[PATCH v2 01/16] rpmsg: introduce RPMsg control driver for channel creation

Arnaud Pouliquen
2020-12-22T11:00:08Z

The RPMsg_ctrl driver is a duplication of the ioctrl part of the
rpmsg_char driver to make generic the ioctl to manage channels by
the userspace applications.

As a first step, this driver just creates the /dev/rpmsg_ctl<x>
( <x> is the instance value). The ioctl is not implemented.

Notice that this driver is associated to a RPMsg device with no endpoint.
Instantiating this device as an RPMsg device allows to retrieve the
associated RPMsg backend.

Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>
---
drivers/rpmsg/Kconfig | 8 ++
drivers/rpmsg/Makefile | 1 +
drivers/rpmsg/rpmsg_ctrl.c | 208 +++++++++++++++++++++++++++++++++++++
3 files changed, 217 insertions(+)
create mode 100644 drivers/rpmsg/rpmsg_ctrl.c

diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
index 0b4407abdf13..c9e602016c3b 100644
--- a/drivers/rpmsg/Kconfig
+++ b/drivers/rpmsg/Kconfig
@@ -23,6 +23,14 @@ config RPMSG_NS
channel that probes the associated RPMsg device on remote endpoint
service announcement.

+config RPMSG_CTRL
+ tristate "RPMSG control interface"
+ depends on RPMSG
+ help
+ Say Y here to enable the support of the /dev/rpmsg_ctl API. this API
+ allows user-space programs to create channels with specific name,
+ source and destination addresses.
+
config RPMSG_MTK_SCP
tristate "MediaTek SCP"
depends on MTK_SCP
diff --git a/drivers/rpmsg/Makefile b/drivers/rpmsg/Makefile
index 8d452656f0ee..3c1bce9d0228 100644
--- a/drivers/rpmsg/Makefile
+++ b/drivers/rpmsg/Makefile
@@ -2,6 +2,7 @@
obj-$(CONFIG_RPMSG) += rpmsg_core.o
obj-$(CONFIG_RPMSG_CHAR) += rpmsg_char.o
obj-$(CONFIG_RPMSG_NS) += rpmsg_ns.o
+obj-$(CONFIG_RPMSG_CTRL) += rpmsg_ctrl.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_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c
new file mode 100644
index 000000000000..425c3e32ada4
--- /dev/null
+++ b/drivers/rpmsg/rpmsg_ctrl.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) STMicroelectronics 2020
+ */
+
+#include <linux/cdev.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include "rpmsg_internal.h"
+#include <uapi/linux/rpmsg.h>
+
+#define RPMSG_DEV_MAX (MINORMASK + 1)
+
+#define dev_to_ctrldev(dev) container_of(dev, struct rpmsg_ctrl_dev, dev)
+#define cdev_to_ctrldev(i_cdev) container_of(i_cdev, struct rpmsg_ctrl_dev, cdev)
+
+/**
+ * struct rpmsg_ctrl_dev - control device for instantiating endpoint devices
+ * @rpdev: underlaying rpmsg device
+ * @cdev: cdev for the ctrl device
+ * @dev: device for the ctrl device
+ */
+struct rpmsg_ctrl_dev {
+ struct rpmsg_device *rpdev;
+ struct cdev cdev;
+ struct device dev;
+};
+
+static DEFINE_IDA(rpmsg_ctrl_ida);
+static DEFINE_IDA(rpmsg_minor_ida);
+
+static dev_t rpmsg_major;
+
+static int rpmsg_ctrl_dev_open(struct inode *inode, struct file *filp)
+{
+ struct rpmsg_ctrl_dev *ctrldev = cdev_to_ctrldev(inode->i_cdev);
+
+ get_device(&ctrldev->dev);
+ filp->private_data = ctrldev;
+
+ return 0;
+}
+
+static long rpmsg_ctrl_dev_ioctl(struct file *fp, unsigned int cmd,
+ unsigned long arg)
+{
+ struct rpmsg_ctrl_dev *ctrldev = fp->private_data;
+
+ dev_info(&ctrldev->dev, "Control not yet implemented\n");
+
+ return 0;
+};
+
+static int rpmsg_ctrl_dev_release(struct inode *inode, struct file *filp)
+{
+ struct rpmsg_ctrl_dev *ctrldev = cdev_to_ctrldev(inode->i_cdev);
+
+ put_device(&ctrldev->dev);
