xref: /openbmc/linux/drivers/tty/serial/fsl_linflexuart.c (revision 06e9b2fe7f1279bea649002cc40cce54a383f052)

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Freescale linflexuart serial port driver
 *
 * Copyright 2012-2016 Freescale Semiconductor, Inc.
 * Copyright 2017-2018 NXP
 */

#if defined(CONFIG_SERIAL_FSL_LINFLEXUART_CONSOLE) && \
	defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/console.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/serial_core.h>
#include <linux/slab.h>
#include <linux/tty_flip.h>
#include <linux/delay.h>

/* All registers are 32-bit width */

#define LINCR1	0x0000	/* LIN control register				*/
#define LINIER	0x0004	/* LIN interrupt enable register		*/
#define LINSR	0x0008	/* LIN status register				*/
#define LINESR	0x000C	/* LIN error status register			*/
#define UARTCR	0x0010	/* UART mode control register			*/
#define UARTSR	0x0014	/* UART mode status register			*/
#define LINTCSR	0x0018	/* LIN timeout control status register		*/
#define LINOCR	0x001C	/* LIN output compare register			*/
#define LINTOCR	0x0020	/* LIN timeout control register			*/
#define LINFBRR	0x0024	/* LIN fractional baud rate register		*/
#define LINIBRR	0x0028	/* LIN integer baud rate register		*/
#define LINCFR	0x002C	/* LIN checksum field register			*/
#define LINCR2	0x0030	/* LIN control register 2			*/
#define BIDR	0x0034	/* Buffer identifier register			*/
#define BDRL	0x0038	/* Buffer data register least significant	*/
#define BDRM	0x003C	/* Buffer data register most significant	*/
#define IFER	0x0040	/* Identifier filter enable register		*/
#define IFMI	0x0044	/* Identifier filter match index		*/
#define IFMR	0x0048	/* Identifier filter mode register		*/
#define GCR	0x004C	/* Global control register			*/
#define UARTPTO	0x0050	/* UART preset timeout register			*/
#define UARTCTO	0x0054	/* UART current timeout register		*/

/*
 * Register field definitions
 */

#define LINFLEXD_LINCR1_INIT		BIT(0)
#define LINFLEXD_LINCR1_MME		BIT(4)
#define LINFLEXD_LINCR1_BF		BIT(7)

#define LINFLEXD_LINSR_LINS_INITMODE	BIT(12)
#define LINFLEXD_LINSR_LINS_MASK	(0xF << 12)

#define LINFLEXD_LINIER_SZIE		BIT(15)
#define LINFLEXD_LINIER_OCIE		BIT(14)
#define LINFLEXD_LINIER_BEIE		BIT(13)
#define LINFLEXD_LINIER_CEIE		BIT(12)
#define LINFLEXD_LINIER_HEIE		BIT(11)
#define LINFLEXD_LINIER_FEIE		BIT(8)
#define LINFLEXD_LINIER_BOIE		BIT(7)
#define LINFLEXD_LINIER_LSIE		BIT(6)
#define LINFLEXD_LINIER_WUIE		BIT(5)
#define LINFLEXD_LINIER_DBFIE		BIT(4)
#define LINFLEXD_LINIER_DBEIETOIE	BIT(3)
#define LINFLEXD_LINIER_DRIE		BIT(2)
#define LINFLEXD_LINIER_DTIE		BIT(1)
#define LINFLEXD_LINIER_HRIE		BIT(0)

#define LINFLEXD_UARTCR_OSR_MASK	(0xF << 24)
#define LINFLEXD_UARTCR_OSR(uartcr)	(((uartcr) \
					& LINFLEXD_UARTCR_OSR_MASK) >> 24)

#define LINFLEXD_UARTCR_ROSE		BIT(23)

#define LINFLEXD_UARTCR_RFBM		BIT(9)
#define LINFLEXD_UARTCR_TFBM		BIT(8)
#define LINFLEXD_UARTCR_WL1		BIT(7)
#define LINFLEXD_UARTCR_PC1		BIT(6)

