Register the channel 54 to manage flow control between endpoints.
the aim of this service is.
- to inform the local endpoint of the state of the associated remote
endpoints.
- to inform remote endpoint about the state of the local endpoint.
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
---
drivers/rpmsg/Kconfig | 10 ++++
drivers/rpmsg/Makefile | 1 +
drivers/rpmsg/rpmsg_fc.c | 113 +++++++++++++++++++++++++++++++++++++++
include/linux/rpmsg/fc.h | 51 ++++++++++++++++++
4 files changed, 175 insertions(+)
create mode 100644 drivers/rpmsg/rpmsg_fc.c
create mode 100644 include/linux/rpmsg/fc.h
diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
index d3795860f5c0..c6659f27c617 100644
--- a/drivers/rpmsg/Kconfig
+++ b/drivers/rpmsg/Kconfig
@@ -31,6 +31,16 @@ config RPMSG_NS
channel that probes the associated RPMsg device on remote endpoint
service announcement.
+config RPMSG_FC
+ tristate "RPMSG endpoint flow control management"
+ depends on RPMSG
+ help
+ Say Y here to enable the support of the flow control management
+ for the rpmsg endpoints.
+
+ To compile this driver as a module, choose M here: the module will be
+ called rpmsg_fc.
+
config RPMSG_MTK_SCP
tristate "MediaTek SCP"
depends on MTK_SCP
diff --git a/drivers/rpmsg/Makefile b/drivers/rpmsg/Makefile
index 58e3b382e316..c70b9864231f 100644
--- a/drivers/rpmsg/Makefile
+++ b/drivers/rpmsg/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_RPMSG) += rpmsg_core.o
obj-$(CONFIG_RPMSG_CHAR) += rpmsg_char.o
obj-$(CONFIG_RPMSG_CTRL) += rpmsg_ctrl.o
obj-$(CONFIG_RPMSG_NS) += rpmsg_ns.o
+obj-$(CONFIG_RPMSG_FC) += rpmsg_fc.o
obj-$(CONFIG_RPMSG_MTK_SCP) += mtk_rpmsg.o
qcom_glink-objs := qcom_glink_native.o qcom_glink_ssr.o
obj-$(CONFIG_RPMSG_QCOM_GLINK) += qcom_glink.o
diff --git a/drivers/rpmsg/rpmsg_fc.c b/drivers/rpmsg/rpmsg_fc.c
new file mode 100644
index 000000000000..d7e17c8cffb0
--- /dev/null
+++ b/drivers/rpmsg/rpmsg_fc.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) STMicroelectronics 2022 - All Rights Reserved
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rpmsg.h>
+#include <linux/rpmsg/fc.h>
+#include <linux/slab.h>
+
+#include "rpmsg_internal.h"
+
+/**
+ * rpmsg_fc_register_device() - register name service device based on rpdev
+ * @rpdev: prepared rpdev to be used catfor creating endpoints
+ *
+ * This function wraps rpmsg_register_device() preparing the rpdev for use as
+ * basis for the rpmsg name service device.
+ */
+int rpmsg_fc_register_device(struct rpmsg_device *rpdev)
+{
+ strcpy(rpdev->id.name, "rpmsg_fc");
+ rpdev->driver_override = KBUILD_MODNAME;
+ rpdev->src = RPMSG_FC_ADDR;
+ rpdev->dst = RPMSG_FC_ADDR;
+
+ return rpmsg_register_device(rpdev);
+}
+EXPORT_SYMBOL(rpmsg_fc_register_device);
+
+/* Invoked when a name service announcement arrives */
+static int rpmsg_fc_cb(struct rpmsg_device *rpdev, void *data, int len,
+ void *priv, u32 src)
+{
+ struct rpmsg_ept_msg *msg = data;
+ struct rpmsg_channel_info chinfo;
+ struct device *dev = rpdev->dev.parent;
+ bool enable;
+ int ret;
+
+ if (len != sizeof(*msg)) {
+ dev_err(dev, "malformed fc msg (%d)\n", len);
+ return -EINVAL;
+ }
+
+ chinfo.src = rpmsg32_to_cpu(rpdev, msg->src);
+ chinfo.dst = rpmsg32_to_cpu(rpdev, msg->dst);
+ enable = rpmsg32_to_cpu(rpdev, msg->flags) & RPMSG_EPT_FC_ON;
+
+ dev_dbg(dev, "remote endpoint 0x%x in state %sable\n", chinfo.src, enable ? "en" : "dis");
+
+ ret = rpmsg_channel_remote_fc(rpdev, &chinfo, enable);
+ if (ret)
+ dev_err(dev, "rpmsg_annouce_flow_ctrl failed: %d\n", ret);
+
+ return ret;
+}
+
+static int rpmsg_fc_probe(struct rpmsg_device *rpdev)
+{
+ struct rpmsg_endpoint *fc_ept;
+ struct rpmsg_channel_info fc_chinfo = {
+ .src = RPMSG_FC_ADDR,
+ .dst = RPMSG_FC_ADDR,
+ .name = "flow_control_service",
+ };
+
+ /*
+ * Create the Flow control (FC) service endpoint associated to the RPMsg
+ * device. The endpoint will be automatically destroyed when the RPMsg
+ * device will be deleted.
