USB: serial: add uPD78F0730 USB to Serial Adaptor Driver

The adaptor can be found on development boards for 78k, RL78 and V850
microcontrollers produced by Renesas Electronics Corporation.

This is not a full-featured USB to serial converter, however it allows
basic communication and simple control which is enough for programming of
on-board flash and debugging through a debug monitor.

uPD78F0730 is a USB-enabled microcontroller with USB-to-UART conversion
implemented in firmware.

This chip is also present in some debugging adaptors which use it for
USB-to-SPI conversion as well. The present driver doesn't cover SPI,
only USB-to-UART conversion is supported.

Signed-off-by: Maksim Salau <[e-mail]>
Signed-off-by: Johan Hovold <[e-mail]>

drivers/usb/serial/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called quatech-serial.
 
+config USB_SERIAL_UPD78F0730
+	tristate "USB Renesas uPD78F0730 Single Port Serial Driver"
+	help
+	  Say Y here if you want to use the Renesas uPD78F0730
+	  serial driver.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called upd78f0730.
+
 config USB_SERIAL_DEBUG
 	tristate "USB Debugging Device"
 	help

drivers/usb/serial/Makefile

···
 obj-$(CONFIG_USB_SERIAL_SYMBOL)			+= symbolserial.o
 obj-$(CONFIG_USB_SERIAL_WWAN)			+= usb_wwan.o
 obj-$(CONFIG_USB_SERIAL_TI)			+= ti_usb_3410_5052.o
+obj-$(CONFIG_USB_SERIAL_UPD78F0730)		+= upd78f0730.o
 obj-$(CONFIG_USB_SERIAL_VISOR)			+= visor.o
 obj-$(CONFIG_USB_SERIAL_WISHBONE)		+= wishbone-serial.o
 obj-$(CONFIG_USB_SERIAL_WHITEHEAT)		+= whiteheat.o

