[PATCH v2 20/23] drm/msm/dcp: Add DCP VirtIO driver

[Jayant Shekhar]

Add the DCP function driver that binds the VirtIO device to MSM
DRM. Without a function driver, Linux cannot establish HFI queues,
discover firmware capabilities, or register the firmware-owned
display backend.

Set up the DCP DMA and IOMMU identity, initialize VirtIO and HFI
transport, register the MSM DRM component, and synchronize suspend,
resume, remove, and shutdown with in-flight HFI activity.

Assisted-by: LLM
Signed-off-by: Jayant Shekhar <jayant.shekhar@xxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/msm/Makefile         |   2 +
 drivers/gpu/drm/msm/dcp/dcp_drv.c    | 191 ++++++++++++++++++++++++++
 drivers/gpu/drm/msm/dcp/dcp_drv.h    |  17 +++
 drivers/gpu/drm/msm/dcp/dcp_virtio.c | 258 +++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/msm/dcp/dcp_virtio.h |   2 +
 drivers/gpu/drm/msm/msm_drv.c        |   6 +-
 drivers/gpu/drm/msm/msm_drv.h        |   2 +
 7 files changed, 475 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile
index e1a995a8c980..ffdb159dd9ad 100644
--- a/drivers/gpu/drm/msm/Makefile
+++ b/drivers/gpu/drm/msm/Makefile
@@ -85,6 +85,8 @@ msm-display-$(CONFIG_DRM_MSM_DCP) += \
 	dcp/dcp_hfi_plane.o \
 	dcp/dcp_ipcc.o \
 	dcp/dcp_encoder.o \
+	dcp/dcp_drv.o \
+	dcp/dcp_virtio.o \
 	dcp/dcp_virtio_transport.o \
 	dcp/hfi/hfi_packer.o \
 	dcp/hfi/hfi_unpacker.o \
diff --git a/drivers/gpu/drm/msm/dcp/dcp_drv.c b/drivers/gpu/drm/msm/dcp/dcp_drv.c
new file mode 100644
index 000000000000..8c38de883bf6
--- /dev/null
+++ b/drivers/gpu/drm/msm/dcp/dcp_drv.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ * DCP VirtIO driver.
+ */
+
+#include <linux/component.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/panic_notifier.h>
+#include <linux/pm_runtime.h>
+
+#define DCP_DPU_AUTOSUSPEND_DELAY_MS	5000
+
+#include "dcp_drv.h"
+#include "dcp_dpu_kms.h"
+#include "dcp_hfi.h"
+#include "dcp_ipcc.h"
+#include "dcp_virtio.h"
+#include "msm_drv.h"
+#include "msm_kms.h"
+
+int dcp_subsystem_dev_init(struct dcp_drv *drv)
+{
+	struct virtio_device *vdev = drv->vdev;
+	struct device_node *dcp_subsystem_node;
+	struct platform_device *pdev;
+	struct device *dev;
+	char busid[32];
+	bool iommu_mapped;
+	int ret;
+
+	dcp_subsystem_node = of_node_get(vdev->dev.of_node);
+	if (!dcp_subsystem_node) {
+		dev_err(&vdev->dev, "no DCP subsystem DT node\n");
+		return -ENODEV;
+	}
+
+	snprintf(busid, sizeof(busid), "dcp-subsystem.%s", dev_name(vdev->dev.parent));
+
+	/*
+	 * DCP is discovered through VirtIO, but display/HFI buffers must be
+	 * mapped through the dcp-subsystem node's DMA/IOMMU identity. Create a
+	 * platform device for that DT node so DMA API and msm_kms_init_vm() use
+	 * the display function's IOMMU domain.
+	 */
+	pdev = of_platform_device_create(dcp_subsystem_node, busid, vdev->dev.parent);
+	if (!pdev) {
+		dev_err(&vdev->dev, "dcp_subsystem_dev creation failed\n");
+		of_node_put(dcp_subsystem_node);
+		return -ENODEV;
+	}
+	dev = &pdev->dev;
+
+	dev->dma_parms = &drv->dcp_subsystem_dma_parms;
+	dma_set_max_seg_size(dev, UINT_MAX);
+
+	ret = of_dma_configure_id(dev, dcp_subsystem_node, true, NULL);
+	if (ret) {
+		dev_err(dev, "of_dma_configure_id failed: %d\n", ret);
+		goto err_destroy;
+	}
+
+	iommu_mapped = device_iommu_mapped(dev);
+	if (!iommu_mapped) {
+		dev_err(dev, "no IOMMU group attached\n");
+		ret = -ENODEV;
+		goto err_destroy;
+	}
+
