omap-serial.c

/*
 * Driver for OMAP-UART controller.
 * Based on drivers/serial/8250.c
 *
 * Copyright (C) 2010 Texas Instruments.
 *
 * Authors:
 *	Govindraj R	<govindraj.raja@ti.com>
 *	Thara Gopinath	<thara@ti.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Note: This driver is made separate from 8250 driver as we cannot
 * over load 8250 driver with omap platform specific configuration for
 * features like DMA, it makes easier to implement features like DMA and
 * hardware flow control and software flow control configuration with
 * this driver as required for the omap-platform.
 */

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

#include <linux/module.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/serial_reg.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/io.h>
#include <linux/dma-mapping.h>
#include <linux/clk.h>
#include <linux/serial_core.h>
#include <linux/irq.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/gpio.h>

#include <plat/dma.h>
#include <plat/dmtimer.h>
#include <plat/omap-serial.h>

#define UART_BUILD_REVISION(x, y)	(((x) << 8) | (y))

#define OMAP_UART_REV_42 0x0402
#define OMAP_UART_REV_46 0x0406
#define OMAP_UART_REV_52 0x0502
#define OMAP_UART_REV_63 0x0603

#define DEFAULT_CLK_SPEED 48000000 /* 48Mhz*/

/* SCR register bitmasks */
#define OMAP_UART_SCR_RX_TRIG_GRANU1_MASK		(1 << 7)

/* FCR register bitmasks */
#define OMAP_UART_FCR_RX_FIFO_TRIG_SHIFT		6
#define OMAP_UART_FCR_RX_FIFO_TRIG_MASK			(0x3 << 6)

/* MVR register bitmasks */
#define OMAP_UART_MVR_SCHEME_SHIFT	30

#define OMAP_UART_LEGACY_MVR_MAJ_MASK	0xf0
#define OMAP_UART_LEGACY_MVR_MAJ_SHIFT	4
#define OMAP_UART_LEGACY_MVR_MIN_MASK	0x0f

#define OMAP_UART_MVR_MAJ_MASK		0x700
#define OMAP_UART_MVR_MAJ_SHIFT		8
#define OMAP_UART_MVR_MIN_MASK		0x3f

static struct uart_omap_port *ui[OMAP_MAX_HSUART_PORTS];

/* Forward declaration of functions */
static void uart_tx_dma_callback(int lch, u16 ch_status, void *data);
static void serial_omap_rxdma_poll(unsigned long uart_no);
static int serial_omap_start_rxdma(struct uart_omap_port *up);
static void serial_omap_mdr1_errataset(struct uart_omap_port *up, u8 mdr1);

static struct workqueue_struct *serial_omap_uart_wq;

static inline unsigned int serial_in(struct uart_omap_port *up, int offset)
{
	offset <<= up->port.regshift;
	return readw(up->port.membase + offset);
}

static inline void serial_out(struct uart_omap_port *up, int offset, int value)
{
	offset <<= up->port.regshift;
	writew(value, up->port.membase + offset);
}

static inline void serial_omap_clear_fifos(struct uart_omap_port *up)
{
	serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO);
	serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO |
		       UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
	serial_out(up, UART_FCR, 0);
}

/*
 * serial_omap_get_divisor - calculate divisor value
 * @port: uart port info
 * @baud: baudrate for which divisor needs to be calculated.
 *
 * We have written our own function to get the divisor so as to support
 * 13x mode. 3Mbps Baudrate as an different divisor.
 * Reference OMAP TRM Chapter 17:
 * Table 17-1. UART Mode Baud Rates, Divisor Values, and Error Rates
 * referring to oversampling - divisor value
 * baudrate 460,800 to 3,686,400 all have divisor 13
 * except 3,000,000 which has divisor value 16
 */
static unsigned int
serial_omap_get_divisor(struct uart_port *port, unsigned int baud)
{
	unsigned int divisor;

	if (baud > OMAP_MODE13X_SPEED && baud != 3000000)
		divisor = 13;
	else
		divisor = 16;
	return port->uartclk/(baud * divisor);
}

static void serial_omap_stop_rxdma(struct uart_omap_port *up)
{
	if (up->uart_dma.rx_dma_used) {
		del_timer(&up->uart_dma.rx_timer);
		omap_stop_dma(up->uart_dma.rx_dma_channel);
		omap_free_dma(up->uart_dma.rx_dma_channel);
		up->uart_dma.rx_dma_channel = OMAP_UART_DMA_CH_FREE;
		up->uart_dma.rx_dma_used = false;
		pm_runtime_mark_last_busy(&up->pdev->dev);
		pm_runtime_put_autosuspend(&up->pdev->dev);
	}
}

static void serial_omap_enable_ms(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);

	dev_dbg(up->port.dev, "serial_omap_enable_ms+%d\n", up->port.line);

	pm_runtime_get_sync(&up->pdev->dev);
	up->ier |= UART_IER_MSI;
	serial_out(up, UART_IER, up->ier);
	pm_runtime_put(&up->pdev->dev);
}

static void serial_omap_stop_tx(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	struct omap_uart_port_info *pdata = up->pdev->dev.platform_data;

	if (up->use_dma &&
		up->uart_dma.tx_dma_channel != OMAP_UART_DMA_CH_FREE) {
		/*
		 * Check if dma is still active. If yes do nothing,
		 * return. Else stop dma
		 */
		if (omap_get_dma_active_status(up->uart_dma.tx_dma_channel))
			return;
		omap_stop_dma(up->uart_dma.tx_dma_channel);
		omap_free_dma(up->uart_dma.tx_dma_channel);
		up->uart_dma.tx_dma_channel = OMAP_UART_DMA_CH_FREE;
		pm_runtime_mark_last_busy(&up->pdev->dev);
		pm_runtime_put_autosuspend(&up->pdev->dev);
	}