drivers/usb/serial/upd78f0730.c

···
+/*
+ * Renesas Electronics uPD78F0730 USB to serial converter driver
+ *
+ * Copyright (C) 2014,2016 Maksim Salau <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * Protocol of the adaptor is described in the application note U19660EJ1V0AN00
+ * μPD78F0730 8-bit Single-Chip Microcontroller
+ * USB-to-Serial Conversion Software
+ * <https://www.renesas.com/en-eu/doc/DocumentServer/026/U19660EJ1V0AN00.pdf>
+ *
+ * The adaptor functionality is limited to the following:
+ * - data bits: 7 or 8
+ * - stop bits: 1 or 2
+ * - parity: even, odd or none
+ * - flow control: none
+ * - baud rates: 0, 2400, 4800, 9600, 19200, 38400, 57600, 115200
+ * - signals: DTR, RTS and BREAK
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+
+#define DRIVER_DESC "Renesas uPD78F0730 USB to serial converter driver"
+
+#define DRIVER_AUTHOR "Maksim Salau <[e-mail]>"
+
+static const struct usb_device_id id_table[] = {
+	{ USB_DEVICE(0x045B, 0x0212) }, /* YRPBRL78G13, YRPBRL78G14 */
+	{ USB_DEVICE(0x0409, 0x0063) }, /* V850ESJX3-STICK */
+	{}
+};
+
+MODULE_DEVICE_TABLE(usb, id_table);
+
+/*
+ * Each adaptor is associated with a private structure, that holds the current
+ * state of control signals (DTR, RTS and BREAK).
+ */
+struct upd78f0730_port_private {
+	struct mutex	lock;		/* mutex to protect line_signals */
+	u8		line_signals;
+};
+
+/* Op-codes of control commands */
+#define UPD78F0730_CMD_LINE_CONTROL	0x00
+#define UPD78F0730_CMD_SET_DTR_RTS	0x01
+#define UPD78F0730_CMD_SET_XON_XOFF_CHR	0x02
+#define UPD78F0730_CMD_OPEN_CLOSE	0x03
+#define UPD78F0730_CMD_SET_ERR_CHR	0x04
+
+/* Data sizes in UPD78F0730_CMD_LINE_CONTROL command */
+#define UPD78F0730_DATA_SIZE_7_BITS	0x00
+#define UPD78F0730_DATA_SIZE_8_BITS	0x01
+#define UPD78F0730_DATA_SIZE_MASK	0x01
+
+/* Stop-bit modes in UPD78F0730_CMD_LINE_CONTROL command */
+#define UPD78F0730_STOP_BIT_1_BIT	0x00
+#define UPD78F0730_STOP_BIT_2_BIT	0x02
+#define UPD78F0730_STOP_BIT_MASK	0x02
+
+/* Parity modes in UPD78F0730_CMD_LINE_CONTROL command */
+#define UPD78F0730_PARITY_NONE	0x00
+#define UPD78F0730_PARITY_EVEN	0x04
+#define UPD78F0730_PARITY_ODD	0x08
+#define UPD78F0730_PARITY_MASK	0x0C
+
+/* Flow control modes in UPD78F0730_CMD_LINE_CONTROL command */
+#define UPD78F0730_FLOW_CONTROL_NONE	0x00
+#define UPD78F0730_FLOW_CONTROL_HW	0x10
+#define UPD78F0730_FLOW_CONTROL_SW	0x20
+#define UPD78F0730_FLOW_CONTROL_MASK	0x30
+
+/* Control signal bits in UPD78F0730_CMD_SET_DTR_RTS command */
+#define UPD78F0730_RTS		0x01
+#define UPD78F0730_DTR		0x02
+#define UPD78F0730_BREAK	0x04
+
+/* Port modes in UPD78F0730_CMD_OPEN_CLOSE command */
+#define UPD78F0730_PORT_CLOSE	0x00
+#define UPD78F0730_PORT_OPEN	0x01
+
+/* Error character substitution modes in UPD78F0730_CMD_SET_ERR_CHR command */
+#define UPD78F0730_ERR_CHR_DISABLED	0x00
+#define UPD78F0730_ERR_CHR_ENABLED	0x01
+
+/*
+ * Declaration of command structures
+ */
+
+/* UPD78F0730_CMD_LINE_CONTROL command */
+struct upd78f0730_line_control {
+	u8	opcode;
+	__le32	baud_rate;
+	u8	params;
+} __packed;
+
+/* UPD78F0730_CMD_SET_DTR_RTS command */
+struct upd78f0730_set_dtr_rts {
+	u8 opcode;
+	u8 params;
+};
+
+/* UPD78F0730_CMD_SET_XON_OFF_CHR command */
+struct upd78f0730_set_xon_xoff_chr {
+	u8 opcode;
+	u8 xon;
+	u8 xoff;
+};
+
+/* UPD78F0730_CMD_OPEN_CLOSE command */
+struct upd78f0730_open_close {
+	u8 opcode;
+	u8 state;
+};
+
+/* UPD78F0730_CMD_SET_ERR_CHR command */
+struct upd78f0730_set_err_chr {
+	u8 opcode;
+	u8 state;
+	u8 err_char;
+};
+
+static int upd78f0730_send_ctl(struct usb_serial_port *port,
+			const void *data, int size)
+{
+	struct usb_device *usbdev = port->serial->dev;
+	void *buf;
+	int res;
+
+	if (size <= 0 || !data)
+		return -EINVAL;
+
+	buf = kmemdup(data, size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	res = usb_control_msg(usbdev, usb_sndctrlpipe(usbdev, 0), 0x00,
