drm/imx: Add initial support for DCSS on iMX8MQ

This adds initial support for iMX8MQ's Display Controller Subsystem (DCSS).
Some of its capabilities include:
 * 4K@60fps;
 * HDR10;
 * one graphics and 2 video pipelines;
 * on-the-fly decompression of compressed video and graphics;

The reference manual can be found here:
https://www.nxp.com/webapp/Download?colCode=IMX8MDQLQRM

The current patch adds only basic functionality: one primary plane for
graphics, linear, tiled and super-tiled buffers support (no graphics
decompression yet), no HDR10 and no video planes.

Video planes support and HDR10 will be added in subsequent patches once
per-plane de-gamma/CSC/gamma support is in.

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@nxp.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20200731081836.3048-3-laurentiu.palcu@oss.nxp.com

drivers/gpu/drm/imx/Kconfig

@@ -39,3 +39,5 @@ config DRM_IMX_HDMI
 	depends on DRM_IMX
 	help
 	  Choose this if you want to use HDMI on i.MX6.
+
+source "drivers/gpu/drm/imx/dcss/Kconfig"

drivers/gpu/drm/imx/Makefile

@@ -9,3 +9,4 @@ obj-$(CONFIG_DRM_IMX_TVE) += imx-tve.o
 obj-$(CONFIG_DRM_IMX_LDB) += imx-ldb.o
 
 obj-$(CONFIG_DRM_IMX_HDMI) += dw_hdmi-imx.o
+obj-$(CONFIG_DRM_IMX_DCSS) += dcss/

drivers/gpu/drm/imx/dcss/Kconfig

@@ -0,0 +1,9 @@
+config DRM_IMX_DCSS
+	tristate "i.MX8MQ DCSS"
+	select IMX_IRQSTEER
+	select DRM_KMS_CMA_HELPER
+	select VIDEOMODE_HELPERS
+	depends on DRM && ARCH_MXC
+	help
+	  Choose this if you have a NXP i.MX8MQ based system and want to use the
+	  Display Controller Subsystem. This option enables DCSS support.

drivers/gpu/drm/imx/dcss/Makefile

@@ -0,0 +1,6 @@
+imx-dcss-objs := dcss-drv.o dcss-dev.o dcss-blkctl.o dcss-ctxld.o dcss-dtg.o \
+				 dcss-ss.o dcss-dpr.o dcss-scaler.o dcss-kms.o dcss-crtc.o \
+				 dcss-plane.o
+
+obj-$(CONFIG_DRM_IMX_DCSS) += imx-dcss.o
+

drivers/gpu/drm/imx/dcss/dcss-blkctl.c

@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP.
+ */
+
+#include <linux/device.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+#include "dcss-dev.h"
+
+#define DCSS_BLKCTL_RESET_CTRL		0x00
+#define   B_CLK_RESETN			BIT(0)
+#define   APB_CLK_RESETN		BIT(1)
+#define   P_CLK_RESETN			BIT(2)
+#define   RTR_CLK_RESETN		BIT(4)
+#define DCSS_BLKCTL_CONTROL0		0x10
+#define   HDMI_MIPI_CLK_SEL		BIT(0)
+#define   DISPMIX_REFCLK_SEL_POS	4
+#define   DISPMIX_REFCLK_SEL_MASK	GENMASK(5, 4)
+#define   DISPMIX_PIXCLK_SEL		BIT(8)
+#define   HDMI_SRC_SECURE_EN		BIT(16)
+
+struct dcss_blkctl {
+	struct dcss_dev *dcss;
+	void __iomem *base_reg;
+};
+
+void dcss_blkctl_cfg(struct dcss_blkctl *blkctl)
+{
+	if (blkctl->dcss->hdmi_output)
+		dcss_writel(0, blkctl->base_reg + DCSS_BLKCTL_CONTROL0);
+	else
+		dcss_writel(DISPMIX_PIXCLK_SEL,
+			    blkctl->base_reg + DCSS_BLKCTL_CONTROL0);
+
+	dcss_set(B_CLK_RESETN | APB_CLK_RESETN | P_CLK_RESETN | RTR_CLK_RESETN,
+		 blkctl->base_reg + DCSS_BLKCTL_RESET_CTRL);
+}
+
+int dcss_blkctl_init(struct dcss_dev *dcss, unsigned long blkctl_base)
+{
+	struct dcss_blkctl *blkctl;
+
+	blkctl = kzalloc(sizeof(*blkctl), GFP_KERNEL);
+	if (!blkctl)
+		return -ENOMEM;
+
+	blkctl->base_reg = ioremap(blkctl_base, SZ_4K);
+	if (!blkctl->base_reg) {
+		dev_err(dcss->dev, "unable to remap BLK CTRL base\n");
+		kfree(blkctl);
+		return -ENOMEM;
+	}
+
+	dcss->blkctl = blkctl;
+	blkctl->dcss = dcss;
+
+	dcss_blkctl_cfg(blkctl);
+
+	return 0;
+}
+
+void dcss_blkctl_exit(struct dcss_blkctl *blkctl)
+{
+	if (blkctl->base_reg)
+		iounmap(blkctl->base_reg);
+
+	kfree(blkctl);
+}

