[RFC PATCH 8/9] tty: serial: add tty over I3C master side driver

[Frank Li]

This is master side tty driver for tty over i3c.

Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
---
 drivers/tty/serial/Kconfig  |   6 +
 drivers/tty/serial/Makefile |   1 +
 drivers/tty/serial/ttyi3c.c | 276 ++++++++++++++++++++++++++++++++++++
 3 files changed, 283 insertions(+)
 create mode 100644 drivers/tty/serial/ttyi3c.c

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index bdc568a4ab669..2ceafe94cd1dc 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1578,6 +1578,12 @@ config SERIAL_NUVOTON_MA35D1_CONSOLE
 	  but you can alter that using a kernel command line option such as
 	  "console=ttyNVTx".
 
+config SERIAL_I3C
+	tristate "tty over i3c"
+	depends on I3C
+	help
+	  Select this options if you'd like use UART over I3C master controller
+
 endmenu
 
 config SERIAL_MCTRL_GPIO
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 138abbc897381..60c101809cdcf 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -88,6 +88,7 @@ obj-$(CONFIG_SERIAL_MILBEAUT_USIO) += milbeaut_usio.o
 obj-$(CONFIG_SERIAL_SIFIVE)	+= sifive.o
 obj-$(CONFIG_SERIAL_LITEUART) += liteuart.o
 obj-$(CONFIG_SERIAL_SUNPLUS)	+= sunplus-uart.o
+obj-$(CONFIG_SERIAL_I3C)	+= ttyi3c.o
 