+			USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
+			0x0000, 0x0000, buf, size, USB_CTRL_SET_TIMEOUT);
+
+	kfree(buf);
+
+	if (res != size) {
+		struct device *dev = &port->dev;
+
+		dev_err(dev, "failed to send control request %02x: %d\n",
+			*(u8 *)data, res);
+		/* The maximum expected length of a transfer is 6 bytes */
+		if (res >= 0)
+			res = -EIO;
+
+		return res;
+	}
+
+	return 0;
+}
+
+static int upd78f0730_port_probe(struct usb_serial_port *port)
+{
+	struct upd78f0730_port_private *private;
+
+	private = kzalloc(sizeof(*private), GFP_KERNEL);
+	if (!private)
+		return -ENOMEM;
+
+	mutex_init(&private->lock);
+	usb_set_serial_port_data(port, private);
+
+	return 0;
+}
+
+static int upd78f0730_port_remove(struct usb_serial_port *port)
+{
+	struct upd78f0730_port_private *private;
+
+	private = usb_get_serial_port_data(port);
+	mutex_destroy(&private->lock);
+	kfree(private);
+
+	return 0;
+}
+
+static int upd78f0730_tiocmget(struct tty_struct *tty)
+{
+	struct device *dev = tty->dev;
+	struct upd78f0730_port_private *private;
+	struct usb_serial_port *port = tty->driver_data;
+	int signals;
+	int res;
+
+	private = usb_get_serial_port_data(port);
+
+	mutex_lock(&private->lock);
+	signals = private->line_signals;
+	mutex_unlock(&private->lock);
+
+	res = ((signals & UPD78F0730_DTR) ? TIOCM_DTR : 0) |
+		((signals & UPD78F0730_RTS) ? TIOCM_RTS : 0);
+
+	dev_dbg(dev, "%s - res = %x\n", __func__, res);
+
+	return res;
+}
+
+static int upd78f0730_tiocmset(struct tty_struct *tty,
+			unsigned int set, unsigned int clear)
+{
+	struct device *dev = tty->dev;
+	struct usb_serial_port *port = tty->driver_data;
+	struct upd78f0730_port_private *private;
+	struct upd78f0730_set_dtr_rts request;
+	int res;
+
+	private = usb_get_serial_port_data(port);
+
+	mutex_lock(&private->lock);
+	if (set & TIOCM_DTR) {
+		private->line_signals |= UPD78F0730_DTR;
+		dev_dbg(dev, "%s - set DTR\n", __func__);
+	}
+	if (set & TIOCM_RTS) {
+		private->line_signals |= UPD78F0730_RTS;
+		dev_dbg(dev, "%s - set RTS\n", __func__);
+	}
+	if (clear & TIOCM_DTR) {
+		private->line_signals &= ~UPD78F0730_DTR;
+		dev_dbg(dev, "%s - clear DTR\n", __func__);
+	}
+	if (clear & TIOCM_RTS) {
+		private->line_signals &= ~UPD78F0730_RTS;
+		dev_dbg(dev, "%s - clear RTS\n", __func__);
+	}
+	request.opcode = UPD78F0730_CMD_SET_DTR_RTS;
+	request.params = private->line_signals;
+
+	res = upd78f0730_send_ctl(port, &request, sizeof(request));
+	mutex_unlock(&private->lock);
+
+	return res;
+}
+
+static void upd78f0730_break_ctl(struct tty_struct *tty, int break_state)
+{
+	struct device *dev = tty->dev;
+	struct upd78f0730_port_private *private;
+	struct usb_serial_port *port = tty->driver_data;
+	struct upd78f0730_set_dtr_rts request;
+
+	private = usb_get_serial_port_data(port);
+
+	mutex_lock(&private->lock);
+	if (break_state) {
+		private->line_signals |= UPD78F0730_BREAK;
+		dev_dbg(dev, "%s - set BREAK\n", __func__);
+	} else {
+		private->line_signals &= ~UPD78F0730_BREAK;
+		dev_dbg(dev, "%s - clear BREAK\n", __func__);
+	}
+	request.opcode = UPD78F0730_CMD_SET_DTR_RTS;
+	request.params = private->line_signals;
+
+	upd78f0730_send_ctl(port, &request, sizeof(request));
+	mutex_unlock(&private->lock);
+}
+
+static void upd78f0730_dtr_rts(struct usb_serial_port *port, int on)
+{
+	struct tty_struct *tty = port->port.tty;
+	unsigned int set = 0;
+	unsigned int clear = 0;
+
+	if (on)
+		set = TIOCM_DTR | TIOCM_RTS;
+	else
+		clear = TIOCM_DTR | TIOCM_RTS;
+
+	upd78f0730_tiocmset(tty, set, clear);
+}
+
+static speed_t upd78f0730_get_baud_rate(struct tty_struct *tty)
+{
+	const speed_t baud_rate = tty_get_baud_rate(tty);
+	const speed_t supported[] = {
+		0, 2400, 4800, 9600, 19200, 38400, 57600, 115200
+	};
+	int i;
+
+	for (i = ARRAY_SIZE(supported) - 1; i >= 0; i--) {
+		if (baud_rate == supported[i])