drivers/gpu/drm/imx/dcss/dcss-crtc.c

@@ -0,0 +1,219 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP.
+ */
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_vblank.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#include "dcss-dev.h"
+#include "dcss-kms.h"
+
+static int dcss_enable_vblank(struct drm_crtc *crtc)
+{
+	struct dcss_crtc *dcss_crtc = container_of(crtc, struct dcss_crtc,
+						   base);
+	struct dcss_dev *dcss = crtc->dev->dev_private;
+
+	dcss_dtg_vblank_irq_enable(dcss->dtg, true);
+
+	dcss_dtg_ctxld_kick_irq_enable(dcss->dtg, true);
+
+	enable_irq(dcss_crtc->irq);
+
+	return 0;
+}
+
+static void dcss_disable_vblank(struct drm_crtc *crtc)
+{
+	struct dcss_crtc *dcss_crtc = container_of(crtc, struct dcss_crtc,
+						   base);
+	struct dcss_dev *dcss = dcss_crtc->base.dev->dev_private;
+
+	disable_irq_nosync(dcss_crtc->irq);
+
+	dcss_dtg_vblank_irq_enable(dcss->dtg, false);
+
+	if (dcss_crtc->disable_ctxld_kick_irq)
+		dcss_dtg_ctxld_kick_irq_enable(dcss->dtg, false);
+}
+
+static const struct drm_crtc_funcs dcss_crtc_funcs = {
+	.set_config = drm_atomic_helper_set_config,
+	.destroy = drm_crtc_cleanup,
+	.page_flip = drm_atomic_helper_page_flip,
+	.reset = drm_atomic_helper_crtc_reset,
+	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+	.enable_vblank = dcss_enable_vblank,
+	.disable_vblank = dcss_disable_vblank,
+};
+
+static void dcss_crtc_atomic_begin(struct drm_crtc *crtc,
+				   struct drm_crtc_state *old_crtc_state)
+{
+	drm_crtc_vblank_on(crtc);
+}
+
+static void dcss_crtc_atomic_flush(struct drm_crtc *crtc,
+				   struct drm_crtc_state *old_crtc_state)
+{
+	struct dcss_crtc *dcss_crtc = container_of(crtc, struct dcss_crtc,
+						   base);
+	struct dcss_dev *dcss = dcss_crtc->base.dev->dev_private;
+
+	spin_lock_irq(&crtc->dev->event_lock);
+	if (crtc->state->event) {
+		WARN_ON(drm_crtc_vblank_get(crtc));
+		drm_crtc_arm_vblank_event(crtc, crtc->state->event);
+		crtc->state->event = NULL;
+	}
+	spin_unlock_irq(&crtc->dev->event_lock);
+
+	if (dcss_dtg_is_enabled(dcss->dtg))
+		dcss_ctxld_enable(dcss->ctxld);
+}
+
+static void dcss_crtc_atomic_enable(struct drm_crtc *crtc,
+				    struct drm_crtc_state *old_crtc_state)
+{
+	struct dcss_crtc *dcss_crtc = container_of(crtc, struct dcss_crtc,
+						   base);
+	struct dcss_dev *dcss = dcss_crtc->base.dev->dev_private;
+	struct drm_display_mode *mode = &crtc->state->adjusted_mode;
+	struct drm_display_mode *old_mode = &old_crtc_state->adjusted_mode;
+	struct videomode vm;
+
+	drm_display_mode_to_videomode(mode, &vm);
+
+	pm_runtime_get_sync(dcss->dev);
+
+	vm.pixelclock = mode->crtc_clock * 1000;
+
+	dcss_ss_subsam_set(dcss->ss);
+	dcss_dtg_css_set(dcss->dtg);
+
+	if (!drm_mode_equal(mode, old_mode) || !old_crtc_state->active) {
+		dcss_dtg_sync_set(dcss->dtg, &vm);
+		dcss_ss_sync_set(dcss->ss, &vm,
+				 mode->flags & DRM_MODE_FLAG_PHSYNC,
+				 mode->flags & DRM_MODE_FLAG_PVSYNC);
+	}
+
+	dcss_enable_dtg_and_ss(dcss);
+
+	dcss_ctxld_enable(dcss->ctxld);
+
+	/* Allow CTXLD kick interrupt to be disabled when VBLANK is disabled. */
+	dcss_crtc->disable_ctxld_kick_irq = true;
