drivers/tty/serial/sprd_serial.c - kernel/bruno - Git at Google

 /*
  * Copyright (C) 2012-2015 Spreadtrum Communications Inc.
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
  * may be copied, distributed, and modified under those terms.
  *
  * 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.
  */

 #if defined(CONFIG_SERIAL_SPRD_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
 #define SUPPORT_SYSRQ
 #endif

 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/serial_core.h>
 #include <linux/serial.h>
 #include <linux/slab.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>

 /* device name */
 #define UART_NR_MAX		8
 #define SPRD_TTY_NAME		"ttyS"
 #define SPRD_FIFO_SIZE		128
 #define SPRD_DEF_RATE		26000000
 #define SPRD_BAUD_IO_LIMIT	3000000
 #define SPRD_TIMEOUT		256

 /* the offset of serial registers and BITs for them */
 /* data registers */
 #define SPRD_TXD		0x0000
 #define SPRD_RXD		0x0004

 /* line status register and its BITs  */
 #define SPRD_LSR		0x0008
 #define SPRD_LSR_OE		BIT(4)
 #define SPRD_LSR_FE		BIT(3)
 #define SPRD_LSR_PE		BIT(2)
 #define SPRD_LSR_BI		BIT(7)
 #define SPRD_LSR_TX_OVER	BIT(15)

 /* data number in TX and RX fifo */
 #define SPRD_STS1		0x000C

 /* interrupt enable register and its BITs */
 #define SPRD_IEN		0x0010
 #define SPRD_IEN_RX_FULL	BIT(0)
 #define SPRD_IEN_TX_EMPTY	BIT(1)
 #define SPRD_IEN_BREAK_DETECT	BIT(7)
 #define SPRD_IEN_TIMEOUT	BIT(13)

 /* interrupt clear register */
 #define SPRD_ICLR		0x0014

 /* line control register */
 #define SPRD_LCR		0x0018
 #define SPRD_LCR_STOP_1BIT	0x10
 #define SPRD_LCR_STOP_2BIT	0x30
 #define SPRD_LCR_DATA_LEN	(BIT(2) | BIT(3))
 #define SPRD_LCR_DATA_LEN5	0x0
 #define SPRD_LCR_DATA_LEN6	0x4
 #define SPRD_LCR_DATA_LEN7	0x8
 #define SPRD_LCR_DATA_LEN8	0xc
 #define SPRD_LCR_PARITY	(BIT(0) | BIT(1))
 #define SPRD_LCR_PARITY_EN	0x2
 #define SPRD_LCR_EVEN_PAR	0x0
 #define SPRD_LCR_ODD_PAR	0x1

 /* control register 1 */
 #define SPRD_CTL1			0x001C
 #define RX_HW_FLOW_CTL_THLD	BIT(6)
 #define RX_HW_FLOW_CTL_EN	BIT(7)
 #define TX_HW_FLOW_CTL_EN	BIT(8)
 #define RX_TOUT_THLD_DEF	0x3E00
 #define RX_HFC_THLD_DEF	0x40

 /* fifo threshold register */
 #define SPRD_CTL2		0x0020
 #define THLD_TX_EMPTY	0x40
 #define THLD_RX_FULL	0x40

 /* config baud rate register */
 #define SPRD_CLKD0		0x0024
 #define SPRD_CLKD1		0x0028

 /* interrupt mask status register */
 #define SPRD_IMSR			0x002C
 #define SPRD_IMSR_RX_FIFO_FULL		BIT(0)
 #define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
 #define SPRD_IMSR_BREAK_DETECT		BIT(7)
 #define SPRD_IMSR_TIMEOUT		BIT(13)

 struct reg_backup {
 	u32 ien;
 	u32 ctrl0;
 	u32 ctrl1;
 	u32 ctrl2;
 	u32 clkd0;
 	u32 clkd1;
 	u32 dspwait;
 };

 struct sprd_uart_port {
 	struct uart_port port;
 	struct reg_backup reg_bak;
 	char name[16];
 };

 static struct sprd_uart_port *sprd_port[UART_NR_MAX];
 static int sprd_ports_num;

 static inline unsigned int serial_in(struct uart_port *port, int offset)
 {
 	return readl_relaxed(port->membase + offset);
 }

 static inline void serial_out(struct uart_port *port, int offset, int value)
 {
 	writel_relaxed(value, port->membase + offset);
 }

 static unsigned int sprd_tx_empty(struct uart_port *port)
 {
 	if (serial_in(port, SPRD_STS1) & 0xff00)
 		return 0;
 	else
 		return TIOCSER_TEMT;
 }

 static unsigned int sprd_get_mctrl(struct uart_port *port)
 {
 	return TIOCM_DSR | TIOCM_CTS;
 }

 static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 	/* nothing to do */
 }

 static void sprd_stop_tx(struct uart_port *port)
 {
 	unsigned int ien, iclr;

 	iclr = serial_in(port, SPRD_ICLR);
 	ien = serial_in(port, SPRD_IEN);

 	iclr |= SPRD_IEN_TX_EMPTY;
 	ien &= ~SPRD_IEN_TX_EMPTY;

 	serial_out(port, SPRD_ICLR, iclr);
 	serial_out(port, SPRD_IEN, ien);
 }

 static void sprd_start_tx(struct uart_port *port)
 {
 	unsigned int ien;

 	ien = serial_in(port, SPRD_IEN);
 	if (!(ien & SPRD_IEN_TX_EMPTY)) {
 		ien |= SPRD_IEN_TX_EMPTY;
 		serial_out(port, SPRD_IEN, ien);
 	}
 }

 static void sprd_stop_rx(struct uart_port *port)
 {
 	unsigned int ien, iclr;

 	iclr = serial_in(port, SPRD_ICLR);
 	ien = serial_in(port, SPRD_IEN);

 	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
 	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;

 	serial_out(port, SPRD_IEN, ien);
 	serial_out(port, SPRD_ICLR, iclr);
 }

 /* The Sprd serial does not support this function. */
 static void sprd_break_ctl(struct uart_port *port, int break_state)
 {
 	/* nothing to do */
 }

 static int handle_lsr_errors(struct uart_port *port,
 			     unsigned int *flag,
 			     unsigned int *lsr)
 {
 	int ret = 0;