	pm_runtime_get_sync(&up->pdev->dev);
	if (up->ier & UART_IER_THRI) {
		up->ier &= ~UART_IER_THRI;
		serial_out(up, UART_IER, up->ier);
	}

	if (!up->use_dma && pdata && pdata->set_forceidle)
		pdata->set_forceidle(up->pdev);

	pm_runtime_mark_last_busy(&up->pdev->dev);
	pm_runtime_put_autosuspend(&up->pdev->dev);
}

static void serial_omap_stop_rx(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);

	pm_runtime_get_sync(&up->pdev->dev);
	if (up->use_dma)
		serial_omap_stop_rxdma(up);
	up->ier &= ~UART_IER_RLSI;
	up->port.read_status_mask &= ~UART_LSR_DR;
	serial_out(up, UART_IER, up->ier);
	pm_runtime_mark_last_busy(&up->pdev->dev);
	pm_runtime_put_autosuspend(&up->pdev->dev);
}

static inline void receive_chars(struct uart_omap_port *up,
		unsigned int *status)
{
	struct tty_struct *tty = up->port.state->port.tty;
	unsigned int flag, lsr = *status;
	unsigned char ch = 0;
	int max_count = 256;

	do {
		if (likely(lsr & UART_LSR_DR))
			ch = serial_in(up, UART_RX);
		flag = TTY_NORMAL;
		up->port.icount.rx++;

		if (unlikely(lsr & UART_LSR_BRK_ERROR_BITS)) {
			/*
			 * For statistics only
			 */
			if (lsr & UART_LSR_BI) {
				lsr &= ~(UART_LSR_FE | UART_LSR_PE);
				up->port.icount.brk++;
				/*
				 * We do the SysRQ and SAK checking
				 * here because otherwise the break
				 * may get masked by ignore_status_mask
				 * or read_status_mask.
				 */
				if (uart_handle_break(&up->port))
					goto ignore_char;
			} else if (lsr & UART_LSR_PE) {
				up->port.icount.parity++;
			} else if (lsr & UART_LSR_FE) {
				up->port.icount.frame++;
			}

			if (lsr & UART_LSR_OE)
				up->port.icount.overrun++;

			/*
			 * Mask off conditions which should be ignored.
			 */
			lsr &= up->port.read_status_mask;

#ifdef CONFIG_SERIAL_OMAP_CONSOLE
			if (up->port.line == up->port.cons->index) {
				/* Recover the break flag from console xmit */
				lsr |= up->lsr_break_flag;
			}
#endif
			if (lsr & UART_LSR_BI)
				flag = TTY_BREAK;
			else if (lsr & UART_LSR_PE)
				flag = TTY_PARITY;
			else if (lsr & UART_LSR_FE)
				flag = TTY_FRAME;
		}

		if (uart_handle_sysrq_char(&up->port, ch))
			goto ignore_char;
		uart_insert_char(&up->port, lsr, UART_LSR_OE, ch, flag);
ignore_char:
		lsr = serial_in(up, UART_LSR);
	} while ((lsr & (UART_LSR_DR | UART_LSR_BI)) && (max_count-- > 0));
	spin_unlock(&up->port.lock);
	tty_flip_buffer_push(tty);
	spin_lock(&up->port.lock);
}

static void transmit_chars(struct uart_omap_port *up)
{
	struct circ_buf *xmit = &up->port.state->xmit;
	int count;

	if (up->port.x_char) {
		serial_out(up, UART_TX, up->port.x_char);
		up->port.icount.tx++;
		up->port.x_char = 0;
		return;
	}
	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
		serial_omap_stop_tx(&up->port);
		return;
	}
	count = up->port.fifosize / 4;
	do {
		serial_out(up, UART_TX, xmit->buf[xmit->tail]);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		up->port.icount.tx++;
		if (uart_circ_empty(xmit))
			break;
	} while (--count > 0);

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(&up->port);

	if (uart_circ_empty(xmit))
		serial_omap_stop_tx(&up->port);
}

static inline void serial_omap_enable_ier_thri(struct uart_omap_port *up)
{
	if (!(up->ier & UART_IER_THRI)) {
		up->ier |= UART_IER_THRI;
		serial_out(up, UART_IER, up->ier);
	}
}

static void serial_omap_start_tx(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	struct omap_uart_port_info *pdata = up->pdev->dev.platform_data;
	struct circ_buf *xmit;
	unsigned int start;
	int ret = 0;

	if (!up->use_dma) {
		pm_runtime_get_sync(&up->pdev->dev);
		serial_omap_enable_ier_thri(up);
		if (pdata && pdata->set_noidle)
			pdata->set_noidle(up->pdev);
		pm_runtime_mark_last_busy(&up->pdev->dev);
		pm_runtime_put_autosuspend(&up->pdev->dev);
		return;
	}

	if (up->uart_dma.tx_dma_used)
		return;

	xmit = &up->port.state->xmit;

	if (up->uart_dma.tx_dma_channel == OMAP_UART_DMA_CH_FREE) {
		pm_runtime_get_sync(&up->pdev->dev);
		ret = omap_request_dma(up->uart_dma.uart_dma_tx,
				"UART Tx DMA",
				(void *)uart_tx_dma_callback, up,
				&(up->uart_dma.tx_dma_channel));

		if (ret < 0) {
			serial_omap_enable_ier_thri(up);
			return;
		}
	}
	spin_lock(&(up->uart_dma.tx_lock));
	up->uart_dma.tx_dma_used = true;
	spin_unlock(&(up->uart_dma.tx_lock));

	start = up->uart_dma.tx_buf_dma_phys +
				(xmit->tail & (UART_XMIT_SIZE - 1));