+	dev_dbg(dev, "dcp-subsystem: iommu_mapped=%d iommu_group=%d\n",
+		iommu_mapped,
+		dev->iommu_group ? iommu_group_id(dev->iommu_group) : -1);
+
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	pm_runtime_set_autosuspend_delay(dev, DCP_DPU_AUTOSUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(dev);
+
+	drv->dcp_subsystem_dev = pdev;
+	drv->dcp_subsystem_node = dcp_subsystem_node;
+
+	return 0;
+
+err_destroy:
+	of_platform_device_destroy(dev, NULL);
+	of_node_put(dcp_subsystem_node);
+	return ret;
+}
+
+void dcp_subsystem_dev_deinit(struct dcp_drv *drv)
+{
+	if (!drv->dcp_subsystem_dev)
+		return;
+
+	pm_runtime_disable(&drv->dcp_subsystem_dev->dev);
+	of_platform_device_destroy(&drv->dcp_subsystem_dev->dev, NULL);
+	of_node_put(drv->dcp_subsystem_node);
+	drv->dcp_subsystem_dev = NULL;
+}
+
+int dcp_pm_prepare(struct device *vdev_dev)
+{
+	struct dcp_drv *drv = vdev_dev ?
+		dev_to_virtio(vdev_dev)->priv : NULL;
+
+	if (!drv || !drv->dcp_subsystem_dev)
+		return 0;
+
+	return msm_kms_pm_prepare(&drv->dcp_subsystem_dev->dev);
+}
+
+void dcp_pm_complete(struct device *vdev_dev)
+{
+	struct dcp_drv *drv = vdev_dev ?
+		dev_to_virtio(vdev_dev)->priv : NULL;
+
+	if (!drv || !drv->dcp_subsystem_dev)
+		return;
+
+	msm_kms_pm_complete(&drv->dcp_subsystem_dev->dev);
+}
+
+int dcp_component_register(struct dcp_drv *drv)
+{
+	struct device *dev = &drv->dcp_subsystem_dev->dev;
+	struct component_match *match = NULL;
+	int ret;
+
+	ret = dcp_dpu_kms_init_dsi_bridges(drv->kms, &match);
+	if (ret) {
+		dev_err(dev, "DSI host initialization failed: %d\n", ret);
+		dcp_dpu_kms_cleanup_bridges(drv->kms);
+		return ret;
+	}
+
+	/* A GPU is optional for the DCP display-only DRM device. */
+	msm_add_gpu_components(dev, &match);
+
+	ret = component_master_add_with_match(dev, &msm_drm_ops, match);
+	if (ret) {
+		dev_err(dev, "component_master_add_with_match failed: %d\n",
+			ret);
+		dcp_dpu_kms_cleanup_bridges(drv->kms);
+		return ret;
+	}
+
+	return 0;
+}
+
+void dcp_component_unregister(struct dcp_drv *drv)
+{
+	struct device *dev = &drv->dcp_subsystem_dev->dev;
+
+	component_master_del(dev, &msm_drm_ops);
+	dcp_dpu_kms_cleanup_bridges(drv->kms);
+}
+
+static int dcp_panic_notifier_cb(struct notifier_block *nb,
+				 unsigned long action, void *data)
+{
+	struct dcp_drv *drv = container_of(nb, struct dcp_drv, panic_notifier);
+
+	if (drv->hfi)
+		atomic_set(&drv->hfi->shutdown_in_progress, 1);
+
+	return NOTIFY_OK;
+}
+
+void dcp_panic_notifier_register(struct dcp_drv *drv)
+{
+	drv->panic_notifier.notifier_call = dcp_panic_notifier_cb;
+	atomic_notifier_chain_register(&panic_notifier_list, &drv->panic_notifier);
+}
+
+void dcp_panic_notifier_unregister(struct dcp_drv *drv)
+{
+	atomic_notifier_chain_unregister(&panic_notifier_list, &drv->panic_notifier);
+}
+
+void __init msm_dcp_register(void)
+{
+	dcp_virtio_register();
+}
+
+void __exit msm_dcp_unregister(void)
+{
+	dcp_virtio_unregister();
+}
diff --git a/drivers/gpu/drm/msm/dcp/dcp_drv.h b/drivers/gpu/drm/msm/dcp/dcp_drv.h
index 16f87035cb9a..3adc5855a9a2 100644
--- a/drivers/gpu/drm/msm/dcp/dcp_drv.h
+++ b/drivers/gpu/drm/msm/dcp/dcp_drv.h
@@ -14,6 +14,7 @@
 #include "dcp_ipcc.h"
 
 struct dcp_dpu_kms;
+struct component_match;
 
 struct dcp_drv {
 	struct virtio_device	*vdev;
@@ -24,6 +25,22 @@ struct dcp_drv {
 	struct dcp_dpu_kms	*kms;
 	struct dcp_caps		 caps;
 	struct notifier_block	 panic_notifier;
+	struct dcp_ipcc		*ipcc;
 };
 
