIZE);
+
+	value = WIN_ENABLE | COLOR_EXPAND;
+	tegra_plane_writel(p, value, DC_WIN_WIN_OPTIONS);
+
+	value = V_SIZE(plane->state->crtc_h) | H_SIZE(plane->state->crtc_w);
+	tegra_plane_writel(p, value, DC_WIN_CROPPED_SIZE);
+
+	tegra_plane_writel(p, upper_32_bits(base), DC_WINBUF_START_ADDR_HI);
+	tegra_plane_writel(p, lower_32_bits(base), DC_WINBUF_START_ADDR);
+
+	value = PITCH(fb->pitches[0]);
+	tegra_plane_writel(p, value, DC_WIN_PLANAR_STORAGE);
+
+	value = CLAMP_BEFORE_BLEND | DEGAMMA_SRGB | INPUT_RANGE_FULL;
+	tegra_plane_writel(p, value, DC_WIN_SET_PARAMS);
+
+	value = OFFSET_X(plane->state->src_y >> 16) |
+		OFFSET_Y(plane->state->src_x >> 16);
+	tegra_plane_writel(p, value, DC_WINBUF_CROPPED_POINT);
+
+	if (dc->soc->supports_block_linear) {
+		unsigned long height = state->tiling.value;
+
+		/* XXX */
+		switch (state->tiling.mode) {
+		case TEGRA_BO_TILING_MODE_PITCH:
+			value = DC_WINBUF_SURFACE_KIND_BLOCK_HEIGHT(0) |
+				DC_WINBUF_SURFACE_KIND_PITCH;
+			break;
+
+		/* XXX not supported on Tegra186 and later */
+		case TEGRA_BO_TILING_MODE_TILED:
+			value = DC_WINBUF_SURFACE_KIND_TILED;
+			break;
+
+		case TEGRA_BO_TILING_MODE_BLOCK:
+			value = DC_WINBUF_SURFACE_KIND_BLOCK_HEIGHT(height) |
+				DC_WINBUF_SURFACE_KIND_BLOCK;
+			break;
+		}
+
+		tegra_plane_writel(p, value, DC_WINBUF_SURFACE_KIND);
+	}
+
+	/* disable gamut CSC */
+	value = tegra_plane_readl(p, DC_WIN_WINDOW_SET_CONTROL);
+	value &= ~CONTROL_CSC_ENABLE;
+	tegra_plane_writel(p, value, DC_WIN_WINDOW_SET_CONTROL);
+
+	pm_runtime_put(dc->dev);
+}
+
+static const struct drm_plane_helper_funcs tegra_shared_plane_helper_funcs = {
+	.atomic_check = tegra_shared_plane_atomic_check,
+	.atomic_update = tegra_shared_plane_atomic_update,
+	.atomic_disable = tegra_shared_plane_atomic_disable,
+};
+
+struct drm_plane *tegra_shared_plane_create(struct drm_device *drm,
+					    struct tegra_dc *dc,
+					    unsigned int wgrp,
+					    unsigned int index)
+{
+	enum drm_plane_type type = DRM_PLANE_TYPE_OVERLAY;
+	struct tegra_drm *tegra = drm->dev_private;
+	struct tegra_display_hub *hub = tegra->hub;
+	/* planes can be assigned to arbitrary CRTCs */
+	unsigned int possible_crtcs = 0x7;
+	struct tegra_shared_plane *plane;
+	unsigned int num_formats;
+	struct drm_plane *p;
+	const u32 *formats;
+	int err;
+
+	plane = kzalloc(sizeof(*plane), GFP_KERNEL);
+	if (!plane)
+		return ERR_PTR(-ENOMEM);
+
+	plane->base.offset = 0x0a00 + 0x0300 * index;
+	plane->base.index = index;
+	plane->base.depth = 0;
+
+	plane->wgrp = &hub->wgrps[wgrp];
+	plane->wgrp->parent = dc->dev;
+
+	p = &plane->base.base;
+
+	num_formats = ARRAY_SIZE(tegra_shared_plane_formats);
+	formats = tegra_shared_plane_formats;
+
+	err = drm_universal_plane_init(drm, p, possible_crtcs,
+				       &tegra_plane_funcs, formats,
+				       num_formats, NULL, type, NULL);
+	if (err < 0) {
+		kfree(plane);
+		return ERR_PTR(err);
+	}
+
+	drm_plane_helper_add(p, &tegra_shared_plane_helper_funcs);
+