	up->uart_dma.tx_buf_size = uart_circ_chars_pending(xmit);
	/*
	 * It is a circular buffer. See if the buffer has wounded back.
	 * If yes it will have to be transferred in two separate dma
	 * transfers
	 */
	if (start + up->uart_dma.tx_buf_size >=
			up->uart_dma.tx_buf_dma_phys + UART_XMIT_SIZE)
		up->uart_dma.tx_buf_size =
			(up->uart_dma.tx_buf_dma_phys +
			UART_XMIT_SIZE) - start;

	omap_set_dma_dest_params(up->uart_dma.tx_dma_channel, 0,
				OMAP_DMA_AMODE_CONSTANT,
				up->uart_dma.uart_base, 0, 0);
	omap_set_dma_src_params(up->uart_dma.tx_dma_channel, 0,
				OMAP_DMA_AMODE_POST_INC, start, 0, 0);
	omap_set_dma_transfer_params(up->uart_dma.tx_dma_channel,
				OMAP_DMA_DATA_TYPE_S8,
				up->uart_dma.tx_buf_size, 1,
				OMAP_DMA_SYNC_ELEMENT,
				up->uart_dma.uart_dma_tx, 0);
	/* FIXME: Cache maintenance needed here? */
	omap_start_dma(up->uart_dma.tx_dma_channel);
}

static unsigned int check_modem_status(struct uart_omap_port *up)
{
	unsigned int status;

	status = serial_in(up, UART_MSR);
	status |= up->msr_saved_flags;
	up->msr_saved_flags = 0;
	if ((status & UART_MSR_ANY_DELTA) == 0)
		return status;

	if (status & UART_MSR_ANY_DELTA && up->ier & UART_IER_MSI &&
	    up->port.state != NULL) {
		if (status & UART_MSR_TERI)
			up->port.icount.rng++;
		if (status & UART_MSR_DDSR)
			up->port.icount.dsr++;
		if (status & UART_MSR_DDCD)
			uart_handle_dcd_change
				(&up->port, status & UART_MSR_DCD);
		if (status & UART_MSR_DCTS)
			uart_handle_cts_change
				(&up->port, status & UART_MSR_CTS);
		wake_up_interruptible(&up->port.state->port.delta_msr_wait);
	}

	return status;
}

/**
 * serial_omap_irq() - This handles the interrupt from one port
 * @irq: uart port irq number
 * @dev_id: uart port info
 */
static inline irqreturn_t serial_omap_irq(int irq, void *dev_id)
{
	struct uart_omap_port *up = dev_id;
	unsigned int iir, lsr;
	unsigned long flags;

	pm_runtime_get_sync(&up->pdev->dev);
	iir = serial_in(up, UART_IIR);
	if (iir & UART_IIR_NO_INT) {
		pm_runtime_mark_last_busy(&up->pdev->dev);
		pm_runtime_put_autosuspend(&up->pdev->dev);
		return IRQ_NONE;
	}

	spin_lock_irqsave(&up->port.lock, flags);
	lsr = serial_in(up, UART_LSR);
	if (iir & UART_IIR_RLSI) {
		if (!up->use_dma) {
			if (lsr & UART_LSR_DR)
				receive_chars(up, &lsr);
		} else {
			up->ier &= ~(UART_IER_RDI | UART_IER_RLSI);
			serial_out(up, UART_IER, up->ier);
			if ((serial_omap_start_rxdma(up) != 0) &&
					(lsr & UART_LSR_DR))
				receive_chars(up, &lsr);
		}
	}

	check_modem_status(up);
	if ((lsr & UART_LSR_THRE) && (iir & UART_IIR_THRI))
		transmit_chars(up);

	spin_unlock_irqrestore(&up->port.lock, flags);
	pm_runtime_mark_last_busy(&up->pdev->dev);
	pm_runtime_put_autosuspend(&up->pdev->dev);

	up->port_activity = jiffies;
	return IRQ_HANDLED;
}

static unsigned int serial_omap_tx_empty(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	unsigned long flags = 0;
	unsigned int ret = 0;

	pm_runtime_get_sync(&up->pdev->dev);
	dev_dbg(up->port.dev, "serial_omap_tx_empty+%d\n", up->port.line);
	spin_lock_irqsave(&up->port.lock, flags);
	ret = serial_in(up, UART_LSR) & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
	spin_unlock_irqrestore(&up->port.lock, flags);
	pm_runtime_put(&up->pdev->dev);
	return ret;
}

static unsigned int serial_omap_get_mctrl(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	unsigned int status;
	unsigned int ret = 0;

	pm_runtime_get_sync(&up->pdev->dev);
	status = check_modem_status(up);
	pm_runtime_put(&up->pdev->dev);

	dev_dbg(up->port.dev, "serial_omap_get_mctrl+%d\n", up->port.line);

	if (status & UART_MSR_DCD)
		ret |= TIOCM_CAR;
	if (status & UART_MSR_RI)
		ret |= TIOCM_RNG;
	if (status & UART_MSR_DSR)
		ret |= TIOCM_DSR;
	if (status & UART_MSR_CTS)
		ret |= TIOCM_CTS;
	return ret;
}

static void serial_omap_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	unsigned char mcr = 0;

	dev_dbg(up->port.dev, "serial_omap_set_mctrl+%d\n", up->port.line);
	if (mctrl & TIOCM_RTS)
		mcr |= UART_MCR_RTS;
	if (mctrl & TIOCM_DTR)
		mcr |= UART_MCR_DTR;
	if (mctrl & TIOCM_OUT1)
		mcr |= UART_MCR_OUT1;
	if (mctrl & TIOCM_OUT2)
		mcr |= UART_MCR_OUT2;
	if (mctrl & TIOCM_LOOP)
		mcr |= UART_MCR_LOOP;

	pm_runtime_get_sync(&up->pdev->dev);
	up->mcr = serial_in(up, UART_MCR);
	up->mcr |= mcr;
	serial_out(up, UART_MCR, up->mcr);
	pm_runtime_put(&up->pdev->dev);

