cdx: add rpmsg communication channel for CDX

RPMsg is used as a transport communication channel. This
change introduces RPMsg driver and integrates it with the
CDX controller.

Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
Signed-off-by: Nipun Gupta <nipun.gupta@amd.com>
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
Tested-by: Nikhil Agarwal <nikhil.agarwal@amd.com>
Link: https://lore.kernel.org/r/20230313132636.31850-7-nipun.gupta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/cdx/controller/Kconfig

@@ -9,6 +9,8 @@ if CDX_BUS
 
 config CDX_CONTROLLER
 	tristate "CDX bus controller"
+	select REMOTEPROC
+	select RPMSG
 	help
 	  CDX controller drives the CDX bus. It interacts with
 	  firmware to get the hardware devices and registers with

drivers/cdx/controller/Makefile

@@ -6,4 +6,4 @@
 #
 
 obj-$(CONFIG_CDX_CONTROLLER) += cdx-controller.o
-cdx-controller-objs := cdx_controller.o mcdi.o mcdi_functions.o
+cdx-controller-objs := cdx_controller.o cdx_rpmsg.o mcdi.o mcdi_functions.o

drivers/cdx/controller/cdx_controller.c

@@ -9,6 +9,7 @@
 #include <linux/slab.h>
 #include <linux/cdx/cdx_bus.h>
 
+#include "cdx_controller.h"
 #include "../cdx.h"
 #include "mcdi_functions.h"
 #include "mcdi.h"
@@ -22,10 +23,8 @@ static void cdx_mcdi_request(struct cdx_mcdi *cdx,
 			     const struct cdx_dword *hdr, size_t hdr_len,
 			     const struct cdx_dword *sdu, size_t sdu_len)
 {
-	/*
-	 * This will get updated by rpmsg APIs, with RPMSG introduction
-	 * in CDX controller as a transport layer.
-	 */
+	if (cdx_rpmsg_send(cdx, hdr, hdr_len, sdu, sdu_len))
+		dev_err(&cdx->rpdev->dev, "Failed to send rpmsg data\n");
 }
 
 static const struct cdx_mcdi_ops mcdi_ops = {
@@ -33,6 +32,19 @@ static const struct cdx_mcdi_ops mcdi_ops = {
 	.mcdi_request = cdx_mcdi_request,
 };
 
+void cdx_rpmsg_post_probe(struct cdx_controller *cdx)
+{
+	/* Register CDX controller with CDX bus driver */
+	if (cdx_register_controller(cdx))
+		dev_err(cdx->dev, "Failed to register CDX controller\n");
+}
+
+void cdx_rpmsg_pre_remove(struct cdx_controller *cdx)
+{
+	cdx_unregister_controller(cdx);
+	cdx_mcdi_wait_for_quiescence(cdx->priv, MCDI_RPC_TIMEOUT);
+}
+
 static int cdx_scan_devices(struct cdx_controller *cdx)
 {
 	struct cdx_mcdi *cdx_mcdi = cdx->priv;
@@ -124,8 +136,18 @@ static int xlnx_cdx_probe(struct platform_device *pdev)
 	cdx->priv = cdx_mcdi;
 	cdx->ops = &cdx_ops;
 
+	ret = cdx_setup_rpmsg(pdev);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "Failed to register CDX RPMsg transport\n");
+		goto cdx_rpmsg_fail;
+	}
+
+	dev_info(&pdev->dev, "Successfully registered CDX controller with RPMsg as transport\n");
 	return 0;
 
+cdx_rpmsg_fail:
+	kfree(cdx);
 cdx_alloc_fail:
 	cdx_mcdi_finish(cdx_mcdi);
 mcdi_init_fail:
@@ -139,6 +161,8 @@ static int xlnx_cdx_remove(struct platform_device *pdev)
 	struct cdx_controller *cdx = platform_get_drvdata(pdev);
 	struct cdx_mcdi *cdx_mcdi = cdx->priv;
 
