drivers/tty/serial/sccnxp.c

// SPDX-License-Identifier: GPL-2.0+
/*
 *  NXP (Philips) SCC+++(SCN+++) serial driver
 *
 *  Copyright (C) 2012 Alexander Shiyan <shc_work@mail.ru>
 *
 *  Based on sc26xx.c, by Thomas Bogendörfer (tsbogend@alpha.franken.de)
 */

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

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/device.h>
#include <linux/console.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/io.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/platform_data/serial-sccnxp.h>
#include <linux/regulator/consumer.h>

#define SCCNXP_NAME			"uart-sccnxp"
#define SCCNXP_MAJOR			204
#define SCCNXP_MINOR			205

#define SCCNXP_MR_REG			(0x00)
#	define MR0_BAUD_NORMAL		(0 << 0)
#	define MR0_BAUD_EXT1		(1 << 0)
#	define MR0_BAUD_EXT2		(5 << 0)
#	define MR0_FIFO			(1 << 3)
#	define MR0_TXLVL		(1 << 4)
#	define MR1_BITS_5		(0 << 0)
#	define MR1_BITS_6		(1 << 0)
#	define MR1_BITS_7		(2 << 0)
#	define MR1_BITS_8		(3 << 0)
#	define MR1_PAR_EVN		(0 << 2)
#	define MR1_PAR_ODD		(1 << 2)
#	define MR1_PAR_NO		(4 << 2)
#	define MR2_STOP1		(7 << 0)
#	define MR2_STOP2		(0xf << 0)
#define SCCNXP_SR_REG			(0x01)
#	define SR_RXRDY			(1 << 0)
#	define SR_FULL			(1 << 1)
#	define SR_TXRDY			(1 << 2)
#	define SR_TXEMT			(1 << 3)
#	define SR_OVR			(1 << 4)
#	define SR_PE			(1 << 5)
#	define SR_FE			(1 << 6)
#	define SR_BRK			(1 << 7)
#define SCCNXP_CSR_REG			(SCCNXP_SR_REG)
#	define CSR_TIMER_MODE		(0x0d)
#define SCCNXP_CR_REG			(0x02)
#	define CR_RX_ENABLE		(1 << 0)
#	define CR_RX_DISABLE		(1 << 1)
#	define CR_TX_ENABLE		(1 << 2)
#	define CR_TX_DISABLE		(1 << 3)
#	define CR_CMD_MRPTR1		(0x01 << 4)
#	define CR_CMD_RX_RESET		(0x02 << 4)
#	define CR_CMD_TX_RESET		(0x03 << 4)
#	define CR_CMD_STATUS_RESET	(0x04 << 4)
#	define CR_CMD_BREAK_RESET	(0x05 << 4)
#	define CR_CMD_START_BREAK	(0x06 << 4)
#	define CR_CMD_STOP_BREAK	(0x07 << 4)
#	define CR_CMD_MRPTR0		(0x0b << 4)
#define SCCNXP_RHR_REG			(0x03)
#define SCCNXP_THR_REG			SCCNXP_RHR_REG
#define SCCNXP_IPCR_REG			(0x04)
#define SCCNXP_ACR_REG			SCCNXP_IPCR_REG
#	define ACR_BAUD0		(0 << 7)
#	define ACR_BAUD1		(1 << 7)
#	define ACR_TIMER_MODE		(6 << 4)
#define SCCNXP_ISR_REG			(0x05)
#define SCCNXP_IMR_REG			SCCNXP_ISR_REG
#	define IMR_TXRDY		(1 << 0)
#	define IMR_RXRDY		(1 << 1)
#	define ISR_TXRDY(x)		(1 << ((x * 4) + 0))
#	define ISR_RXRDY(x)		(1 << ((x * 4) + 1))
#define SCCNXP_CTPU_REG			(0x06)
#define SCCNXP_CTPL_REG			(0x07)
#define SCCNXP_IPR_REG			(0x0d)
#define SCCNXP_OPCR_REG			SCCNXP_IPR_REG
#define SCCNXP_SOP_REG			(0x0e)
#define SCCNXP_START_COUNTER_REG	SCCNXP_SOP_REG
#define SCCNXP_ROP_REG			(0x0f)

/* Route helpers */
#define MCTRL_MASK(sig)			(0xf << (sig))
#define MCTRL_IBIT(cfg, sig)		((((cfg) >> (sig)) & 0xf) - LINE_IP0)
#define MCTRL_OBIT(cfg, sig)		((((cfg) >> (sig)) & 0xf) - LINE_OP0)

