[PATCH] usb:serial: Add Fintek F81532/534 driver

[Ji-Ze Hong (Peter Hong)]

This driver is for Fintek F81532/F81534 USB to Serial Ports IC.

F81532 spec:
https://drive.google.com/file/d/0B8vRwwYO7aMFOTRRMmhWQVNvajQ/view?
usp=sharing

F81534 spec:
https://drive.google.com/file/d/0B8vRwwYO7aMFV29pQWJqbVBNc00/view?
usp=sharing

Features:
1. F81532 is 1-to-2 & F81534 is 1-to-4 serial ports IC
2. Support Baudrate from B50 to B115200.

Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@xxxxxxxxx>
---
Changelog:
v9
    1. Remove lots of code to make more generic for F81532/534. e.g.,
       high baud rate support, RS485/422 mode switch, most of GPIO
       control and internal storage write functional.
    2. Change f81534_tiocmget() MSR delay from schedule_timeout_killable()
       to wait_for_completion_killable_timeout(). This IC will delayed
       receiving MSR change when doing loop-back test e.g., BurnInTest.
       We'll reset completion "msr_done" in f81534_update_mctrl(). If we
       changed MCR, the next f81534_tiocmget() will delay for 20ms or
       continue with new MSR arrived.
    3. Fix for non-zero buffer allocated in f81534_setup_ports(). It'll
       make device malfunctional with incorrect tx length for other ports.

v8
    1. Remove driver mode GPIOLIB & RS485 control support, the driver will
       only load GPIO/UART Mode when driver attach() & port_probe().
    2. Add more documents for 3 generation IC with f81534_calc_num_ports().
    3. Simplify the GPIO register structure "f81534_pin_control".
    4. Change all counter type from int to size_t.
    5. Change some failed message with failed: "status code" and remove all
       exclamation mark in messages.
    6. Change all save blocks to block0 due to the driver is only used 1
       block (block0) to save data.
    7. Change read MSR in open() instead of port_probe().
    8. use GFP_ATOMIC kmalloc mode in write().
    9. Maintain old style with 1 read URBs and 4 write URBs like mxuports.c
       I had tested with submit 4 read URBs, but it'll make some port freeze
       when doing BurnInTest Port test.

v7
    1. Make all gpiolib function with #ifdef CONFIG_GPIOLIB marco block.
       Due to F81532/534 could run without gpiolib, we implements
       f81534_prepare_gpio()/f81534_release_gpio() always success without
       CONFIG_GPIOLIB.
    2. Fix crash when receiving MSR change on driver load/unload. It's cause
       by f81534_process_read_urb() get read URB callback data, but port
       private data is not init complete or released. We solve with 2
       modifications.

       1. add null pointer check with f81534_process_read_urb(). We'll skip
          this report when port_priv = NULL.
       2. when "one" port f81534_port_remove() is called, kill the port-0
          read URB before kfree port_priv.

v6
    1. Re-implement the write()/resume() function. Due to this device cant be
       suitable with generic write(), we'll do the submit write URB when
       write()/received tx empty/set_termios()/resume()
    2. Logic/Phy Port mapping rewrite in f81534_port_probe() &
       f81534_phy_to_logic_port().
    3. Introduced "Port Hide" function. Some customer use F81532 reference
       design for HW layout, but really use F81534 IC. We'll check
       F81534_PORT_CONF_DISABLE_PORT flag with in uart mode field to do
       port hide with port not used. It can be avoid end-user to use not
       layouted port.
    4. The 4x3 output-only open-drain pins for F81532/534 is designed for
       control outer devices (with our EVB for examples, the 4 sets of pins
       are designed to control transceiver mode). So we decide to implement
       with gpiolib interface.
    5. Add device vendor id with 0x2c42

v5
    1. Change f81534_port_disable/enable() from H/W mode to S/W mode
       It'll skip all rx data when port is not opened.
    2. Some function modifier add with static (Thanks for Paul Bolle)
    3. It's will direct return when count=0 in f81534_write() to
       reduce spin_lock usage.

v4
    1. clearify f81534_process_read_urb() with
       f81534_process_per_serial_block(). (referenced from mxuport.c)
    2. We limited f81534_write() max tx kfifo with 124Bytes.
       Original subsystem is designed for auto tranmiting fifo data
       if available. But we must wait for tx_empty for next tx data
       (H/W design).

       With this kfifo size limit, we can use generic subsystem api with
       f81534_write(). When usb_serial_generic_write_start() called after
       first write URB complete, the fifo will no data. The generic
       subsystem of write will go to idle state. Until we received
       TX_EMPTY and release write spinlock, the fifo will fill max
       124Bytes by following f81534_write().

v3
    1. Migrate read, write and some routine from custom code to usbserial
       subsystem callback function.
    2. Use more defines to replece magic numbers to make it meaningful
    3. Make more comments as document in source code.

v2
    1. v1 version submit to staging tree, but Greg KH advised me to
       cleanup source code & re-submit it to correct subsystem
    2. Remove all custom ioctl commands

 drivers/usb/serial/Kconfig  |   10 +
 drivers/usb/serial/Makefile |    1 +
 drivers/usb/serial/f81534.c | 1528 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1539 insertions(+)
 create mode 100644 drivers/usb/serial/f81534.c

diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
index 56ecb8b..0642864 100644
--- a/drivers/usb/serial/Kconfig
+++ b/drivers/usb/serial/Kconfig
@@ -255,6 +255,16 @@ config USB_SERIAL_F81232
 	  To compile this driver as a module, choose M here: the
 	  module will be called f81232.
 