#define LINFLEXD_UARTCR_RXEN		BIT(5)
#define LINFLEXD_UARTCR_TXEN		BIT(4)
#define LINFLEXD_UARTCR_PC0		BIT(3)

#define LINFLEXD_UARTCR_PCE		BIT(2)
#define LINFLEXD_UARTCR_WL0		BIT(1)
#define LINFLEXD_UARTCR_UART		BIT(0)

#define LINFLEXD_UARTSR_SZF		BIT(15)
#define LINFLEXD_UARTSR_OCF		BIT(14)
#define LINFLEXD_UARTSR_PE3		BIT(13)
#define LINFLEXD_UARTSR_PE2		BIT(12)
#define LINFLEXD_UARTSR_PE1		BIT(11)
#define LINFLEXD_UARTSR_PE0		BIT(10)
#define LINFLEXD_UARTSR_RMB		BIT(9)
#define LINFLEXD_UARTSR_FEF		BIT(8)
#define LINFLEXD_UARTSR_BOF		BIT(7)
#define LINFLEXD_UARTSR_RPS		BIT(6)
#define LINFLEXD_UARTSR_WUF		BIT(5)
#define LINFLEXD_UARTSR_4		BIT(4)

#define LINFLEXD_UARTSR_TO		BIT(3)

#define LINFLEXD_UARTSR_DRFRFE		BIT(2)
#define LINFLEXD_UARTSR_DTFTFF		BIT(1)
#define LINFLEXD_UARTSR_NF		BIT(0)
#define LINFLEXD_UARTSR_PE		(LINFLEXD_UARTSR_PE0 |\
					 LINFLEXD_UARTSR_PE1 |\
					 LINFLEXD_UARTSR_PE2 |\
					 LINFLEXD_UARTSR_PE3)

#define LINFLEX_LDIV_MULTIPLIER		(16)

#define DRIVER_NAME	"fsl-linflexuart"
#define DEV_NAME	"ttyLF"
#define UART_NR		4

#define EARLYCON_BUFFER_INITIAL_CAP	8

#define PREINIT_DELAY			2000 /* us */

static const struct of_device_id linflex_dt_ids[] = {
	{
		.compatible = "fsl,s32-linflexuart",
	},
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, linflex_dt_ids);

#ifdef CONFIG_SERIAL_FSL_LINFLEXUART_CONSOLE
static struct uart_port *earlycon_port;
static bool linflex_earlycon_same_instance;
static DEFINE_SPINLOCK(init_lock);
static bool during_init;

static struct {
	char *content;
	unsigned int len, cap;
} earlycon_buf;
#endif

static void linflex_stop_tx(struct uart_port *port)
{
	unsigned long ier;

	ier = readl(port->membase + LINIER);
	ier &= ~(LINFLEXD_LINIER_DTIE);
	writel(ier, port->membase + LINIER);
}

static void linflex_stop_rx(struct uart_port *port)
{
	unsigned long ier;

	ier = readl(port->membase + LINIER);
	writel(ier & ~LINFLEXD_LINIER_DRIE, port->membase + LINIER);
}

static inline void linflex_transmit_buffer(struct uart_port *sport)
{
	struct circ_buf *xmit = &sport->state->xmit;
	unsigned char c;
	unsigned long status;

	while (!uart_circ_empty(xmit)) {
		c = xmit->buf[xmit->tail];
		writeb(c, sport->membase + BDRL);

		/* Waiting for data transmission completed. */
		while (((status = readl(sport->membase + UARTSR)) &
					LINFLEXD_UARTSR_DTFTFF) !=
					LINFLEXD_UARTSR_DTFTFF)
			;

		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		sport->icount.tx++;

		writel(status | LINFLEXD_UARTSR_DTFTFF,
		       sport->membase + UARTSR);
	}

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

	if (uart_circ_empty(xmit))
		linflex_stop_tx(sport);
}

static void linflex_start_tx(struct uart_port *port)
{
	unsigned long ier;

	linflex_transmit_buffer(port);
	ier = readl(port->membase + LINIER);
	writel(ier | LINFLEXD_LINIER_DTIE, port->membase + LINIER);
}

static irqreturn_t linflex_txint(int irq, void *dev_id)
{
	struct uart_port *sport = dev_id;
	struct circ_buf *xmit = &sport->state->xmit;
	unsigned long flags;
	unsigned long status;

	spin_lock_irqsave(&sport->lock, flags);

	if (sport->x_char) {
		writeb(sport->x_char, sport->membase + BDRL);