#define SCCNXP_HAVE_IO		0x00000001
#define SCCNXP_HAVE_MR0		0x00000002

struct sccnxp_chip {
	const char		*name;
	unsigned int		nr;
	unsigned long		freq_min;
	unsigned long		freq_std;
	unsigned long		freq_max;
	unsigned int		flags;
	unsigned int		fifosize;
	/* Time between read/write cycles */
	unsigned int		trwd;
};

struct sccnxp_port {
	struct uart_driver	uart;
	struct uart_port	port[SCCNXP_MAX_UARTS];
	bool			opened[SCCNXP_MAX_UARTS];

	int			irq;
	u8			imr;

	struct sccnxp_chip	*chip;

#ifdef CONFIG_SERIAL_SCCNXP_CONSOLE
	struct console		console;
#endif

	spinlock_t		lock;

	bool			poll;
	struct timer_list	timer;

	struct sccnxp_pdata	pdata;

	struct regulator	*regulator;
};

static const struct sccnxp_chip sc2681 = {
	.name		= "SC2681",
	.nr		= 2,
	.freq_min	= 1000000,
	.freq_std	= 3686400,
	.freq_max	= 4000000,
	.flags		= SCCNXP_HAVE_IO,
	.fifosize	= 3,
	.trwd		= 200,
};

static const struct sccnxp_chip sc2691 = {
	.name		= "SC2691",
	.nr		= 1,
	.freq_min	= 1000000,
	.freq_std	= 3686400,
	.freq_max	= 4000000,
	.flags		= 0,
	.fifosize	= 3,
	.trwd		= 150,
};

static const struct sccnxp_chip sc2692 = {
	.name		= "SC2692",
	.nr		= 2,
	.freq_min	= 1000000,
	.freq_std	= 3686400,
	.freq_max	= 4000000,
	.flags		= SCCNXP_HAVE_IO,
	.fifosize	= 3,
	.trwd		= 30,
};

static const struct sccnxp_chip sc2891 = {
	.name		= "SC2891",
	.nr		= 1,
	.freq_min	= 100000,
	.freq_std	= 3686400,
	.freq_max	= 8000000,
	.flags		= SCCNXP_HAVE_IO | SCCNXP_HAVE_MR0,
	.fifosize	= 16,
	.trwd		= 27,
};

static const struct sccnxp_chip sc2892 = {
	.name		= "SC2892",
	.nr		= 2,
	.freq_min	= 100000,
	.freq_std	= 3686400,
	.freq_max	= 8000000,
	.flags		= SCCNXP_HAVE_IO | SCCNXP_HAVE_MR0,
	.fifosize	= 16,
	.trwd		= 17,
};

static const struct sccnxp_chip sc28202 = {
	.name		= "SC28202",
	.nr		= 2,
	.freq_min	= 1000000,
	.freq_std	= 14745600,
	.freq_max	= 50000000,
	.flags		= SCCNXP_HAVE_IO | SCCNXP_HAVE_MR0,
	.fifosize	= 256,
	.trwd		= 10,
};

static const struct sccnxp_chip sc68681 = {
	.name		= "SC68681",
	.nr		= 2,
	.freq_min	= 1000000,
	.freq_std	= 3686400,
	.freq_max	= 4000000,
	.flags		= SCCNXP_HAVE_IO,
	.fifosize	= 3,
	.trwd		= 200,
};

static const struct sccnxp_chip sc68692 = {
	.name		= "SC68692",
	.nr		= 2,
	.freq_min	= 1000000,
	.freq_std	= 3686400,
	.freq_max	= 4000000,
	.flags		= SCCNXP_HAVE_IO,
	.fifosize	= 3,
	.trwd		= 200,
};

static u8 sccnxp_read(struct uart_port *port, u8 reg)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	u8 ret;

	ret = readb(port->membase + (reg << port->regshift));

	ndelay(s->chip->trwd);

	return ret;
}

static void sccnxp_write(struct uart_port *port, u8 reg, u8 v)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);

	writeb(v, port->membase + (reg << port->regshift));

	ndelay(s->chip->trwd);
}

static u8 sccnxp_port_read(struct uart_port *port, u8 reg)
{
	return sccnxp_read(port, (port->line << 3) + reg);
}

static void sccnxp_port_write(struct uart_port *port, u8 reg, u8 v)
{
	sccnxp_write(port, (port->line << 3) + reg, v);
}

static int sccnxp_update_best_err(int a, int b, int *besterr)
{
	int err = abs(a - b);