+config USB_SERIAL_F8153X
+	tristate "USB Fintek F81532/534 Multi-Ports Serial Driver"
+	help
+	  Say Y here if you want to use the Fintek F81532/534 Multi-Ports
+	  usb to serial adapter.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called f81534.
+
+
 config USB_SERIAL_GARMIN
        tristate "USB Garmin GPS driver"
        help
diff --git a/drivers/usb/serial/Makefile b/drivers/usb/serial/Makefile
index 349d9df..9e43b7b 100644
--- a/drivers/usb/serial/Makefile
+++ b/drivers/usb/serial/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_USB_SERIAL_EDGEPORT)		+= io_edgeport.o
 obj-$(CONFIG_USB_SERIAL_EDGEPORT_TI)		+= io_ti.o
 obj-$(CONFIG_USB_SERIAL_EMPEG)			+= empeg.o
 obj-$(CONFIG_USB_SERIAL_F81232)			+= f81232.o
+obj-$(CONFIG_USB_SERIAL_F8153X)			+= f81534.o
 obj-$(CONFIG_USB_SERIAL_FTDI_SIO)		+= ftdi_sio.o
 obj-$(CONFIG_USB_SERIAL_GARMIN)			+= garmin_gps.o
 obj-$(CONFIG_USB_SERIAL_IPAQ)			+= ipaq.o
diff --git a/drivers/usb/serial/f81534.c b/drivers/usb/serial/f81534.c
new file mode 100644
index 0000000..c1cb52d
--- /dev/null
+++ b/drivers/usb/serial/f81534.c
@@ -0,0 +1,1528 @@
+/*
+ * F81532/F81534 USB to Serial Ports Bridge
+ *
+ * F81532 => 2 Serial Ports
+ * F81534 => 4 Serial Ports
+ *
+ * Copyright (C) 2016 Tom Tsai (Tom_Tsai@xxxxxxxxxxxxx)
+ *		 2016 Peter Hong (Peter_Hong@xxxxxxxxxxxxx)
+ *
+ * The F81532/F81534 had 1 control endpoint for setting, 1 endpoint bulk-out
+ * for all serial port TX and 1 endpoint bulk-in for all serial port read in
+ * (Read Data/MSR/LSR).
+ *
+ * Write URB is fixed with 512bytes, per serial port used 128Bytes.
+ * It can be described by f81534_prepare_write_buffer()
+ *
+ * Read URB is 512Bytes max, per serial port used 128Bytes.
+ * It can be described by f81534_process_read_urb() and maybe received with
+ * 128x1,2,3,4 bytes.
+ *
+ */
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+#include <linux/serial_reg.h>
+#include <linux/module.h>
+
+/* Serial Port register Address */
+#define SERIAL_BASE_ADDRESS		0x1200
+#define DIVISOR_LATCH_LSB		(0x00 + SERIAL_BASE_ADDRESS)
+#define DIVISOR_LATCH_MSB		(0x01 + SERIAL_BASE_ADDRESS)
+#define FIFO_CONTROL_REGISTER		(0x02 + SERIAL_BASE_ADDRESS)
+#define LINE_CONTROL_REGISTER		(0x03 + SERIAL_BASE_ADDRESS)
+#define MODEM_CONTROL_REGISTER		(0x04 + SERIAL_BASE_ADDRESS)
+#define MODEM_STATUS_REGISTER		(0x06 + SERIAL_BASE_ADDRESS)
+#define CONFIG1_REGISTER		(0x09 + SERIAL_BASE_ADDRESS)
+
+#define F81534_DEF_CONF_ADDRESS_START	0x3000
+#define F81534_DEF_CONF_SIZE		8
+
+#define F81534_CUSTOM_ADDRESS_START	0x2f00
+#define F81534_CUSTOM_DATA_SIZE		0x10
+#define F81534_CUSTOM_NO_CUSTOM_DATA	(-1)
+#define F81534_CUSTOM_VALID_TOKEN	0xf0
+#define F81534_CONF_OFFSET		1
+
+#define F81534_MAX_DATA_BLOCK		64
+#define F81534_MAX_BUS_RETRY		2000
+
+/* Default URB timeout for USB operations */
+#define F81534_USB_MAX_RETRY		10
+#define F81534_USB_TIMEOUT		1000
+#define F81534_SET_GET_REGISTER		0xA0
+#define F81534_DELAY_READ_MSR		10
+
+#define F81534_NUM_PORT			4
+#define F81534_UNUSED_PORT		0xff
+#define F81534_WRITE_BUFFER_SIZE	512
+
+#define IC_NAME				"f81534"
+#define DRIVER_DESC			"Fintek F81532/F81534"
+#define FINTEK_VENDOR_ID_1		0x1934
+#define FINTEK_VENDOR_ID_2		0x2C42
+#define FINTEK_DEVICE_ID		0x1202
+#define F81534_MAX_TX_SIZE		100
+#define F81534_RECEIVE_BLOCK_SIZE	128
+
+#define F81534_TOKEN_RECEIVE		0x01
+#define F81534_TOKEN_WRITE		0x02
+#define F81534_TOKEN_TX_EMPTY		0x03
+#define F81534_TOKEN_MSR_CHANGE		0x04
+
+#define F81534_BUS_BUSY			0x03
+#define F81534_BUS_IDLE			0x04
+#define F81534_BUS_READ_DATA		0x1004
+#define F81534_BUS_REG_STATUS		0x1003
+#define F81534_BUS_REG_START		0x1002
+#define F81534_BUS_REG_END		0x1001
+
+#define F81534_CMD_READ			0x03
+#define F81534_CMD_ENABLE_WR		0x06
+#define F81534_CMD_PROGRAM		0x02
+#define F81534_CMD_ERASE		0x20
+
+#define F81534_DEFAULT_BAUD_RATE	9600
+#define F81534_MAX_BAUDRATE		115200
+
+#define F81534_PORT_CONF_DISABLE_PORT	BIT(3)
+#define F81534_PORT_CONF_NOT_EXIST_PORT	BIT(7)
+#define F81534_PORT_UNAVAILABLE		\
+	(F81534_PORT_CONF_DISABLE_PORT | F81534_PORT_CONF_NOT_EXIST_PORT)
+
+#define F81534_1X_RXTRIGGER		0xc3
+#define F81534_8X_RXTRIGGER		0xcf
+
+/* Default put M0/M1/M2 as 0/0/1 */
+#define F81534_PIN_SET_DEFAULT		0x01
+
+/* Save for a control register and bit offset */
+struct reg_value {
+	const u16 reg_address;
+	const u16 reg_offset;
+};
+
+/*
+ * The following register is for F81532/534 output pin register maps to control
+ * F81532/534 M0_SD/M1/M2 per port and we can reference f81438/439 transceiver
+ * spec to get mode list. If you are not use F81438/439, please review
+ * f81534_switch_gpio_mode() for desire gpio out value.
+ *
+ * For examples, we want to control F81532/534 port 0 M0_SD/M1/M2 to 0/0/1.
+ * We'll do with following instructions.
+ *
+ *	1. set reg 0x2ae8 bit7 to 0 (M0_SD)
+ *	2. set reg 0x2a90 bit5 to 0 (M1)
+ *	3. set reg 0x2a90 bit4 to 1 (M2)
+ *
+ * F81438 Spec:
+ * http://www.alldatasheet.com/datasheet-pdf/pdf/459082/FINTEK/F81438.html
+ */
+static const struct reg_value f81534_pin_control[4][3] = {
+	/* M0_SD	M1		M2 */
+	{{0x2ae8, 7}, {0x2a90, 5}, {0x2a90, 4}, },	/* port 0 pins */
+	{{0x2ae8, 6}, {0x2ae8, 0}, {0x2ae8, 3}, },	/* port 1 pins */
+	{{0x2a90, 0}, {0x2ae8, 2}, {0x2a80, 6}, },	/* port 2 pins */
+	{{0x2a90, 3}, {0x2a90, 2}, {0x2a90, 1}, },	/* port 3 pins */
+};
+
+static const struct usb_device_id f81534_id_table[] = {
+	{USB_DEVICE(FINTEK_VENDOR_ID_1, FINTEK_DEVICE_ID)},
+	{USB_DEVICE(FINTEK_VENDOR_ID_2, FINTEK_DEVICE_ID)},
+	{}			/* Terminating entry */
+};
+
+struct f81534_serial_private {
+	bool is_phy_port_not_empty[F81534_NUM_PORT];
+	u8 default_conf_data[F81534_DEF_CONF_SIZE];
+	atomic_t port_active[F81534_NUM_PORT];
+	spinlock_t tx_empty_lock;
+	u32 setting_idx;
+};
+
+struct f81534_port_private {
+	struct completion msr_done;
+	struct mutex mcr_mutex;
+	spinlock_t msr_lock;
+	u8 shadow_mcr;
+	u8 shadow_msr;
