A number of CPC features, like retransmission or remote's receive
window, are cport-based. In order to prepare for these features,
introduce a CPC CPort context structure.

The CPC Host Device module now implements cport_allocate and
cport_release callbacks in order to allocate and release these
structures when requested by Greybus module.

Signed-off-by: Damien Riégel <damien.riegel@silabs.com>
---
Changes in v3:
  - simplify cpc_hd_cport_allocate so that cport with ID "i"is at offset
    "i" in cpc_hd->cports array

 drivers/greybus/cpc/Makefile |   2 +-
 drivers/greybus/cpc/cpc.h    |  29 +++++++++
 drivers/greybus/cpc/cport.c  |  37 +++++++++++
 drivers/greybus/cpc/host.c   | 115 ++++++++++++++++++++++++++++++++++-
 drivers/greybus/cpc/host.h   |  12 ++++
 5 files changed, 193 insertions(+), 2 deletions(-)
 create mode 100644 drivers/greybus/cpc/cpc.h
 create mode 100644 drivers/greybus/cpc/cport.c

diff --git a/drivers/greybus/cpc/Makefile b/drivers/greybus/cpc/Makefile
index 490982a0ff5..3d50f8c5473 100644
--- a/drivers/greybus/cpc/Makefile
+++ b/drivers/greybus/cpc/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-gb-cpc-y := host.o
+gb-cpc-y := cport.o host.o
 
 # CPC core
 obj-$(CONFIG_GREYBUS_CPC)	+= gb-cpc.o
diff --git a/drivers/greybus/cpc/cpc.h b/drivers/greybus/cpc/cpc.h
new file mode 100644
index 00000000000..3915a7fbc4f
--- /dev/null
+++ b/drivers/greybus/cpc/cpc.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2025, Silicon Laboratories, Inc.
+ */
+
+#ifndef __CPC_H
+#define __CPC_H
+
+#include <linux/device.h>
+#include <linux/greybus.h>
+#include <linux/types.h>
+
+/**
+ * struct cpc_cport - CPC cport
+ * @id: cport ID
+ * @cpc_hd: pointer to the CPC host device this cport belongs to
+ */
+struct cpc_cport {
+	u16 id;
+
+	struct cpc_host_device *cpc_hd;
+};
+
+struct cpc_cport *cpc_cport_alloc(u16 cport_id, gfp_t gfp_mask);
+void cpc_cport_release(struct cpc_cport *cport);
+
+int cpc_cport_message_send(struct cpc_cport *cport, struct gb_message *message, gfp_t gfp_mask);
+
+#endif
diff --git a/drivers/greybus/cpc/cport.c b/drivers/greybus/cpc/cport.c
new file mode 100644
index 00000000000..88bdb2f8182
--- /dev/null
+++ b/drivers/greybus/cpc/cport.c
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2025, Silicon Laboratories, Inc.
+ */
+
+#include "cpc.h"
+#include "host.h"
+
+/**
+ * cpc_cport_alloc() - Allocate and initialize CPC cport.
+ * @cport_id: cport ID.
+ * @gfp_mask: GFP mask for allocation.
+ *
+ * Return: Pointer to allocated and initialized cpc_cport, or NULL on failure.
+ */
+struct cpc_cport *cpc_cport_alloc(u16 cport_id, gfp_t gfp_mask)
+{
+	struct cpc_cport *cport;
+
+	cport = kzalloc(sizeof(*cport), gfp_mask);
+	if (!cport)
+		return NULL;
+
+	cport->id = cport_id;
+
+	return cport;
+}
+
+void cpc_cport_release(struct cpc_cport *cport)
+{
+	kfree(cport);
+}
+
+int cpc_cport_message_send(struct cpc_cport *cport, struct gb_message *message, gfp_t gfp_mask)
+{
+	return cport->cpc_hd->driver->message_send(cport->cpc_hd, cport->id, message, gfp_mask);
+}
diff --git a/drivers/greybus/cpc/host.c b/drivers/greybus/cpc/host.c
index 80516517ff6..3dda5b06590 100644
--- a/drivers/greybus/cpc/host.c
+++ b/drivers/greybus/cpc/host.c
@@ -7,6 +7,7 @@
 #include <linux/greybus.h>
 #include <linux/module.h>
 
+#include "cpc.h"
 #include "host.h"
 
 static struct cpc_host_device *gb_hd_to_cpc_hd(struct gb_host_device *hd)
@@ -14,12 +15,101 @@ static struct cpc_host_device *gb_hd_to_cpc_hd(struct gb_host_device *hd)
 	return (struct cpc_host_device *)&hd->hd_priv;
 }
 