 	/* statistics */
 	if (*lsr & SPRD_LSR_BI) {
 		*lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
 		port->icount.brk++;
 		ret = uart_handle_break(port);
 		if (ret)
 			return ret;
 	} else if (*lsr & SPRD_LSR_PE)
 		port->icount.parity++;
 	else if (*lsr & SPRD_LSR_FE)
 		port->icount.frame++;
 	if (*lsr & SPRD_LSR_OE)
 		port->icount.overrun++;

 	/* mask off conditions which should be ignored */
 	*lsr &= port->read_status_mask;
 	if (*lsr & SPRD_LSR_BI)
 		*flag = TTY_BREAK;
 	else if (*lsr & SPRD_LSR_PE)
 		*flag = TTY_PARITY;
 	else if (*lsr & SPRD_LSR_FE)
 		*flag = TTY_FRAME;

 	return ret;
 }

 static inline void sprd_rx(struct uart_port *port)
 {
 	struct tty_port *tty = &port->state->port;
 	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;

 	while ((serial_in(port, SPRD_STS1) & 0x00ff) && max_count--) {
 		lsr = serial_in(port, SPRD_LSR);
 		ch = serial_in(port, SPRD_RXD);
 		flag = TTY_NORMAL;
 		port->icount.rx++;

 		if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE |
 			SPRD_LSR_FE | SPRD_LSR_OE))
 			if (handle_lsr_errors(port, &lsr, &flag))
 				continue;
 		if (uart_handle_sysrq_char(port, ch))
 			continue;

 		uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
 	}

 	tty_flip_buffer_push(tty);
 }

 static inline void sprd_tx(struct uart_port *port)
 {
 	struct circ_buf *xmit = &port->state->xmit;
 	int count;

 	if (port->x_char) {
 		serial_out(port, SPRD_TXD, port->x_char);
 		port->icount.tx++;
 		port->x_char = 0;
 		return;
 	}

 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
 		sprd_stop_tx(port);
 		return;
 	}

 	count = THLD_TX_EMPTY;
 	do {
 		serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		port->icount.tx++;
 		if (uart_circ_empty(xmit))
 			break;
 	} while (--count > 0);

 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);

 	if (uart_circ_empty(xmit))
 		sprd_stop_tx(port);
 }

 /* this handles the interrupt from one port */
 static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
 	unsigned int ims;

 	spin_lock(&port->lock);

 	ims = serial_in(port, SPRD_IMSR);

 	if (!ims) {
 		spin_unlock(&port->lock);
 		return IRQ_NONE;
 	}

 	serial_out(port, SPRD_ICLR, ~0);

 	if (ims & (SPRD_IMSR_RX_FIFO_FULL |
 		SPRD_IMSR_BREAK_DETECT | SPRD_IMSR_TIMEOUT))
 		sprd_rx(port);

 	if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
 		sprd_tx(port);

 	spin_unlock(&port->lock);

 	return IRQ_HANDLED;
 }

 static int sprd_startup(struct uart_port *port)
 {
 	int ret = 0;
 	unsigned int ien, fc;
 	unsigned int timeout;
 	struct sprd_uart_port *sp;
 	unsigned long flags;

 	serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY << 8) | THLD_RX_FULL));

 	/* clear rx fifo */
 	timeout = SPRD_TIMEOUT;
 	while (timeout-- && serial_in(port, SPRD_STS1) & 0x00ff)
 		serial_in(port, SPRD_RXD);

 	/* clear tx fifo */
 	timeout = SPRD_TIMEOUT;
 	while (timeout-- && serial_in(port, SPRD_STS1) & 0xff00)
 		cpu_relax();

 	/* clear interrupt */
 	serial_out(port, SPRD_IEN, 0);
 	serial_out(port, SPRD_ICLR, ~0);

 	/* allocate irq */
 	sp = container_of(port, struct sprd_uart_port, port);
 	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
 	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
 				IRQF_SHARED, sp->name, port);
 	if (ret) {
 		dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
 			port->irq, ret);
 		return ret;
 	}
 	fc = serial_in(port, SPRD_CTL1);
 	fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
 	serial_out(port, SPRD_CTL1, fc);

 	/* enable interrupt */
 	spin_lock_irqsave(&port->lock, flags);
 	ien = serial_in(port, SPRD_IEN);
 	ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
 	serial_out(port, SPRD_IEN, ien);
 	spin_unlock_irqrestore(&port->lock, flags);

 	return 0;
 }

 static void sprd_shutdown(struct uart_port *port)
 {
 	serial_out(port, SPRD_IEN, 0);
 	serial_out(port, SPRD_ICLR, ~0);
 	devm_free_irq(port->dev, port->irq, port);
 }

 static void sprd_set_termios(struct uart_port *port,
 				    struct ktermios *termios,
 				    struct ktermios *old)
 {
 	unsigned int baud, quot;
 	unsigned int lcr = 0, fc;
 	unsigned long flags;

 	/* ask the core to calculate the divisor for us */
 	baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);

 	quot = (unsigned int)((port->uartclk + baud / 2) / baud);

 	/* set data length */
 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
 		lcr |= SPRD_LCR_DATA_LEN5;
 		break;
 	case CS6:
 		lcr |= SPRD_LCR_DATA_LEN6;
 		break;
 	case CS7:
 		lcr |= SPRD_LCR_DATA_LEN7;
 		break;
 	case CS8:
 	default:
 		lcr |= SPRD_LCR_DATA_LEN8;
 		break;
 	}

 	/* calculate stop bits */
 	lcr &= ~(SPRD_LCR_STOP_1BIT | SPRD_LCR_STOP_2BIT);
 	if (termios->c_cflag & CSTOPB)
 		lcr |= SPRD_LCR_STOP_2BIT;
 	else
 		lcr |= SPRD_LCR_STOP_1BIT;