+}
+
+static void dcss_crtc_atomic_disable(struct drm_crtc *crtc,
+				     struct drm_crtc_state *old_crtc_state)
+{
+	struct dcss_crtc *dcss_crtc = container_of(crtc, struct dcss_crtc,
+						   base);
+	struct dcss_dev *dcss = dcss_crtc->base.dev->dev_private;
+	struct drm_display_mode *mode = &crtc->state->adjusted_mode;
+	struct drm_display_mode *old_mode = &old_crtc_state->adjusted_mode;
+
+	drm_atomic_helper_disable_planes_on_crtc(old_crtc_state, false);
+
+	spin_lock_irq(&crtc->dev->event_lock);
+	if (crtc->state->event) {
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		crtc->state->event = NULL;
+	}
+	spin_unlock_irq(&crtc->dev->event_lock);
+
+	dcss_dtg_ctxld_kick_irq_enable(dcss->dtg, true);
+
+	reinit_completion(&dcss->disable_completion);
+
+	dcss_disable_dtg_and_ss(dcss);
+
+	dcss_ctxld_enable(dcss->ctxld);
+
+	if (!drm_mode_equal(mode, old_mode) || !crtc->state->active)
+		if (!wait_for_completion_timeout(&dcss->disable_completion,
+						 msecs_to_jiffies(100)))
+			dev_err(dcss->dev, "Shutting off DTG timed out.\n");
+
+	/*
+	 * Do not shut off CTXLD kick interrupt when shutting VBLANK off. It
+	 * will be needed to commit the last changes, before going to suspend.
+	 */
+	dcss_crtc->disable_ctxld_kick_irq = false;
+
+	drm_crtc_vblank_off(crtc);
+
+	pm_runtime_mark_last_busy(dcss->dev);
+	pm_runtime_put_autosuspend(dcss->dev);
+}
+
+static const struct drm_crtc_helper_funcs dcss_helper_funcs = {
+	.atomic_begin = dcss_crtc_atomic_begin,
+	.atomic_flush = dcss_crtc_atomic_flush,
+	.atomic_enable = dcss_crtc_atomic_enable,
+	.atomic_disable = dcss_crtc_atomic_disable,
+};
+
+static irqreturn_t dcss_crtc_irq_handler(int irq, void *dev_id)
+{
+	struct dcss_crtc *dcss_crtc = dev_id;
+	struct dcss_dev *dcss = dcss_crtc->base.dev->dev_private;
+
+	if (!dcss_dtg_vblank_irq_valid(dcss->dtg))
+		return IRQ_NONE;
+
+	if (dcss_ctxld_is_flushed(dcss->ctxld))
+		drm_crtc_handle_vblank(&dcss_crtc->base);
+
+	dcss_dtg_vblank_irq_clear(dcss->dtg);
+
+	return IRQ_HANDLED;
+}
+
+int dcss_crtc_init(struct dcss_crtc *crtc, struct drm_device *drm)
+{
+	struct dcss_dev *dcss = drm->dev_private;
+	struct platform_device *pdev = to_platform_device(dcss->dev);
+	int ret;
+
+	crtc->plane[0] = dcss_plane_init(drm, drm_crtc_mask(&crtc->base),
+					 DRM_PLANE_TYPE_PRIMARY, 0);
+	if (IS_ERR(crtc->plane[0]))
+		return PTR_ERR(crtc->plane[0]);
+
+	crtc->base.port = dcss->of_port;
+
+	drm_crtc_helper_add(&crtc->base, &dcss_helper_funcs);
+	ret = drm_crtc_init_with_planes(drm, &crtc->base, &crtc->plane[0]->base,
+					NULL, &dcss_crtc_funcs, NULL);
+	if (ret) {
+		dev_err(dcss->dev, "failed to init crtc\n");
+		return ret;
+	}
+
+	crtc->irq = platform_get_irq_byname(pdev, "vblank");
+	if (crtc->irq < 0)
+		return crtc->irq;
+
+	ret = request_irq(crtc->irq, dcss_crtc_irq_handler,
+			  0, "dcss_drm", crtc);
+	if (ret) {
+		dev_err(dcss->dev, "irq request failed with %d.\n", ret);
+		return ret;
+	}
+
+	disable_irq(crtc->irq);
+
+	return 0;
+}
+
+void dcss_crtc_deinit(struct dcss_crtc *crtc, struct drm_device *drm)
+{
+	free_irq(crtc->irq, crtc);
+}