		/* waiting for data transmission completed */
		while (((status = readl(sport->membase + UARTSR)) &
			LINFLEXD_UARTSR_DTFTFF) != LINFLEXD_UARTSR_DTFTFF)
			;

		writel(status | LINFLEXD_UARTSR_DTFTFF,
		       sport->membase + UARTSR);

		goto out;
	}

	if (uart_circ_empty(xmit) || uart_tx_stopped(sport)) {
		linflex_stop_tx(sport);
		goto out;
	}

	linflex_transmit_buffer(sport);

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

out:
	spin_unlock_irqrestore(&sport->lock, flags);
	return IRQ_HANDLED;
}

static irqreturn_t linflex_rxint(int irq, void *dev_id)
{
	struct uart_port *sport = dev_id;
	unsigned int flg;
	struct tty_port *port = &sport->state->port;
	unsigned long flags, status;
	unsigned char rx;

	spin_lock_irqsave(&sport->lock, flags);

	status = readl(sport->membase + UARTSR);
	while (status & LINFLEXD_UARTSR_RMB) {
		rx = readb(sport->membase + BDRM);
		flg = TTY_NORMAL;
		sport->icount.rx++;

		if (status & (LINFLEXD_UARTSR_BOF | LINFLEXD_UARTSR_SZF |
			      LINFLEXD_UARTSR_FEF | LINFLEXD_UARTSR_PE)) {
			if (status & LINFLEXD_UARTSR_SZF)
				status |= LINFLEXD_UARTSR_SZF;
			if (status & LINFLEXD_UARTSR_BOF)
				status |= LINFLEXD_UARTSR_BOF;
			if (status & LINFLEXD_UARTSR_FEF)
				status |= LINFLEXD_UARTSR_FEF;
			if (status & LINFLEXD_UARTSR_PE)
				status |=  LINFLEXD_UARTSR_PE;
		}

		writel(status | LINFLEXD_UARTSR_RMB | LINFLEXD_UARTSR_DRFRFE,
		       sport->membase + UARTSR);
		status = readl(sport->membase + UARTSR);

		if (uart_handle_sysrq_char(sport, (unsigned char)rx))
			continue;

#ifdef SUPPORT_SYSRQ
			sport->sysrq = 0;
#endif
		tty_insert_flip_char(port, rx, flg);
	}

	spin_unlock_irqrestore(&sport->lock, flags);

	tty_flip_buffer_push(port);

	return IRQ_HANDLED;
}

static irqreturn_t linflex_int(int irq, void *dev_id)
{
	struct uart_port *sport = dev_id;
	unsigned long status;

	status = readl(sport->membase + UARTSR);

	if (status & LINFLEXD_UARTSR_DRFRFE)
		linflex_rxint(irq, dev_id);
	if (status & LINFLEXD_UARTSR_DTFTFF)
		linflex_txint(irq, dev_id);

	return IRQ_HANDLED;
}

/* return TIOCSER_TEMT when transmitter is not busy */
static unsigned int linflex_tx_empty(struct uart_port *port)
{
	unsigned long status;

	status = readl(port->membase + UARTSR) & LINFLEXD_UARTSR_DTFTFF;

	return status ? TIOCSER_TEMT : 0;
}

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

static void linflex_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}

static void linflex_break_ctl(struct uart_port *port, int break_state)
{
}

static void linflex_setup_watermark(struct uart_port *sport)
{
	unsigned long cr, ier, cr1;

	/* Disable transmission/reception */
	ier = readl(sport->membase + LINIER);
	ier &= ~(LINFLEXD_LINIER_DRIE | LINFLEXD_LINIER_DTIE);
	writel(ier, sport->membase + LINIER);

	cr = readl(sport->membase + UARTCR);
	cr &= ~(LINFLEXD_UARTCR_RXEN | LINFLEXD_UARTCR_TXEN);
	writel(cr, sport->membase + UARTCR);