	if (*besterr > err) {
		*besterr = err;
		return 0;
	}

	return 1;
}

static const struct {
	u8	csr;
	u8	acr;
	u8	mr0;
	int	baud;
} baud_std[] = {
	{ 0,	ACR_BAUD0,	MR0_BAUD_NORMAL,	50, },
	{ 0,	ACR_BAUD1,	MR0_BAUD_NORMAL,	75, },
	{ 1,	ACR_BAUD0,	MR0_BAUD_NORMAL,	110, },
	{ 2,	ACR_BAUD0,	MR0_BAUD_NORMAL,	134, },
	{ 3,	ACR_BAUD1,	MR0_BAUD_NORMAL,	150, },
	{ 3,	ACR_BAUD0,	MR0_BAUD_NORMAL,	200, },
	{ 4,	ACR_BAUD0,	MR0_BAUD_NORMAL,	300, },
	{ 0,	ACR_BAUD1,	MR0_BAUD_EXT1,		450, },
	{ 1,	ACR_BAUD0,	MR0_BAUD_EXT2,		880, },
	{ 3,	ACR_BAUD1,	MR0_BAUD_EXT1,		900, },
	{ 5,	ACR_BAUD0,	MR0_BAUD_NORMAL,	600, },
	{ 7,	ACR_BAUD0,	MR0_BAUD_NORMAL,	1050, },
	{ 2,	ACR_BAUD0,	MR0_BAUD_EXT2,		1076, },
	{ 6,	ACR_BAUD0,	MR0_BAUD_NORMAL,	1200, },
	{ 10,	ACR_BAUD1,	MR0_BAUD_NORMAL,	1800, },
	{ 7,	ACR_BAUD1,	MR0_BAUD_NORMAL,	2000, },
	{ 8,	ACR_BAUD0,	MR0_BAUD_NORMAL,	2400, },
	{ 5,	ACR_BAUD1,	MR0_BAUD_EXT1,		3600, },
	{ 9,	ACR_BAUD0,	MR0_BAUD_NORMAL,	4800, },
	{ 10,	ACR_BAUD0,	MR0_BAUD_NORMAL,	7200, },
	{ 11,	ACR_BAUD0,	MR0_BAUD_NORMAL,	9600, },
	{ 8,	ACR_BAUD0,	MR0_BAUD_EXT1,		14400, },
	{ 12,	ACR_BAUD1,	MR0_BAUD_NORMAL,	19200, },
	{ 9,	ACR_BAUD0,	MR0_BAUD_EXT1,		28800, },
	{ 12,	ACR_BAUD0,	MR0_BAUD_NORMAL,	38400, },
	{ 11,	ACR_BAUD0,	MR0_BAUD_EXT1,		57600, },
	{ 12,	ACR_BAUD1,	MR0_BAUD_EXT1,		115200, },
	{ 12,	ACR_BAUD0,	MR0_BAUD_EXT1,		230400, },
	{ 0, 0, 0, 0 }
};

static int sccnxp_set_baud(struct uart_port *port, int baud)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	int div_std, tmp_baud, bestbaud = INT_MAX, besterr = INT_MAX;
	struct sccnxp_chip *chip = s->chip;
	u8 i, acr = 0, csr = 0, mr0 = 0;

	/* Find divisor to load to the timer preset registers */
	div_std = DIV_ROUND_CLOSEST(port->uartclk, 2 * 16 * baud);
	if ((div_std >= 2) && (div_std <= 0xffff)) {
		bestbaud = DIV_ROUND_CLOSEST(port->uartclk, 2 * 16 * div_std);
		sccnxp_update_best_err(baud, bestbaud, &besterr);
		csr = CSR_TIMER_MODE;
		sccnxp_port_write(port, SCCNXP_CTPU_REG, div_std >> 8);
		sccnxp_port_write(port, SCCNXP_CTPL_REG, div_std);
		/* Issue start timer/counter command */
		sccnxp_port_read(port, SCCNXP_START_COUNTER_REG);
	}

	/* Find best baud from table */
	for (i = 0; baud_std[i].baud && besterr; i++) {
		if (baud_std[i].mr0 && !(chip->flags & SCCNXP_HAVE_MR0))
			continue;
		div_std = DIV_ROUND_CLOSEST(chip->freq_std, baud_std[i].baud);
		tmp_baud = DIV_ROUND_CLOSEST(port->uartclk, div_std);
		if (!sccnxp_update_best_err(baud, tmp_baud, &besterr)) {
			acr = baud_std[i].acr;
			csr = baud_std[i].csr;
			mr0 = baud_std[i].mr0;
			bestbaud = tmp_baud;
		}
	}

	if (chip->flags & SCCNXP_HAVE_MR0) {
		/* Enable FIFO, set half level for TX */
		mr0 |= MR0_FIFO | MR0_TXLVL;
		/* Update MR0 */
		sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_MRPTR0);
		sccnxp_port_write(port, SCCNXP_MR_REG, mr0);
	}

	sccnxp_port_write(port, SCCNXP_ACR_REG, acr | ACR_TIMER_MODE);
	sccnxp_port_write(port, SCCNXP_CSR_REG, (csr << 4) | csr);