	if (gpio_is_valid(up->DTR_gpio) &&
	    !!(mctrl & TIOCM_DTR) != up->DTR_active) {
		up->DTR_active = !up->DTR_active;
		if (gpio_cansleep(up->DTR_gpio))
			schedule_work(&up->qos_work);
		else
			gpio_set_value(up->DTR_gpio,
				       up->DTR_active != up->DTR_inverted);
	}
}

static void serial_omap_break_ctl(struct uart_port *port, int break_state)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	unsigned long flags = 0;

	dev_dbg(up->port.dev, "serial_omap_break_ctl+%d\n", up->port.line);
	pm_runtime_get_sync(&up->pdev->dev);
	spin_lock_irqsave(&up->port.lock, flags);
	if (break_state == -1)
		up->lcr |= UART_LCR_SBC;
	else
		up->lcr &= ~UART_LCR_SBC;
	serial_out(up, UART_LCR, up->lcr);
	spin_unlock_irqrestore(&up->port.lock, flags);
	pm_runtime_put(&up->pdev->dev);
}

static int serial_omap_startup(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	unsigned long flags = 0;
	int retval;

	/*
	 * Allocate the IRQ
	 */
	retval = request_irq(up->port.irq, serial_omap_irq, up->port.irqflags,
				up->name, up);
	if (retval)
		return retval;

	dev_dbg(up->port.dev, "serial_omap_startup+%d\n", up->port.line);

	pm_runtime_get_sync(&up->pdev->dev);
	/*
	 * Clear the FIFO buffers and disable them.
	 * (they will be reenabled in set_termios())
	 */
	serial_omap_clear_fifos(up);
	/* For Hardware flow control */
	serial_out(up, UART_MCR, UART_MCR_RTS);

	/*
	 * Clear the interrupt registers.
	 */
	(void) serial_in(up, UART_LSR);
	if (serial_in(up, UART_LSR) & UART_LSR_DR)
		(void) serial_in(up, UART_RX);
	(void) serial_in(up, UART_IIR);
	(void) serial_in(up, UART_MSR);

	/*
	 * Now, initialize the UART
	 */
	serial_out(up, UART_LCR, UART_LCR_WLEN8);
	spin_lock_irqsave(&up->port.lock, flags);
	/*
	 * Most PC uarts need OUT2 raised to enable interrupts.
	 */
	up->port.mctrl |= TIOCM_OUT2;
	serial_omap_set_mctrl(&up->port, up->port.mctrl);
	spin_unlock_irqrestore(&up->port.lock, flags);

	up->msr_saved_flags = 0;
	if (up->use_dma) {
		free_page((unsigned long)up->port.state->xmit.buf);
		up->port.state->xmit.buf = dma_alloc_coherent(NULL,
			UART_XMIT_SIZE,
			(dma_addr_t *)&(up->uart_dma.tx_buf_dma_phys),
			0);
		init_timer(&(up->uart_dma.rx_timer));
		up->uart_dma.rx_timer.function = serial_omap_rxdma_poll;
		up->uart_dma.rx_timer.data = up->port.line;
		/* Currently the buffer size is 4KB. Can increase it */
		up->uart_dma.rx_buf = dma_alloc_coherent(NULL,
			up->uart_dma.rx_buf_size,
			(dma_addr_t *)&(up->uart_dma.rx_buf_dma_phys), 0);
	}
	/*
	 * Finally, enable interrupts. Note: Modem status interrupts
	 * are set via set_termios(), which will be occurring imminently
	 * anyway, so we don't enable them here.
	 */
	up->ier = UART_IER_RLSI | UART_IER_RDI;
	serial_out(up, UART_IER, up->ier);

	/* Enable module level wake up */
	serial_out(up, UART_OMAP_WER, OMAP_UART_WER_MOD_WKUP);

	pm_runtime_mark_last_busy(&up->pdev->dev);
	pm_runtime_put_autosuspend(&up->pdev->dev);
	up->port_activity = jiffies;
	return 0;
}

static void serial_omap_shutdown(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	unsigned long flags = 0;

	dev_dbg(up->port.dev, "serial_omap_shutdown+%d\n", up->port.line);

	pm_runtime_get_sync(&up->pdev->dev);
	/*
	 * Disable interrupts from this port
	 */
	up->ier = 0;
	serial_out(up, UART_IER, 0);

	spin_lock_irqsave(&up->port.lock, flags);
	up->port.mctrl &= ~TIOCM_OUT2;
	serial_omap_set_mctrl(&up->port, up->port.mctrl);
	spin_unlock_irqrestore(&up->port.lock, flags);

	/*
	 * Disable break condition and FIFOs
	 */
	serial_out(up, UART_LCR, serial_in(up, UART_LCR) & ~UART_LCR_SBC);
	serial_omap_clear_fifos(up);

	/*
	 * Read data port to reset things, and then free the irq
	 */
	if (serial_in(up, UART_LSR) & UART_LSR_DR)
		(void) serial_in(up, UART_RX);
	if (up->use_dma) {
		dma_free_coherent(up->port.dev,
			UART_XMIT_SIZE,	up->port.state->xmit.buf,
			up->uart_dma.tx_buf_dma_phys);
		up->port.state->xmit.buf = NULL;
		serial_omap_stop_rx(port);
		dma_free_coherent(up->port.dev,
			up->uart_dma.rx_buf_size, up->uart_dma.rx_buf,
			up->uart_dma.rx_buf_dma_phys);
		up->uart_dma.rx_buf = NULL;
	}

	pm_runtime_put(&up->pdev->dev);
	free_irq(up->port.irq, up);
}

static inline void
serial_omap_configure_xonxoff
		(struct uart_omap_port *up, struct ktermios *termios)
{
	up->lcr = serial_in(up, UART_LCR);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
	up->efr = serial_in(up, UART_EFR);
	serial_out(up, UART_EFR, up->efr & ~UART_EFR_ECB);

	serial_out(up, UART_XON1, termios->c_cc[VSTART]);
	serial_out(up, UART_XOFF1, termios->c_cc[VSTOP]);