	/* Enter initialization mode by setting INIT bit */

	/* set the Linflex in master mode and activate by-pass filter */
	cr1 = LINFLEXD_LINCR1_BF | LINFLEXD_LINCR1_MME
	      | LINFLEXD_LINCR1_INIT;
	writel(cr1, sport->membase + LINCR1);

	/* wait for init mode entry */
	while ((readl(sport->membase + LINSR)
		& LINFLEXD_LINSR_LINS_MASK)
		!= LINFLEXD_LINSR_LINS_INITMODE)
		;

	/*
	 *	UART = 0x1;		- Linflex working in UART mode
	 *	TXEN = 0x1;		- Enable transmission of data now
	 *	RXEn = 0x1;		- Receiver enabled
	 *	WL0 = 0x1;		- 8 bit data
	 *	PCE = 0x0;		- No parity
	 */

	/* set UART bit to allow writing other bits */
	writel(LINFLEXD_UARTCR_UART, sport->membase + UARTCR);

	cr = (LINFLEXD_UARTCR_RXEN | LINFLEXD_UARTCR_TXEN |
	      LINFLEXD_UARTCR_WL0 | LINFLEXD_UARTCR_UART);

	writel(cr, sport->membase + UARTCR);

	cr1 &= ~(LINFLEXD_LINCR1_INIT);

	writel(cr1, sport->membase + LINCR1);

	ier = readl(sport->membase + LINIER);
	ier |= LINFLEXD_LINIER_DRIE;
	ier |= LINFLEXD_LINIER_DTIE;

	writel(ier, sport->membase + LINIER);
}

static int linflex_startup(struct uart_port *port)
{
	int ret = 0;
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);

	linflex_setup_watermark(port);

	spin_unlock_irqrestore(&port->lock, flags);

	ret = devm_request_irq(port->dev, port->irq, linflex_int, 0,
			       DRIVER_NAME, port);

	return ret;
}

static void linflex_shutdown(struct uart_port *port)
{
	unsigned long ier;
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);

	/* disable interrupts */
	ier = readl(port->membase + LINIER);
	ier &= ~(LINFLEXD_LINIER_DRIE | LINFLEXD_LINIER_DTIE);
	writel(ier, port->membase + LINIER);

	spin_unlock_irqrestore(&port->lock, flags);

	devm_free_irq(port->dev, port->irq, port);
}

static void
linflex_set_termios(struct uart_port *port, struct ktermios *termios,
		    struct ktermios *old)
{
	unsigned long flags;
	unsigned long cr, old_cr, cr1;
	unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;

	cr = readl(port->membase + UARTCR);
	old_cr = cr;

	/* Enter initialization mode by setting INIT bit */
	cr1 = readl(port->membase + LINCR1);
	cr1 |= LINFLEXD_LINCR1_INIT;
	writel(cr1, port->membase + LINCR1);

	/* wait for init mode entry */
	while ((readl(port->membase + LINSR)
		& LINFLEXD_LINSR_LINS_MASK)
		!= LINFLEXD_LINSR_LINS_INITMODE)
		;

	/*
	 * only support CS8 and CS7, and for CS7 must enable PE.
	 * supported mode:
	 *	- (7,e/o,1)
	 *	- (8,n,1)
	 *	- (8,e/o,1)
	 */
	/* enter the UART into configuration mode */

	while ((termios->c_cflag & CSIZE) != CS8 &&
	       (termios->c_cflag & CSIZE) != CS7) {
		termios->c_cflag &= ~CSIZE;
		termios->c_cflag |= old_csize;
		old_csize = CS8;
	}

	if ((termios->c_cflag & CSIZE) == CS7) {
		/* Word length: WL1WL0:00 */
		cr = old_cr & ~LINFLEXD_UARTCR_WL1 & ~LINFLEXD_UARTCR_WL0;
	}

