[RFC PATCH 2/2] accel/npac: Add NPAC client driver

[Jaspinder Budhal <j-budhal@ti.com>]

Add the Linux client driver for the Network Packet ACcelerator (NPAC).
The driver communicates with the NPAC host driver via RPMsg,
allowing offloading of ethernet-related packet processing tasks.

The driver provides the basic framework for receiving offload commands
via IOCTL and communicating with the NPAC hardware accelerator.

Signed-off-by: Jaspinder Budhal <j-budhal@ti.com>
---
 drivers/accel/Kconfig         |   1 +
 drivers/accel/Makefile        |   1 +
 drivers/accel/npac/Kconfig    |  13 ++
 drivers/accel/npac/Makefile   |   3 +
 drivers/accel/npac/npac_drv.c | 218 ++++++++++++++++++++++++++++++++++
 5 files changed, 236 insertions(+)
 create mode 100644 drivers/accel/npac/Kconfig
 create mode 100644 drivers/accel/npac/Makefile
 create mode 100644 drivers/accel/npac/npac_drv.c

diff --git a/drivers/accel/Kconfig b/drivers/accel/Kconfig
index bdf48ccafcf2..a6d8c1ebfcf1 100644
--- a/drivers/accel/Kconfig
+++ b/drivers/accel/Kconfig
@@ -28,6 +28,7 @@ source "drivers/accel/amdxdna/Kconfig"
 source "drivers/accel/ethosu/Kconfig"
 source "drivers/accel/habanalabs/Kconfig"
 source "drivers/accel/ivpu/Kconfig"
+source "drivers/accel/npac/Kconfig"
 source "drivers/accel/qaic/Kconfig"
 source "drivers/accel/rocket/Kconfig"
 