+	u8 phy;
+};
+
+/*
+ * Get the current logical port index of this device. e.g., If this port is
+ * ttyUSB2 and start port is ttyUSB0, this will return 2.
+ */
+static int f81534_port_index(struct usb_serial_port *port)
+{
+	return port->port_number;
+}
+
+/*
+ * Find logic serial port index with H/W phy index mapping. Due to our device
+ * can be enable/disable port by internal storage to make the port phy no
+ * continuously, we can use this to find phy & logical port mapping.
+ */
+static int f81534_phy_to_logic_port(struct usb_serial *serial, int phy)
+{
+	struct f81534_serial_private *priv = usb_get_serial_data(serial);
+	size_t count = 0, i;
+
+	for (i = 0; i < phy; ++i) {
+		if (priv->default_conf_data[i] & F81534_PORT_UNAVAILABLE)
+			continue;
+
+		++count;
+	}
+
+	dev_dbg(&serial->dev->dev, "%s: phy: %d count: %zu\n", __func__, phy,
+			count);
+	return count;
+}
+
+static int f81534_set_normal_register(struct usb_device *dev, u16 reg, u8 data)
+{
+	size_t count = F81534_USB_MAX_RETRY;
+	int status;
+	u8 *tmp;
+
+	tmp = kmalloc(sizeof(u8), GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	*tmp = data;
+
+	/*
+	 * Our device maybe not reply when heavily loading, We'll retry for
+	 * F81534_USB_MAX_RETRY times.
+	 */
+	while (count--) {
+		status = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
+					 F81534_SET_GET_REGISTER,
+					 USB_TYPE_VENDOR | USB_DIR_OUT,
+					 reg, 0, tmp, sizeof(u8),
+					 F81534_USB_TIMEOUT);
+		if (status > 0)
+			break;
+
+		if (status == 0)
+			status = -EIO;
+	}
+
+	if (status < 0) {
+		dev_err(&dev->dev, "%s: reg: %x data: %x failed: %d\n",
+				__func__, reg, data, status);
+		kfree(tmp);
+		return status;
+	}
+
+	kfree(tmp);
+	return 0;
+}
+
+static int f81534_get_normal_register(struct usb_device *dev, u16 reg,
+					u8 *data)
+{
+	size_t count = F81534_USB_MAX_RETRY;
+	int status;
+	u8 *tmp;
+
+	tmp = kmalloc(sizeof(u8), GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	/*
+	 * Our device maybe not reply when heavily loading, We'll retry for
+	 * F81534_USB_MAX_RETRY times.
+	 */
+	while (count--) {
+		status = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+					 F81534_SET_GET_REGISTER,
+					 USB_TYPE_VENDOR | USB_DIR_IN,
+					 reg, 0, tmp, sizeof(u8),
+					 F81534_USB_TIMEOUT);
+		if (status > 0)
+			break;
+
+		if (status == 0)
+			status = -EIO;
+	}
+
+	if (status < 0) {
+		dev_err(&dev->dev, "%s: reg: %x failed: %d\n", __func__, reg,
+				status);
+		kfree(tmp);
+		return status;
+	}
+
+	*data = *tmp;
+	kfree(tmp);
+	return 0;
+}
+
+static int f81534_set_mask_normal_register(struct usb_device *dev, u16 reg,
+						u8 mask, u8 data)
+{
+	int status;
+	u8 tmp;
+
+	status = f81534_get_normal_register(dev, reg, &tmp);
+	if (status)
+		return status;
+
+	tmp = (tmp & ~mask) | (mask & data);
+
+	status = f81534_set_normal_register(dev, reg, tmp);
+	if (status)
+		return status;
+
+	return 0;
+}
+
+static int f81534_setregister(struct usb_device *dev, u8 uart, u16 reg,
+				u8 data)
+{
+	return f81534_set_normal_register(dev, reg + uart * 0x10, data);
+}
+
+static int f81534_getregister(struct usb_device *dev, u8 uart, u16 reg,
+				u8 *data)
+{
+	return f81534_get_normal_register(dev, reg + uart * 0x10, data);
+}
+
+static int f81534_command_delay(struct usb_serial *usbserial)
+{
+	struct usb_device *dev = usbserial->dev;
+	size_t count = F81534_MAX_BUS_RETRY;
+	unsigned char tmp;
+	int status;
+
+	do {
+		status = f81534_get_normal_register(dev, F81534_BUS_REG_STATUS,
+							&tmp);
+		if (status)
+			return status;
+
+		if (tmp & F81534_BUS_BUSY)
+			continue;
+
+		if (tmp & F81534_BUS_IDLE)
+			break;
+
+	} while (--count);
+
+	if (!count)
+		return -EIO;
+
+	status = f81534_set_normal_register(dev, F81534_BUS_REG_STATUS,
+				tmp & ~F81534_BUS_IDLE);
+	if (status)
+		return status;
+
+	return 0;
+}
+
+static int f81534_get_normal_register_with_delay(struct usb_serial *usbserial,
+							u16 reg, u8 *data)
+{
+	struct usb_device *dev = usbserial->dev;
+	int status;
+
+	status = f81534_get_normal_register(dev, reg, data);
+	if (status)
+		return status;
+
+	status = f81534_command_delay(usbserial);
+	if (status)
+		return status;
+
+	return 0;
+}
+
+static int f81534_set_normal_register_with_delay(struct usb_serial *usbserial,
+							u16 reg, u8 data)
+{
+	struct usb_device *dev = usbserial->dev;
+	int status;
+
+	status = f81534_set_normal_register(dev, reg, data);
+	if (status)
+		return status;
+
+	status = f81534_command_delay(usbserial);
+	if (status)
+		return status;
+
+	return 0;
+}
+
+static int f81534_read_data(struct usb_serial *usbserial, u32 address,
+				size_t size, unsigned char *buf)
+{
+	u8 tmp_buf[F81534_MAX_DATA_BLOCK];
+	size_t read_size, count, block = 0;
+	int status, offset;
+	u16 reg_tmp;
+
+	status = f81534_set_normal_register_with_delay(usbserial,
+				F81534_BUS_REG_START, F81534_CMD_READ);
+	if (status)
+		return status;
+
+	status = f81534_set_normal_register_with_delay(usbserial,
+				F81534_BUS_REG_START, (address >> 16) & 0xff);
+	if (status)
+		return status;
+
+	status = f81534_set_normal_register_with_delay(usbserial,
+				F81534_BUS_REG_START, (address >> 8) & 0xff);
+	if (status)
+		return status;
+
+	status = f81534_set_normal_register_with_delay(usbserial,
+				F81534_BUS_REG_START, (address >> 0) & 0xff);
+	if (status)
+		return status;
+
+	/* Continuous read mode */
+	do {
+		read_size = min_t(u32, F81534_MAX_DATA_BLOCK, size);
+
+		for (count = 0; count < read_size; ++count) {
+			/* To write F81534_BUS_REG_END when final byte */
+			if (size <= F81534_MAX_DATA_BLOCK && read_size ==
+					count + 1)
+				reg_tmp = F81534_BUS_REG_END;
+			else
+				reg_tmp = F81534_BUS_REG_START;
+
+			/*
+			 * Dummy code, force IC to generate a read pulse, the
+			 * set of value 0xf1 is dont care (any value is ok)
+			 */
+			status = f81534_set_normal_register_with_delay(
+					usbserial, reg_tmp, 0xf1);