	if ((termios->c_cflag & CSIZE) == CS8) {
		/* Word length: WL1WL0:01 */
		cr = (old_cr | LINFLEXD_UARTCR_WL0) & ~LINFLEXD_UARTCR_WL1;
	}

	if (termios->c_cflag & CMSPAR) {
		if ((termios->c_cflag & CSIZE) != CS8) {
			termios->c_cflag &= ~CSIZE;
			termios->c_cflag |= CS8;
		}
		/* has a space/sticky bit */
		cr |= LINFLEXD_UARTCR_WL0;
	}

	if (termios->c_cflag & CSTOPB)
		termios->c_cflag &= ~CSTOPB;

	/* parity must be enabled when CS7 to match 8-bits format */
	if ((termios->c_cflag & CSIZE) == CS7)
		termios->c_cflag |= PARENB;

	if ((termios->c_cflag & PARENB)) {
		cr |= LINFLEXD_UARTCR_PCE;
		if (termios->c_cflag & PARODD)
			cr = (cr | LINFLEXD_UARTCR_PC0) &
			     (~LINFLEXD_UARTCR_PC1);
		else
			cr = cr & (~LINFLEXD_UARTCR_PC1 &
				   ~LINFLEXD_UARTCR_PC0);
	} else {
		cr &= ~LINFLEXD_UARTCR_PCE;
	}

	spin_lock_irqsave(&port->lock, flags);

	port->read_status_mask = 0;

	if (termios->c_iflag & INPCK)
		port->read_status_mask |=	(LINFLEXD_UARTSR_FEF |
						 LINFLEXD_UARTSR_PE0 |
						 LINFLEXD_UARTSR_PE1 |
						 LINFLEXD_UARTSR_PE2 |
						 LINFLEXD_UARTSR_PE3);
	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
		port->read_status_mask |= LINFLEXD_UARTSR_FEF;

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

	writel(cr, port->membase + UARTCR);

	cr1 &= ~(LINFLEXD_LINCR1_INIT);

	writel(cr1, port->membase + LINCR1);

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

static const char *linflex_type(struct uart_port *port)
{
	return "FSL_LINFLEX";
}

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

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

/* configure/auto-configure the port */
static void linflex_config_port(struct uart_port *port, int flags)
{
	if (flags & UART_CONFIG_TYPE)
		port->type = PORT_LINFLEXUART;
}

static const struct uart_ops linflex_pops = {
	.tx_empty	= linflex_tx_empty,
	.set_mctrl	= linflex_set_mctrl,
	.get_mctrl	= linflex_get_mctrl,
	.stop_tx	= linflex_stop_tx,
	.start_tx	= linflex_start_tx,
	.stop_rx	= linflex_stop_rx,
	.break_ctl	= linflex_break_ctl,
	.startup	= linflex_startup,
	.shutdown	= linflex_shutdown,
	.set_termios	= linflex_set_termios,
	.type		= linflex_type,
	.request_port	= linflex_request_port,
	.release_port	= linflex_release_port,
	.config_port	= linflex_config_port,
};

static struct uart_port *linflex_ports[UART_NR];

#ifdef CONFIG_SERIAL_FSL_LINFLEXUART_CONSOLE
static void linflex_console_putchar(struct uart_port *port, int ch)
{
	unsigned long cr;

	cr = readl(port->membase + UARTCR);

	writeb(ch, port->membase + BDRL);

	if (!(cr & LINFLEXD_UARTCR_TFBM))
		while ((readl(port->membase + UARTSR) &
					LINFLEXD_UARTSR_DTFTFF)
				!= LINFLEXD_UARTSR_DTFTFF)
			;
	else
		while (readl(port->membase + UARTSR) &
					LINFLEXD_UARTSR_DTFTFF)
			;

	if (!(cr & LINFLEXD_UARTCR_TFBM)) {
		writel((readl(port->membase + UARTSR) |
					LINFLEXD_UARTSR_DTFTFF),
					port->membase + UARTSR);
	}
}

static void linflex_earlycon_putchar(struct uart_port *port, int ch)
{
	unsigned long flags;
	char *ret;