diff --git a/drivers/accel/Makefile b/drivers/accel/Makefile
index 1d3a7251b950..0df7b9f2ae18 100644
--- a/drivers/accel/Makefile
+++ b/drivers/accel/Makefile
@@ -4,5 +4,6 @@ obj-$(CONFIG_DRM_ACCEL_AMDXDNA)		+= amdxdna/
 obj-$(CONFIG_DRM_ACCEL_ARM_ETHOSU)	+= ethosu/
 obj-$(CONFIG_DRM_ACCEL_HABANALABS)	+= habanalabs/
 obj-$(CONFIG_DRM_ACCEL_IVPU)		+= ivpu/
+obj-$(CONFIG_DRM_ACCEL_NPAC_CLIENT)	+= npac/
 obj-$(CONFIG_DRM_ACCEL_QAIC)		+= qaic/
 obj-$(CONFIG_DRM_ACCEL_ROCKET)		+= rocket/
\ No newline at end of file
diff --git a/drivers/accel/npac/Kconfig b/drivers/accel/npac/Kconfig
new file mode 100644
index 000000000000..a9543ac2c7aa
--- /dev/null
+++ b/drivers/accel/npac/Kconfig
@@ -0,0 +1,13 @@
+config DRM_ACCEL_NPAC_CLIENT
+	tristate "NPAC Client Driver"
+	depends on DRM_ACCEL
+	depends on RPMSG
+	help
+	  This driver is the NPAC (Network Packet ACcelerator) client,
+	  communicating with the NPAC host driver running on a remote
+	  processor over RPMsg. The driver registers with the DRM accelerator
+	  framework and exposes /dev/accel/accel* as the userspace interface
+	  for ACL rule offload operations.
+	  If you have a device with NPAC and wish to use it with this
+	  driver, say M to compile this driver as a module, or Y to
+	  compile it into the kernel.
diff --git a/drivers/accel/npac/Makefile b/drivers/accel/npac/Makefile
new file mode 100644
index 000000000000..89f4773d7041
--- /dev/null
+++ b/drivers/accel/npac/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+obj-$(CONFIG_DRM_ACCEL_NPAC_CLIENT) += npac_drv.o
diff --git a/drivers/accel/npac/npac_drv.c b/drivers/accel/npac/npac_drv.c
new file mode 100644
index 000000000000..7516382ba74b
--- /dev/null
+++ b/drivers/accel/npac/npac_drv.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/*
+ * Copyright (C) 2026 Texas Instruments Incorporated - https://www.ti.com/
+ */
+
+#include <drm/drm_accel.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_file.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_ioctl.h>
+#include <linux/completion.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/rpmsg.h>
+
+#define NPAC_RPMSG_SERVICE_NAME	"ti.npac"
+#define NPAC_ACK_TIMEOUT_MS	1000
+
+/**
+ * enum npac_acl_cmd - IOCTL command numbers for NPAC ACL operations.
+ */
+enum npac_acl_cmd {
+	/** @NPAC_ACL_ADD_RULE: Add an ACL rule. */
+	NPAC_ACL_ADD_RULE,
+
+	/** @NPAC_ACL_DELETE_RULE: Delete an ACL rule. */
+	NPAC_ACL_DELETE_RULE,
+};
+
+/**
+ * enum npac_acl_match_type - Match field selector for an ACL rule.
+ */
+enum npac_acl_match_type {
+	/** @NPAC_ACL_MATCH_SRC_IPV4: Match on source IPv4 address. */
+	NPAC_ACL_MATCH_SRC_IPV4 = 1,
+
+	/** @NPAC_ACL_MATCH_DST_IPV4: Match on destination IPv4 address. */
+	NPAC_ACL_MATCH_DST_IPV4,
+
+	/** @NPAC_ACL_MATCH_SRC_MAC: Match on source MAC address. */
+	NPAC_ACL_MATCH_SRC_MAC,
+
+	/** @NPAC_ACL_MATCH_DST_MAC: Match on destination MAC address. */
+	NPAC_ACL_MATCH_DST_MAC,
+};
+
+/**
+ * enum npac_acl_verdict - Action to apply when an ACL rule matches.
+ */
+enum npac_acl_verdict {
+	/** @NPAC_ACL_VERDICT_ALLOW: Accept the matched packet. */
+	NPAC_ACL_VERDICT_ALLOW = 1,
+
+	/** @NPAC_ACL_VERDICT_DROP: Drop the matched packet. */
+	NPAC_ACL_VERDICT_DROP,
+};
+
+/* Sized for the largest match field: a 6-byte MAC address. */
+#define NPAC_ACL_MATCH_VALUE_MAX	6
+
+struct npac_acl_offload_rule {
+	__u32 match_type;
+	__u32 verdict;
+	__u8  match_value[NPAC_ACL_MATCH_VALUE_MAX];
+};
+
+#define DRM_IOCTL_NPAC_ACL_ADD_RULE \
+	DRM_IOWR(DRM_COMMAND_BASE + NPAC_ACL_ADD_RULE, struct npac_acl_offload_rule)
+
+#define DRM_IOCTL_NPAC_ACL_DELETE_RULE \
+	DRM_IOWR(DRM_COMMAND_BASE + NPAC_ACL_DELETE_RULE, struct npac_acl_offload_rule)
+
+struct npac_device {
+	struct drm_device drm;
+	struct rpmsg_device *rpdev;
