LF-44 rpmsg: imx: add the rpmsg tty demo

Add the rpmsg tty demo for iMX AMP platforms.
Use the "echo <string> > /dev/*RPMSG*", after insmod the module.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Acked-by: Fugang Duan <fugang.duan@nxp.com>

3 files changed, 255 insertions, 0 deletions

diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
index 636460edcd83..5cd69052e79e 100644
--- a/drivers/rpmsg/Kconfig
+++ b/drivers/rpmsg/Kconfig
@@ -79,4 +79,17 @@ config IMX_RPMSG_PINGPONG
 	  Only the module mode is supported here, the demo would be kicked off
 	  immediately when this module is insmoded.
 
+config IMX_RPMSG_TTY
+	tristate "IMX RPMSG tty driver -- loadable modules only"
+	default m
+	depends on HAVE_IMX_RPMSG && m
+	help
+	  Demostrate the string transmission from A core to the remote M core
+	  on the iMX AMP platforms.
+
+	  Only the module mode is supported here. The according device node
+	  would be created after this module is insmoded. the demo would be
+	  executed by the command "echo <string> > <accordingly node>", thus
+	  remote M core would receive the string.
+
 endmenu
diff --git a/drivers/rpmsg/Makefile b/drivers/rpmsg/Makefile
index 9c6fce52e432..3a1f0e97e3c0 100644
--- a/drivers/rpmsg/Makefile
+++ b/drivers/rpmsg/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_RPMSG_QCOM_SMD)	+= qcom_smd.o
 obj-$(CONFIG_RPMSG_VIRTIO)	+= virtio_rpmsg_bus.o
 obj-$(CONFIG_HAVE_IMX_RPMSG)	+= imx_rpmsg.o
 obj-$(CONFIG_IMX_RPMSG_PINGPONG)	+= imx_rpmsg_pingpong.o
+obj-$(CONFIG_IMX_RPMSG_TTY)	+= imx_rpmsg_tty.o
diff --git a/drivers/rpmsg/imx_rpmsg_tty.c b/drivers/rpmsg/imx_rpmsg_tty.c
new file mode 100644
index 000000000000..008c998b610e
--- /dev/null
+++ b/drivers/rpmsg/imx_rpmsg_tty.c
@@ -0,0 +1,241 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 NXP
+ */
+
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/rpmsg.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+#include <linux/virtio.h>
+
+/* this needs to be less then (RPMSG_BUF_SIZE - sizeof(struct rpmsg_hdr)) */
+#define RPMSG_MAX_SIZE		256
+#define MSG		"hello world!"
+
+/*
+ * struct rpmsgtty_port - Wrapper struct for imx rpmsg tty port.
+ * @port:		TTY port data
+ */
+struct rpmsgtty_port {
+	struct tty_port		port;
+	spinlock_t		rx_lock;
+	struct rpmsg_device	*rpdev;
+	struct tty_driver	*rpmsgtty_driver;
+};
+
+static int rpmsg_tty_cb(struct rpmsg_device *rpdev, void *data, int len,
+						void *priv, u32 src)
+{
+	int space;
+	unsigned char *cbuf;
+	struct rpmsgtty_port *cport = dev_get_drvdata(&rpdev->dev);
+
+	/* flush the recv-ed none-zero data to tty node */
+	if (len == 0)
+		return 0;
+
+	dev_dbg(&rpdev->dev, "msg(<- src 0x%x) len %d\n", src, len);
+
+	print_hex_dump(KERN_DEBUG, __func__, DUMP_PREFIX_NONE, 16, 1,
+			data, len,  true);
+
+	spin_lock_bh(&cport->rx_lock);
+	space = tty_prepare_flip_string(&cport->port, &cbuf, len);
+	if (space <= 0) {
+		dev_err(&rpdev->dev, "No memory for tty_prepare_flip_string\n");
+		spin_unlock_bh(&cport->rx_lock);
+		return -ENOMEM;
+	}
+
+	memcpy(cbuf, data, len);
+	tty_flip_buffer_push(&cport->port);
+	spin_unlock_bh(&cport->rx_lock);
+
+	return 0;
+}
+
+static struct tty_port_operations  rpmsgtty_port_ops = { };
+
+static int rpmsgtty_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+	struct rpmsgtty_port *cport = driver->driver_state;
+
+	return tty_port_install(&cport->port, driver, tty);
+}
+
+static int rpmsgtty_open(struct tty_struct *tty, struct file *filp)
+{
+	return tty_port_open(tty->port, tty, filp);
+}
+
+static void rpmsgtty_close(struct tty_struct *tty, struct file *filp)
+{
+	return tty_port_close(tty->port, tty, filp);
+}
+
+static int rpmsgtty_write(struct tty_struct *tty, const unsigned char *buf,
+			 int total)
+{
+	int count, ret = 0;
+	const unsigned char *tbuf;
+	struct rpmsgtty_port *rptty_port = container_of(tty->port,
+			struct rpmsgtty_port, port);
+	struct rpmsg_device *rpdev = rptty_port->rpdev;
+