	/* clear SW control mode bits */
	up->efr &= OMAP_UART_SW_CLR;

	/*
	 * IXON Flag:
	 * Enable XON/XOFF flow control on output.
	 * Transmit XON1, XOFF1
	 */
	if (termios->c_iflag & IXON)
		up->efr |= OMAP_UART_SW_TX;

	/*
	 * IXOFF Flag:
	 * Enable XON/XOFF flow control on input.
	 * Receiver compares XON1, XOFF1.
	 */
	if (termios->c_iflag & IXOFF)
		up->efr |= OMAP_UART_SW_RX;

	serial_out(up, UART_EFR, up->efr | UART_EFR_ECB);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);

	up->mcr = serial_in(up, UART_MCR);

	/*
	 * IXANY Flag:
	 * Enable any character to restart output.
	 * Operation resumes after receiving any
	 * character after recognition of the XOFF character
	 */
	if (termios->c_iflag & IXANY)
		up->mcr |= UART_MCR_XONANY;

	serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
	serial_out(up, UART_TI752_TCR, OMAP_UART_TCR_TRIG);
	/* Enable special char function UARTi.EFR_REG[5] and
	 * load the new software flow control mode IXON or IXOFF
	 * and restore the UARTi.EFR_REG[4] ENHANCED_EN value.
	 */
	serial_out(up, UART_EFR, up->efr | UART_EFR_SCD);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);

	serial_out(up, UART_MCR, up->mcr & ~UART_MCR_TCRTLR);
	serial_out(up, UART_LCR, up->lcr);
}

static void serial_omap_uart_qos_work(struct work_struct *work)
{
	struct uart_omap_port *up = container_of(work, struct uart_omap_port,
						qos_work);

	pm_qos_update_request(&up->pm_qos_request, up->latency);
	if (gpio_is_valid(up->DTR_gpio))
		gpio_set_value_cansleep(up->DTR_gpio,
					up->DTR_active != up->DTR_inverted);
}

static void
serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
			struct ktermios *old)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	unsigned char cval = 0;
	unsigned char efr = 0;
	unsigned long flags = 0;
	unsigned int baud, quot;

	switch (termios->c_cflag & CSIZE) {
	case CS5:
		cval = UART_LCR_WLEN5;
		break;
	case CS6:
		cval = UART_LCR_WLEN6;
		break;
	case CS7:
		cval = UART_LCR_WLEN7;
		break;
	default:
	case CS8:
		cval = UART_LCR_WLEN8;
		break;
	}

	if (termios->c_cflag & CSTOPB)
		cval |= UART_LCR_STOP;
	if (termios->c_cflag & PARENB)
		cval |= UART_LCR_PARITY;
	if (!(termios->c_cflag & PARODD))
		cval |= UART_LCR_EPAR;

	/*
	 * Ask the core to calculate the divisor for us.
	 */

	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/13);
	quot = serial_omap_get_divisor(port, baud);

	/* calculate wakeup latency constraint */
	up->calc_latency = (USEC_PER_SEC * up->port.fifosize) / (baud / 8);
	up->latency = up->calc_latency;
	schedule_work(&up->qos_work);

	up->dll = quot & 0xff;
	up->dlh = quot >> 8;
	up->mdr1 = UART_OMAP_MDR1_DISABLE;

	up->fcr = UART_FCR_R_TRIG_01 | UART_FCR_T_TRIG_01 |
			UART_FCR_ENABLE_FIFO;
	if (up->use_dma)
		up->fcr |= UART_FCR_DMA_SELECT;

	/*
	 * Ok, we're now changing the port state. Do it with
	 * interrupts disabled.
	 */
	pm_runtime_get_sync(&up->pdev->dev);
	spin_lock_irqsave(&up->port.lock, flags);

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

	up->port.read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
	if (termios->c_iflag & INPCK)
		up->port.read_status_mask |= UART_LSR_FE | UART_LSR_PE;
	if (termios->c_iflag & (BRKINT | PARMRK))
		up->port.read_status_mask |= UART_LSR_BI;

	/*
	 * Characters to ignore
	 */
	up->port.ignore_status_mask = 0;
	if (termios->c_iflag & IGNPAR)
		up->port.ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
	if (termios->c_iflag & IGNBRK) {
		up->port.ignore_status_mask |= UART_LSR_BI;
		/*
		 * If we're ignoring parity and break indicators,
		 * ignore overruns too (for real raw support).
		 */
		if (termios->c_iflag & IGNPAR)
			up->port.ignore_status_mask |= UART_LSR_OE;
	}

	/*
	 * ignore all characters if CREAD is not set
	 */
	if ((termios->c_cflag & CREAD) == 0)
		up->port.ignore_status_mask |= UART_LSR_DR;

	/*
	 * Modem status interrupts
	 */
	up->ier &= ~UART_IER_MSI;
	if (UART_ENABLE_MS(&up->port, termios->c_cflag))
		up->ier |= UART_IER_MSI;
	serial_out(up, UART_IER, up->ier);
	serial_out(up, UART_LCR, cval);		/* reset DLAB */
	up->lcr = cval;
	up->scr = OMAP_UART_SCR_TX_EMPTY;

	/* FIFOs and DMA Settings */

	/* FCR can be changed only when the
	 * baud clock is not running
	 * DLL_REG and DLH_REG set to 0.
	 */
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
	serial_out(up, UART_DLL, 0);
	serial_out(up, UART_DLM, 0);
	serial_out(up, UART_LCR, 0);

	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);

	up->efr = serial_in(up, UART_EFR);
	serial_out(up, UART_EFR, up->efr | UART_EFR_ECB);