+			if (status)
+				return status;
+
+			status = f81534_get_normal_register_with_delay(
+						usbserial,
+						F81534_BUS_READ_DATA,
+						&tmp_buf[count]);
+			if (status)
+				return status;
+
+			offset = count + block * F81534_MAX_DATA_BLOCK;
+			buf[offset] = tmp_buf[count];
+		}
+
+		size -= read_size;
+		++block;
+	} while (size);
+
+	return 0;
+}
+
+static int f81534_prepare_write_buffer(struct usb_serial_port *port,
+					void *dest, size_t size)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	unsigned char *ptr = (unsigned char *)dest;
+	int port_num = port_priv->phy;
+
+	/*
+	 * The block layout is fixed with 4x128 Bytes, per 128 Bytes a port.
+	 * index 0: port phy idx (e.g., 0,1,2,3)
+	 * index 1: only F81534_TOKEN_WRITE
+	 * index 2: serial out size
+	 * index 3: fix to 0
+	 * index 4~127: serial out data block
+	 */
+	ptr[F81534_RECEIVE_BLOCK_SIZE * 0] = 0;
+	ptr[F81534_RECEIVE_BLOCK_SIZE * 1] = 1;
+	ptr[F81534_RECEIVE_BLOCK_SIZE * 2] = 2;
+	ptr[F81534_RECEIVE_BLOCK_SIZE * 3] = 3;
+	ptr[F81534_RECEIVE_BLOCK_SIZE * port_num + 1] = F81534_TOKEN_WRITE;
+	ptr[F81534_RECEIVE_BLOCK_SIZE * port_num + 3] = 0;
+	ptr[F81534_RECEIVE_BLOCK_SIZE * port_num + 2] =
+		kfifo_out_locked(&port->write_fifo,
+				&ptr[F81534_RECEIVE_BLOCK_SIZE * port_num + 4],
+				F81534_MAX_TX_SIZE, &port->lock);
+
+	return F81534_WRITE_BUFFER_SIZE;
+}
+
+static int f81534_submit_writer(struct usb_serial_port *port, gfp_t mem_flags)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	struct f81534_serial_private *serial_priv =
+			usb_get_serial_data(port->serial);
+	struct urb *urb;
+	unsigned long flags;
+	int result;
+
+	/* Check is any data in write_fifo */
+	spin_lock_irqsave(&port->lock, flags);
+
+	if (kfifo_is_empty(&port->write_fifo)) {
+		spin_unlock_irqrestore(&port->lock, flags);
+		return 0;
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	/* Check H/W is TXEMPTY */
+	spin_lock_irqsave(&serial_priv->tx_empty_lock, flags);
+
+	if (serial_priv->is_phy_port_not_empty[port_priv->phy]) {
+		spin_unlock_irqrestore(&serial_priv->tx_empty_lock, flags);
+		return 0;
+	}
+
+	serial_priv->is_phy_port_not_empty[port_priv->phy] = true;
+	spin_unlock_irqrestore(&serial_priv->tx_empty_lock, flags);
+
+	urb = port->write_urbs[0];
+	f81534_prepare_write_buffer(port, port->bulk_out_buffers[0],
+					port->bulk_out_size);
+	urb->transfer_buffer_length = F81534_WRITE_BUFFER_SIZE;
+
+	result = usb_submit_urb(urb, mem_flags);
+	if (result) {
+		dev_err(&port->dev, "%s: submit failed: %d\n", __func__,
+				result);
+		return result;
+	}
+
+	return 0;
+}
+
+static int f81534_switch_gpio_mode(struct usb_serial_port *port, u8 mode)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	struct usb_device *dev = port->serial->dev;
+	const struct reg_value *ptr;
+	int x = port_priv->phy, val, status;
+	size_t y;
+
+	ptr = f81534_pin_control[x];
+	for (y = 0; y < ARRAY_SIZE(f81534_pin_control[x]); ++y) {
+		val = mode & BIT(y) ? BIT(ptr[y].reg_offset) : 0;
+		status = f81534_set_mask_normal_register(dev,
+					ptr[y].reg_address,
+					BIT(ptr[y].reg_offset), val);
+		if (status) {
+			dev_err(&port->dev, "%s: index: %zu failed: %d\n",
+					__func__, y, status);
+			return status;
+		}
+	}
+
+	return 0;
+}
+
+static u32 f81534_calc_baud_divisor(u32 baudrate, u32 clockrate)
+{
+	if (!baudrate)
+		return 0;
+
+	/* Round to nearest divisor */
+	return DIV_ROUND_CLOSEST(clockrate, baudrate);
+}
+
+static int f81534_set_port_config(struct usb_device *dev, u8 port_number,
+					 struct usb_serial_port *port,
+					 u32 baudrate, u8 lcr)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	struct usb_serial *serial = port->serial;
+	u16 device_port = port_priv->phy;
+	u32 divisor;
+	int status;
+	u8 value;
+
+	if (baudrate <= 1200)
+		value = F81534_1X_RXTRIGGER;	/* 128 FIFO & TL: 1x */
+	else
+		value = F81534_8X_RXTRIGGER;	/* 128 FIFO & TL: 8x */
+
+	status = f81534_setregister(serial->dev, device_port, CONFIG1_REGISTER,
+					value);
+	if (status) {
+		dev_err(&port->dev, "%s: CONFIG1 setting failed.\n", __func__);
+		return status;
+	}
+
+	if (baudrate <= 1200)
+		value = UART_FCR_TRIGGER_1 | UART_FCR_ENABLE_FIFO; /* TL: 1 */
+	else if (baudrate >= 1152000)
+		value = UART_FCR_R_TRIG_10 | UART_FCR_ENABLE_FIFO; /* TL: 8 */
+	else
+		value = UART_FCR_R_TRIG_11 | UART_FCR_ENABLE_FIFO; /* TL: 14 */
+
+	status = f81534_setregister(serial->dev, device_port,
+					    FIFO_CONTROL_REGISTER, value);
+	if (status) {
+		dev_err(&port->dev, "%s: FCR setting failed.\n", __func__);
+		return status;
+	}
+
+	divisor = f81534_calc_baud_divisor(baudrate, F81534_MAX_BAUDRATE);
+	value = UART_LCR_DLAB;
+	status = f81534_setregister(serial->dev, device_port,
+						LINE_CONTROL_REGISTER, value);
+	if (status) {
+		dev_err(&port->dev, "%s: set LCR failed.\n", __func__);
+		return status;
+	}
+
+	value = divisor & 0xff;
+	status = f81534_setregister(serial->dev, device_port,
+					DIVISOR_LATCH_LSB, value);
+	if (status) {
+		dev_err(&port->dev, "%s: set DLAB LSB failed.\n", __func__);
+		return status;
+	}
+
+	value = (divisor >> 8) & 0xff;
+	status = f81534_setregister(serial->dev, device_port,
+					DIVISOR_LATCH_MSB, value);
+	if (status) {
+		dev_err(&port->dev, "%s: set DLAB MSB failed.\n", __func__);
+		return status;
+	}
+
+	status = f81534_setregister(serial->dev, device_port,
+						LINE_CONTROL_REGISTER, lcr);
+	if (status) {
+		dev_err(&port->dev, "%s: set LCR failed.\n", __func__);
+		return status;
+	}
+
+	return 0;
+}
+
+static int f81534_update_mctrl(struct usb_serial_port *port, unsigned int set,
+				unsigned int clear)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	struct usb_device *dev = port->serial->dev;
+	int status;
+	u8 tmp;
+
+	reinit_completion(&port_priv->msr_done);
+	mutex_lock(&port_priv->mcr_mutex);
+
+	if (((set | clear) & (TIOCM_DTR | TIOCM_RTS)) == 0) {
+		dev_dbg(&dev->dev, "%s: DTR|RTS not being set/cleared\n",