+	if (buf == NULL) {
+		pr_err("buf shouldn't be null.\n");
+		return -ENOMEM;
+	}
+
+	count = total;
+	tbuf = buf;
+	do {
+		/* send a message to our remote processor */
+		ret = rpmsg_send(rpdev->ept, (void *)tbuf,
+			count > RPMSG_MAX_SIZE ? RPMSG_MAX_SIZE : count);
+		if (ret) {
+			dev_err(&rpdev->dev, "rpmsg_send failed: %d\n", ret);
+			return ret;
+		}
+
+		if (count > RPMSG_MAX_SIZE) {
+			count -= RPMSG_MAX_SIZE;
+			tbuf += RPMSG_MAX_SIZE;
+		} else {
+			count = 0;
+		}
+	} while (count > 0);
+
+	return total;
+}
+
+static int rpmsgtty_write_room(struct tty_struct *tty)
+{
+	/* report the space in the rpmsg buffer */
+	return RPMSG_MAX_SIZE;
+}
+
+static const struct tty_operations imxrpmsgtty_ops = {
+	.install		= rpmsgtty_install,
+	.open			= rpmsgtty_open,
+	.close			= rpmsgtty_close,
+	.write			= rpmsgtty_write,
+	.write_room		= rpmsgtty_write_room,
+};
+
+static int rpmsg_tty_probe(struct rpmsg_device *rpdev)
+{
+	int ret;
+	struct rpmsgtty_port *cport;
+	struct tty_driver *rpmsgtty_driver;
+
+	dev_info(&rpdev->dev, "new channel: 0x%x -> 0x%x!\n",
+			rpdev->src, rpdev->dst);
+
+	cport = devm_kzalloc(&rpdev->dev, sizeof(*cport), GFP_KERNEL);
+	if (!cport)
+		return -ENOMEM;
+
+	rpmsgtty_driver = tty_alloc_driver(1, TTY_DRIVER_UNNUMBERED_NODE);
+	if (IS_ERR(rpmsgtty_driver)) {
+		kfree(cport);
+		return PTR_ERR(rpmsgtty_driver);
+	}
+
+	rpmsgtty_driver->driver_name = "rpmsg_tty";
+	rpmsgtty_driver->name = kasprintf(GFP_KERNEL, "ttyRPMSG%d", rpdev->dst);
+	rpmsgtty_driver->major = UNNAMED_MAJOR;
+	rpmsgtty_driver->minor_start = 0;
+	rpmsgtty_driver->type = TTY_DRIVER_TYPE_CONSOLE;
+	rpmsgtty_driver->init_termios = tty_std_termios;
+
+	tty_set_operations(rpmsgtty_driver, &imxrpmsgtty_ops);
+
+	tty_port_init(&cport->port);
+	cport->port.ops = &rpmsgtty_port_ops;
+	spin_lock_init(&cport->rx_lock);
+	cport->port.low_latency = cport->port.flags | ASYNC_LOW_LATENCY;
+	cport->rpdev = rpdev;
+	dev_set_drvdata(&rpdev->dev, cport);
+	rpmsgtty_driver->driver_state = cport;
+	cport->rpmsgtty_driver = rpmsgtty_driver;
+
+	ret = tty_register_driver(cport->rpmsgtty_driver);
+	if (ret < 0) {
+		pr_err("Couldn't install rpmsg tty driver: ret %d\n", ret);
+		goto error1;
+	} else {
+		pr_info("Install rpmsg tty driver!\n");
+	}
+
+	/*
+	 * send a message to our remote processor, and tell remote
+	 * processor about this channel
+	 */
+	ret = rpmsg_send(rpdev->ept, MSG, strlen(MSG));
+	if (ret) {
+		dev_err(&rpdev->dev, "rpmsg_send failed: %d\n", ret);
+		goto error;
+	}
+
+	return 0;
+
+error:
+	tty_unregister_driver(cport->rpmsgtty_driver);
+error1:
+	put_tty_driver(cport->rpmsgtty_driver);
+	tty_port_destroy(&cport->port);
+	cport->rpmsgtty_driver = NULL;
+	kfree(cport);
+
+	return ret;
+}
+
+static void rpmsg_tty_remove(struct rpmsg_device *rpdev)
+{
+	struct rpmsgtty_port *cport = dev_get_drvdata(&rpdev->dev);
+
+	dev_info(&rpdev->dev, "rpmsg tty driver is removed\n");
+
+	tty_unregister_driver(cport->rpmsgtty_driver);
+	kfree(cport->rpmsgtty_driver->name);
+	put_tty_driver(cport->rpmsgtty_driver);
+	tty_port_destroy(&cport->port);
+	cport->rpmsgtty_driver = NULL;
+}
+
+static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = {
+	{ .name	= "rpmsg-virtual-tty-channel-1" },
+	{ .name	= "rpmsg-virtual-tty-channel" },
+	{ .name = "rpmsg-openamp-demo-channel" },
+	{ },
+};
+
+static struct rpmsg_driver rpmsg_tty_driver = {
+	.drv.name	= KBUILD_MODNAME,
+	.drv.owner	= THIS_MODULE,
+	.id_table	= rpmsg_driver_tty_id_table,
+	.probe		= rpmsg_tty_probe,
+	.callback	= rpmsg_tty_cb,
+	.remove		= rpmsg_tty_remove,
+};
+
+static int __init init(void)
+{
+	return register_rpmsg_driver(&rpmsg_tty_driver);
+}
+
+static void __exit fini(void)
+{
+	unregister_rpmsg_driver(&rpmsg_tty_driver);
+}
+module_init(init);
+module_exit(fini);
+
+MODULE_AUTHOR("Freescale Semiconductor, Inc.");
+MODULE_DESCRIPTION("iMX virtio remote processor messaging tty driver");
+MODULE_LICENSE("GPL v2");