 	/* calculate parity */
 	lcr &= ~SPRD_LCR_PARITY;
 	termios->c_cflag &= ~CMSPAR;	/* no support mark/space */
 	if (termios->c_cflag & PARENB) {
 		lcr |= SPRD_LCR_PARITY_EN;
 		if (termios->c_cflag & PARODD)
 			lcr |= SPRD_LCR_ODD_PAR;
 		else
 			lcr |= SPRD_LCR_EVEN_PAR;
 	}

 	spin_lock_irqsave(&port->lock, flags);

 	/* update the per-port timeout */
 	uart_update_timeout(port, termios->c_cflag, baud);

 	port->read_status_mask = SPRD_LSR_OE;
 	if (termios->c_iflag & INPCK)
 		port->read_status_mask |= SPRD_LSR_FE | SPRD_LSR_PE;
 	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
 		port->read_status_mask |= SPRD_LSR_BI;

 	/* characters to ignore */
 	port->ignore_status_mask = 0;
 	if (termios->c_iflag & IGNPAR)
 		port->ignore_status_mask |= SPRD_LSR_PE | SPRD_LSR_FE;
 	if (termios->c_iflag & IGNBRK) {
 		port->ignore_status_mask |= SPRD_LSR_BI;
 		/*
 		 * If we're ignoring parity and break indicators,
 		 * ignore overruns too (for real raw support).
 		 */
 		if (termios->c_iflag & IGNPAR)
 			port->ignore_status_mask |= SPRD_LSR_OE;
 	}

 	/* flow control */
 	fc = serial_in(port, SPRD_CTL1);
 	fc &= ~(RX_HW_FLOW_CTL_THLD | RX_HW_FLOW_CTL_EN | TX_HW_FLOW_CTL_EN);
 	if (termios->c_cflag & CRTSCTS) {
 		fc |= RX_HW_FLOW_CTL_THLD;
 		fc |= RX_HW_FLOW_CTL_EN;
 		fc |= TX_HW_FLOW_CTL_EN;
 	}

 	/* clock divider bit0~bit15 */
 	serial_out(port, SPRD_CLKD0, quot & 0xffff);

 	/* clock divider bit16~bit20 */
 	serial_out(port, SPRD_CLKD1, (quot & 0x1f0000) >> 16);
 	serial_out(port, SPRD_LCR, lcr);
 	fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
 	serial_out(port, SPRD_CTL1, fc);

 	spin_unlock_irqrestore(&port->lock, flags);

 	/* Don't rewrite B0 */
 	if (tty_termios_baud_rate(termios))
 		tty_termios_encode_baud_rate(termios, baud, baud);
 }

 static const char *sprd_type(struct uart_port *port)
 {
 	return "SPX";
 }

 static void sprd_release_port(struct uart_port *port)
 {
 	/* nothing to do */
 }

 static int sprd_request_port(struct uart_port *port)
 {
 	return 0;
 }

 static void sprd_config_port(struct uart_port *port, int flags)
 {
 	if (flags & UART_CONFIG_TYPE)
 		port->type = PORT_SPRD;
 }

 static int sprd_verify_port(struct uart_port *port,
 				   struct serial_struct *ser)
 {
 	if (ser->type != PORT_SPRD)
 		return -EINVAL;
 	if (port->irq != ser->irq)
 		return -EINVAL;
 	if (port->iotype != ser->io_type)
 		return -EINVAL;
 	return 0;
 }

 static struct uart_ops serial_sprd_ops = {
 	.tx_empty = sprd_tx_empty,
 	.get_mctrl = sprd_get_mctrl,
 	.set_mctrl = sprd_set_mctrl,
 	.stop_tx = sprd_stop_tx,
 	.start_tx = sprd_start_tx,
 	.stop_rx = sprd_stop_rx,
 	.break_ctl = sprd_break_ctl,
 	.startup = sprd_startup,
 	.shutdown = sprd_shutdown,
 	.set_termios = sprd_set_termios,
 	.type = sprd_type,
 	.release_port = sprd_release_port,
 	.request_port = sprd_request_port,
 	.config_port = sprd_config_port,
 	.verify_port = sprd_verify_port,
 };

 #ifdef CONFIG_SERIAL_SPRD_CONSOLE
 static inline void wait_for_xmitr(struct uart_port *port)
 {
 	unsigned int status, tmout = 10000;

 	/* wait up to 10ms for the character(s) to be sent */
 	do {
 		status = serial_in(port, SPRD_STS1);
 		if (--tmout == 0)
 			break;
 		udelay(1);
 	} while (status & 0xff00);
 }

 static void sprd_console_putchar(struct uart_port *port, int ch)
 {
 	wait_for_xmitr(port);
 	serial_out(port, SPRD_TXD, ch);
 }

 static void sprd_console_write(struct console *co, const char *s,
 				      unsigned int count)
 {
 	struct uart_port *port = &sprd_port[co->index]->port;
 	int locked = 1;
 	unsigned long flags;

 	if (port->sysrq)
 		locked = 0;
 	else if (oops_in_progress)
 		locked = spin_trylock_irqsave(&port->lock, flags);
 	else
 		spin_lock_irqsave(&port->lock, flags);

 	uart_console_write(port, s, count, sprd_console_putchar);

 	/* wait for transmitter to become empty */
 	wait_for_xmitr(port);

 	if (locked)
 		spin_unlock_irqrestore(&port->lock, flags);
 }

 static int __init sprd_console_setup(struct console *co, char *options)
 {
 	struct uart_port *port;
 	int baud = 115200;
 	int bits = 8;
 	int parity = 'n';
 	int flow = 'n';

 	if (co->index >= UART_NR_MAX || co->index < 0)
 		co->index = 0;

 	port = &sprd_port[co->index]->port;
 	if (port == NULL) {
 		pr_info("serial port %d not yet initialized\n", co->index);
 		return -ENODEV;
 	}
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);

 	return uart_set_options(port, co, baud, parity, bits, flow);
 }

 static struct uart_driver sprd_uart_driver;
 static struct console sprd_console = {
 	.name = SPRD_TTY_NAME,
 	.write = sprd_console_write,
 	.device = uart_console_device,
 	.setup = sprd_console_setup,
 	.flags = CON_PRINTBUFFER,
 	.index = -1,
 	.data = &sprd_uart_driver,
 };