	if (baud != bestbaud)
		dev_dbg(port->dev, "Baudrate desired: %i, calculated: %i\n",
			baud, bestbaud);

	return bestbaud;
}

static void sccnxp_enable_irq(struct uart_port *port, int mask)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);

	s->imr |= mask << (port->line * 4);
	sccnxp_write(port, SCCNXP_IMR_REG, s->imr);
}

static void sccnxp_disable_irq(struct uart_port *port, int mask)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);

	s->imr &= ~(mask << (port->line * 4));
	sccnxp_write(port, SCCNXP_IMR_REG, s->imr);
}

static void sccnxp_set_bit(struct uart_port *port, int sig, int state)
{
	u8 bitmask;
	struct sccnxp_port *s = dev_get_drvdata(port->dev);

	if (s->pdata.mctrl_cfg[port->line] & MCTRL_MASK(sig)) {
		bitmask = 1 << MCTRL_OBIT(s->pdata.mctrl_cfg[port->line], sig);
		if (state)
			sccnxp_write(port, SCCNXP_SOP_REG, bitmask);
		else
			sccnxp_write(port, SCCNXP_ROP_REG, bitmask);
	}
}

static void sccnxp_handle_rx(struct uart_port *port)
{
	u8 sr;
	unsigned int ch, flag;

	for (;;) {
		sr = sccnxp_port_read(port, SCCNXP_SR_REG);
		if (!(sr & SR_RXRDY))
			break;
		sr &= SR_PE | SR_FE | SR_OVR | SR_BRK;

		ch = sccnxp_port_read(port, SCCNXP_RHR_REG);

		port->icount.rx++;
		flag = TTY_NORMAL;

		if (unlikely(sr)) {
			if (sr & SR_BRK) {
				port->icount.brk++;
				sccnxp_port_write(port, SCCNXP_CR_REG,
						  CR_CMD_BREAK_RESET);
				if (uart_handle_break(port))
					continue;
			} else if (sr & SR_PE)
				port->icount.parity++;
			else if (sr & SR_FE)
				port->icount.frame++;
			else if (sr & SR_OVR) {
				port->icount.overrun++;
				sccnxp_port_write(port, SCCNXP_CR_REG,
						  CR_CMD_STATUS_RESET);
			}

			sr &= port->read_status_mask;
			if (sr & SR_BRK)
				flag = TTY_BREAK;
			else if (sr & SR_PE)
				flag = TTY_PARITY;
			else if (sr & SR_FE)
				flag = TTY_FRAME;
			else if (sr & SR_OVR)
				flag = TTY_OVERRUN;
		}

		if (uart_handle_sysrq_char(port, ch))
			continue;

		if (sr & port->ignore_status_mask)
			continue;

		uart_insert_char(port, sr, SR_OVR, ch, flag);
	}

	tty_flip_buffer_push(&port->state->port);
}

static void sccnxp_handle_tx(struct uart_port *port)
{
	u8 sr;
	struct circ_buf *xmit = &port->state->xmit;
	struct sccnxp_port *s = dev_get_drvdata(port->dev);

	if (unlikely(port->x_char)) {
		sccnxp_port_write(port, SCCNXP_THR_REG, port->x_char);
		port->icount.tx++;
		port->x_char = 0;
		return;
	}

	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
		/* Disable TX if FIFO is empty */
		if (sccnxp_port_read(port, SCCNXP_SR_REG) & SR_TXEMT) {
			sccnxp_disable_irq(port, IMR_TXRDY);

			/* Set direction to input */
			if (s->chip->flags & SCCNXP_HAVE_IO)
				sccnxp_set_bit(port, DIR_OP, 0);
		}
		return;
	}

	while (!uart_circ_empty(xmit)) {
		sr = sccnxp_port_read(port, SCCNXP_SR_REG);
		if (!(sr & SR_TXRDY))
			break;

		sccnxp_port_write(port, SCCNXP_THR_REG, xmit->buf[xmit->tail]);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		port->icount.tx++;
	}