	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
	up->mcr = serial_in(up, UART_MCR);
	serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
	/* FIFO ENABLE, DMA MODE */

	up->scr |= OMAP_UART_SCR_RX_TRIG_GRANU1_MASK;

	if (up->use_dma) {
		serial_out(up, UART_TI752_TLR, 0);
		up->scr |= UART_FCR_TRIGGER_4;
	} else {
		/* Set receive FIFO threshold to 1 byte */
		up->fcr &= ~OMAP_UART_FCR_RX_FIFO_TRIG_MASK;
		up->fcr |= (0x1 << OMAP_UART_FCR_RX_FIFO_TRIG_SHIFT);
	}

	serial_out(up, UART_FCR, up->fcr);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);

	serial_out(up, UART_OMAP_SCR, up->scr);

	serial_out(up, UART_EFR, up->efr);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
	serial_out(up, UART_MCR, up->mcr);

	/* Protocol, Baud Rate, and Interrupt Settings */

	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
		serial_omap_mdr1_errataset(up, up->mdr1);
	else
		serial_out(up, UART_OMAP_MDR1, up->mdr1);

	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);

	up->efr = serial_in(up, UART_EFR);
	serial_out(up, UART_EFR, up->efr | UART_EFR_ECB);

	serial_out(up, UART_LCR, 0);
	serial_out(up, UART_IER, 0);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);

	serial_out(up, UART_DLL, up->dll);	/* LS of divisor */
	serial_out(up, UART_DLM, up->dlh);	/* MS of divisor */

	serial_out(up, UART_LCR, 0);
	serial_out(up, UART_IER, up->ier);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);

	serial_out(up, UART_EFR, up->efr);
	serial_out(up, UART_LCR, cval);

	if (baud > 230400 && baud != 3000000)
		up->mdr1 = UART_OMAP_MDR1_13X_MODE;
	else
		up->mdr1 = UART_OMAP_MDR1_16X_MODE;

	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
		serial_omap_mdr1_errataset(up, up->mdr1);
	else
		serial_out(up, UART_OMAP_MDR1, up->mdr1);

	/* Hardware Flow Control Configuration */

	if (termios->c_cflag & CRTSCTS) {
		efr |= (UART_EFR_CTS | UART_EFR_RTS);
		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);

		up->mcr = serial_in(up, UART_MCR);
		serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);

		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
		up->efr = serial_in(up, UART_EFR);
		serial_out(up, UART_EFR, up->efr | UART_EFR_ECB);

		serial_out(up, UART_TI752_TCR, OMAP_UART_TCR_TRIG);
		serial_out(up, UART_EFR, efr); /* Enable AUTORTS and AUTOCTS */
		serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
		serial_out(up, UART_MCR, up->mcr | UART_MCR_RTS);
		serial_out(up, UART_LCR, cval);
	}

	serial_omap_set_mctrl(&up->port, up->port.mctrl);
	/* Software Flow Control Configuration */
	serial_omap_configure_xonxoff(up, termios);

	spin_unlock_irqrestore(&up->port.lock, flags);
	pm_runtime_put(&up->pdev->dev);
	dev_dbg(up->port.dev, "serial_omap_set_termios+%d\n", up->port.line);
}

static void
serial_omap_pm(struct uart_port *port, unsigned int state,
	       unsigned int oldstate)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	unsigned char efr;

	dev_dbg(up->port.dev, "serial_omap_pm+%d\n", up->port.line);

	pm_runtime_get_sync(&up->pdev->dev);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
	efr = serial_in(up, UART_EFR);
	serial_out(up, UART_EFR, efr | UART_EFR_ECB);
	serial_out(up, UART_LCR, 0);

	serial_out(up, UART_IER, (state != 0) ? UART_IERX_SLEEP : 0);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
	serial_out(up, UART_EFR, efr);
	serial_out(up, UART_LCR, 0);

	if (!device_may_wakeup(&up->pdev->dev)) {
		if (!state)
			pm_runtime_forbid(&up->pdev->dev);
		else
			pm_runtime_allow(&up->pdev->dev);
	}

	pm_runtime_put(&up->pdev->dev);
}

static void serial_omap_release_port(struct uart_port *port)
{
	dev_dbg(port->dev, "serial_omap_release_port+\n");
}

static int serial_omap_request_port(struct uart_port *port)
{
	dev_dbg(port->dev, "serial_omap_request_port+\n");
	return 0;
}

static void serial_omap_config_port(struct uart_port *port, int flags)
{
	struct uart_omap_port *up = to_uart_omap_port(port);

	dev_dbg(up->port.dev, "serial_omap_config_port+%d\n",
							up->port.line);
	up->port.type = PORT_OMAP;
}

static int
serial_omap_verify_port(struct uart_port *port, struct serial_struct *ser)
{
	/* we don't want the core code to modify any port params */
	dev_dbg(port->dev, "serial_omap_verify_port+\n");
	return -EINVAL;
}

static const char *
serial_omap_type(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);

	dev_dbg(up->port.dev, "serial_omap_type+%d\n", up->port.line);
	return up->name;
}

#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)

static inline void wait_for_xmitr(struct uart_omap_port *up)
{
	unsigned int status, tmout = 10000;

	/* Wait up to 10ms for the character(s) to be sent. */
	do {
		status = serial_in(up, UART_LSR);

		if (status & UART_LSR_BI)
			up->lsr_break_flag = UART_LSR_BI;

		if (--tmout == 0)
			break;
		udelay(1);
	} while ((status & BOTH_EMPTY) != BOTH_EMPTY);