	if (!linflex_earlycon_same_instance) {
		linflex_console_putchar(port, ch);
		return;
	}

	spin_lock_irqsave(&init_lock, flags);
	if (!during_init)
		goto outside_init;

	if (earlycon_buf.len >= 1 << CONFIG_LOG_BUF_SHIFT)
		goto init_release;

	if (!earlycon_buf.cap) {
		earlycon_buf.content = kmalloc(EARLYCON_BUFFER_INITIAL_CAP,
					       GFP_ATOMIC);
		earlycon_buf.cap = earlycon_buf.content ?
				   EARLYCON_BUFFER_INITIAL_CAP : 0;
	} else if (earlycon_buf.len == earlycon_buf.cap) {
		ret = krealloc(earlycon_buf.content, earlycon_buf.cap << 1,
			       GFP_ATOMIC);
		if (ret) {
			earlycon_buf.content = ret;
			earlycon_buf.cap <<= 1;
		}
	}

	if (earlycon_buf.len < earlycon_buf.cap)
		earlycon_buf.content[earlycon_buf.len++] = ch;

	goto init_release;

outside_init:
	linflex_console_putchar(port, ch);
init_release:
	spin_unlock_irqrestore(&init_lock, flags);
}

static void linflex_string_write(struct uart_port *sport, const char *s,
				 unsigned int count)
{
	unsigned long cr, ier = 0;

	ier = readl(sport->membase + LINIER);
	linflex_stop_tx(sport);

	cr = readl(sport->membase + UARTCR);
	cr |= (LINFLEXD_UARTCR_TXEN);
	writel(cr, sport->membase + UARTCR);

	uart_console_write(sport, s, count, linflex_console_putchar);

	writel(ier, sport->membase + LINIER);
}

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

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

	linflex_string_write(sport, s, count);

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

/*
 * if the port was already initialised (eg, by a boot loader),
 * try to determine the current setup.
 */
static void __init
linflex_console_get_options(struct uart_port *sport, int *parity, int *bits)
{
	unsigned long cr;

	cr = readl(sport->membase + UARTCR);
	cr &= LINFLEXD_UARTCR_RXEN | LINFLEXD_UARTCR_TXEN;

	if (!cr)
		return;

	/* ok, the port was enabled */

	*parity = 'n';
	if (cr & LINFLEXD_UARTCR_PCE) {
		if (cr & LINFLEXD_UARTCR_PC0)
			*parity = 'o';
		else
			*parity = 'e';
	}

	if ((cr & LINFLEXD_UARTCR_WL0) && ((cr & LINFLEXD_UARTCR_WL1) == 0)) {
		if (cr & LINFLEXD_UARTCR_PCE)
			*bits = 9;
		else
			*bits = 8;
	}
}

static int __init linflex_console_setup(struct console *co, char *options)
{
	struct uart_port *sport;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';
	int ret;
	int i;
	unsigned long flags;
	/*
	 * check whether an invalid uart number has been specified, and
	 * if so, search for the first available port that does have
	 * console support.
	 */
	if (co->index == -1 || co->index >= ARRAY_SIZE(linflex_ports))
		co->index = 0;

	sport = linflex_ports[co->index];
	if (!sport)
		return -ENODEV;

	if (options)
		uart_parse_options(options, &baud, &parity, &bits, &flow);
	else
		linflex_console_get_options(sport, &parity, &bits);

	if (earlycon_port && sport->mapbase == earlycon_port->mapbase) {
		linflex_earlycon_same_instance = true;

		spin_lock_irqsave(&init_lock, flags);
		during_init = true;
		spin_unlock_irqrestore(&init_lock, flags);

		/* Workaround for character loss or output of many invalid
		 * characters, when INIT mode is entered shortly after a
		 * character has just been printed.
		 */
		udelay(PREINIT_DELAY);
	}

	linflex_setup_watermark(sport);

	ret = uart_set_options(sport, co, baud, parity, bits, flow);

	if (!linflex_earlycon_same_instance)
		goto done;

	spin_lock_irqsave(&init_lock, flags);

