[PATCH 8/9] serdev: add a tty port controller driver

Rob Herring
2017-01-06T16:26:34Z

Add a serdev controller driver for tty ports.

The controller is registered with serdev when tty ports are registered
with the TTY core. As the TTY core is built-in only, this has the side
effect of making serdev built-in as well.

Signed-off-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
drivers/tty/serdev/Kconfig | 8 ++
drivers/tty/serdev/Makefile | 2 +
drivers/tty/serdev/serdev-ttyport.c | 244 ++++++++++++++++++++++++++++++++++++
include/linux/serdev.h | 20 +++
4 files changed, 274 insertions(+)
create mode 100644 drivers/tty/serdev/serdev-ttyport.c

diff --git a/drivers/tty/serdev/Kconfig b/drivers/tty/serdev/Kconfig
index 3b6ecd187bef..7eac4cc42785 100644
--- a/drivers/tty/serdev/Kconfig
+++ b/drivers/tty/serdev/Kconfig
@@ -6,3 +6,11 @@ menuconfig SERIAL_DEV_BUS
help
Core support for devices connected via a serial port.

+if SERIAL_DEV_BUS
+
+config SERIAL_DEV_CTRL_TTYPORT
+ bool "Serial device TTY port controller"
+ depends on TTY
+ depends on SERIAL_DEV_BUS=y
+
+endif
diff --git a/drivers/tty/serdev/Makefile b/drivers/tty/serdev/Makefile
index 01a9b62183f4..0cbdb9444d9d 100644
--- a/drivers/tty/serdev/Makefile
+++ b/drivers/tty/serdev/Makefile
@@ -1,3 +1,5 @@
serdev-objs := core.o