 #define SPRD_CONSOLE	(&sprd_console)

 /* Support for earlycon */
 static void sprd_putc(struct uart_port *port, int c)
 {
 	unsigned int timeout = SPRD_TIMEOUT;

 	while (timeout-- &&
 		   !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
 		cpu_relax();

 	writeb(c, port->membase + SPRD_TXD);
 }

 static void sprd_early_write(struct console *con, const char *s,
 				    unsigned n)
 {
 	struct earlycon_device *dev = con->data;

 	uart_console_write(&dev->port, s, n, sprd_putc);
 }

 static int __init sprd_early_console_setup(
 				struct earlycon_device *device,
 				const char *opt)
 {
 	if (!device->port.membase)
 		return -ENODEV;

 	device->con->write = sprd_early_write;
 	return 0;
 }

 EARLYCON_DECLARE(sprd_serial, sprd_early_console_setup);
 OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
 		    sprd_early_console_setup);

 #else /* !CONFIG_SERIAL_SPRD_CONSOLE */
 #define SPRD_CONSOLE		NULL
 #endif

 static struct uart_driver sprd_uart_driver = {
 	.owner = THIS_MODULE,
 	.driver_name = "sprd_serial",
 	.dev_name = SPRD_TTY_NAME,
 	.major = 0,
 	.minor = 0,
 	.nr = UART_NR_MAX,
 	.cons = SPRD_CONSOLE,
 };

 static int sprd_probe_dt_alias(int index, struct device *dev)
 {
 	struct device_node *np;
 	int ret = index;

 	if (!IS_ENABLED(CONFIG_OF))
 		return ret;

 	np = dev->of_node;
 	if (!np)
 		return ret;

 	ret = of_alias_get_id(np, "serial");
 	if (IS_ERR_VALUE(ret))
 		ret = index;
 	else if (ret >= ARRAY_SIZE(sprd_port) || sprd_port[ret] != NULL) {
 		dev_warn(dev, "requested serial port %d not available.\n", ret);
 		ret = index;
 	}

 	return ret;
 }

 static int sprd_remove(struct platform_device *dev)
 {
 	struct sprd_uart_port *sup = platform_get_drvdata(dev);

 	if (sup) {
 		uart_remove_one_port(&sprd_uart_driver, &sup->port);
 		sprd_port[sup->port.line] = NULL;
 		sprd_ports_num--;
 	}

 	if (!sprd_ports_num)
 		uart_unregister_driver(&sprd_uart_driver);

 	return 0;
 }

 static int sprd_probe(struct platform_device *pdev)
 {
 	struct resource *res;
 	struct uart_port *up;
 	struct clk *clk;
 	int irq;
 	int index;
 	int ret;

 	for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
 		if (sprd_port[index] == NULL)
 			break;

 	if (index == ARRAY_SIZE(sprd_port))
 		return -EBUSY;

 	index = sprd_probe_dt_alias(index, &pdev->dev);

 	sprd_port[index] = devm_kzalloc(&pdev->dev,
 		sizeof(*sprd_port[index]), GFP_KERNEL);
 	if (!sprd_port[index])
 		return -ENOMEM;

 	up = &sprd_port[index]->port;
 	up->dev = &pdev->dev;
 	up->line = index;
 	up->type = PORT_SPRD;
 	up->iotype = UPIO_MEM;
 	up->uartclk = SPRD_DEF_RATE;
 	up->fifosize = SPRD_FIFO_SIZE;
 	up->ops = &serial_sprd_ops;
 	up->flags = UPF_BOOT_AUTOCONF;

 	clk = devm_clk_get(&pdev->dev, NULL);
 	if (!IS_ERR_OR_NULL(clk))
 		up->uartclk = clk_get_rate(clk);

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
 		dev_err(&pdev->dev, "not provide mem resource\n");
 		return -ENODEV;
 	}
 	up->mapbase = res->start;
 	up->membase = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(up->membase))
 		return PTR_ERR(up->membase);

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		dev_err(&pdev->dev, "not provide irq resource\n");
 		return -ENODEV;
 	}
 	up->irq = irq;

 	if (!sprd_ports_num) {
 		ret = uart_register_driver(&sprd_uart_driver);
 		if (ret < 0) {
 			pr_err("Failed to register SPRD-UART driver\n");
 			return ret;
 		}
 	}
 	sprd_ports_num++;

 	ret = uart_add_one_port(&sprd_uart_driver, up);
 	if (ret) {
 		sprd_port[index] = NULL;
 		sprd_remove(pdev);
 	}

 	platform_set_drvdata(pdev, up);

 	return ret;
 }

 #ifdef CONFIG_PM_SLEEP
 static int sprd_suspend(struct device *dev)
 {
 	struct sprd_uart_port *sup = dev_get_drvdata(dev);

 	uart_suspend_port(&sprd_uart_driver, &sup->port);

 	return 0;
 }

 static int sprd_resume(struct device *dev)
 {
 	struct sprd_uart_port *sup = dev_get_drvdata(dev);

 	uart_resume_port(&sprd_uart_driver, &sup->port);

 	return 0;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);

 static const struct of_device_id serial_ids[] = {
 	{.compatible = "sprd,sc9836-uart",},
 	{}
 };
 MODULE_DEVICE_TABLE(of, serial_ids);

 static struct platform_driver sprd_platform_driver = {
 	.probe		= sprd_probe,
 	.remove		= sprd_remove,
 	.driver		= {
 		.name	= "sprd_serial",
 		.of_match_table = of_match_ptr(serial_ids),
 		.pm	= &sprd_pm_ops,
 	},
 };

 module_platform_driver(sprd_platform_driver);

 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");
	/*
	* Copyright (C) 2012-2015 Spreadtrum Communications Inc.
	*
	* This software is licensed under the terms of the GNU General Public
	* License version 2, as published by the Free Software Foundation, and
	* may be copied, distributed, and modified under those terms.
	*
	* 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.
	*/