	/* Emptying buffer */
	if (earlycon_buf.len) {
		for (i = 0; i < earlycon_buf.len; i++)
			linflex_console_putchar(earlycon_port,
				earlycon_buf.content[i]);

		kfree(earlycon_buf.content);
		earlycon_buf.len = 0;
	}

	during_init = false;
	spin_unlock_irqrestore(&init_lock, flags);

done:
	return ret;
}

static struct uart_driver linflex_reg;
static struct console linflex_console = {
	.name		= DEV_NAME,
	.write		= linflex_console_write,
	.device		= uart_console_device,
	.setup		= linflex_console_setup,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
	.data		= &linflex_reg,
};

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

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

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

	device->con->write = linflex_earlycon_write;
	earlycon_port = &device->port;

	return 0;
}

OF_EARLYCON_DECLARE(linflex, "fsl,s32-linflexuart",
		    linflex_early_console_setup);

#define LINFLEX_CONSOLE	(&linflex_console)
#else
#define LINFLEX_CONSOLE	NULL
#endif

static struct uart_driver linflex_reg = {
	.owner		= THIS_MODULE,
	.driver_name	= DRIVER_NAME,
	.dev_name	= DEV_NAME,
	.nr		= ARRAY_SIZE(linflex_ports),
	.cons		= LINFLEX_CONSOLE,
};

static int linflex_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct uart_port *sport;
	struct resource *res;
	int ret;

	sport = devm_kzalloc(&pdev->dev, sizeof(*sport), GFP_KERNEL);
	if (!sport)
		return -ENOMEM;

	ret = of_alias_get_id(np, "serial");
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to get alias id, errno %d\n", ret);
		return ret;
	}
	if (ret >= UART_NR) {
		dev_err(&pdev->dev, "driver limited to %d serial ports\n",
			UART_NR);
		return -ENOMEM;
	}

	sport->line = ret;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res)
		return -ENODEV;

	sport->mapbase = res->start;
	sport->membase = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(sport->membase))
		return PTR_ERR(sport->membase);

	sport->dev = &pdev->dev;
	sport->type = PORT_LINFLEXUART;
	sport->iotype = UPIO_MEM;
	sport->irq = platform_get_irq(pdev, 0);
	sport->ops = &linflex_pops;
	sport->flags = UPF_BOOT_AUTOCONF;

	linflex_ports[sport->line] = sport;

	platform_set_drvdata(pdev, sport);

	ret = uart_add_one_port(&linflex_reg, sport);
	if (ret)
		return ret;

	return 0;
}

static int linflex_remove(struct platform_device *pdev)
{
	struct uart_port *sport = platform_get_drvdata(pdev);

	uart_remove_one_port(&linflex_reg, sport);

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int linflex_suspend(struct device *dev)
{
	struct uart_port *sport = dev_get_drvdata(dev);

	uart_suspend_port(&linflex_reg, sport);

	return 0;
}

static int linflex_resume(struct device *dev)
{
	struct uart_port *sport = dev_get_drvdata(dev);

	uart_resume_port(&linflex_reg, sport);

	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(linflex_pm_ops, linflex_suspend, linflex_resume);

static struct platform_driver linflex_driver = {
	.probe		= linflex_probe,
	.remove		= linflex_remove,
	.driver		= {
		.name	= DRIVER_NAME,
		.owner	= THIS_MODULE,
		.of_match_table	= linflex_dt_ids,
		.pm	= &linflex_pm_ops,
	},
};

static int __init linflex_serial_init(void)
{
	int ret;

	ret = uart_register_driver(&linflex_reg);
	if (ret)
		return ret;

	ret = platform_driver_register(&linflex_driver);
	if (ret)
		uart_unregister_driver(&linflex_reg);

	return ret;
}

static void __exit linflex_serial_exit(void)
{
	platform_driver_unregister(&linflex_driver);
	uart_unregister_driver(&linflex_reg);
}

module_init(linflex_serial_init);
module_exit(linflex_serial_exit);

MODULE_DESCRIPTION("Freescale linflex serial port driver");
MODULE_LICENSE("GPL v2");