+	cdx_destroy_rpmsg(pdev);
+
 	kfree(cdx);
 
 	cdx_mcdi_finish(cdx_mcdi);

drivers/cdx/controller/cdx_controller.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Header file for the CDX Controller
+ *
+ * Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
+ */
+
+#ifndef _CDX_CONTROLLER_H_
+#define _CDX_CONTROLLER_H_
+
+#include <linux/cdx/cdx_bus.h>
+#include "mcdi_functions.h"
+
+void cdx_rpmsg_post_probe(struct cdx_controller *cdx);
+
+void cdx_rpmsg_pre_remove(struct cdx_controller *cdx);
+
+int cdx_rpmsg_send(struct cdx_mcdi *cdx_mcdi,
+		   const struct cdx_dword *hdr, size_t hdr_len,
+		   const struct cdx_dword *sdu, size_t sdu_len);
+
+void cdx_rpmsg_read_resp(struct cdx_mcdi *cdx_mcdi,
+			 struct cdx_dword *outbuf, size_t offset,
+			 size_t outlen);
+
+int cdx_setup_rpmsg(struct platform_device *pdev);
+
+void cdx_destroy_rpmsg(struct platform_device *pdev);
+
+#endif /* _CDX_CONT_PRIV_H_ */

drivers/cdx/controller/cdx_rpmsg.c

@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Platform driver for CDX bus.
+ *
+ * Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
+ */
+
+#include <linux/rpmsg.h>
+#include <linux/remoteproc.h>
+#include <linux/of_platform.h>
+#include <linux/cdx/cdx_bus.h>
+#include <linux/module.h>
+
+#include "../cdx.h"
+#include "cdx_controller.h"
+#include "mcdi_functions.h"
+#include "mcdi.h"
+
+static struct rpmsg_device_id cdx_rpmsg_id_table[] = {
+	{ .name = "mcdi_ipc" },
+	{ },
+};
+MODULE_DEVICE_TABLE(rpmsg, cdx_rpmsg_id_table);
+
+int cdx_rpmsg_send(struct cdx_mcdi *cdx_mcdi,
+		   const struct cdx_dword *hdr, size_t hdr_len,
+		   const struct cdx_dword *sdu, size_t sdu_len)
+{
+	unsigned char *send_buf;
+	int ret;
+
+	send_buf = kzalloc(hdr_len + sdu_len, GFP_KERNEL);
+	if (!send_buf)
+		return -ENOMEM;
+
+	memcpy(send_buf, hdr, hdr_len);
+	memcpy(send_buf + hdr_len, sdu, sdu_len);
+
+	ret = rpmsg_send(cdx_mcdi->ept, send_buf, hdr_len + sdu_len);
+	kfree(send_buf);
+
+	return ret;
+}
+
+static int cdx_attach_to_rproc(struct platform_device *pdev)
+{
+	struct device_node *r5_core_node;
+	struct cdx_controller *cdx_c;
+	struct cdx_mcdi *cdx_mcdi;
+	struct device *dev;
+	struct rproc *rp;
+	int ret;
+
+	dev = &pdev->dev;
+	cdx_c = platform_get_drvdata(pdev);
+	cdx_mcdi = cdx_c->priv;
+
+	r5_core_node = of_parse_phandle(dev->of_node, "xlnx,rproc", 0);
+	if (!r5_core_node) {
+		dev_err(&pdev->dev, "xlnx,rproc: invalid phandle\n");
+		return -EINVAL;
+	}
+
+	rp = rproc_get_by_phandle(r5_core_node->phandle);
+	if (!rp) {
+		ret = -EPROBE_DEFER;
+		goto pdev_err;
+	}
+
+	/* Attach to remote processor */
+	ret = rproc_boot(rp);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to attach to remote processor\n");
+		rproc_put(rp);
+		goto pdev_err;
+	}
+
+	cdx_mcdi->r5_rproc = rp;
+pdev_err:
+	of_node_put(r5_core_node);
+	return ret;
+}
+
+static void cdx_detach_to_r5(struct platform_device *pdev)
+{
+	struct cdx_controller *cdx_c;
+	struct cdx_mcdi *cdx_mcdi;
+
+	cdx_c = platform_get_drvdata(pdev);
+	cdx_mcdi = cdx_c->priv;
+
+	rproc_detach(cdx_mcdi->r5_rproc);
+	rproc_put(cdx_mcdi->r5_rproc);
+}
+
+static int cdx_rpmsg_cb(struct rpmsg_device *rpdev, void *data,
+			int len, void *priv, u32 src)
+{