+int dcp_subsystem_dev_init(struct dcp_drv *drv);
+void dcp_subsystem_dev_deinit(struct dcp_drv *drv);
+
+int dcp_component_register(struct dcp_drv *drv);
+void dcp_component_unregister(struct dcp_drv *drv);
+
+int dcp_pm_prepare(struct device *vdev_dev);
+void dcp_pm_complete(struct device *vdev_dev);
+
+void dcp_panic_notifier_register(struct dcp_drv *drv);
+void dcp_panic_notifier_unregister(struct dcp_drv *drv);
+
+void __init msm_dcp_register(void);
+void __exit msm_dcp_unregister(void);
+
 #endif /* __DCP_DRV_H__ */
diff --git a/drivers/gpu/drm/msm/dcp/dcp_virtio.c b/drivers/gpu/drm/msm/dcp/dcp_virtio.c
new file mode 100644
index 000000000000..15d5caf02ff5
--- /dev/null
+++ b/drivers/gpu/drm/msm/dcp/dcp_virtio.c
@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ * DCP VirtIO device driver.
+ */
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/pm_runtime.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/slab.h>
+
+#include "dcp_drv.h"
+#include "dcp_dpu_kms.h"
+#include "dcp_hfi.h"
+#include "dcp_ipcc.h"
+#include "dcp_virtio.h"
+#include "msm_drv.h"
+#include "msm_kms.h"
+
+static void dcp_virtio_hfi_cleanup(struct dcp_drv *drv);
+
+static const unsigned int dcp_virtio_features[] = {
+	VIRTIO_F_VERSION_1,
+	VIRTIO_F_NOTIFICATION_DATA,
+	VIRTIO_F_RING_RESET,
+	VIRTIO_F_ACCESS_PLATFORM,
+};
+
+/*
+ * The VirtIO core owns transport discovery. This driver owns HFI setup and
+ * creates the DRM component only after firmware capabilities are available.
+ */
+static int dcp_virtio_probe(struct virtio_device *vdev)
+{
+	struct dcp_drv *drv;
+	struct virtqueue *vqs[DCP_NUM_VQS];
+	struct virtqueue_info vqs_info[DCP_NUM_VQS] = {
+		[DCP_VQ_CMD]  = { .name = "cmd",  .callback = dcp_hfi_cmd_callback },
+		[DCP_VQ_RESP] = { .name = "resp", .callback = dcp_hfi_resp_callback },
+	};
+	struct dcp_dpu_kms *dcp_kms;
+	struct msm_drm_private *priv;
+	int ret;
+
+	dev_dbg(&vdev->dev, "DCP VirtIO probe started\n");
+
+	drv = devm_kzalloc(&vdev->dev, sizeof(*drv), GFP_KERNEL);
+	if (!drv)
+		return -ENOMEM;
+
+	drv->vdev = vdev;
+	vdev->priv = drv;
+
+	if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
+		dev_err(&vdev->dev, "VIRTIO_F_VERSION_1 not negotiated\n");
+		return -ENODEV;
+	}
+
+	drv->ipcc = dcp_virtio_get_ipcc(vdev);
+	/* Access-platform is required for the firmware-visible IOVA mappings. */
+	if (!virtio_has_feature(vdev, VIRTIO_F_ACCESS_PLATFORM)) {
+		dev_err(&vdev->dev, "VIRTIO_F_ACCESS_PLATFORM not negotiated\n");
+		return -ENODEV;
+	}
+
+	ret = dcp_subsystem_dev_init(drv);
+	if (ret)
+		return ret;
+
+	ret = virtio_find_vqs(vdev, DCP_NUM_VQS, vqs, vqs_info, NULL);
+	if (ret) {
+		dev_err(&vdev->dev, "virtqueue allocation failed: %d\n", ret);
+		goto err_fn_dev;
+	}
+
+	ret = dcp_hfi_init(drv, vdev, vqs[DCP_VQ_CMD], vqs[DCP_VQ_RESP],
+			   vdev->dev.parent);
+	if (ret) {
+		dev_err(&vdev->dev, "HFI init failed: %d\n", ret);
+		goto err_del_vqs;
+	}
+
+	dcp_ipcc_set_resp_vq(drv->ipcc, vqs[DCP_VQ_RESP]);
+
+	/*
+	 * Keep the device unready until HFI state and virtqueues are initialized.
+	 * KMS registration below depends on synchronous firmware initialization.
+	 */
+	virtio_device_ready(vdev);
+	virtqueue_kick(drv->hfi->resp_vq);
+
+	ret = dcp_hfi_send_device_init(drv->hfi);
+	if (ret) {
+		dev_err(&vdev->dev, "HFI DEVICE_INIT failed: %d\n", ret);
+		goto err_hfi_deinit;
+	}
+
+	ret = dcp_hfi_get_capabilities(drv->hfi, &drv->caps);
+	if (ret) {
+		dev_err(&vdev->dev, "HFI GET_CAPS failed: %d\n", ret);
+		goto err_hfi_deinit;
+	}
+
+	/* Register the display resources before exposing the DRM component. */
+	ret = dcp_hfi_send_resource_register(drv->hfi);
+	if (ret) {
+		dev_err(&vdev->dev, "HFI RESOURCE_REGISTER failed: %d\n", ret);
+		goto err_hfi_deinit;
+	}
+
+	dev_dbg(&vdev->dev,
+		"DCP caps: %u displays, max %ux%u, %u planes\n",
+		drv->caps.num_displays, drv->caps.max_width, drv->caps.max_height,