+	return p;
+}
+
+static void tegra_display_hub_update(struct tegra_dc *dc)
+{
+	u32 value;
+
+	pm_runtime_get_sync(dc->dev);
+
+	value = tegra_dc_readl(dc, DC_CMD_IHUB_COMMON_MISC_CTL);
+	value &= ~LATENCY_EVENT;
+	tegra_dc_writel(dc, value, DC_CMD_IHUB_COMMON_MISC_CTL);
+
+	value = tegra_dc_readl(dc, DC_DISP_IHUB_COMMON_DISPLAY_FETCH_METER);
+	value = CURS_SLOTS(1) | WGRP_SLOTS(1);
+	tegra_dc_writel(dc, value, DC_DISP_IHUB_COMMON_DISPLAY_FETCH_METER);
+
+	tegra_dc_writel(dc, COMMON_UPDATE, DC_CMD_STATE_CONTROL);
+	tegra_dc_readl(dc, DC_CMD_STATE_CONTROL);
+	tegra_dc_writel(dc, COMMON_ACTREQ, DC_CMD_STATE_CONTROL);
+	tegra_dc_readl(dc, DC_CMD_STATE_CONTROL);
+
+	pm_runtime_put(dc->dev);
+}
+
+void tegra_display_hub_atomic_commit(struct drm_device *drm,
+				     struct drm_atomic_state *state)
+{
+	struct tegra_atomic_state *s = to_tegra_atomic_state(state);
+	struct tegra_drm *tegra = drm->dev_private;
+	struct tegra_display_hub *hub = tegra->hub;
+	struct device *dev = hub->client.dev;
+	int err;
+
+	if (s->clk_disp) {
+		err = clk_set_rate(s->clk_disp, s->rate);
+		if (err < 0)
+			dev_err(dev, "failed to set rate of %pC to %lu Hz\n",
+				s->clk_disp, s->rate);
+
+		err = clk_set_parent(hub->clk_disp, s->clk_disp);
+		if (err < 0)
+			dev_err(dev, "failed to set parent of %pC to %pC: %d\n",
+				hub->clk_disp, s->clk_disp, err);
+	}
+
+	if (s->dc)
+		tegra_display_hub_update(s->dc);
+}
+
+static int tegra_display_hub_init(struct host1x_client *client)
+{
+	struct tegra_display_hub *hub = to_tegra_display_hub(client);
+	struct drm_device *drm = dev_get_drvdata(client->parent);
+	struct tegra_drm *tegra = drm->dev_private;
+
+	tegra->hub = hub;
+
+	return 0;
+}
+
+static int tegra_display_hub_exit(struct host1x_client *client)
+{
+	struct drm_device *drm = dev_get_drvdata(client->parent);
+	struct tegra_drm *tegra = drm->dev_private;
+
+	tegra->hub = NULL;
+
+	return 0;
+}
+
+static const struct host1x_client_ops tegra_display_hub_ops = {
+	.init = tegra_display_hub_init,
+	.exit = tegra_display_hub_exit,
+};
+
+static int tegra_display_hub_probe(struct platform_device *pdev)
+{
+	struct tegra_display_hub *hub;
+	unsigned int i;
+	int err;
+
+	hub = devm_kzalloc(&pdev->dev, sizeof(*hub), GFP_KERNEL);
+	if (!hub)
+		return -ENOMEM;
+
+	hub->soc = of_device_get_match_data(&pdev->dev);
+
+	hub->clk_disp = devm_clk_get(&pdev->dev, "disp");
+	if (IS_ERR(hub->clk_disp)) {
+		err = PTR_ERR(hub->clk_disp);
+		return err;
+	}
+
+	hub->clk_dsc = devm_clk_get(&pdev->dev, "dsc");
+	if (IS_ERR(hub->clk_dsc)) {
+		err = PTR_ERR(hub->clk_dsc);
+		return err;
+	}
+
+	hub->clk_hub = devm_clk_get(&pdev->dev, "hub");
+	if (IS_ERR(hub->clk_hub)) {
+		err = PTR_ERR(hub->clk_hub);
+		return err;
+	}
+
+	hub->rst = devm_reset_control_get(&pdev->dev, "misc");
+	if (IS_ERR(hub->rst)) {
+		err = PTR_ERR(hub->rst);
+		return err;
+	}
+
+	hub->wgrps = devm_kcalloc(&pdev->dev, hub->soc->num_wgrps,
+				  sizeof(*hub->wgrps), GFP_KERNEL);
+	if (!hub->wgrps)