+			return baud_rate;
+	}
+
+	/* If the baud rate is not supported, switch to the default one */
+	tty_encode_baud_rate(tty, 9600, 9600);
+
+	return tty_get_baud_rate(tty);
+}
+
+static void upd78f0730_set_termios(struct tty_struct *tty,
+				struct usb_serial_port *port,
+				struct ktermios *old_termios)
+{
+	struct device *dev = &port->dev;
+	struct upd78f0730_line_control request;
+	speed_t baud_rate;
+
+	if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
+		return;
+
+	if (C_BAUD(tty) == B0)
+		upd78f0730_dtr_rts(port, 0);
+	else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
+		upd78f0730_dtr_rts(port, 1);
+
+	baud_rate = upd78f0730_get_baud_rate(tty);
+	request.opcode = UPD78F0730_CMD_LINE_CONTROL;
+	request.baud_rate = cpu_to_le32(baud_rate);
+	request.params = 0;
+	dev_dbg(dev, "%s - baud rate = %d\n", __func__, baud_rate);
+
+	switch (C_CSIZE(tty)) {
+	case CS7:
+		request.params |= UPD78F0730_DATA_SIZE_7_BITS;
+		dev_dbg(dev, "%s - 7 data bits\n", __func__);
+		break;
+	default:
+		tty->termios.c_cflag &= ~CSIZE;
+		tty->termios.c_cflag |= CS8;
+		dev_warn(dev, "data size is not supported, using 8 bits\n");
+		/* fall through */
+	case CS8:
+		request.params |= UPD78F0730_DATA_SIZE_8_BITS;
+		dev_dbg(dev, "%s - 8 data bits\n", __func__);
+		break;
+	}
+
+	if (C_PARENB(tty)) {
+		if (C_PARODD(tty)) {
+			request.params |= UPD78F0730_PARITY_ODD;
+			dev_dbg(dev, "%s - odd parity\n", __func__);
+		} else {
+			request.params |= UPD78F0730_PARITY_EVEN;
+			dev_dbg(dev, "%s - even parity\n", __func__);
+		}
+
+		if (C_CMSPAR(tty)) {
+			tty->termios.c_cflag &= ~CMSPAR;
+			dev_warn(dev, "MARK/SPACE parity is not supported\n");
+		}
+	} else {
+		request.params |= UPD78F0730_PARITY_NONE;
+		dev_dbg(dev, "%s - no parity\n", __func__);
+	}
+
+	if (C_CSTOPB(tty)) {
+		request.params |= UPD78F0730_STOP_BIT_2_BIT;
+		dev_dbg(dev, "%s - 2 stop bits\n", __func__);
+	} else {
+		request.params |= UPD78F0730_STOP_BIT_1_BIT;
+		dev_dbg(dev, "%s - 1 stop bit\n", __func__);
+	}
+
+	if (C_CRTSCTS(tty)) {
+		tty->termios.c_cflag &= ~CRTSCTS;
+		dev_warn(dev, "RTSCTS flow control is not supported\n");
+	}
+	if (I_IXOFF(tty) || I_IXON(tty)) {
+		tty->termios.c_iflag &= ~(IXOFF | IXON);
+		dev_warn(dev, "XON/XOFF flow control is not supported\n");
+	}
+	request.params |= UPD78F0730_FLOW_CONTROL_NONE;
+	dev_dbg(dev, "%s - no flow control\n", __func__);
+
+	upd78f0730_send_ctl(port, &request, sizeof(request));
+}
+
+static int upd78f0730_open(struct tty_struct *tty, struct usb_serial_port *port)
+{
+	struct upd78f0730_open_close request = {
+		.opcode = UPD78F0730_CMD_OPEN_CLOSE,
+		.state = UPD78F0730_PORT_OPEN
+	};
+	int res;
+
+	res = upd78f0730_send_ctl(port, &request, sizeof(request));
+	if (res)
+		return res;
+
+	if (tty)
+		upd78f0730_set_termios(tty, port, NULL);
+
+	return usb_serial_generic_open(tty, port);
+}
+
+static void upd78f0730_close(struct usb_serial_port *port)
+{
+	struct upd78f0730_open_close request = {
+		.opcode = UPD78F0730_CMD_OPEN_CLOSE,
+		.state = UPD78F0730_PORT_CLOSE
+	};
+
+	usb_serial_generic_close(port);
+	upd78f0730_send_ctl(port, &request, sizeof(request));
+}
+
+static struct usb_serial_driver upd78f0730_device = {
+	.driver	 = {
+		.owner	= THIS_MODULE,
+		.name	= "upd78f0730",
+	},
+	.id_table	= id_table,
+	.num_ports	= 1,
+	.port_probe	= upd78f0730_port_probe,
+	.port_remove	= upd78f0730_port_remove,
+	.open		= upd78f0730_open,
+	.close		= upd78f0730_close,
+	.set_termios	= upd78f0730_set_termios,
+	.tiocmget	= upd78f0730_tiocmget,
+	.tiocmset	= upd78f0730_tiocmset,
+	.dtr_rts	= upd78f0730_dtr_rts,
+	.break_ctl	= upd78f0730_break_ctl,
+};
+
+static struct usb_serial_driver * const serial_drivers[] = {
+	&upd78f0730_device,
+	NULL
+};
+
+module_usb_serial_driver(serial_drivers, id_table);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_LICENSE("GPL v2");