+				__func__);
+		mutex_unlock(&port_priv->mcr_mutex);
+		return 0;	/* no change */
+	}
+
+	/* 'Set' takes precedence over 'Clear' */
+	clear &= ~set;
+
+	/* Always enable UART_MCR_OUT2 */
+	tmp = UART_MCR_OUT2 | port_priv->shadow_mcr;
+
+	if (clear & TIOCM_DTR)
+		tmp &= ~UART_MCR_DTR;
+
+	if (clear & TIOCM_RTS)
+		tmp &= ~UART_MCR_RTS;
+
+	if (set & TIOCM_DTR)
+		tmp |= UART_MCR_DTR;
+
+	if (set & TIOCM_RTS)
+		tmp |= UART_MCR_RTS;
+
+	status = f81534_setregister(dev, port_priv->phy,
+					MODEM_CONTROL_REGISTER, tmp);
+	if (status < 0) {
+		dev_err(&port->dev, "%s: MCR write failed.\n", __func__);
+		mutex_unlock(&port_priv->mcr_mutex);
+		return status;
+	}
+
+	port_priv->shadow_mcr = tmp;
+	mutex_unlock(&port_priv->mcr_mutex);
+	return 0;
+}
+
+/*
+ * This function will search the data area with token F81534_CUSTOM_VALID_TOKEN
+ * for latest configuration index. If nothing found (*index = -1), the caller
+ * will load default configure in F81534_DEF_CONF_ADDRESS_START section.
+ *
+ * Due to we only use block0 to save data, so *index should be 0 or
+ * F81534_CUSTOM_NO_CUSTOM_DATA(-1).
+ */
+static int f81534_find_config_idx(struct usb_serial *serial, uintptr_t *index)
+{
+	u8 custom_data;
+	int status;
+
+	status = f81534_read_data(serial, F81534_CUSTOM_ADDRESS_START, 1,
+				&custom_data);
+	if (status) {
+		dev_err(&serial->dev->dev, "%s: read failed: %d\n", __func__,
+				status);
+		return status;
+	}
+
+	/*
+	 * If had custom setting, override. The 1st byte is a
+	 * indicator. 0xff is empty, F81534_CUSTOM_VALID_TOKEN is had
+	 * data. read and skip with 1st data.
+	 */
+	if (custom_data == F81534_CUSTOM_VALID_TOKEN)
+		*index = 0;
+	else
+		*index = F81534_CUSTOM_NO_CUSTOM_DATA;
+
+	return 0;
+}
+
+/*
+ * We had 2 generation of F81532/534 IC. All has an internal storage.
+ *
+ * 1st is pure USB-to-TTL RS232 IC and designed for 4 ports only, no any
+ * internal data will used. All mode and gpio control should manually set
+ * by AP or Driver and all storage space value are 0xff. The
+ * f81534_calc_num_ports() will run to final we marked as "oldest version"
+ * for this IC.
+ *
+ * 2rd is designed to more generic to use any transceiver and this is our
+ * mass production type. We'll save data in F81534_CUSTOM_ADDRESS_START
+ * (0x2f00) with 9bytes. The 1st byte is a indicater. If the token is not
+ * F81534_CUSTOM_VALID_TOKEN(0xf0), the IC is 2nd gen type, the following
+ * 4bytes save port mode (0:RS232/1:RS485 Invert/2:RS485), and the last
+ * 4bytes save GPIO state(value from 0~7 to represent 3 GPIO output pin).
+ * The f81534_calc_num_ports() will run to "new style" with checking
+ * F81534_PORT_UNAVAILABLE section.
+ */
+static int f81534_calc_num_ports(struct usb_serial *serial)
+{
+	unsigned char setting[F81534_CUSTOM_DATA_SIZE];
+	uintptr_t setting_idx;
+	u8 num_port = 0;
+	int status;
+	size_t i;
+
+	/* Check had custom setting */
+	status = f81534_find_config_idx(serial, &setting_idx);
+	if (status) {
+		dev_err(&serial->dev->dev, "%s: find idx failed: %d\n",
+				__func__, status);
+		return 0;
+	}
+
+	/* Save the configuration area idx as private data for attach() */
+	usb_set_serial_data(serial, (void *)setting_idx);
+
+	/* Read default board setting */
+	status = f81534_read_data(serial, F81534_DEF_CONF_ADDRESS_START,
+				  F81534_NUM_PORT, setting);
+	if (status) {
+		dev_err(&serial->dev->dev, "%s: read failed: %d\n", __func__,
+				status);
+		return 0;
+	}
+
+	/*
+	 * If had custom setting, override it. 1st byte is a indicator, 0xff
+	 * is empty, F81534_CUSTOM_VALID_TOKEN is had data, then skip with 1st
+	 * data
+	 */
+	if (setting_idx != F81534_CUSTOM_NO_CUSTOM_DATA) {
+		status = f81534_read_data(serial, F81534_CUSTOM_ADDRESS_START +
+						F81534_CONF_OFFSET,
+						sizeof(setting), setting);
+		if (status) {
+			dev_err(&serial->dev->dev,
+					"%s: get custom data failed: %d\n",
+					__func__, status);
+			return 0;
+		}
+
+		dev_dbg(&serial->dev->dev,
+				"%s: read configure from block: %d\n",
+				__func__, (unsigned int)setting_idx);
+	} else {
+		dev_dbg(&serial->dev->dev, "%s: read configure default\n",
+				__func__);
+	}
+
+	/* New style, find all possible ports */
+	num_port = 0;
+	for (i = 0; i < F81534_NUM_PORT; ++i) {
+		if (setting[i] & F81534_PORT_UNAVAILABLE)
+			continue;
+
+		++num_port;
+	}
+
+	if (num_port)
+		return num_port;
+
+	dev_warn(&serial->dev->dev, "Read Failed. default 4 ports\n");
+	return 4;		/* Nothing found, oldest version IC */
+}
+
+static void f81534_set_termios(struct tty_struct *tty,
+				struct usb_serial_port *port,
+				struct ktermios *old_termios)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	struct usb_device *dev = port->serial->dev;
+	u8 new_lcr = 0;
+	int status;
+	u32 baud;
+
+	if (C_BAUD(tty) == B0)
+		f81534_update_mctrl(port, 0, TIOCM_DTR | TIOCM_RTS);
+	else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
+		f81534_update_mctrl(port, TIOCM_DTR | TIOCM_RTS, 0);
+
+	if (C_PARENB(tty)) {
+		new_lcr |= UART_LCR_PARITY;
+
+		if (!C_PARODD(tty))
+			new_lcr |= UART_LCR_EPAR;
+
+		if (C_CMSPAR(tty))
+			new_lcr |= UART_LCR_SPAR;
+	}
+
+	if (C_CSTOPB(tty))
+		new_lcr |= UART_LCR_STOP;
+
+	switch (C_CSIZE(tty)) {
+	case CS5:
+		new_lcr |= UART_LCR_WLEN5;
+		break;
+	case CS6:
+		new_lcr |= UART_LCR_WLEN6;
+		break;
+	case CS7:
+		new_lcr |= UART_LCR_WLEN7;
+		break;
+	default:
+	case CS8:
+		new_lcr |= UART_LCR_WLEN8;
+		break;
+	}
+
+	baud = tty_get_baud_rate(tty);
+	if (!baud)
+		return;
+
+	if (baud > F81534_MAX_BAUDRATE) {
+		if (old_termios)
+			baud = old_termios->c_ospeed;
+		else
+			baud = F81534_DEFAULT_BAUD_RATE;
+	}
+
+	dev_dbg(&dev->dev, "%s: baud: %d\n", __func__, baud);
+	tty_encode_baud_rate(tty, baud, baud);
+
+	status = f81534_set_port_config(dev, port_priv->phy, port, baud,
+						new_lcr);
+	if (status < 0) {
+		dev_err(&port->dev, "%s: set port config failed: %d\n",