obj-$(CONFIG_SERIAL_DEV_BUS) += serdev.o
+
+obj-$(CONFIG_SERIAL_DEV_CTRL_TTYPORT) += serdev-ttyport.o
diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
new file mode 100644
index 000000000000..ed6fd675ece6
--- /dev/null
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -0,0 +1,244 @@
+/*
+ * Copyright (C) 2016 Linaro Ltd., Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/serdev.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+
+#define SERPORT_BUSY 1
+#define SERPORT_ACTIVE 2
+#define SERPORT_DEAD 3
+
+struct serport {
+ struct tty_port *port;
+ struct tty_struct *tty;
+ struct tty_driver *tty_drv;
+ int tty_idx;
+ struct mutex lock;
+ unsigned long flags;
+};
+
+/*
+ * Callback functions from the tty port.
+ */
+
+static int ttyport_receive_buf(struct tty_port *port, const unsigned char *cp,
+ const unsigned char *fp, size_t count)
+{
+ struct serdev_controller *ctrl = port->client_data;
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+
+ mutex_lock(&serport->lock);
+
+ if (!test_bit(SERPORT_ACTIVE, &serport->flags))
+ goto out;
+
+ serdev_controller_receive_buf(ctrl, cp, count);
+
+out:
+ mutex_unlock(&serport->lock);
+ return count;
+}
+
+static void ttyport_write_wakeup(struct tty_port *port)
+{
+ struct serdev_controller *ctrl = port->client_data;
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+
+ clear_bit(TTY_DO_WRITE_WAKEUP, &port->tty->flags);
+
+ if (test_bit(SERPORT_ACTIVE, &serport->flags))
+ serdev_controller_write_wakeup(ctrl);
+}
+
+static const struct tty_port_client_operations client_ops = {
+ .receive_buf = ttyport_receive_buf,
+ .write_wakeup = ttyport_write_wakeup,
+};
+
+/*
+ * Callback functions from the serdev core.
+ */
+
+static int ttyport_write_buf(struct serdev_controller *ctrl, const unsigned char *data, size_t len)
+{
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+ struct tty_struct *tty = serport->tty;
+
+ set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+ return serport->tty->ops->write(serport->tty, data, len);
+}
+
+static void ttyport_write_flush(struct serdev_controller *ctrl)
+{
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+ struct tty_struct *tty = serport->tty;
+
+ tty_driver_flush_buffer(tty);
+}
+
+static int ttyport_write_room(struct serdev_controller *ctrl)
+{
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+ struct tty_struct *tty = serport->tty;
+
+ return tty_write_room(tty);
+}
+
+
+static int ttyport_open(struct serdev_controller *ctrl)
+{
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+ struct tty_struct *tty;
+ struct ktermios ktermios;
+
+ tty = tty_init_dev(serport->tty_drv, serport->tty_idx);
+ serport->tty = tty;
+
+ serport->port->client_ops = &client_ops;
+ serport->port->client_data = ctrl;
+
+ tty->receive_room = 65536;
+
+ if (tty->ops->open)
+ tty->ops->open(serport->tty, NULL);
+ else
+ tty_port_open(serport->port, tty, NULL);
+
+ /* Bring the UART into a known 8 bits no parity hw fc state */
+ ktermios = tty->termios;
+ ktermios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP |
+ INLCR | IGNCR | ICRNL | IXON);
+ ktermios.c_oflag &= ~OPOST;
+ ktermios.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
+ ktermios.c_cflag &= ~(CSIZE | PARENB);
+ ktermios.c_cflag |= CS8;
+ ktermios.c_cflag |= CRTSCTS;
+ tty_set_termios(tty, &ktermios);
+
+ set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+
+ mutex_lock(&serport->lock);
+ set_bit(SERPORT_ACTIVE, &serport->flags);
+ mutex_unlock(&serport->lock);
+
+ tty_unlock(serport->tty);
+ return 0;
+}
+
+static void ttyport_close(struct serdev_controller *ctrl)
+{
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+ struct tty_struct *tty = serport->tty;
+
+ mutex_lock(&serport->lock);
+
+ if (tty->ops->close)
+ tty->ops->close(tty, NULL);
+
+ tty_release_struct(tty, serport->tty_idx);
+
+ clear_bit(SERPORT_ACTIVE, &serport->flags);
+ mutex_unlock(&serport->lock);
+}
+
+static unsigned int ttyport_set_baudrate(struct serdev_controller *ctrl, unsigned int speed)
+{
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+ struct tty_struct *tty = serport->tty;
+ struct ktermios ktermios = tty->termios;
+
+ ktermios.c_cflag &= ~CBAUD;
+ tty_termios_encode_baud_rate(&ktermios, speed, speed);
+
+ /* tty_set_termios() return not checked as it is always 0 */
+ tty_set_termios(tty, &ktermios);
+ return speed;
+}
+
+static void ttyport_set_flow_control(struct serdev_controller *ctrl, bool enable)
+{
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+ struct tty_struct *tty = serport->tty;
+ struct ktermios ktermios = tty->termios;
+
+ if (enable)
+ ktermios.c_cflag |= CRTSCTS;
+ else
+ ktermios.c_cflag &= ~CRTSCTS;
+
+ tty_set_termios(tty, &ktermios);
+}
+
+struct serdev_controller_ops ctrl_ops = {
+ .write_buf = ttyport_write_buf,
+ .write_flush = ttyport_write_flush,
+ .write_room = ttyport_write_room,
+ .open = ttyport_open,
+ .close = ttyport_close,
+ .set_flow_control = ttyport_set_flow_control,
+ .set_baudrate = ttyport_set_baudrate,
+};
+
+int serdev_tty_port_register(struct tty_port *port, struct device *parent,
+ struct tty_driver *drv, int idx)
+{
+ struct serdev_controller *ctrl;
+ struct serport *serport;
+ int ret;
+
+ if (!port || !drv || !parent || !parent->of_node)
+ return -ENODEV;
+
+ ctrl = serdev_controller_alloc(parent, sizeof(struct serport));
+ if (!ctrl)
+ return -ENOMEM;
+ serport = serdev_controller_get_drvdata(ctrl);
+
+ mutex_init(&serport->lock);
+ serport->port = port;
+ serport->tty_idx = idx;
+ serport->tty_drv = drv;
+
+ ctrl->ops = &ctrl_ops;
+
+ ret = serdev_controller_add(ctrl);
+ if (ret)
+ goto err;
+
+ printk(KERN_INFO "serdev: Serial port %s\n", drv->name);
+ return 0;
+
+err:
+ serdev_controller_put(ctrl);
+ return ret;
+}
+
+void serdev_tty_port_unregister(struct tty_port *port)
+{
+ struct serdev_controller *ctrl = port->client_data;
+ struct serport *serport = serdev_controller_get_drvdata(ctrl);
+
+ if (!serport)
+ return;
+
+ serdev_controller_remove(ctrl);
+ port->client_ops = NULL;
+ port->client_data = NULL;
+ serdev_controller_put(ctrl);
+}
+
+MODULE_AUTHOR("Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org");
+MODULE_DESCRIPTION("TTY port serial bus controller");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/serdev.h b/include/linux/serdev.h
index 4dc4ee62c2bb..d0e396744da5 100644
--- a/include/linux/serdev.h
+++ b/include/linux/serdev.h
@@ -204,4 +204,24 @@ static inline int serdev_controller_receive_buf(struct serdev_controller *ctrl,
return 0;
}

+/*
+ * serdev hooks into TTY core
+ */
+struct tty_port;
+struct tty_driver;
+
+#ifdef CONFIG_SERIAL_DEV_CTRL_TTYPORT
+int serdev_tty_port_register(struct tty_port *port, struct device *parent,
+ struct tty_driver *drv, int idx);
+void serdev_tty_port_unregister(struct tty_port *port);
+#else
+static inline int serdev_tty_port_register(struct tty_port *port,
+ struct device *parent,
+ struct tty_driver *drv, int idx)
+{
+ return -ENODEV;
+}
+static inline void serdev_tty_port_unregister(struct tty_port *port) {}
+#endif
+
#endif
--
2.10.1