	#if defined(CONFIG_SERIAL_SPRD_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
	#define SUPPORT_SYSRQ
	#endif

	#include <linux/clk.h>
	#include <linux/console.h>
	#include <linux/delay.h>
	#include <linux/io.h>
	#include <linux/ioport.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/serial_core.h>
	#include <linux/serial.h>
	#include <linux/slab.h>
	#include <linux/tty.h>
	#include <linux/tty_flip.h>

	/* device name */
	#define UART_NR_MAX 8
	#define SPRD_TTY_NAME "ttyS"
	#define SPRD_FIFO_SIZE 128
	#define SPRD_DEF_RATE 26000000
	#define SPRD_BAUD_IO_LIMIT 3000000
	#define SPRD_TIMEOUT 256

	/* the offset of serial registers and BITs for them */
	/* data registers */
	#define SPRD_TXD 0x0000
	#define SPRD_RXD 0x0004

	/* line status register and its BITs */
	#define SPRD_LSR 0x0008
	#define SPRD_LSR_OE BIT(4)
	#define SPRD_LSR_FE BIT(3)
	#define SPRD_LSR_PE BIT(2)
	#define SPRD_LSR_BI BIT(7)
	#define SPRD_LSR_TX_OVER BIT(15)

	/* data number in TX and RX fifo */
	#define SPRD_STS1 0x000C

	/* interrupt enable register and its BITs */
	#define SPRD_IEN 0x0010
	#define SPRD_IEN_RX_FULL BIT(0)
	#define SPRD_IEN_TX_EMPTY BIT(1)
	#define SPRD_IEN_BREAK_DETECT BIT(7)
	#define SPRD_IEN_TIMEOUT BIT(13)

	/* interrupt clear register */
	#define SPRD_ICLR 0x0014

	/* line control register */
	#define SPRD_LCR 0x0018
	#define SPRD_LCR_STOP_1BIT 0x10
	#define SPRD_LCR_STOP_2BIT 0x30
	#define SPRD_LCR_DATA_LEN (BIT(2) \| BIT(3))
	#define SPRD_LCR_DATA_LEN5 0x0
	#define SPRD_LCR_DATA_LEN6 0x4
	#define SPRD_LCR_DATA_LEN7 0x8
	#define SPRD_LCR_DATA_LEN8 0xc
	#define SPRD_LCR_PARITY (BIT(0) \| BIT(1))
	#define SPRD_LCR_PARITY_EN 0x2
	#define SPRD_LCR_EVEN_PAR 0x0
	#define SPRD_LCR_ODD_PAR 0x1

	/* control register 1 */
	#define SPRD_CTL1 0x001C
	#define RX_HW_FLOW_CTL_THLD BIT(6)
	#define RX_HW_FLOW_CTL_EN BIT(7)
	#define TX_HW_FLOW_CTL_EN BIT(8)
	#define RX_TOUT_THLD_DEF 0x3E00
	#define RX_HFC_THLD_DEF 0x40

	/* fifo threshold register */
	#define SPRD_CTL2 0x0020
	#define THLD_TX_EMPTY 0x40
	#define THLD_RX_FULL 0x40

	/* config baud rate register */
	#define SPRD_CLKD0 0x0024
	#define SPRD_CLKD1 0x0028

	/* interrupt mask status register */
	#define SPRD_IMSR 0x002C
	#define SPRD_IMSR_RX_FIFO_FULL BIT(0)
	#define SPRD_IMSR_TX_FIFO_EMPTY BIT(1)
	#define SPRD_IMSR_BREAK_DETECT BIT(7)
	#define SPRD_IMSR_TIMEOUT BIT(13)

	struct reg_backup {
	u32 ien;
	u32 ctrl0;
	u32 ctrl1;
	u32 ctrl2;
	u32 clkd0;
	u32 clkd1;
	u32 dspwait;
	};

	struct sprd_uart_port {
	struct uart_port port;
	struct reg_backup reg_bak;
	char name[16];
	};

	static struct sprd_uart_port *sprd_port[UART_NR_MAX];
	static int sprd_ports_num;

	static inline unsigned int serial_in(struct uart_port *port, int offset)
	{
	return readl_relaxed(port->membase + offset);
	}

	static inline void serial_out(struct uart_port *port, int offset, int value)
	{
	writel_relaxed(value, port->membase + offset);
	}

	static unsigned int sprd_tx_empty(struct uart_port *port)
	{
	if (serial_in(port, SPRD_STS1) & 0xff00)
	return 0;
	else
	return TIOCSER_TEMT;
	}

	static unsigned int sprd_get_mctrl(struct uart_port *port)
	{
	return TIOCM_DSR \| TIOCM_CTS;
	}

	static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
	{
	/* nothing to do */
	}

	static void sprd_stop_tx(struct uart_port *port)
	{
	unsigned int ien, iclr;

	iclr = serial_in(port, SPRD_ICLR);
	ien = serial_in(port, SPRD_IEN);

	iclr \|= SPRD_IEN_TX_EMPTY;
	ien &= ~SPRD_IEN_TX_EMPTY;

	serial_out(port, SPRD_ICLR, iclr);
	serial_out(port, SPRD_IEN, ien);
	}

	static void sprd_start_tx(struct uart_port *port)
	{
	unsigned int ien;

	ien = serial_in(port, SPRD_IEN);
	if (!(ien & SPRD_IEN_TX_EMPTY)) {
	ien \|= SPRD_IEN_TX_EMPTY;
	serial_out(port, SPRD_IEN, ien);
	}
	}

	static void sprd_stop_rx(struct uart_port *port)
	{
	unsigned int ien, iclr;

	iclr = serial_in(port, SPRD_ICLR);
	ien = serial_in(port, SPRD_IEN);

	ien &= ~(SPRD_IEN_RX_FULL \| SPRD_IEN_BREAK_DETECT);
	iclr \|= SPRD_IEN_RX_FULL \| SPRD_IEN_BREAK_DETECT;

	serial_out(port, SPRD_IEN, ien);
	serial_out(port, SPRD_ICLR, iclr);
	}

	/* The Sprd serial does not support this function. */
	static void sprd_break_ctl(struct uart_port *port, int break_state)
	{
	/* nothing to do */
	}

	static int handle_lsr_errors(struct uart_port *port,
	unsigned int *flag,
	unsigned int *lsr)
	{
	int ret = 0;

