From a834f4e143ff647e7677dc60ab57ee5883f3ac8f Mon Sep 17 00:00:00 2001
From: Emekcan <emekcan.aras@arm.com>
Date: Wed, 17 Aug 2022 14:21:42 +0100
Subject: [PATCH] Add rpmsg driver for corstone1000

Adds rpmsg driver to communicate with external
system in corstone1000 platform.

Upstream-Status: Pending
Signed-off-by: Emekcan Aras <emekcan.aras@arm.com>
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
---
 drivers/rpmsg/Kconfig             |  10 ++
 drivers/rpmsg/Makefile            |   1 +
 drivers/rpmsg/rpmsg_arm_mailbox.c | 164 ++++++++++++++++++++++++++++++
 3 files changed, 175 insertions(+)
 create mode 100644 drivers/rpmsg/rpmsg_arm_mailbox.c

diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
index d3795860f5c0..fc6916d7b523 100644
--- a/drivers/rpmsg/Kconfig
+++ b/drivers/rpmsg/Kconfig
@@ -81,4 +81,14 @@ config RPMSG_VIRTIO
 	select RPMSG_NS
 	select VIRTIO
 
+config RPMSG_ARM
+	tristate "ARM RPMSG driver"
+	select     RPMSG
+	depends on HAS_IOMEM
+	depends on MAILBOX
+	help
+	  Say y here to enable support for rpmsg lient driver which is built
+	  around mailbox client using Arm MHUv2.1 as physical medium.This
+	  driver enables communication which remote processor using MHU.
+
 endmenu
diff --git a/drivers/rpmsg/Makefile b/drivers/rpmsg/Makefile
index 58e3b382e316..6bdcc69688b2 100644
--- a/drivers/rpmsg/Makefile
+++ b/drivers/rpmsg/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_RPMSG)		+= rpmsg_core.o
+obj-$(CONFIG_RPMSG_ARM)		+= rpmsg_arm_mailbox.o
 obj-$(CONFIG_RPMSG_CHAR)	+= rpmsg_char.o
 obj-$(CONFIG_RPMSG_CTRL)	+= rpmsg_ctrl.o
 obj-$(CONFIG_RPMSG_NS)		+= rpmsg_ns.o
diff --git a/drivers/rpmsg/rpmsg_arm_mailbox.c b/drivers/rpmsg/rpmsg_arm_mailbox.c
new file mode 100644
index 000000000000..4a80102669f6
--- /dev/null
+++ b/drivers/rpmsg/rpmsg_arm_mailbox.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rpmsg client driver using mailbox client interface
+ *
+ * Copyright (C) 2019 ARM Ltd.
+ *
+ */
+
+#include <linux/bitmap.h>
+#include <linux/export.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/processor.h>
+#include <linux/semaphore.h>
+#include <linux/slab.h>
+#include <linux/rpmsg.h>
+#include "rpmsg_internal.h"
+#include <linux/mailbox/arm_mhuv2_message.h>
+
+#define RPMSG_NAME	"arm_rpmsg"
+#define RPMSG_ADDR_ANY	0xFFFFFFFF
+
+struct arm_channel {
+	struct rpmsg_endpoint ept;
+	struct mbox_client cl;
+	struct mbox_chan *mbox;
+};
+
+#define arm_channel_from_rpmsg(_ept) container_of(_ept, struct arm_channel, ept)
+#define arm_channel_from_mbox(_ept) container_of(_ept, struct arm_channel, cl)
+
+
+static void arm_msg_rx_handler(struct mbox_client *cl, void *mssg)
+{
+	struct arm_mhuv2_mbox_msg *msg = mssg;
+	struct arm_channel* channel = arm_channel_from_mbox(cl);
+	int err = channel->ept.cb(channel->ept.rpdev, msg->data, 4, channel->ept.priv, RPMSG_ADDR_ANY);
+	if(err) {
+		printk("ARM Mailbox: Endpoint callback failed with error: %d", err);
+	}
+}
+
+
+static void arm_destroy_ept(struct rpmsg_endpoint *ept)
+{
+	struct arm_channel *channel = arm_channel_from_rpmsg(ept);
+	mbox_free_channel(channel->mbox);
+	kfree(channel);
+}
+
+static int arm_send(struct rpmsg_endpoint *ept, void *data, int len)
+{
+	struct arm_channel *channel = arm_channel_from_rpmsg(ept);
+
+	mbox_send_message(channel->mbox, data);
+	return 0;
+}
+
+static int arm_sendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dest)
+{
+	struct arm_mhuv2_mbox_msg msg;
+	struct arm_channel *channel = arm_channel_from_rpmsg(ept);
+	msg.data = data;
+	msg.len = len;
+	mbox_send_message(channel->mbox, &msg);
+	return 0;
+}
+
+
+static const struct rpmsg_endpoint_ops arm_endpoint_ops = {
+	.destroy_ept = arm_destroy_ept,
+	.send = arm_send,
+	.sendto = arm_sendto,
+};
+
+
+static struct rpmsg_endpoint *arm_create_ept(struct rpmsg_device *rpdev,
+		rpmsg_rx_cb_t cb, void *priv, struct rpmsg_channel_info chinfo)
+{
+	struct arm_channel *channel;
+
+	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
+
+	// Initialize rpmsg endpoint
+	kref_init(&channel->ept.refcount);
+	channel->ept.rpdev = rpdev;
+	channel->ept.cb = cb;
+	channel->ept.priv = priv;
+	channel->ept.ops = &arm_endpoint_ops;
+
+	// Initialize mailbox client
+	channel->cl.dev = rpdev->dev.parent;
+	channel->cl.rx_callback = arm_msg_rx_handler;
+	channel->cl.tx_done = NULL; /* operate in blocking mode */
+	channel->cl.tx_block = true;
+	channel->cl.tx_tout = 500; /* by half a second */
+	channel->cl.knows_txdone = false; /* depending upon protocol */
+
+	channel->mbox = mbox_request_channel_byname(&channel->cl, chinfo.name);
+	if (IS_ERR_OR_NULL(channel->mbox)) {
+		printk("RPMsg ARM: Cannot get channel by name: '%s'\n", chinfo.name);
+		return -1;
+	}
+
+	return &channel->ept;
+}
+
+static const struct rpmsg_device_ops arm_device_ops = {
+	.create_ept = arm_create_ept,
+};
+
+
+static void arm_release_device(struct device *dev)
+{
+	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
+
+	kfree(rpdev);
+}
+
+
+static int client_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rpmsg_device *rpdev;
+
+	rpdev = kzalloc(sizeof(*rpdev), GFP_KERNEL);
+	if (!rpdev)
+		return -ENOMEM;
+
+	/* Assign callbacks for rpmsg_device */
+	rpdev->ops = &arm_device_ops;
+
+	/* Assign public information to the rpmsg_device */
+	memcpy(rpdev->id.name, RPMSG_NAME, strlen(RPMSG_NAME));
+
+	rpdev->dev.parent = dev;
+	rpdev->dev.release = arm_release_device;
+
+	return rpmsg_chrdev_register_device(rpdev);
+}
+
+static const struct of_device_id client_of_match[] = {
+	{ .compatible = "arm,client", .data = NULL },
+	{ /* Sentinel */ },
+};
+
+static struct platform_driver client_driver = {
+	.driver = {
+		.name = "arm-mhu-client",
+		.of_match_table = client_of_match,
+	},
+	.probe = client_probe,
+};
+
+module_platform_driver(client_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("ARM RPMSG Driver");
+MODULE_AUTHOR("Tushar Khandelwal <tushar.khandelwal@arm.com>");