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

static void sccnxp_handle_events(struct sccnxp_port *s)
{
	int i;
	u8 isr;

	do {
		isr = sccnxp_read(&s->port[0], SCCNXP_ISR_REG);
		isr &= s->imr;
		if (!isr)
			break;

		for (i = 0; i < s->uart.nr; i++) {
			if (s->opened[i] && (isr & ISR_RXRDY(i)))
				sccnxp_handle_rx(&s->port[i]);
			if (s->opened[i] && (isr & ISR_TXRDY(i)))
				sccnxp_handle_tx(&s->port[i]);
		}
	} while (1);
}

static void sccnxp_timer(struct timer_list *t)
{
	struct sccnxp_port *s = from_timer(s, t, timer);
	unsigned long flags;

	spin_lock_irqsave(&s->lock, flags);
	sccnxp_handle_events(s);
	spin_unlock_irqrestore(&s->lock, flags);

	mod_timer(&s->timer, jiffies + usecs_to_jiffies(s->pdata.poll_time_us));
}

static irqreturn_t sccnxp_ist(int irq, void *dev_id)
{
	struct sccnxp_port *s = (struct sccnxp_port *)dev_id;
	unsigned long flags;

	spin_lock_irqsave(&s->lock, flags);
	sccnxp_handle_events(s);
	spin_unlock_irqrestore(&s->lock, flags);

	return IRQ_HANDLED;
}

static void sccnxp_start_tx(struct uart_port *port)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	unsigned long flags;

	spin_lock_irqsave(&s->lock, flags);

	/* Set direction to output */
	if (s->chip->flags & SCCNXP_HAVE_IO)
		sccnxp_set_bit(port, DIR_OP, 1);

	sccnxp_enable_irq(port, IMR_TXRDY);

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

static void sccnxp_stop_tx(struct uart_port *port)
{
	/* Do nothing */
}

static void sccnxp_stop_rx(struct uart_port *port)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	unsigned long flags;

	spin_lock_irqsave(&s->lock, flags);
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_RX_DISABLE);
	spin_unlock_irqrestore(&s->lock, flags);
}

static unsigned int sccnxp_tx_empty(struct uart_port *port)
{
	u8 val;
	unsigned long flags;
	struct sccnxp_port *s = dev_get_drvdata(port->dev);

	spin_lock_irqsave(&s->lock, flags);
	val = sccnxp_port_read(port, SCCNXP_SR_REG);
	spin_unlock_irqrestore(&s->lock, flags);

	return (val & SR_TXEMT) ? TIOCSER_TEMT : 0;
}

static void sccnxp_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	unsigned long flags;

	if (!(s->chip->flags & SCCNXP_HAVE_IO))
		return;

	spin_lock_irqsave(&s->lock, flags);

	sccnxp_set_bit(port, DTR_OP, mctrl & TIOCM_DTR);
	sccnxp_set_bit(port, RTS_OP, mctrl & TIOCM_RTS);

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

static unsigned int sccnxp_get_mctrl(struct uart_port *port)
{
	u8 bitmask, ipr;
	unsigned long flags;
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	unsigned int mctrl = TIOCM_DSR | TIOCM_CTS | TIOCM_CAR;

	if (!(s->chip->flags & SCCNXP_HAVE_IO))
		return mctrl;

	spin_lock_irqsave(&s->lock, flags);

	ipr = ~sccnxp_read(port, SCCNXP_IPCR_REG);

	if (s->pdata.mctrl_cfg[port->line] & MCTRL_MASK(DSR_IP)) {
		bitmask = 1 << MCTRL_IBIT(s->pdata.mctrl_cfg[port->line],
					  DSR_IP);
		mctrl &= ~TIOCM_DSR;
		mctrl |= (ipr & bitmask) ? TIOCM_DSR : 0;
	}
	if (s->pdata.mctrl_cfg[port->line] & MCTRL_MASK(CTS_IP)) {
		bitmask = 1 << MCTRL_IBIT(s->pdata.mctrl_cfg[port->line],
					  CTS_IP);
		mctrl &= ~TIOCM_CTS;
		mctrl |= (ipr & bitmask) ? TIOCM_CTS : 0;
	}
	if (s->pdata.mctrl_cfg[port->line] & MCTRL_MASK(DCD_IP)) {
		bitmask = 1 << MCTRL_IBIT(s->pdata.mctrl_cfg[port->line],
					  DCD_IP);
		mctrl &= ~TIOCM_CAR;
		mctrl |= (ipr & bitmask) ? TIOCM_CAR : 0;
	}
	if (s->pdata.mctrl_cfg[port->line] & MCTRL_MASK(RNG_IP)) {
		bitmask = 1 << MCTRL_IBIT(s->pdata.mctrl_cfg[port->line],
					  RNG_IP);
		mctrl &= ~TIOCM_RNG;
		mctrl |= (ipr & bitmask) ? TIOCM_RNG : 0;
	}

	spin_unlock_irqrestore(&s->lock, flags);

	return mctrl;
}

static void sccnxp_break_ctl(struct uart_port *port, int break_state)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	unsigned long flags;

	spin_lock_irqsave(&s->lock, flags);
	sccnxp_port_write(port, SCCNXP_CR_REG, break_state ?
			  CR_CMD_START_BREAK : CR_CMD_STOP_BREAK);
	spin_unlock_irqrestore(&s->lock, flags);
}

static void sccnxp_set_termios(struct uart_port *port,
			       struct ktermios *termios, struct ktermios *old)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	unsigned long flags;
	u8 mr1, mr2;
	int baud;

	spin_lock_irqsave(&s->lock, flags);