+static struct cpc_cport *cpc_hd_get_cport_unlocked(struct cpc_host_device *cpc_hd, u16 cport_id)
+{
+	if (cport_id >= ARRAY_SIZE(cpc_hd->cports))
+		return NULL;
+
+	return cpc_hd->cports[cport_id];
+}
+
+static struct cpc_cport *cpc_hd_get_cport(struct cpc_host_device *cpc_hd, u16 cport_id)
+{
+	struct cpc_cport *cport;
+
+	mutex_lock(&cpc_hd->lock);
+	cport = cpc_hd_get_cport_unlocked(cpc_hd, cport_id);
+	mutex_unlock(&cpc_hd->lock);
+
+	return cport;
+}
+
+static int cpc_hd_message_send(struct cpc_host_device *cpc_hd, u16 cport_id,
+			       struct gb_message *message, gfp_t gfp_mask)
+{
+	struct cpc_cport *cport;
+
+	cport = cpc_hd_get_cport(cpc_hd, cport_id);
+	if (!cport) {
+		dev_err(cpc_hd_dev(cpc_hd), "message_send: cport %u not found\n", cport_id);
+		return -EINVAL;
+	}
+
+	return cpc_cport_message_send(cport, message, gfp_mask);
+}
+
+static int cpc_hd_cport_allocate(struct cpc_host_device *cpc_hd, int cport_id, unsigned long flags)
+{
+	struct cpc_cport *cport;
+	int ret;
+
+	mutex_lock(&cpc_hd->lock);
+	if (cport_id < 0) {
+		for (cport_id = 0; cport_id < ARRAY_SIZE(cpc_hd->cports); cport_id++) {
+			if (cpc_hd->cports[cport_id] == NULL)
+				break;
+		}
+	}
+
+	if (cport_id >= ARRAY_SIZE(cpc_hd->cports)) {
+		ret = -ENOSPC;
+		goto unlock;
+	}
+
+	cport = cpc_hd_get_cport_unlocked(cpc_hd, cport_id);
+	if (cport) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	cport = cpc_cport_alloc(cport_id, GFP_KERNEL);
+	if (!cport) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	cport->cpc_hd = cpc_hd;
+
+	cpc_hd->cports[cport_id] = cport;
+	ret = cport_id;
+
+unlock:
+	mutex_unlock(&cpc_hd->lock);
+
+	return ret;
+}
+
+static void cpc_hd_cport_release(struct cpc_host_device *cpc_hd, u16 cport_id)
+{
+	struct cpc_cport *cport;
+
+	mutex_lock(&cpc_hd->lock);
+
+	cport = cpc_hd->cports[cport_id];
+	if (cport) {
+		cpc_cport_release(cport);
+		cpc_hd->cports[cport_id] = NULL;
+	}
+
+	mutex_unlock(&cpc_hd->lock);
+}
+
 static int cpc_gb_message_send(struct gb_host_device *gb_hd, u16 cport_id,
 			       struct gb_message *message, gfp_t gfp_mask)
 {
 	struct cpc_host_device *cpc_hd = gb_hd_to_cpc_hd(gb_hd);
 
-	return cpc_hd->driver->message_send(cpc_hd, cport_id, message, gfp_mask);
+	return cpc_hd_message_send(cpc_hd, cport_id, message, gfp_mask);
 }
 
 static void cpc_gb_message_cancel(struct gb_message *message)
@@ -27,12 +117,33 @@ static void cpc_gb_message_cancel(struct gb_message *message)
 	/* Not implemented */
 }
 
+static int cpc_gb_cport_allocate(struct gb_host_device *gb_hd, int cport_id, unsigned long flags)
+{
+	struct cpc_host_device *cpc_hd = gb_hd_to_cpc_hd(gb_hd);
+
+	return cpc_hd_cport_allocate(cpc_hd, cport_id, flags);
+}
+
+static void cpc_gb_cport_release(struct gb_host_device *gb_hd, u16 cport_id)
+{
+	struct cpc_host_device *cpc_hd = gb_hd_to_cpc_hd(gb_hd);
+
+	return cpc_hd_cport_release(cpc_hd, cport_id);
+}
+
 static struct gb_hd_driver cpc_gb_driver = {
 	.hd_priv_size = sizeof(struct cpc_host_device),
 	.message_send = cpc_gb_message_send,
 	.message_cancel = cpc_gb_message_cancel,
+	.cport_allocate = cpc_gb_cport_allocate,
+	.cport_release = cpc_gb_cport_release,
 };
 
+static void cpc_hd_init(struct cpc_host_device *cpc_hd)
+{
+	mutex_init(&cpc_hd->lock);
+}
+
 struct cpc_host_device *cpc_hd_create(struct cpc_hd_driver *driver, struct device *parent)
 {
 	struct cpc_host_device *cpc_hd;
@@ -51,6 +162,8 @@ struct cpc_host_device *cpc_hd_create(struct cpc_hd_driver *driver, struct devic
 	cpc_hd->gb_hd = hd;
 	cpc_hd->driver = driver;
 
+	cpc_hd_init(cpc_hd);
+
 	return cpc_hd;
 }
 EXPORT_SYMBOL_GPL(cpc_hd_create);
diff --git a/drivers/greybus/cpc/host.h b/drivers/greybus/cpc/host.h
index f55feb303f4..c3f2f56a939 100644
--- a/drivers/greybus/cpc/host.h
+++ b/drivers/greybus/cpc/host.h
@@ -8,11 +8,13 @@
 
 #include <linux/device.h>
 #include <linux/greybus.h>
+#include <linux/mutex.h>
 #include <linux/types.h>
 
 #define GB_CPC_MSG_SIZE_MAX 4096
 #define GB_CPC_NUM_CPORTS 8
 
+struct cpc_cport;
 struct cpc_host_device;
 
 struct cpc_hd_driver {
@@ -25,12 +27,22 @@ struct cpc_hd_driver {
  * struct cpc_host_device - CPC host device.
  * @gb_hd: pointer to Greybus Host Device this device belongs to.
  * @driver: driver operations.
+ * @lock: mutex to synchronize access to cport array.
+ * @cports: array of cport pointers allocated by Greybus core.
  */
 struct cpc_host_device {
 	struct gb_host_device *gb_hd;
 	const struct cpc_hd_driver *driver;
+
+	struct mutex lock; /* Synchronize access to cports */
+	struct cpc_cport *cports[GB_CPC_NUM_CPORTS];
 };
 
+static inline struct device *cpc_hd_dev(struct cpc_host_device *cpc_hd)
+{
+	return &cpc_hd->gb_hd->dev;
+}
+
 struct cpc_host_device *cpc_hd_create(struct cpc_hd_driver *driver, struct device *parent);
 int cpc_hd_add(struct cpc_host_device *cpc_hd);
 void cpc_hd_put(struct cpc_host_device *cpc_hd);
-- 
2.52.0