+	struct cdx_controller *cdx_c = dev_get_drvdata(&rpdev->dev);
+	struct cdx_mcdi *cdx_mcdi = cdx_c->priv;
+
+	if (len > MCDI_BUF_LEN)
+		return -EINVAL;
+
+	cdx_mcdi_process_cmd(cdx_mcdi, (struct cdx_dword *)data, len);
+
+	return 0;
+}
+
+static void cdx_rpmsg_post_probe_work(struct work_struct *work)
+{
+	struct cdx_controller *cdx_c;
+	struct cdx_mcdi *cdx_mcdi;
+
+	cdx_mcdi = container_of(work, struct cdx_mcdi, work);
+	cdx_c = dev_get_drvdata(&cdx_mcdi->rpdev->dev);
+	cdx_rpmsg_post_probe(cdx_c);
+}
+
+static int cdx_rpmsg_probe(struct rpmsg_device *rpdev)
+{
+	struct rpmsg_channel_info chinfo = {0};
+	struct cdx_controller *cdx_c;
+	struct cdx_mcdi *cdx_mcdi;
+
+	cdx_c = (struct cdx_controller *)cdx_rpmsg_id_table[0].driver_data;
+	cdx_mcdi = cdx_c->priv;
+
+	chinfo.src = RPMSG_ADDR_ANY;
+	chinfo.dst = rpdev->dst;
+	strscpy(chinfo.name, cdx_rpmsg_id_table[0].name,
+		strlen(cdx_rpmsg_id_table[0].name));
+
+	cdx_mcdi->ept = rpmsg_create_ept(rpdev, cdx_rpmsg_cb, NULL, chinfo);
+	if (!cdx_mcdi->ept) {
+		dev_err_probe(&rpdev->dev, -ENXIO,
+			      "Failed to create ept for channel %s\n",
+			      chinfo.name);
+		return -EINVAL;
+	}
+
+	cdx_mcdi->rpdev = rpdev;
+	dev_set_drvdata(&rpdev->dev, cdx_c);
+
+	schedule_work(&cdx_mcdi->work);
+	return 0;
+}
+
+static void cdx_rpmsg_remove(struct rpmsg_device *rpdev)
+{
+	struct cdx_controller *cdx_c = dev_get_drvdata(&rpdev->dev);
+	struct cdx_mcdi *cdx_mcdi = cdx_c->priv;
+
+	flush_work(&cdx_mcdi->work);
+	cdx_rpmsg_pre_remove(cdx_c);
+
+	rpmsg_destroy_ept(cdx_mcdi->ept);
+	dev_set_drvdata(&rpdev->dev, NULL);
+}
+
+static struct rpmsg_driver cdx_rpmsg_driver = {
+	.drv.name = KBUILD_MODNAME,
+	.id_table = cdx_rpmsg_id_table,
+	.probe = cdx_rpmsg_probe,
+	.remove = cdx_rpmsg_remove,
+	.callback = cdx_rpmsg_cb,
+};
+
+int cdx_setup_rpmsg(struct platform_device *pdev)
+{
+	struct cdx_controller *cdx_c;
+	struct cdx_mcdi *cdx_mcdi;
+	int ret;
+
+	/* Attach to remote processor */
+	ret = cdx_attach_to_rproc(pdev);
+	if (ret)
+		return ret;
+
+	cdx_c = platform_get_drvdata(pdev);
+	cdx_mcdi = cdx_c->priv;
+
+	/* Register RPMsg driver */
+	cdx_rpmsg_id_table[0].driver_data = (kernel_ulong_t)cdx_c;
+
+	INIT_WORK(&cdx_mcdi->work, cdx_rpmsg_post_probe_work);
+	ret = register_rpmsg_driver(&cdx_rpmsg_driver);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Failed to register cdx RPMsg driver: %d\n", ret);
+		cdx_detach_to_r5(pdev);
+	}
+
+	return ret;
+}
+
+void cdx_destroy_rpmsg(struct platform_device *pdev)
+{
+	unregister_rpmsg_driver(&cdx_rpmsg_driver);
+
+	cdx_detach_to_r5(pdev);
+}

drivers/cdx/controller/mcdi.h

@@ -9,6 +9,7 @@
 
 #include <linux/mutex.h>
 #include <linux/kref.h>
+#include <linux/rpmsg.h>
 
 #include "bitfield.h"
 #include "mc_cdx_pcol.h"
@@ -62,11 +63,20 @@ enum cdx_mcdi_cmd_state {
  *	with CDX controller.
  * @mcdi: MCDI interface
  * @mcdi_ops: MCDI operations
+ * @r5_rproc : R5 Remoteproc device handle
+ * @rpdev: RPMsg device
+ * @ept: RPMsg endpoint
+ * @work: Post probe work
  */
 struct cdx_mcdi {
 	/* MCDI interface */
 	struct cdx_mcdi_data *mcdi;
 	const struct cdx_mcdi_ops *mcdi_ops;
+
+	struct rproc *r5_rproc;
+	struct rpmsg_device *rpdev;
+	struct rpmsg_endpoint *ept;
+	struct work_struct work;
 };
 
 struct cdx_mcdi_ops {