+		drv->caps.max_planes);
+
+	dcp_kms = devm_kzalloc(&drv->dcp_subsystem_dev->dev, sizeof(*dcp_kms), GFP_KERNEL);
+	if (!dcp_kms) {
+		ret = -ENOMEM;
+		goto err_hfi_deinit;
+	}
+
+	dcp_kms->drv       = drv;
+	dcp_kms->pm_dev    = &drv->dcp_subsystem_dev->dev;
+	dcp_kms->hfi       = drv->hfi;
+	dcp_kms->caps      = &drv->caps;
+	dcp_kms->dpus_np   = drv->dcp_subsystem_node;
+	dcp_kms->iommu_dev = &drv->dcp_subsystem_dev->dev;
+	drv->kms        = dcp_kms;
+
+	ret = msm_kms_init(&dcp_kms->base, &dcp_dpu_kms_funcs);
+	if (ret) {
+		dev_err(&vdev->dev, "msm_kms_init failed: %d\n", ret);
+		goto err_hfi_deinit;
+	}
+
+	priv = devm_kzalloc(&drv->dcp_subsystem_dev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv) {
+		ret = -ENOMEM;
+		goto err_hfi_deinit;
+	}
+
+	priv->kms      = &dcp_kms->base;
+	priv->kms_init = dcp_kms_init;
+	dev_set_drvdata(&drv->dcp_subsystem_dev->dev, priv);
+	dcp_kms->rpm_enabled = true;
+
+	/* Component binding now sees initialized HFI, capabilities, and IOMMU state. */
+	ret = dcp_component_register(drv);
+	if (ret) {
+		dev_err_probe(&vdev->dev, ret, "component register failed\n");
+		goto err_hfi_deinit;
+	}
+
+	dcp_panic_notifier_register(drv);
+
+	dev_dbg(&vdev->dev, "DCP VirtIO probe complete\n");
+	return 0;
+
+err_hfi_deinit:
+	dcp_virtio_hfi_cleanup(drv);
+	goto err_fn_dev;
+err_del_vqs:
+	virtio_reset_device(vdev);
+	vdev->config->del_vqs(vdev);
+err_fn_dev:
+	dcp_subsystem_dev_deinit(drv);
+	return ret;
+}
+
+static void dcp_virtio_hfi_cleanup(struct dcp_drv *drv)
+{
+	struct virtio_device *vdev = drv->vdev;
+
+	if (!drv->hfi)
+		return;
+
+	dcp_ipcc_set_resp_vq(drv->ipcc, NULL);
+
+	dcp_hfi_stop(drv->hfi);
+	virtio_reset_device(vdev);
+	virtio_synchronize_cbs(vdev);
+	dcp_hfi_quiesce_queues(drv->hfi);
+	vdev->config->del_vqs(vdev);
+	dcp_hfi_deinit(drv->hfi);
+}
+
+/* Remove DRM users before tearing down HFI, IPCC, or the VirtIO queues. */
+static void dcp_virtio_remove(struct virtio_device *vdev)
+{
+	struct dcp_drv *drv = vdev->priv;
+
+	dev_dbg(&vdev->dev, "DCP VirtIO remove\n");
+
+	dcp_component_unregister(drv);
+	dcp_panic_notifier_unregister(drv);
+
+	dcp_virtio_hfi_cleanup(drv);
+
+	dcp_subsystem_dev_deinit(drv);
+}
+
+/* KMS shutdown must complete while the firmware transport is available. */
+static void dcp_virtio_shutdown(struct virtio_device *vdev)
+{
+	struct dcp_drv *drv = vdev->priv;
+
+	pm_runtime_get_sync(&drv->dcp_subsystem_dev->dev);
+	msm_kms_shutdown(drv->dcp_subsystem_dev);
+	pm_runtime_put_noidle(&drv->dcp_subsystem_dev->dev);
+}
+
+static const struct virtio_device_id dcp_virtio_id_table[] = {
+	{ VIRTIO_ID_QPSFI, VIRTIO_VENDOR_ID_DCP_HFI },
+	{ 0 },
+};
+MODULE_DEVICE_TABLE(virtio, dcp_virtio_id_table);
+
+static const struct dev_pm_ops dcp_virtio_pm_ops = {
+	.prepare = dcp_pm_prepare,
+	.complete = dcp_pm_complete,
+};
+
+static struct virtio_driver dcp_virtio_driver = {
+	.driver = {
+		.name  = "qcom-dcp-hfi",
+		.owner = THIS_MODULE,
+		.pm    = &dcp_virtio_pm_ops,
+	},
+	.id_table           = dcp_virtio_id_table,
+	.feature_table      = dcp_virtio_features,
+	.feature_table_size = ARRAY_SIZE(dcp_virtio_features),
+	.probe              = dcp_virtio_probe,
+	.remove             = dcp_virtio_remove,
+	.shutdown           = dcp_virtio_shutdown,
+};
+
+int dcp_virtio_register(void)
+{
+	int ret;
+
+	ret = dcp_virtio_transport_register();
+	if (ret)
+		return ret;
+
+	ret = register_virtio_driver(&dcp_virtio_driver);
+	if (ret)
+		dcp_virtio_transport_unregister();
+
+	return ret;
+}
+
+void dcp_virtio_unregister(void)
+{
+	unregister_virtio_driver(&dcp_virtio_driver);
+	dcp_virtio_transport_unregister();
+}
diff --git a/drivers/gpu/drm/msm/dcp/dcp_virtio.h b/drivers/gpu/drm/msm/dcp/dcp_virtio.h
index a9c3b9aff61d..3ded8293ab18 100644
--- a/drivers/gpu/drm/msm/dcp/dcp_virtio.h
+++ b/drivers/gpu/drm/msm/dcp/dcp_virtio.h
@@ -8,9 +8,11 @@
 