+		return -ENOMEM;
+
+	for (i = 0; i < hub->soc->num_wgrps; i++) {
+		struct tegra_windowgroup *wgrp = &hub->wgrps[i];
+		char id[8];
+
+		snprintf(id, sizeof(id), "wgrp%u", i);
+		mutex_init(&wgrp->lock);
+		wgrp->usecount = 0;
+		wgrp->index = i;
+
+		wgrp->rst = devm_reset_control_get(&pdev->dev, id);
+		if (IS_ERR(wgrp->rst))
+			return PTR_ERR(wgrp->rst);
+
+		err = reset_control_assert(wgrp->rst);
+		if (err < 0)
+			return err;
+	}
+
+	/* XXX: enable clock across reset? */
+	err = reset_control_assert(hub->rst);
+	if (err < 0)
+		return err;
+
+	platform_set_drvdata(pdev, hub);
+	pm_runtime_enable(&pdev->dev);
+
+	INIT_LIST_HEAD(&hub->client.list);
+	hub->client.ops = &tegra_display_hub_ops;
+	hub->client.dev = &pdev->dev;
+
+	err = host1x_client_register(&hub->client);
+	if (err < 0)
+		dev_err(&pdev->dev, "failed to register host1x client: %d\n",
+			err);
+
+	return err;
+}
+
+static int tegra_display_hub_remove(struct platform_device *pdev)
+{
+	struct tegra_display_hub *hub = platform_get_drvdata(pdev);
+	int err;
+
+	err = host1x_client_unregister(&hub->client);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to unregister host1x client: %d\n",
+			err);
+	}
+
+	pm_runtime_disable(&pdev->dev);
+
+	return err;
+}
+
+static int tegra_display_hub_suspend(struct device *dev)
+{
+	struct tegra_display_hub *hub = dev_get_drvdata(dev);
+	int err;
+
+	err = reset_control_assert(hub->rst);
+	if (err < 0)
+		return err;
+
+	clk_disable_unprepare(hub->clk_hub);
+	clk_disable_unprepare(hub->clk_dsc);
+	clk_disable_unprepare(hub->clk_disp);
+
+	return 0;
+}
+
+static int tegra_display_hub_resume(struct device *dev)
+{
+	struct tegra_display_hub *hub = dev_get_drvdata(dev);
+	int err;
+
+	err = clk_prepare_enable(hub->clk_disp);
+	if (err < 0)
+		return err;
+
+	err = clk_prepare_enable(hub->clk_dsc);
+	if (err < 0)
+		goto disable_disp;
+
+	err = clk_prepare_enable(hub->clk_hub);
+	if (err < 0)
+		goto disable_dsc;
+
+	err = reset_control_deassert(hub->rst);
+	if (err < 0)
+		goto disable_hub;
+
+	return 0;
+
+disable_hub:
+	clk_disable_unprepare(hub->clk_hub);
+disable_dsc:
+	clk_disable_unprepare(hub->clk_dsc);
+disable_disp:
+	clk_disable_unprepare(hub->clk_disp);
+	return err;
+}
+
+static const struct dev_pm_ops tegra_display_hub_pm_ops = {
+	SET_RUNTIME_PM_OPS(tegra_display_hub_suspend,
+			   tegra_display_hub_resume, NULL)
+};
+
+static const struct tegra_display_hub_soc tegra186_display_hub = {
+	.num_wgrps = 6,
+};
+
+static const struct of_device_id tegra_display_hub_of_match[] = {
+	{
+		.compatible = "nvidia,tegra186-display",
+		.data = &tegra186_display_hub
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, tegra_display_hub_of_match);
+
+struct platform_driver tegra_display_hub_driver = {
+	.driver = {
+		.name = "tegra-display-hub",
+		.of_match_table = tegra_display_hub_of_match,
+		.pm = &tegra_display_hub_pm_ops,
+	},
+	.probe = tegra_display_hub_probe,
+	.remove = tegra_display_hub_remove,
+};