+				__func__, status);
+	}
+}
+
+static int f81534_submit_read_urb(struct usb_serial *serial, gfp_t flags)
+{
+	int status;
+
+	status = usb_serial_generic_submit_read_urbs(serial->port[0], flags);
+	if (status) {
+		dev_err(&serial->dev->dev, "%s: submit read URB failed: %d\n",
+				__func__, status);
+		return status;
+	}
+
+	return 0;
+}
+
+static void f81534_msr_changed(struct usb_serial_port *port, u8 msr,
+				bool is_port_open)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	struct tty_struct *tty;
+	unsigned long flags;
+	u8 old_msr;
+
+	if (!(msr & UART_MSR_ANY_DELTA))
+		return;
+
+	spin_lock_irqsave(&port_priv->msr_lock, flags);
+	old_msr = port_priv->shadow_msr;
+	port_priv->shadow_msr = msr;
+	spin_unlock_irqrestore(&port_priv->msr_lock, flags);
+
+	dev_dbg(&port->dev, "%s: MSR from %02x to %02x\n", __func__, old_msr,
+			msr);
+
+	if (!is_port_open)
+		return;
+
+	/* Update input line counters */
+	if (msr & UART_MSR_DCTS)
+		port->icount.cts++;
+	if (msr & UART_MSR_DDSR)
+		port->icount.dsr++;
+	if (msr & UART_MSR_DDCD)
+		port->icount.dcd++;
+	if (msr & UART_MSR_TERI)
+		port->icount.rng++;
+
+	wake_up_interruptible(&port->port.delta_msr_wait);
+	complete(&port_priv->msr_done);
+
+	if (!(msr & UART_MSR_DDCD))
+		return;
+
+	dev_dbg(&port->dev, "%s: DCD Changed: port %d from %x to %x.\n",
+			__func__, port_priv->phy, old_msr, msr);
+
+	tty = tty_port_tty_get(&port->port);
+	if (!tty)
+		return;
+
+	usb_serial_handle_dcd_change(port, tty, msr & UART_MSR_DCD);
+	tty_kref_put(tty);
+}
+
+static int f81534_read_msr(struct usb_serial_port *port)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	struct usb_serial *serial = port->serial;
+	int phy = port_priv->phy, status;
+	unsigned long flags;
+	u8 msr;
+
+	/* Get MSR initial value*/
+	status = f81534_getregister(serial->dev, phy, MODEM_STATUS_REGISTER,
+					&msr);
+	if (status)
+		return status;
+
+	/* Force update current state */
+	spin_lock_irqsave(&port_priv->msr_lock, flags);
+	port_priv->shadow_msr = msr;
+	spin_unlock_irqrestore(&port_priv->msr_lock, flags);
+
+	f81534_msr_changed(port, msr, true);
+	return 0;
+}
+
+static int f81534_open(struct tty_struct *tty, struct usb_serial_port *port)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	struct f81534_serial_private *serial_priv =
+			usb_get_serial_data(port->serial);
+	int status, phy = port_priv->phy;
+
+	status = f81534_setregister(port->serial->dev, phy,
+				FIFO_CONTROL_REGISTER, UART_FCR_ENABLE_FIFO |
+				UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
+	if (status) {
+		dev_err(&port->dev, "%s: Clear FIFO failed: %d\n", __func__,
+				status);
+		return status;
+	}
+
+	if (tty)
+		f81534_set_termios(tty, port, &tty->termios);
+
+	status = f81534_read_msr(port);
+	if (status)
+		return status;
+
+	atomic_inc(&serial_priv->port_active[phy]);
+	return 0;
+}
+
+static void f81534_close(struct usb_serial_port *port)
+{
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	struct f81534_serial_private *serial_priv =
+			usb_get_serial_data(port->serial);
+	int phy = port_priv->phy;
+	unsigned long flags;
+	size_t i;
+
+	atomic_dec(&serial_priv->port_active[phy]);
+
+	/* Referenced from usb_serial_generic_close() */
+	for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
+		usb_kill_urb(port->write_urbs[i]);
+
+	spin_lock_irqsave(&port->lock, flags);
+	kfifo_reset_out(&port->write_fifo);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int f81534_get_serial_info(struct usb_serial_port *port,
+				  struct serial_struct __user *retinfo)
+{
+	struct f81534_port_private *port_priv;
+	struct serial_struct tmp;
+
+	port_priv = usb_get_serial_port_data(port);
+	if (!port_priv)
+		return -EFAULT;
+
+	if (!retinfo)
+		return -EFAULT;
+
+	memset(&tmp, 0, sizeof(tmp));
+
+	tmp.type = PORT_16550A;
+	tmp.port = port->port_number;
+	tmp.line = port->minor;
+	tmp.baud_base = F81534_MAX_BAUDRATE;
+
+	if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int f81534_ioctl(struct tty_struct *tty, unsigned int cmd,
+			unsigned long arg)
+{
+	struct usb_serial_port *port = tty->driver_data;
+
+	switch (cmd) {
+	case TIOCGSERIAL:
+		return f81534_get_serial_info(port,
+						(struct serial_struct __user *)
+						arg);
+	default:
+		break;
+	}
+
+	return -ENOIOCTLCMD;
+}
+
+static void f81534_process_per_serial_block(struct usb_serial_port *port,
+		unsigned char *data)
+{
+	struct f81534_serial_private *priv = usb_get_serial_data(port->serial);
+	int phy_port_num = data[0];
+	size_t i, read_size = 0;
+	unsigned long flags;
+	bool available;
+	char tty_flag;
+	int status;
+	u8 lsr;
+
+	available = !!atomic_read(&priv->port_active[phy_port_num]);
+
+	/*
+	 * The block layout is 128 Bytes
+	 * index 0: port phy idx (e.g., 0,1,2,3),
+	 * index 1: It's could be
+	 *			F81534_TOKEN_RECEIVE
+	 *			F81534_TOKEN_TX_EMPTY
+	 *			F81534_TOKEN_MSR_CHANGE
+	 * index 2: serial in size (data+lsr, must be even)
+	 *			meaningful for F81534_TOKEN_RECEIVE only
+	 * index 3: current MSR with this device
+	 * index 4~127: serial in data block (data+lsr, must be even)
+	 */
+	switch (data[1]) {
+	case F81534_TOKEN_TX_EMPTY:
+		/*
+		 * We should save TX_EMPTY flag even the port is not opened
+		 */
+		spin_lock_irqsave(&priv->tx_empty_lock, flags);
+		priv->is_phy_port_not_empty[phy_port_num] = false;
+		spin_unlock_irqrestore(&priv->tx_empty_lock, flags);
+		usb_serial_port_softint(port);
+
+		if (!available)
+			return;
+
+		/* Try to submit writer only when port is opened */
+		status = f81534_submit_writer(port, GFP_ATOMIC);
+		if (status)
+			dev_err(&port->dev, "%s: submit failed\n", __func__);
+		return;
+
+	case F81534_TOKEN_MSR_CHANGE:
+		/*
+		 * We'll save MSR value when device reported even when port
+		 * is not opened. If the port is not opened, the MSR will only
+		 * recorded without any future process.
+		 */
+		f81534_msr_changed(port, data[3], available);
+		return;
+