+	struct mutex req_lock; /* lock for request */
+	struct completion ack;
+};
+
+static inline struct npac_device *drm_to_npac_device(struct drm_device *dev)
+{
+	return container_of(dev, struct npac_device, drm);
+}
+
+static int npac_add_rule_ioctl(struct drm_device *dev, void *data,
+			       struct drm_file *file)
+{
+	struct npac_device *npac = drm_to_npac_device(dev);
+	struct npac_acl_offload_rule *rule = data;
+	int ret;
+
+	dev_dbg(dev->dev, "add rule ioctl received\n");
+
+	mutex_lock(&npac->req_lock);
+	reinit_completion(&npac->ack);
+	ret = rpmsg_send(npac->rpdev->ept, rule, sizeof(*rule));
+	if (ret) {
+		dev_err(dev->dev, "rpmsg_send failed: %d\n", ret);
+		mutex_unlock(&npac->req_lock);
+		return ret;
+	}
+	if (!wait_for_completion_timeout(&npac->ack,
+					 msecs_to_jiffies(NPAC_ACK_TIMEOUT_MS))) {
+		dev_err(dev->dev, "ack timed out\n");
+		mutex_unlock(&npac->req_lock);
+		return -ETIMEDOUT;
+	}
+	mutex_unlock(&npac->req_lock);
+	return 0;
+}
+
+static int npac_delete_rule_ioctl(struct drm_device *dev, void *data,
+				  struct drm_file *file)
+{
+	struct npac_device *npac = drm_to_npac_device(dev);
+	struct npac_acl_offload_rule *rule = data;
+	int ret;
+
+	dev_dbg(dev->dev, "delete rule ioctl received\n");
+
+	mutex_lock(&npac->req_lock);
+	reinit_completion(&npac->ack);
+	ret = rpmsg_send(npac->rpdev->ept, rule, sizeof(*rule));
+	if (ret) {
+		dev_err(dev->dev, "rpmsg_send failed: %d\n", ret);
+		mutex_unlock(&npac->req_lock);
+		return ret;
+	}
+	if (!wait_for_completion_timeout(&npac->ack,
+					 msecs_to_jiffies(NPAC_ACK_TIMEOUT_MS))) {
+		dev_err(dev->dev, "ack timed out\n");
+		mutex_unlock(&npac->req_lock);
+		return -ETIMEDOUT;
+	}
+	mutex_unlock(&npac->req_lock);
+	return 0;
+}
+
+static const struct drm_ioctl_desc npac_drm_ioctls[] = {
+	DRM_IOCTL_DEF_DRV(NPAC_ACL_ADD_RULE,    npac_add_rule_ioctl,    DRM_ROOT_ONLY),
+	DRM_IOCTL_DEF_DRV(NPAC_ACL_DELETE_RULE, npac_delete_rule_ioctl, DRM_ROOT_ONLY),
+};
+
+DEFINE_DRM_ACCEL_FOPS(npac_fops);
+
+static const struct drm_driver npac_drm_driver = {
+	.driver_features	= DRIVER_COMPUTE_ACCEL,
+	.ioctls			= npac_drm_ioctls,
+	.num_ioctls		= ARRAY_SIZE(npac_drm_ioctls),
+	.fops			= &npac_fops,
+	.name			= "npac",
+	.desc			= "NPAC Client Driver",
+};
+
+static int npac_cb(struct rpmsg_device *rpdev, void *data, int len,
+		   void *priv, u32 src)
+{
+	struct npac_device *npac = dev_get_drvdata(&rpdev->dev);
+
+	dev_dbg(&rpdev->dev, "ack received\n");
+	complete(&npac->ack);
+	return 0;
+}
+
+static int npac_probe(struct rpmsg_device *rpdev)
+{
+	struct npac_device *npac;
+	int ret;
+
+	npac = devm_drm_dev_alloc(&rpdev->dev, &npac_drm_driver,
+				  struct npac_device, drm);
+	if (IS_ERR(npac))
+		return PTR_ERR(npac);
+
+	npac->rpdev = rpdev;
+	mutex_init(&npac->req_lock);
+	init_completion(&npac->ack);
+	dev_set_drvdata(&rpdev->dev, npac);
+
+	ret = drm_dev_register(&npac->drm, 0);
+	if (ret) {
+		dev_err(&rpdev->dev, "Failed to register DRM accel device: %d\n", ret);
+		return ret;
+	}
+
+	dev_info(&rpdev->dev, "NPAC Client driver probed\n");
+	return 0;
+}
+
+static void npac_remove(struct rpmsg_device *rpdev)
+{
+	struct npac_device *npac = dev_get_drvdata(&rpdev->dev);
+
+	drm_dev_unplug(&npac->drm);
+
+	dev_info(&rpdev->dev, "NPAC Client Driver removed\n");
+}
+
+static struct rpmsg_device_id npac_id_table[] = {
+	{ .name = NPAC_RPMSG_SERVICE_NAME },
+	{},
+};
+MODULE_DEVICE_TABLE(rpmsg, npac_id_table);
+
+static struct rpmsg_driver npac_driver = {
+	.drv.name	= KBUILD_MODNAME,
+	.id_table	= npac_id_table,
+	.probe		= npac_probe,
+	.callback	= npac_cb,
+	.remove		= npac_remove,
+};
+
+module_rpmsg_driver(npac_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("NPAC Client Driver");
+MODULE_AUTHOR("Jaspinder Budhal <j-budhal@ti.com>");
-- 
2.34.1