 # GPIOLIB helpers for modem control lines
 obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/ttyi3c.c b/drivers/tty/serial/ttyi3c.c
new file mode 100644
index 0000000000000..e2912c8bac87d
--- /dev/null
+++ b/drivers/tty/serial/ttyi3c.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2023 NXP.
+ *
+ * Author: Frank Li <Frank.Li@xxxxxxx>
+ */
+
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/i3c/device.h>
+#include <linux/i3c/master.h>
+#include <linux/slab.h>
+#include <linux/console.h>
+#include <linux/serial_core.h>
+#include <linux/dmaengine.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/tty_flip.h>
+
+#define DEVICE_NAME "ttyI3C"
+#define PORT_I3C 124
+
+struct ttyi3c_port {
+	struct uart_port	port;
+	unsigned int		txfifo_size;
+	unsigned int		rxfifo_size;
+	void			*buffer;
+	struct i3c_device	*i3cdev;
+	struct work_struct	work;
+	struct workqueue_struct *workqueue;
+};
+
+static struct uart_driver ttyi3c_reg = {
+	.owner		= THIS_MODULE,
+	.driver_name	= "fsl_ttyi3c",
+	.dev_name	= DEVICE_NAME,
+	.nr		= 1,
+};
+
+static const struct i3c_device_id fsl_tty_i3c_ids[] = {
+	I3C_DEVICE(0x011B, 0x1000, NULL),
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(i3c, fsl_tty_i3c_ids);
+
+static unsigned int ttyi3c_tx_empty(struct uart_port *port)
+{
+	return 0;
+}
+
+static void ttyi3c_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+
+}
+
+static unsigned int ttyi3c_get_mctrl(struct uart_port *port)
+{
+	return 0;
+}
+
+static void ttyi3c_stop_tx(struct uart_port *port)
+{
+}
+
+static void ttyi3c_stop_rx(struct uart_port *port)
+{
+
+}
+
+static void ttyi3c_break_ctl(struct uart_port *port, int break_state)
+{
+
+}
+
+static int ttyi3c_startup(struct uart_port *port)
+{
+	return 0;
+}
+
+static void ttyi3c_shutdown(struct uart_port *port)
+{
+
+}
+
+static void ttyi3c_uart_pm(struct uart_port *port, unsigned int state, unsigned int oldstate)
+{
+
+}
+
+static void
+ttyi3c_set_termios(struct uart_port *port, struct ktermios *termios, const struct ktermios *old)
+{
+
+}
+
+static const char *ttyi3c_type(struct uart_port *port)
+{
+	return "I3CTTY";
+}
+
+static void ttyi3c_release_port(struct uart_port *port)
+{
+
+}
+
+static int ttyi3c_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+static void ttyi3c_config_port(struct uart_port *port, int flags)
+{
+
+}
+
+static int ttyi3c_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	return 0;
+}
+
+static void ttyi3c_flush_buffer(struct uart_port *port)
+{
+
+}
+
+static void ttyi3c_start_tx(struct uart_port *port)
+{
+	struct ttyi3c_port *sport = container_of(port, struct ttyi3c_port, port);
+
+	queue_work(sport->workqueue, &sport->work);
+}
+
+static const struct uart_ops ttyi3c_pops = {
+	.tx_empty	= ttyi3c_tx_empty,
+	.set_mctrl	= ttyi3c_set_mctrl,
+	.get_mctrl	= ttyi3c_get_mctrl,
+	.stop_tx	= ttyi3c_stop_tx,
+	.start_tx	= ttyi3c_start_tx,
+	.stop_rx	= ttyi3c_stop_rx,
+	.break_ctl	= ttyi3c_break_ctl,
+	.startup	= ttyi3c_startup,
+	.shutdown	= ttyi3c_shutdown,
+	.pm		= ttyi3c_uart_pm,
+	.set_termios	= ttyi3c_set_termios,
+	.type		= ttyi3c_type,
+	.request_port	= ttyi3c_request_port,
+	.release_port	= ttyi3c_release_port,
+	.config_port	= ttyi3c_config_port,
+	.verify_port	= ttyi3c_verify_port,
+	.flush_buffer	= ttyi3c_flush_buffer,
+};
+
+static void
+i3c_controller_irq_handler(struct i3c_device *dev, const struct i3c_ibi_payload *payload)
+{
+
+	struct ttyi3c_port *sport =  dev_get_drvdata(&dev->dev);
+	struct i3c_priv_xfer xfers;
+	int i = 0;
+
+	memset(&xfers, 0, sizeof(xfers));
+
+	xfers.data.in = sport->buffer;
+	xfers.len = 16;
+	xfers.rnw = 1;
+
+	i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1);
+
+	for (i = 0; i < xfers.actual; i++)
+		if (tty_insert_flip_char(&sport->port.state->port, *(u8 *)(sport->buffer + i), 0)
+		    == 0)
+			sport->port.icount.buf_overrun++;
+
+	tty_flip_buffer_push(&sport->port.state->port);
+}
+
+static void fsl_tty_i3c_work(struct work_struct *work)
+{
+	struct ttyi3c_port *sport = container_of(work, struct ttyi3c_port, work);
+	struct circ_buf *xmit = &sport->port.state->xmit;
+	int cnt = CIRC_CNT(xmit->head, xmit->tail, UART_XMIT_SIZE);
+	struct i3c_priv_xfer xfers;
+	int actual;
+	int ret;
+
+	if (cnt == 0)
+		return;
+
+	if (cnt > 0) {
+		xfers.rnw = 0;
+		xfers.len = ((xmit->tail + cnt) > UART_XMIT_SIZE) ? UART_XMIT_SIZE - xmit->tail :
+								    cnt;
+		xfers.data.out = xmit->buf + xmit->tail;
+
+		ret = i3c_device_do_priv_xfers(sport->i3cdev, &xfers, 1);
+
+		actual = ret ? xfers.actual : xfers.len;
+
+		uart_xmit_advance(&sport->port, actual);
+
+		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+			uart_write_wakeup(&sport->port);
+
+		cnt -= actual;
+	}
+
+	if (cnt)
+		queue_work(sport->workqueue, &sport->work);
+}
+
+static int fsl_tty_i3c_probe(struct i3c_device *i3cdev)
+{
+	struct ttyi3c_port *port;
+	struct i3c_ibi_setup req;
+	int ret;
+
+	port = devm_kzalloc(&i3cdev->dev, sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	port->i3cdev = i3cdev;
+	port->port.ops = &ttyi3c_pops;
+	port->port.type = PORT_I3C;
+	port->port.dev = &i3cdev->dev;
+	port->buffer = devm_kzalloc(&i3cdev->dev, UART_XMIT_SIZE, GFP_KERNEL);
+
+	req.max_payload_len = 8;
+	req.num_slots = 4;
+	req.handler = &i3c_controller_irq_handler;
+
+	dev_set_drvdata(&i3cdev->dev, port);
+
+	INIT_WORK(&port->work, fsl_tty_i3c_work);
+	port->workqueue = alloc_workqueue("%s", 0, 0, dev_name(&i3cdev->dev));
+	if (!port->workqueue)
+		return -ENOMEM;
+
+	ret = uart_register_driver(&ttyi3c_reg);
+	if (ret)
+		return ret;
+
+	ret = uart_add_one_port(&ttyi3c_reg, &port->port);
+	if (ret)
+		goto err_add_one_port;
+
+	ret = i3c_device_request_ibi(i3cdev, &req);
+	if (ret)
+		goto err_request_ibi;
+
+	ret = i3c_device_enable_ibi(i3cdev);
+	if (ret)
+		goto  err_enable_ibi;
+
+	return 0;
+
+err_enable_ibi:
+	i3c_device_free_ibi(i3cdev);
+err_request_ibi:
+	uart_remove_one_port(&ttyi3c_reg, &port->port);
+err_add_one_port:
+	uart_unregister_driver(&ttyi3c_reg);
+
+	return ret;
+}
+
+static struct i3c_driver fsl_tty_i3c_driver = {
+	.driver = {
+		.name = "ttyi3c",
+	},
+	.probe = fsl_tty_i3c_probe,
+	.id_table = fsl_tty_i3c_ids,
+};
+
+module_i3c_driver(fsl_tty_i3c_driver);
+MODULE_LICENSE("GPL");
-- 
2.34.1