+	case F81534_TOKEN_RECEIVE:
+		if (!available)
+			return;
+
+		read_size = data[2];
+		break;
+
+	default:
+		dev_warn(&port->dev, "%s: unknown token:%02x\n", __func__,
+				data[1]);
+		return;
+	}
+
+	for (i = 4; i < 4 + read_size; i += 2) {
+		tty_flag = TTY_NORMAL;
+		lsr = data[i + 1];
+
+		if (lsr & UART_LSR_BRK_ERROR_BITS) {
+			if (lsr & UART_LSR_BI) {
+				tty_flag = TTY_BREAK;
+				port->icount.brk++;
+				usb_serial_handle_break(port);
+			} else if (lsr & UART_LSR_PE) {
+				tty_flag = TTY_PARITY;
+				port->icount.parity++;
+			} else if (lsr & UART_LSR_FE) {
+				tty_flag = TTY_FRAME;
+				port->icount.frame++;
+			}
+
+			if (lsr & UART_LSR_OE) {
+				port->icount.overrun++;
+				tty_insert_flip_char(&port->port, 0,
+						TTY_OVERRUN);
+			}
+		}
+
+		if (port->port.console && port->sysrq) {
+			if (usb_serial_handle_sysrq_char(port, data[i]))
+				continue;
+		}
+
+		tty_insert_flip_char(&port->port, data[i], tty_flag);
+	}
+
+	tty_flip_buffer_push(&port->port);
+}
+
+static void f81534_process_read_urb(struct urb *urb)
+{
+	struct f81534_port_private *port_priv;
+	struct usb_serial_port *port;
+	struct usb_serial *serial;
+	unsigned char *ch;
+	int phy_port_num;
+	int tty_port_num;
+	size_t i;
+
+	if (!urb->actual_length)
+		return;
+
+	port = urb->context;
+	serial = port->serial;
+	ch = urb->transfer_buffer;
+
+	for (i = 0; i < urb->actual_length; i += F81534_RECEIVE_BLOCK_SIZE) {
+		phy_port_num = ch[i];
+		tty_port_num = f81534_phy_to_logic_port(serial, phy_port_num);
+		port = serial->port[tty_port_num];
+
+		/*
+		 * The device will send back all information when we submitted
+		 * a read URB (MSR/DATA/TX_EMPTY). But it maybe get callback
+		 * before port_probe() or after port_remove().
+		 *
+		 * So we'll verify the pointer. If the pointer is NULL, it's
+		 * mean the port not init complete and the block will skip.
+		 */
+		port_priv = usb_get_serial_port_data(port);
+		if (!port_priv) {
+			dev_warn(&serial->dev->dev,
+					"%s: phy: %d not ready\n", __func__,
+					phy_port_num);
+			continue;
+		}
+
+		f81534_process_per_serial_block(port, &ch[i]);
+	}
+}
+
+static void f81534_write_usb_callback(struct urb *urb)
+{
+	struct usb_serial_port *port = urb->context;
+
+	switch (urb->status) {
+	case 0:
+		break;
+	case -ENOENT:
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		dev_dbg(&port->dev, "%s - urb stopped: %d\n",
+				__func__, urb->status);
+		return;
+	case -EPIPE:
+		dev_err(&port->dev, "%s - urb stopped: %d\n",
+				__func__, urb->status);
+		return;
+	default:
+		dev_dbg(&port->dev, "%s - nonzero urb status: %d\n",
+				__func__, urb->status);
+		break;
+	}
+
+	usb_serial_port_softint(port);
+}
+
+static int f81534_setup_ports(struct usb_serial *serial)
+{
+	struct usb_serial_port *port;
+	u8 port0_out_address;
+	int buffer_size;
+	size_t i, j;
+
+	/*
+	 * In our system architecture, we had 2 or 4 serial ports,
+	 * but only get 1 set of bulk in/out endpoints.
+	 *
+	 * The usb-serial subsystem will generate port 0 data,
+	 * but port 1/2/3 will not. It's will generate write URB and buffer
+	 * by following code and use the port0 read URB for read operation.
+	 */
+	for (i = 1; i < serial->num_ports; ++i) {
+		port0_out_address = serial->port[0]->bulk_out_endpointAddress;
+		buffer_size = serial->port[0]->bulk_out_size;
+		port = serial->port[i];
+
+		if (kfifo_alloc(&port->write_fifo, PAGE_SIZE, GFP_KERNEL))
+			goto failed;
+
+		port->bulk_out_size = buffer_size;
+		port->bulk_out_endpointAddress = port0_out_address;
+
+		for (j = 0; j < ARRAY_SIZE(port->write_urbs); ++j) {
+			set_bit(j, &port->write_urbs_free);
+
+			port->write_urbs[j] = usb_alloc_urb(0, GFP_KERNEL);
+			if (!port->write_urbs[j])
+				goto failed;
+
+			port->bulk_out_buffers[j] = kzalloc(buffer_size,
+								GFP_KERNEL);
+			if (!port->bulk_out_buffers[j])
+				goto failed;
+
+			usb_fill_bulk_urb(port->write_urbs[j], serial->dev,
+					usb_sndbulkpipe(serial->dev,
+						port0_out_address),
+					port->bulk_out_buffers[j], buffer_size,
+					serial->type->write_bulk_callback,
+					port);
+		}
+
+		port->write_urb = port->write_urbs[0];
+		port->bulk_out_buffer = port->bulk_out_buffers[0];
+	}
+
+	return 0;
+failed:
+	return -ENOMEM;
+}
+
+static int f81534_load_configure_data(struct usb_serial_port *port)
+{
+	int status;
+
+	/* Force GPIO to 0/0/1 currently */
+	status = f81534_switch_gpio_mode(port, F81534_PIN_SET_DEFAULT);
+	if (status) {
+		dev_err(&port->dev,
+				"%s: switch gpio mode failed: %d\n", __func__,
+				status);
+		return status;
+	}
+
+	return 0;
+}
+
+static int f81534_attach(struct usb_serial *serial)
+{
+	uintptr_t setting_idx = (uintptr_t)usb_get_serial_data(serial);
+	struct f81534_serial_private *serial_priv;
+	int status;
+	size_t i;
+
+	serial_priv = devm_kzalloc(&serial->dev->dev, sizeof(*serial_priv),
+					GFP_KERNEL);
+	if (!serial_priv)
+		return -ENOMEM;
+
+	usb_set_serial_data(serial, serial_priv);
+	serial_priv->setting_idx = setting_idx;
+
+	for (i = 0; i < F81534_NUM_PORT; ++i)
+		atomic_set(&serial_priv->port_active[i], 0);
+
+	spin_lock_init(&serial_priv->tx_empty_lock);
+
+	status = f81534_setup_ports(serial);
+	if (status)
+		return status;
+
+	/*
+	 * The default configuration layout:
+	 *	byte 0/1/2/3: uart setting
+	 *
+	 * We can reference from f81534_load_configure_data().
+	 */
+	status = f81534_read_data(serial, F81534_DEF_CONF_ADDRESS_START,
+				F81534_DEF_CONF_SIZE,
+				serial_priv->default_conf_data);
+	if (status) {
+		dev_err(&serial->dev->dev, "%s: read reserve data failed\n",
+				__func__);
+		return status;
+	}
+
+	/*
+	 * If serial_priv->setting_idx == F81534_CUSTOM_NO_CUSTOM_DATA
+	 * it's mean for no configuration in custom section, so we'll use
+	 * default config read from F81534_DEF_CONF_ADDRESS_START
+	 */
+	if (serial_priv->setting_idx == F81534_CUSTOM_NO_CUSTOM_DATA)
+		return 0;
+
+	/* Only read 8 bytes for mode & GPIO */