	/* Wait up to 1s for flow control if necessary */
	if (up->port.flags & UPF_CONS_FLOW) {
		tmout = 1000000;
		for (tmout = 1000000; tmout; tmout--) {
			unsigned int msr = serial_in(up, UART_MSR);

			up->msr_saved_flags |= msr & MSR_SAVE_FLAGS;
			if (msr & UART_MSR_CTS)
				break;

			udelay(1);
		}
	}
}

#ifdef CONFIG_CONSOLE_POLL

static void serial_omap_poll_put_char(struct uart_port *port, unsigned char ch)
{
	struct uart_omap_port *up = to_uart_omap_port(port);

	pm_runtime_get_sync(&up->pdev->dev);
	wait_for_xmitr(up);
	serial_out(up, UART_TX, ch);
	pm_runtime_put(&up->pdev->dev);
}

static int serial_omap_poll_get_char(struct uart_port *port)
{
	struct uart_omap_port *up = to_uart_omap_port(port);
	unsigned int status;

	pm_runtime_get_sync(&up->pdev->dev);
	status = serial_in(up, UART_LSR);
	if (!(status & UART_LSR_DR))
		return NO_POLL_CHAR;

	status = serial_in(up, UART_RX);
	pm_runtime_put(&up->pdev->dev);
	return status;
}

#endif /* CONFIG_CONSOLE_POLL */

#ifdef CONFIG_SERIAL_OMAP_CONSOLE

static struct uart_omap_port *serial_omap_console_ports[4];

static struct uart_driver serial_omap_reg;

static void serial_omap_console_putchar(struct uart_port *port, int ch)
{
	struct uart_omap_port *up = to_uart_omap_port(port);

	wait_for_xmitr(up);
	serial_out(up, UART_TX, ch);
}

static void
serial_omap_console_write(struct console *co, const char *s,
		unsigned int count)
{
	struct uart_omap_port *up = serial_omap_console_ports[co->index];
	unsigned long flags;
	unsigned int ier;
	int locked = 1;

	pm_runtime_get_sync(&up->pdev->dev);

	local_irq_save(flags);
	if (up->port.sysrq)
		locked = 0;
	else if (oops_in_progress)
		locked = spin_trylock(&up->port.lock);
	else
		spin_lock(&up->port.lock);

	/*
	 * First save the IER then disable the interrupts
	 */
	ier = serial_in(up, UART_IER);
	serial_out(up, UART_IER, 0);

	uart_console_write(&up->port, s, count, serial_omap_console_putchar);

	/*
	 * Finally, wait for transmitter to become empty
	 * and restore the IER
	 */
	wait_for_xmitr(up);
	serial_out(up, UART_IER, ier);
	/*
	 * The receive handling will happen properly because the
	 * receive ready bit will still be set; it is not cleared
	 * on read.  However, modem control will not, we must
	 * call it if we have saved something in the saved flags
	 * while processing with interrupts off.
	 */
	if (up->msr_saved_flags)
		check_modem_status(up);

	pm_runtime_mark_last_busy(&up->pdev->dev);
	pm_runtime_put_autosuspend(&up->pdev->dev);
	if (locked)
		spin_unlock(&up->port.lock);
	local_irq_restore(flags);
}

static int __init
serial_omap_console_setup(struct console *co, char *options)
{
	struct uart_omap_port *up;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	if (serial_omap_console_ports[co->index] == NULL)
		return -ENODEV;
	up = serial_omap_console_ports[co->index];

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

	return uart_set_options(&up->port, co, baud, parity, bits, flow);
}

static struct console serial_omap_console = {
	.name		= OMAP_SERIAL_NAME,
	.write		= serial_omap_console_write,
	.device		= uart_console_device,
	.setup		= serial_omap_console_setup,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
	.data		= &serial_omap_reg,
};

static void serial_omap_add_console_port(struct uart_omap_port *up)
{
	serial_omap_console_ports[up->port.line] = up;
}

#define OMAP_CONSOLE	(&serial_omap_console)

#else

#define OMAP_CONSOLE	NULL

static inline void serial_omap_add_console_port(struct uart_omap_port *up)
{}

#endif

static struct uart_ops serial_omap_pops = {
	.tx_empty	= serial_omap_tx_empty,
	.set_mctrl	= serial_omap_set_mctrl,
	.get_mctrl	= serial_omap_get_mctrl,
	.stop_tx	= serial_omap_stop_tx,
	.start_tx	= serial_omap_start_tx,
	.stop_rx	= serial_omap_stop_rx,
	.enable_ms	= serial_omap_enable_ms,
	.break_ctl	= serial_omap_break_ctl,
	.startup	= serial_omap_startup,
	.shutdown	= serial_omap_shutdown,
	.set_termios	= serial_omap_set_termios,
	.pm		= serial_omap_pm,
	.type		= serial_omap_type,
	.release_port	= serial_omap_release_port,
	.request_port	= serial_omap_request_port,
	.config_port	= serial_omap_config_port,
	.verify_port	= serial_omap_verify_port,
#ifdef CONFIG_CONSOLE_POLL
	.poll_put_char  = serial_omap_poll_put_char,
	.poll_get_char  = serial_omap_poll_get_char,
#endif
};

static struct uart_driver serial_omap_reg = {
	.owner		= THIS_MODULE,
	.driver_name	= "OMAP-SERIAL",
	.dev_name	= OMAP_SERIAL_NAME,
	.nr		= OMAP_MAX_HSUART_PORTS,
	.cons		= OMAP_CONSOLE,
};