	/* Mask termios capabilities we don't support */
	termios->c_cflag &= ~CMSPAR;

	/* Disable RX & TX, reset break condition, status and FIFOs */
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_RX_RESET |
					       CR_RX_DISABLE | CR_TX_DISABLE);
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_TX_RESET);
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_STATUS_RESET);
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_BREAK_RESET);

	/* Word size */
	switch (termios->c_cflag & CSIZE) {
	case CS5:
		mr1 = MR1_BITS_5;
		break;
	case CS6:
		mr1 = MR1_BITS_6;
		break;
	case CS7:
		mr1 = MR1_BITS_7;
		break;
	case CS8:
	default:
		mr1 = MR1_BITS_8;
		break;
	}

	/* Parity */
	if (termios->c_cflag & PARENB) {
		if (termios->c_cflag & PARODD)
			mr1 |= MR1_PAR_ODD;
	} else
		mr1 |= MR1_PAR_NO;

	/* Stop bits */
	mr2 = (termios->c_cflag & CSTOPB) ? MR2_STOP2 : MR2_STOP1;

	/* Update desired format */
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_MRPTR1);
	sccnxp_port_write(port, SCCNXP_MR_REG, mr1);
	sccnxp_port_write(port, SCCNXP_MR_REG, mr2);

	/* Set read status mask */
	port->read_status_mask = SR_OVR;
	if (termios->c_iflag & INPCK)
		port->read_status_mask |= SR_PE | SR_FE;
	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
		port->read_status_mask |= SR_BRK;

	/* Set status ignore mask */
	port->ignore_status_mask = 0;
	if (termios->c_iflag & IGNBRK)
		port->ignore_status_mask |= SR_BRK;
	if (termios->c_iflag & IGNPAR)
		port->ignore_status_mask |= SR_PE;
	if (!(termios->c_cflag & CREAD))
		port->ignore_status_mask |= SR_PE | SR_OVR | SR_FE | SR_BRK;

	/* Setup baudrate */
	baud = uart_get_baud_rate(port, termios, old, 50,
				  (s->chip->flags & SCCNXP_HAVE_MR0) ?
				  230400 : 38400);
	baud = sccnxp_set_baud(port, baud);

	/* Update timeout according to new baud rate */
	uart_update_timeout(port, termios->c_cflag, baud);

	/* Report actual baudrate back to core */
	if (tty_termios_baud_rate(termios))
		tty_termios_encode_baud_rate(termios, baud, baud);

	/* Enable RX & TX */
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_RX_ENABLE | CR_TX_ENABLE);

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

static int sccnxp_startup(struct uart_port *port)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	unsigned long flags;

	spin_lock_irqsave(&s->lock, flags);

	if (s->chip->flags & SCCNXP_HAVE_IO) {
		/* Outputs are controlled manually */
		sccnxp_write(port, SCCNXP_OPCR_REG, 0);
	}

	/* Reset break condition, status and FIFOs */
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_RX_RESET);
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_TX_RESET);
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_STATUS_RESET);
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_CMD_BREAK_RESET);

	/* Enable RX & TX */
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_RX_ENABLE | CR_TX_ENABLE);

	/* Enable RX interrupt */
	sccnxp_enable_irq(port, IMR_RXRDY);

	s->opened[port->line] = 1;

	spin_unlock_irqrestore(&s->lock, flags);

	return 0;
}

static void sccnxp_shutdown(struct uart_port *port)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);
	unsigned long flags;

	spin_lock_irqsave(&s->lock, flags);

	s->opened[port->line] = 0;

	/* Disable interrupts */
	sccnxp_disable_irq(port, IMR_TXRDY | IMR_RXRDY);

	/* Disable TX & RX */
	sccnxp_port_write(port, SCCNXP_CR_REG, CR_RX_DISABLE | CR_TX_DISABLE);

	/* Leave direction to input */
	if (s->chip->flags & SCCNXP_HAVE_IO)
		sccnxp_set_bit(port, DIR_OP, 0);