+ */
+ fc_ept = rpmsg_create_ept(rpdev, rpmsg_fc_cb, NULL, fc_chinfo);
+ if (!fc_ept) {
+ dev_err(&rpdev->dev, "failed to create the FC ept\n");
+ return -ENOMEM;
+ }
+ rpdev->ept = fc_ept;
+
+ return 0;
+}
+
+static struct rpmsg_driver rpmsg_fc_driver = {
+ .drv.name = KBUILD_MODNAME,
+ .probe = rpmsg_fc_probe,
+};
+
+static int rpmsg_fc_init(void)
+{
+ int ret;
+
+ ret = register_rpmsg_driver(&rpmsg_fc_driver);
+ if (ret < 0)
+ pr_err("%s: Failed to register FC rpmsg driver\n", __func__);
+
+ return ret;
+}
+postcore_initcall(rpmsg_fc_init);
+
+static void rpmsg_fc_exit(void)
+{
+ unregister_rpmsg_driver(&rpmsg_fc_driver);
+}
+module_exit(rpmsg_fc_exit);
+
+MODULE_DESCRIPTION("Flow control service rpmsg driver");
+MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>");
+MODULE_ALIAS("rpmsg:" KBUILD_MODNAME);
+MODULE_LICENSE("GPL");
diff --git a/include/linux/rpmsg/fc.h b/include/linux/rpmsg/fc.h
new file mode 100644
index 000000000000..5284ea410673
--- /dev/null
+++ b/include/linux/rpmsg/fc.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_RPMSG_FC_H
+#define _LINUX_RPMSG_FC_H
+
+#include <linux/mod_devicetable.h>
+#include <linux/rpmsg.h>
+#include <linux/rpmsg/byteorder.h>
+#include <linux/types.h>
+
+/* The feature bitmap for the endpoint flow control flags */
+#define RPMSG_EPT_FC_ON BIT(0) /* Set when endpoint is ready to communicate */
+
+/**
+ * struct rpmsg_ept_msg - dynamic endpoint announcement message
+ * @src: address of the endpoint that sends the message
+ * @dest: address of the destination endpoint.
+ * @flags: indicates the state of the endpoint based on @rpmsg_ept_flags enum.
+ *
+ * This message is sent across to inform the remote about the state of a local
+ * endpoint associated with a remote endpoint:
+ * - a RPMSG_EPT_OFF can be sent to inform that a local endpoint is suspended.
+ * - a RPMSG_EPT_ON can be sent to inform that a local endpoint is ready to communicate.
+ *
+ * When we receive these messages, the appropriate endpoint is informed.
+ */
+struct rpmsg_ept_msg {
+ __rpmsg32 src;
+ __rpmsg32 dst;
+ __rpmsg32 flags;
+} __packed;
+
+/* Address 54 is reserved for flow control advertising */
+#define RPMSG_FC_ADDR (54)
+
+#if IS_ENABLED(CONFIG_RPMSG_FC)
+
+int rpmsg_fc_register_device(struct rpmsg_device *rpdev);
+
+#else
+
+static inline int rpmsg_fc_register_device(struct rpmsg_device *rpdev)
+{
+ /* This shouldn't be possible */
+ WARN_ON(1);
+
+ return -ENXIO;
+}
+#endif /* IS_ENABLED(CONFIG_RPMSG_FC)*/
+
+#endif
--
2.25.1