+	status = f81534_read_data(serial, F81534_CUSTOM_ADDRESS_START +
+					F81534_CONF_OFFSET,
+					sizeof(serial_priv->default_conf_data),
+					serial_priv->default_conf_data);
+	if (status) {
+		dev_err(&serial->dev->dev,
+				"%s: idx: %d get data failed: %d\n", __func__,
+				serial_priv->setting_idx, status);
+		return status;
+	}
+
+	/*
+	 * We'll register port 0 bulkin only once, It'll take all port received
+	 * data, MSR register change and TX_EMPTY information.
+	 */
+	status = f81534_submit_read_urb(serial, GFP_KERNEL);
+	if (status)
+		return status;
+
+	return 0;
+}
+
+static int f81534_port_probe(struct usb_serial_port *port)
+{
+	struct f81534_serial_private *serial_priv =
+			usb_get_serial_data(port->serial);
+	struct f81534_port_private *port_priv;
+	int port_index = f81534_port_index(port);
+	size_t i, count = 0;
+
+	port_priv = devm_kzalloc(&port->dev, sizeof(*port_priv), GFP_KERNEL);
+	if (!port_priv)
+		return -ENOMEM;
+
+	init_completion(&port_priv->msr_done);
+	spin_lock_init(&port_priv->msr_lock);
+	mutex_init(&port_priv->mcr_mutex);
+
+	/* Assign logic-to-phy mapping */
+	port_priv->phy = F81534_UNUSED_PORT;
+
+	for (i = 0; i < F81534_NUM_PORT; ++i) {
+		if (serial_priv->default_conf_data[i] &
+				F81534_PORT_UNAVAILABLE)
+			continue;
+
+		if (port_index == count) {
+			port_priv->phy = i;
+			break;
+		}
+
+		++count;
+	}
+
+	if (port_priv->phy == F81534_UNUSED_PORT)
+		return -ENODEV;
+
+	usb_set_serial_port_data(port, port_priv);
+	dev_dbg(&port->dev, "%s: mapping to phy: %d\n", __func__,
+			port_priv->phy);
+
+	return f81534_load_configure_data(port);
+}
+
+static int f81534_port_remove(struct usb_serial_port *port)
+{
+	size_t i;
+
+	/*
+	 * We had only submit port0 read URB for use, but we'll kill all port
+	 * read URBs for code consistency
+	 */
+	for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i)
+		usb_kill_urb(port->read_urbs[i]);
+
+	return 0;
+}
+
+static int f81534_tiocmget(struct tty_struct *tty)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	struct f81534_port_private *port_priv = usb_get_serial_port_data(port);
+	unsigned long flags;
+	int r;
+	u8 msr, mcr;
+
+	/*
+	 * We'll avoid to direct read MSR register without open(). The IC will
+	 * read the MSR changed and report it f81534_process_per_serial_block()
+	 * by F81534_TOKEN_MSR_CHANGE.
+	 *
+	 * When this device in heavy loading (e.g., BurnInTest Loopback Test)
+	 * The report of MSR register will delay received a bit. It's due to
+	 * MSR interrupt is lowest priority in 16550A. So we decide to sleep
+	 * a little time to pass the test.
+	 */
+	r = wait_for_completion_killable_timeout(&port_priv->msr_done,
+				msecs_to_jiffies(F81534_DELAY_READ_MSR));
+	if (r < 0)
+		return -EINTR;
+
+	mutex_lock(&port_priv->mcr_mutex);
+	spin_lock_irqsave(&port_priv->msr_lock, flags);
+
+	msr = port_priv->shadow_msr;
+	mcr = port_priv->shadow_mcr;
+
+	spin_unlock_irqrestore(&port_priv->msr_lock, flags);
+	mutex_unlock(&port_priv->mcr_mutex);
+
+	r = (mcr & UART_MCR_DTR ? TIOCM_DTR : 0) |
+	    (mcr & UART_MCR_RTS ? TIOCM_RTS : 0) |
+	    (msr & UART_MSR_CTS ? TIOCM_CTS : 0) |
+	    (msr & UART_MSR_DCD ? TIOCM_CAR : 0) |
+	    (msr & UART_MSR_RI ? TIOCM_RI : 0) |
+	    (msr & UART_MSR_DSR ? TIOCM_DSR : 0);
+
+	return r;
+}
+
+static int f81534_tiocmset(struct tty_struct *tty,
+			   unsigned int set, unsigned int clear)
+{
+	struct usb_serial_port *port = tty->driver_data;
+
+	return f81534_update_mctrl(port, set, clear);
+}
+
+static void f81534_dtr_rts(struct usb_serial_port *port, int on)
+{
+	if (on)
+		f81534_update_mctrl(port, TIOCM_DTR | TIOCM_RTS, 0);
+	else
+		f81534_update_mctrl(port, 0, TIOCM_DTR | TIOCM_RTS);
+}
+
+static int f81534_write(struct tty_struct *tty,
+			struct usb_serial_port *port,
+			const unsigned char *buf, int count)
+{
+	int bytes_out, status;
+
+	if (!count)
+		return 0;
+
+	bytes_out = kfifo_in_locked(&port->write_fifo, buf, count,
+					&port->lock);
+
+	status = f81534_submit_writer(port, GFP_ATOMIC);
+	if (status) {
+		dev_err(&port->dev, "%s: submit failed\n", __func__);
+		return status;
+	}
+
+	return bytes_out;
+}
+
+static int f81534_resume(struct usb_serial *serial)
+{
+	struct usb_serial_port *port;
+	int status, error = 0;
+	size_t i;
+
+	/*
+	 * We'll register port 0 bulkin only once, It'll take all port received
+	 * data, MSR register change and TX_EMPTY information.
+	 */
+	status = f81534_submit_read_urb(serial, GFP_NOIO);
+	if (status)
+		return status;
+
+	for (i = 0; i < serial->num_ports; i++) {
+		port = serial->port[i];
+		if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags))
+			continue;
+
+		status = f81534_submit_writer(port, GFP_NOIO);
+		if (status) {
+			dev_err(&port->dev, "%s: submit failed\n", __func__);
+			++error;
+		}
+	}
+
+	return error ? -EIO : 0;
+}
+
+static struct usb_serial_driver f81534_device = {
+	.driver = {
+		   .owner = THIS_MODULE,
+		   .name = IC_NAME,
+		   },
+	.description = DRIVER_DESC,
+	.id_table = f81534_id_table,
+	.open = f81534_open,
+	.close = f81534_close,
+	.write = f81534_write,
+	.calc_num_ports = f81534_calc_num_ports,
+	.attach = f81534_attach,
+	.port_probe = f81534_port_probe,
+	.port_remove = f81534_port_remove,
+	.dtr_rts = f81534_dtr_rts,
+	.process_read_urb = f81534_process_read_urb,
+	.ioctl = f81534_ioctl,
+	.tiocmget = f81534_tiocmget,
+	.tiocmset = f81534_tiocmset,
+	.write_bulk_callback = f81534_write_usb_callback,
+	.set_termios = f81534_set_termios,
+	.resume = f81534_resume,
+};
+
+static struct usb_serial_driver *const serial_drivers[] = {
+	&f81534_device, NULL
+};
+
+module_usb_serial_driver(serial_drivers, f81534_id_table);
+
+MODULE_DEVICE_TABLE(usb, f81534_id_table);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("Peter Hong <Peter_Hong@xxxxxxxxxxxxx>");
+MODULE_AUTHOR("Tom Tsai <Tom_Tsai@xxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL");
-- 
1.9.1