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

static const char *sccnxp_type(struct uart_port *port)
{
	struct sccnxp_port *s = dev_get_drvdata(port->dev);

	return (port->type == PORT_SC26XX) ? s->chip->name : NULL;
}

static void sccnxp_release_port(struct uart_port *port)
{
	/* Do nothing */
}

static int sccnxp_request_port(struct uart_port *port)
{
	/* Do nothing */
	return 0;
}

static void sccnxp_config_port(struct uart_port *port, int flags)
{
	if (flags & UART_CONFIG_TYPE)
		port->type = PORT_SC26XX;
}

static int sccnxp_verify_port(struct uart_port *port, struct serial_struct *s)
{
	if ((s->type == PORT_UNKNOWN) || (s->type == PORT_SC26XX))
		return 0;
	if (s->irq == port->irq)
		return 0;

	return -EINVAL;
}

static const struct uart_ops sccnxp_ops = {
	.tx_empty	= sccnxp_tx_empty,
	.set_mctrl	= sccnxp_set_mctrl,
	.get_mctrl	= sccnxp_get_mctrl,
	.stop_tx	= sccnxp_stop_tx,
	.start_tx	= sccnxp_start_tx,
	.stop_rx	= sccnxp_stop_rx,
	.break_ctl	= sccnxp_break_ctl,
	.startup	= sccnxp_startup,
	.shutdown	= sccnxp_shutdown,
	.set_termios	= sccnxp_set_termios,
	.type		= sccnxp_type,
	.release_port	= sccnxp_release_port,
	.request_port	= sccnxp_request_port,
	.config_port	= sccnxp_config_port,
	.verify_port	= sccnxp_verify_port,
};

#ifdef CONFIG_SERIAL_SCCNXP_CONSOLE
static void sccnxp_console_putchar(struct uart_port *port, int c)
{
	int tryes = 100000;

	while (tryes--) {
		if (sccnxp_port_read(port, SCCNXP_SR_REG) & SR_TXRDY) {
			sccnxp_port_write(port, SCCNXP_THR_REG, c);
			break;
		}
		barrier();
	}
}

static void sccnxp_console_write(struct console *co, const char *c, unsigned n)
{
	struct sccnxp_port *s = (struct sccnxp_port *)co->data;
	struct uart_port *port = &s->port[co->index];
	unsigned long flags;

	spin_lock_irqsave(&s->lock, flags);
	uart_console_write(port, c, n, sccnxp_console_putchar);
	spin_unlock_irqrestore(&s->lock, flags);
}

static int sccnxp_console_setup(struct console *co, char *options)
{
	struct sccnxp_port *s = (struct sccnxp_port *)co->data;
	struct uart_port *port = &s->port[(co->index > 0) ? co->index : 0];
	int baud = 9600, bits = 8, parity = 'n', flow = 'n';

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

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

static const struct platform_device_id sccnxp_id_table[] = {
	{ .name = "sc2681",	.driver_data = (kernel_ulong_t)&sc2681, },
	{ .name = "sc2691",	.driver_data = (kernel_ulong_t)&sc2691, },
	{ .name = "sc2692",	.driver_data = (kernel_ulong_t)&sc2692, },
	{ .name = "sc2891",	.driver_data = (kernel_ulong_t)&sc2891, },
	{ .name = "sc2892",	.driver_data = (kernel_ulong_t)&sc2892, },
	{ .name = "sc28202",	.driver_data = (kernel_ulong_t)&sc28202, },
	{ .name = "sc68681",	.driver_data = (kernel_ulong_t)&sc68681, },
	{ .name = "sc68692",	.driver_data = (kernel_ulong_t)&sc68692, },
	{ }
};
MODULE_DEVICE_TABLE(platform, sccnxp_id_table);

static int sccnxp_probe(struct platform_device *pdev)
{
	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	struct sccnxp_pdata *pdata = dev_get_platdata(&pdev->dev);
	int i, ret, uartclk;
	struct sccnxp_port *s;
	void __iomem *membase;
	struct clk *clk;

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

	s = devm_kzalloc(&pdev->dev, sizeof(struct sccnxp_port), GFP_KERNEL);
	if (!s) {
		dev_err(&pdev->dev, "Error allocating port structure\n");
		return -ENOMEM;
	}
	platform_set_drvdata(pdev, s);

	spin_lock_init(&s->lock);

	s->chip = (struct sccnxp_chip *)pdev->id_entry->driver_data;

	s->regulator = devm_regulator_get(&pdev->dev, "vcc");
	if (!IS_ERR(s->regulator)) {
		ret = regulator_enable(s->regulator);
		if (ret) {
			dev_err(&pdev->dev,
				"Failed to enable regulator: %i\n", ret);
			return ret;
		}
	} else if (PTR_ERR(s->regulator) == -EPROBE_DEFER)
		return -EPROBE_DEFER;

	clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(clk)) {
		ret = PTR_ERR(clk);
		if (ret == -EPROBE_DEFER)
			goto err_out;
		uartclk = 0;
	} else {
		ret = clk_prepare_enable(clk);
		if (ret)
			goto err_out;

		ret = devm_add_action_or_reset(&pdev->dev,
				(void(*)(void *))clk_disable_unprepare,
				clk);
		if (ret)
			goto err_out;

		uartclk = clk_get_rate(clk);
	}

	if (!uartclk) {
		dev_notice(&pdev->dev, "Using default clock frequency\n");
		uartclk = s->chip->freq_std;
	}