	/* statistics */
	if (*lsr & SPRD_LSR_BI) {
	*lsr &= ~(SPRD_LSR_FE \| SPRD_LSR_PE);
	port->icount.brk++;
	ret = uart_handle_break(port);
	if (ret)
	return ret;
	} else if (*lsr & SPRD_LSR_PE)
	port->icount.parity++;
	else if (*lsr & SPRD_LSR_FE)
	port->icount.frame++;
	if (*lsr & SPRD_LSR_OE)
	port->icount.overrun++;

	/* mask off conditions which should be ignored */
	*lsr &= port->read_status_mask;
	if (*lsr & SPRD_LSR_BI)
	*flag = TTY_BREAK;
	else if (*lsr & SPRD_LSR_PE)
	*flag = TTY_PARITY;
	else if (*lsr & SPRD_LSR_FE)
	*flag = TTY_FRAME;

	return ret;
	}

	static inline void sprd_rx(struct uart_port *port)
	{
	struct tty_port *tty = &port->state->port;
	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;

	while ((serial_in(port, SPRD_STS1) & 0x00ff) && max_count--) {
	lsr = serial_in(port, SPRD_LSR);
	ch = serial_in(port, SPRD_RXD);
	flag = TTY_NORMAL;
	port->icount.rx++;

	if (lsr & (SPRD_LSR_BI \| SPRD_LSR_PE \|
	SPRD_LSR_FE \| SPRD_LSR_OE))
	if (handle_lsr_errors(port, &lsr, &flag))
	continue;
	if (uart_handle_sysrq_char(port, ch))
	continue;

	uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
	}

	tty_flip_buffer_push(tty);
	}

	static inline void sprd_tx(struct uart_port *port)
	{
	struct circ_buf *xmit = &port->state->xmit;
	int count;

	if (port->x_char) {
	serial_out(port, SPRD_TXD, port->x_char);
	port->icount.tx++;
	port->x_char = 0;
	return;
	}

	if (uart_circ_empty(xmit) \|\| uart_tx_stopped(port)) {
	sprd_stop_tx(port);
	return;
	}

	count = THLD_TX_EMPTY;
	do {
	serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
	port->icount.tx++;
	if (uart_circ_empty(xmit))
	break;
	} while (--count > 0);

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
	uart_write_wakeup(port);

	if (uart_circ_empty(xmit))
	sprd_stop_tx(port);
	}

	/* this handles the interrupt from one port */
	static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
	{
	struct uart_port *port = dev_id;
	unsigned int ims;

	spin_lock(&port->lock);

	ims = serial_in(port, SPRD_IMSR);

	if (!ims) {
	spin_unlock(&port->lock);
	return IRQ_NONE;
	}

	serial_out(port, SPRD_ICLR, ~0);

	if (ims & (SPRD_IMSR_RX_FIFO_FULL \|
	SPRD_IMSR_BREAK_DETECT \| SPRD_IMSR_TIMEOUT))
	sprd_rx(port);

	if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
	sprd_tx(port);

	spin_unlock(&port->lock);

	return IRQ_HANDLED;
	}

	static int sprd_startup(struct uart_port *port)
	{
	int ret = 0;
	unsigned int ien, fc;
	unsigned int timeout;
	struct sprd_uart_port *sp;
	unsigned long flags;

	serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY << 8) \| THLD_RX_FULL));

	/* clear rx fifo */
	timeout = SPRD_TIMEOUT;
	while (timeout-- && serial_in(port, SPRD_STS1) & 0x00ff)
	serial_in(port, SPRD_RXD);

	/* clear tx fifo */
	timeout = SPRD_TIMEOUT;
	while (timeout-- && serial_in(port, SPRD_STS1) & 0xff00)
	cpu_relax();

	/* clear interrupt */
	serial_out(port, SPRD_IEN, 0);
	serial_out(port, SPRD_ICLR, ~0);

	/* allocate irq */
	sp = container_of(port, struct sprd_uart_port, port);
	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
	IRQF_SHARED, sp->name, port);
	if (ret) {
	dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
	port->irq, ret);
	return ret;
	}
	fc = serial_in(port, SPRD_CTL1);
	fc \|= RX_TOUT_THLD_DEF \| RX_HFC_THLD_DEF;
	serial_out(port, SPRD_CTL1, fc);

	/* enable interrupt */
	spin_lock_irqsave(&port->lock, flags);
	ien = serial_in(port, SPRD_IEN);
	ien \|= SPRD_IEN_RX_FULL \| SPRD_IEN_BREAK_DETECT \| SPRD_IEN_TIMEOUT;
	serial_out(port, SPRD_IEN, ien);
	spin_unlock_irqrestore(&port->lock, flags);

	return 0;
	}

	static void sprd_shutdown(struct uart_port *port)
	{
	serial_out(port, SPRD_IEN, 0);
	serial_out(port, SPRD_ICLR, ~0);
	devm_free_irq(port->dev, port->irq, port);
	}

	static void sprd_set_termios(struct uart_port *port,
	struct ktermios *termios,
	struct ktermios *old)
	{
	unsigned int baud, quot;
	unsigned int lcr = 0, fc;
	unsigned long flags;

	/* ask the core to calculate the divisor for us */
	baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);

	quot = (unsigned int)((port->uartclk + baud / 2) / baud);

	/* set data length */
	switch (termios->c_cflag & CSIZE) {
	case CS5:
	lcr \|= SPRD_LCR_DATA_LEN5;
	break;
	case CS6:
	lcr \|= SPRD_LCR_DATA_LEN6;
	break;
	case CS7:
	lcr \|= SPRD_LCR_DATA_LEN7;
	break;
	case CS8:
	default:
	lcr \|= SPRD_LCR_DATA_LEN8;
	break;
	}