 #include <linux/device.h>
 #include <linux/virtio.h>
+#include <linux/virtio_ids.h>
 
 struct dcp_drv;
 struct dcp_ipcc;
+#define VIRTIO_VENDOR_ID_DCP_HFI		1
 
 struct dcp_ipcc *dcp_virtio_get_ipcc(struct virtio_device *vdev);
 
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 5e8f3ce26b32..5816c64d7ce7 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -1093,8 +1093,8 @@ static const struct of_device_id msm_gpu_match[] = {
 	{ },
 };
 
-static int add_gpu_components(struct device *dev,
-			      struct component_match **matchptr)
+int msm_add_gpu_components(struct device *dev,
+			   struct component_match **matchptr)
 {
 	struct device_node *np;
 
@@ -1153,7 +1153,7 @@ int msm_drv_probe(struct device *master_dev,
 	}
 
 	if (!msm_separate_gpu_kms_components()) {
-		ret = add_gpu_components(master_dev, &match);
+		ret = msm_add_gpu_components(master_dev, &match);
 		if (ret)
 			return ret;
 	}
diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index 2840e8a5052d..aa5dfd82ac6f 100644
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -523,6 +523,8 @@ static inline unsigned long timeout_to_jiffies(const ktime_t *timeout)
 /* Driver helpers */
 
 extern const struct component_master_ops msm_drm_ops;
+int msm_add_gpu_components(struct device *dev,
+			   struct component_match **matchptr);
 
 int msm_kms_pm_prepare(struct device *dev);
 void msm_kms_pm_complete(struct device *dev);

-- 
2.43.0