	/* Check input frequency */
	if ((uartclk < s->chip->freq_min) || (uartclk > s->chip->freq_max)) {
		dev_err(&pdev->dev, "Frequency out of bounds\n");
		ret = -EINVAL;
		goto err_out;
	}

	if (pdata)
		memcpy(&s->pdata, pdata, sizeof(struct sccnxp_pdata));

	if (s->pdata.poll_time_us) {
		dev_info(&pdev->dev, "Using poll mode, resolution %u usecs\n",
			 s->pdata.poll_time_us);
		s->poll = 1;
	}

	if (!s->poll) {
		s->irq = platform_get_irq(pdev, 0);
		if (s->irq < 0) {
			dev_err(&pdev->dev, "Missing irq resource data\n");
			ret = -ENXIO;
			goto err_out;
		}
	}

	s->uart.owner		= THIS_MODULE;
	s->uart.dev_name	= "ttySC";
	s->uart.major		= SCCNXP_MAJOR;
	s->uart.minor		= SCCNXP_MINOR;
	s->uart.nr		= s->chip->nr;
#ifdef CONFIG_SERIAL_SCCNXP_CONSOLE
	s->uart.cons		= &s->console;
	s->uart.cons->device	= uart_console_device;
	s->uart.cons->write	= sccnxp_console_write;
	s->uart.cons->setup	= sccnxp_console_setup;
	s->uart.cons->flags	= CON_PRINTBUFFER;
	s->uart.cons->index	= -1;
	s->uart.cons->data	= s;
	strcpy(s->uart.cons->name, "ttySC");
#endif
	ret = uart_register_driver(&s->uart);
	if (ret) {
		dev_err(&pdev->dev, "Registering UART driver failed\n");
		goto err_out;
	}

	for (i = 0; i < s->uart.nr; i++) {
		s->port[i].line		= i;
		s->port[i].dev		= &pdev->dev;
		s->port[i].irq		= s->irq;
		s->port[i].type		= PORT_SC26XX;
		s->port[i].fifosize	= s->chip->fifosize;
		s->port[i].flags	= UPF_SKIP_TEST | UPF_FIXED_TYPE;
		s->port[i].iotype	= UPIO_MEM;
		s->port[i].mapbase	= res->start;
		s->port[i].membase	= membase;
		s->port[i].regshift	= s->pdata.reg_shift;
		s->port[i].uartclk	= uartclk;
		s->port[i].ops		= &sccnxp_ops;
		uart_add_one_port(&s->uart, &s->port[i]);
		/* Set direction to input */
		if (s->chip->flags & SCCNXP_HAVE_IO)
			sccnxp_set_bit(&s->port[i], DIR_OP, 0);
	}

	/* Disable interrupts */
	s->imr = 0;
	sccnxp_write(&s->port[0], SCCNXP_IMR_REG, 0);

	if (!s->poll) {
		ret = devm_request_threaded_irq(&pdev->dev, s->irq, NULL,
						sccnxp_ist,
						IRQF_TRIGGER_FALLING |
						IRQF_ONESHOT,
						dev_name(&pdev->dev), s);
		if (!ret)
			return 0;

		dev_err(&pdev->dev, "Unable to reguest IRQ %i\n", s->irq);
	} else {
		timer_setup(&s->timer, sccnxp_timer, 0);
		mod_timer(&s->timer, jiffies +
			  usecs_to_jiffies(s->pdata.poll_time_us));
		return 0;
	}

	uart_unregister_driver(&s->uart);
err_out:
	if (!IS_ERR(s->regulator))
		regulator_disable(s->regulator);

	return ret;
}

static int sccnxp_remove(struct platform_device *pdev)
{
	int i;
	struct sccnxp_port *s = platform_get_drvdata(pdev);

	if (!s->poll)
		devm_free_irq(&pdev->dev, s->irq, s);
	else
		del_timer_sync(&s->timer);

	for (i = 0; i < s->uart.nr; i++)
		uart_remove_one_port(&s->uart, &s->port[i]);

	uart_unregister_driver(&s->uart);

	if (!IS_ERR(s->regulator))
		return regulator_disable(s->regulator);

	return 0;
}

static struct platform_driver sccnxp_uart_driver = {
	.driver = {
		.name	= SCCNXP_NAME,
	},
	.probe		= sccnxp_probe,
	.remove		= sccnxp_remove,
	.id_table	= sccnxp_id_table,
};
module_platform_driver(sccnxp_uart_driver);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
MODULE_DESCRIPTION("SCCNXP serial driver");