	/* calculate stop bits */
	lcr &= ~(SPRD_LCR_STOP_1BIT \| SPRD_LCR_STOP_2BIT);
	if (termios->c_cflag & CSTOPB)
	lcr \|= SPRD_LCR_STOP_2BIT;
	else
	lcr \|= SPRD_LCR_STOP_1BIT;

	/* calculate parity */
	lcr &= ~SPRD_LCR_PARITY;
	termios->c_cflag &= ~CMSPAR; /* no support mark/space */
	if (termios->c_cflag & PARENB) {
	lcr \|= SPRD_LCR_PARITY_EN;
	if (termios->c_cflag & PARODD)
	lcr \|= SPRD_LCR_ODD_PAR;
	else
	lcr \|= SPRD_LCR_EVEN_PAR;
	}

	spin_lock_irqsave(&port->lock, flags);

	/* update the per-port timeout */
	uart_update_timeout(port, termios->c_cflag, baud);

	port->read_status_mask = SPRD_LSR_OE;
	if (termios->c_iflag & INPCK)
	port->read_status_mask \|= SPRD_LSR_FE \| SPRD_LSR_PE;
	if (termios->c_iflag & (IGNBRK \| BRKINT \| PARMRK))
	port->read_status_mask \|= SPRD_LSR_BI;

	/* characters to ignore */
	port->ignore_status_mask = 0;
	if (termios->c_iflag & IGNPAR)
	port->ignore_status_mask \|= SPRD_LSR_PE \| SPRD_LSR_FE;
	if (termios->c_iflag & IGNBRK) {
	port->ignore_status_mask \|= SPRD_LSR_BI;
	/*
	* If we're ignoring parity and break indicators,
	* ignore overruns too (for real raw support).
	*/
	if (termios->c_iflag & IGNPAR)
	port->ignore_status_mask \|= SPRD_LSR_OE;
	}

	/* flow control */
	fc = serial_in(port, SPRD_CTL1);
	fc &= ~(RX_HW_FLOW_CTL_THLD \| RX_HW_FLOW_CTL_EN \| TX_HW_FLOW_CTL_EN);
	if (termios->c_cflag & CRTSCTS) {
	fc \|= RX_HW_FLOW_CTL_THLD;
	fc \|= RX_HW_FLOW_CTL_EN;
	fc \|= TX_HW_FLOW_CTL_EN;
	}

	/* clock divider bit0~bit15 */
	serial_out(port, SPRD_CLKD0, quot & 0xffff);

	/* clock divider bit16~bit20 */
	serial_out(port, SPRD_CLKD1, (quot & 0x1f0000) >> 16);
	serial_out(port, SPRD_LCR, lcr);
	fc \|= RX_TOUT_THLD_DEF \| RX_HFC_THLD_DEF;
	serial_out(port, SPRD_CTL1, fc);

	spin_unlock_irqrestore(&port->lock, flags);

	/* Don't rewrite B0 */
	if (tty_termios_baud_rate(termios))
	tty_termios_encode_baud_rate(termios, baud, baud);
	}

	static const char sprd_type(struct uart_port port)
	{
	return "SPX";
	}

	static void sprd_release_port(struct uart_port *port)
	{
	/* nothing to do */
	}

	static int sprd_request_port(struct uart_port *port)
	{
	return 0;
	}

	static void sprd_config_port(struct uart_port *port, int flags)
	{
	if (flags & UART_CONFIG_TYPE)
	port->type = PORT_SPRD;
	}

	static int sprd_verify_port(struct uart_port *port,
	struct serial_struct *ser)
	{
	if (ser->type != PORT_SPRD)
	return -EINVAL;
	if (port->irq != ser->irq)
	return -EINVAL;
	if (port->iotype != ser->io_type)
	return -EINVAL;
	return 0;
	}

	static struct uart_ops serial_sprd_ops = {
	.tx_empty = sprd_tx_empty,
	.get_mctrl = sprd_get_mctrl,
	.set_mctrl = sprd_set_mctrl,
	.stop_tx = sprd_stop_tx,
	.start_tx = sprd_start_tx,
	.stop_rx = sprd_stop_rx,
	.break_ctl = sprd_break_ctl,
	.startup = sprd_startup,
	.shutdown = sprd_shutdown,
	.set_termios = sprd_set_termios,
	.type = sprd_type,
	.release_port = sprd_release_port,
	.request_port = sprd_request_port,
	.config_port = sprd_config_port,
	.verify_port = sprd_verify_port,
	};

	#ifdef CONFIG_SERIAL_SPRD_CONSOLE
	static inline void wait_for_xmitr(struct uart_port *port)
	{
	unsigned int status, tmout = 10000;

	/* wait up to 10ms for the character(s) to be sent */
	do {
	status = serial_in(port, SPRD_STS1);
	if (--tmout == 0)
	break;
	udelay(1);
	} while (status & 0xff00);
	}

	static void sprd_console_putchar(struct uart_port *port, int ch)
	{
	wait_for_xmitr(port);
	serial_out(port, SPRD_TXD, ch);
	}

	static void sprd_console_write(struct console co, const char s,
	unsigned int count)
	{
	struct uart_port *port = &sprd_port[co->index]->port;
	int locked = 1;
	unsigned long flags;

	if (port->sysrq)
	locked = 0;
	else if (oops_in_progress)
	locked = spin_trylock_irqsave(&port->lock, flags);
	else
	spin_lock_irqsave(&port->lock, flags);

	uart_console_write(port, s, count, sprd_console_putchar);