+
+ return 0;
+}
+
+static void rpmsg_ctrl_dev_release_device(struct device *dev)
+{
+ struct rpmsg_ctrl_dev *ctrldev = dev_to_ctrldev(dev);
+
+ dev_err(dev, "%s\n", __func__);
+
+ ida_simple_remove(&rpmsg_ctrl_ida, dev->id);
+ ida_simple_remove(&rpmsg_minor_ida, MINOR(dev->devt));
+ cdev_del(&ctrldev->cdev);
+ kfree(ctrldev);
+}
+
+static const struct file_operations rpmsg_ctrl_fops = {
+ .owner = THIS_MODULE,
+ .open = rpmsg_ctrl_dev_open,
+ .release = rpmsg_ctrl_dev_release,
+ .unlocked_ioctl = rpmsg_ctrl_dev_ioctl,
+ .compat_ioctl = compat_ptr_ioctl,
+};
+
+static int rpmsg_ctrl_add_control(struct rpmsg_ctrl_dev *ctrldev)
+{
+ struct device *dev = &ctrldev->dev;
+ int ret;
+
+ cdev_init(&ctrldev->cdev, &rpmsg_ctrl_fops);
+ ctrldev->cdev.owner = THIS_MODULE;
+
+ ret = ida_simple_get(&rpmsg_minor_ida, 0, RPMSG_DEV_MAX, GFP_KERNEL);
+ if (ret < 0)
+ return ret;
+ dev->devt = MKDEV(MAJOR(rpmsg_major), ret);
+
+ dev_set_name(dev, "rpmsg_ctrl%d", dev->id);
+
+ ret = cdev_add(&ctrldev->cdev, dev->devt, 1);
+ if (ret)
+ goto free_minor_ida;
+
+ dev_info(dev, "add %s control for %s driver\n",
+ dev_name(dev), dev_name(dev->parent));
+
+ return 0;
+
+free_minor_ida:
+ ida_simple_remove(&rpmsg_minor_ida, MINOR(dev->devt));
+
+ return ret;
+}
+
+static int rpmsg_ctrl_probe(struct rpmsg_device *rpdev)
+{
+ struct rpmsg_ctrl_dev *ctrldev;
+ struct device *dev;
+ int ret;
+
+ ctrldev = kzalloc(sizeof(*ctrldev), GFP_KERNEL);
+ if (!ctrldev)
+ return -ENOMEM;
+
+ ctrldev->rpdev = rpdev;
+
+ dev = &ctrldev->dev;
+ device_initialize(dev);
+ dev->parent = &rpdev->dev;
+
+ ret = ida_simple_get(&rpmsg_ctrl_ida, 0, 0, GFP_KERNEL);
+ if (ret < 0)
+ goto free_ctrldev;
+
+ dev->id = ret;
+
+ ret = rpmsg_ctrl_add_control(ctrldev);
+ if (ret < 0)
+ goto free_ctrl_ida;
+
+ /* We can now rely on the release function for cleanup */
+ dev->release = rpmsg_ctrl_dev_release_device;
+
+ ret = device_add(dev);
+ if (ret) {
+ dev_err(&rpdev->dev, "device_add failed: %d\n", ret);
+ put_device(dev);
+ goto free_ctrl_ida;
+ }
+
+ dev_set_drvdata(dev, ctrldev);
+ dev_set_drvdata(&rpdev->dev, ctrldev);
+
+ return 0;
+
+free_ctrl_ida:
+ ida_simple_remove(&rpmsg_ctrl_ida, dev->id);
+free_ctrldev:
+ put_device(dev);
+ kfree(ctrldev);
+
+ return ret;
+}
+
+static void rpmsg_ctrl_remove(struct rpmsg_device *rpdev)
+{
+ struct rpmsg_ctrl_dev *ctrldev = dev_get_drvdata(&rpdev->dev);
+
+ device_del(&ctrldev->dev);
+ put_device(&ctrldev->dev);
+}
+
+static struct rpmsg_driver rpmsg_ctrl_driver = {
+ .drv.name = KBUILD_MODNAME,
+ .probe = rpmsg_ctrl_probe,
+ .remove = rpmsg_ctrl_remove,
+};
+
+static int rpmsg_ctrl_init(void)
+{
+ int ret;
+
+ ret = alloc_chrdev_region(&rpmsg_major, 0, RPMSG_DEV_MAX, "rpmsg");
+ if (ret < 0) {
+ pr_err("rpmsg_ctrl: failed to allocate char dev region\n");
+ return ret;
+ }
+
+ ret = register_rpmsg_driver(&rpmsg_ctrl_driver);
+ if (ret < 0) {
+ pr_err("rpmsg_ctrl: failed to register rpmsg driver\n");
+ unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
+ }
+
+ return ret;
+}
+postcore_initcall(rpmsg_ctrl_init);
+
+static void rpmsg_ctrl_exit(void)
+{
+ unregister_rpmsg_driver(&rpmsg_ctrl_driver);
+ unregister_chrdev_region(rpmsg_major, RPMSG_DEV_MAX);
+}
+module_exit(rpmsg_ctrl_exit);
+
+MODULE_DESCRIPTION("ioctl rpmsg driver");
+MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>");
+MODULE_ALIAS("rpmsg:" KBUILD_MODNAME);
+MODULE_LICENSE("GPL v2");
--
2.17.1