	/* wait for transmitter to become empty */
	wait_for_xmitr(port);

	if (locked)
	spin_unlock_irqrestore(&port->lock, flags);
	}

	static int __init sprd_console_setup(struct console co, char options)
	{
	struct uart_port *port;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	if (co->index >= UART_NR_MAX \|\| co->index < 0)
	co->index = 0;

	port = &sprd_port[co->index]->port;
	if (port == NULL) {
	pr_info("serial port %d not yet initialized\n", co->index);
	return -ENODEV;
	}
	if (options)
	uart_parse_options(options, &baud, &parity, &bits, &flow);

	return uart_set_options(port, co, baud, parity, bits, flow);
	}

	static struct uart_driver sprd_uart_driver;
	static struct console sprd_console = {
	.name = SPRD_TTY_NAME,
	.write = sprd_console_write,
	.device = uart_console_device,
	.setup = sprd_console_setup,
	.flags = CON_PRINTBUFFER,
	.index = -1,
	.data = &sprd_uart_driver,
	};

	#define SPRD_CONSOLE (&sprd_console)

	/* Support for earlycon */
	static void sprd_putc(struct uart_port *port, int c)
	{
	unsigned int timeout = SPRD_TIMEOUT;

	while (timeout-- &&
	!(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
	cpu_relax();

	writeb(c, port->membase + SPRD_TXD);
	}

	static void sprd_early_write(struct console con, const char s,
	unsigned n)
	{
	struct earlycon_device *dev = con->data;

	uart_console_write(&dev->port, s, n, sprd_putc);
	}

	static int __init sprd_early_console_setup(
	struct earlycon_device *device,
	const char *opt)
	{
	if (!device->port.membase)
	return -ENODEV;

	device->con->write = sprd_early_write;
	return 0;
	}

	EARLYCON_DECLARE(sprd_serial, sprd_early_console_setup);
	OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
	sprd_early_console_setup);

	#else /* !CONFIG_SERIAL_SPRD_CONSOLE */
	#define SPRD_CONSOLE NULL
	#endif

	static struct uart_driver sprd_uart_driver = {
	.owner = THIS_MODULE,
	.driver_name = "sprd_serial",
	.dev_name = SPRD_TTY_NAME,
	.major = 0,
	.minor = 0,
	.nr = UART_NR_MAX,
	.cons = SPRD_CONSOLE,
	};

	static int sprd_probe_dt_alias(int index, struct device *dev)
	{
	struct device_node *np;
	int ret = index;

	if (!IS_ENABLED(CONFIG_OF))
	return ret;

	np = dev->of_node;
	if (!np)
	return ret;

	ret = of_alias_get_id(np, "serial");
	if (IS_ERR_VALUE(ret))
	ret = index;
	else if (ret >= ARRAY_SIZE(sprd_port) \|\| sprd_port[ret] != NULL) {
	dev_warn(dev, "requested serial port %d not available.\n", ret);
	ret = index;
	}

	return ret;
	}

	static int sprd_remove(struct platform_device *dev)
	{
	struct sprd_uart_port *sup = platform_get_drvdata(dev);

	if (sup) {
	uart_remove_one_port(&sprd_uart_driver, &sup->port);
	sprd_port[sup->port.line] = NULL;
	sprd_ports_num--;
	}

	if (!sprd_ports_num)
	uart_unregister_driver(&sprd_uart_driver);

	return 0;
	}

	static int sprd_probe(struct platform_device *pdev)
	{
	struct resource *res;
	struct uart_port *up;
	struct clk *clk;
	int irq;
	int index;
	int ret;

	for (index = 0; index < ARRAY_SIZE(sprd_port); index++)
	if (sprd_port[index] == NULL)
	break;

	if (index == ARRAY_SIZE(sprd_port))
	return -EBUSY;

	index = sprd_probe_dt_alias(index, &pdev->dev);

	sprd_port[index] = devm_kzalloc(&pdev->dev,
	sizeof(*sprd_port[index]), GFP_KERNEL);
	if (!sprd_port[index])
	return -ENOMEM;

	up = &sprd_port[index]->port;
	up->dev = &pdev->dev;
	up->line = index;
	up->type = PORT_SPRD;
	up->iotype = UPIO_MEM;
	up->uartclk = SPRD_DEF_RATE;
	up->fifosize = SPRD_FIFO_SIZE;
	up->ops = &serial_sprd_ops;
	up->flags = UPF_BOOT_AUTOCONF;

	clk = devm_clk_get(&pdev->dev, NULL);
	if (!IS_ERR_OR_NULL(clk))
	up->uartclk = clk_get_rate(clk);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
	dev_err(&pdev->dev, "not provide mem resource\n");
	return -ENODEV;
	}
	up->mapbase = res->start;
	up->membase = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(up->membase))
	return PTR_ERR(up->membase);

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	dev_err(&pdev->dev, "not provide irq resource\n");
	return -ENODEV;
	}
	up->irq = irq;

	if (!sprd_ports_num) {
	ret = uart_register_driver(&sprd_uart_driver);
	if (ret < 0) {
	pr_err("Failed to register SPRD-UART driver\n");
	return ret;
	}
	}
	sprd_ports_num++;

	ret = uart_add_one_port(&sprd_uart_driver, up);
	if (ret) {
	sprd_port[index] = NULL;
	sprd_remove(pdev);
	}

	platform_set_drvdata(pdev, up);

	return ret;
	}

	#ifdef CONFIG_PM_SLEEP
	static int sprd_suspend(struct device *dev)
	{
	struct sprd_uart_port *sup = dev_get_drvdata(dev);

	uart_suspend_port(&sprd_uart_driver, &sup->port);

	return 0;
	}

	static int sprd_resume(struct device *dev)
	{
	struct sprd_uart_port *sup = dev_get_drvdata(dev);

	uart_resume_port(&sprd_uart_driver, &sup->port);

	return 0;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);

	static const struct of_device_id serial_ids[] = {
	{.compatible = "sprd,sc9836-uart",},
	{}
	};
	MODULE_DEVICE_TABLE(of, serial_ids);

	static struct platform_driver sprd_platform_driver = {
	.probe = sprd_probe,
	.remove = sprd_remove,
	.driver = {
	.name = "sprd_serial",
	.of_match_table = of_match_ptr(serial_ids),
	.pm = &sprd_pm_ops,
	},
	};

	module_platform_driver(sprd_platform_driver);

	MODULE_LICENSE("GPL v2");
	MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");