#ifdef CONFIG_PM_SLEEP
static int serial_omap_suspend(struct device *dev)
{
	struct uart_omap_port *up = dev_get_drvdata(dev);

	if (up) {
		uart_suspend_port(&serial_omap_reg, &up->port);
		flush_work_sync(&up->qos_work);
	}

	return 0;
}

static int serial_omap_resume(struct device *dev)
{
	struct uart_omap_port *up = dev_get_drvdata(dev);

	if (up)
		uart_resume_port(&serial_omap_reg, &up->port);
	return 0;
}
#endif

static void serial_omap_rxdma_poll(unsigned long uart_no)
{
	struct uart_omap_port *up = ui[uart_no];
	unsigned int curr_dma_pos, curr_transmitted_size;
	int ret = 0;

	curr_dma_pos = omap_get_dma_dst_pos(up->uart_dma.rx_dma_channel);
	if ((curr_dma_pos == up->uart_dma.prev_rx_dma_pos) ||
			     (curr_dma_pos == 0)) {
		if (jiffies_to_msecs(jiffies - up->port_activity) <
						up->uart_dma.rx_timeout) {
			mod_timer(&up->uart_dma.rx_timer, jiffies +
				usecs_to_jiffies(up->uart_dma.rx_poll_rate));
		} else {
			serial_omap_stop_rxdma(up);
			up->ier |= (UART_IER_RDI | UART_IER_RLSI);
			serial_out(up, UART_IER, up->ier);
		}
		return;
	}

	curr_transmitted_size = curr_dma_pos -
					up->uart_dma.prev_rx_dma_pos;
	up->port.icount.rx += curr_transmitted_size;
	tty_insert_flip_string(up->port.state->port.tty,
			up->uart_dma.rx_buf +
			(up->uart_dma.prev_rx_dma_pos -
			up->uart_dma.rx_buf_dma_phys),
			curr_transmitted_size);
	tty_flip_buffer_push(up->port.state->port.tty);
	up->uart_dma.prev_rx_dma_pos = curr_dma_pos;
	if (up->uart_dma.rx_buf_size +
			up->uart_dma.rx_buf_dma_phys == curr_dma_pos) {
		ret = serial_omap_start_rxdma(up);
		if (ret < 0) {
			serial_omap_stop_rxdma(up);
			up->ier |= (UART_IER_RDI | UART_IER_RLSI);
			serial_out(up, UART_IER, up->ier);
		}
	} else  {
		mod_timer(&up->uart_dma.rx_timer, jiffies +
			usecs_to_jiffies(up->uart_dma.rx_poll_rate));
	}
	up->port_activity = jiffies;
}

static void uart_rx_dma_callback(int lch, u16 ch_status, void *data)
{
	return;
}

static int serial_omap_start_rxdma(struct uart_omap_port *up)
{
	int ret = 0;

	if (up->uart_dma.rx_dma_channel == -1) {
		pm_runtime_get_sync(&up->pdev->dev);
		ret = omap_request_dma(up->uart_dma.uart_dma_rx,
				"UART Rx DMA",
				(void *)uart_rx_dma_callback, up,
				&(up->uart_dma.rx_dma_channel));
		if (ret < 0)
			return ret;

		omap_set_dma_src_params(up->uart_dma.rx_dma_channel, 0,
				OMAP_DMA_AMODE_CONSTANT,
				up->uart_dma.uart_base, 0, 0);
		omap_set_dma_dest_params(up->uart_dma.rx_dma_channel, 0,
				OMAP_DMA_AMODE_POST_INC,
				up->uart_dma.rx_buf_dma_phys, 0, 0);
		omap_set_dma_transfer_params(up->uart_dma.rx_dma_channel,
				OMAP_DMA_DATA_TYPE_S8,
				up->uart_dma.rx_buf_size, 1,
				OMAP_DMA_SYNC_ELEMENT,
				up->uart_dma.uart_dma_rx, 0);
	}
	up->uart_dma.prev_rx_dma_pos = up->uart_dma.rx_buf_dma_phys;
	/* FIXME: Cache maintenance needed here? */
	omap_start_dma(up->uart_dma.rx_dma_channel);
	mod_timer(&up->uart_dma.rx_timer, jiffies +
				usecs_to_jiffies(up->uart_dma.rx_poll_rate));
	up->uart_dma.rx_dma_used = true;
	return ret;
}

static void serial_omap_continue_tx(struct uart_omap_port *up)
{
	struct circ_buf *xmit = &up->port.state->xmit;
	unsigned int start = up->uart_dma.tx_buf_dma_phys
			+ (xmit->tail & (UART_XMIT_SIZE - 1));

	if (uart_circ_empty(xmit))
		return;

	up->uart_dma.tx_buf_size = uart_circ_chars_pending(xmit);
	/*
	 * It is a circular buffer. See if the buffer has wounded back.
	 * If yes it will have to be transferred in two separate dma
	 * transfers
	 */
	if (start + up->uart_dma.tx_buf_size >=
			up->uart_dma.tx_buf_dma_phys + UART_XMIT_SIZE)
		up->uart_dma.tx_buf_size =
			(up->uart_dma.tx_buf_dma_phys + UART_XMIT_SIZE) - start;
	omap_set_dma_dest_params(up->uart_dma.tx_dma_channel, 0,
				OMAP_DMA_AMODE_CONSTANT,
				up->uart_dma.uart_base, 0, 0);
	omap_set_dma_src_params(up->uart_dma.tx_dma_channel, 0,
				OMAP_DMA_AMODE_POST_INC, start, 0, 0);
	omap_set_dma_transfer_params(up->uart_dma.tx_dma_channel,
				OMAP_DMA_DATA_TYPE_S8,
				up->uart_dma.tx_buf_size, 1,
				OMAP_DMA_SYNC_ELEMENT,
				up->uart_dma.uart_dma_tx, 0);
	/* FIXME: Cache maintenance needed here? */
	omap_start_dma(up->uart_dma.tx_dma_channel);
}

static void uart_tx_dma_callback(int lch, u16 ch_status, void *data)
{
	struct uart_omap_port *up = data;
	struct circ_buf *xmit = &up->port.state->xmit;

	xmit->tail = (xmit->tail + up->uart_dma.tx_buf_size) & \
			(UART_XMIT_SIZE - 1);
	up->port.icount.tx += up->uart_dma.tx_buf_size;

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(&up->port);

	if (uart_circ_empty(xmit)) {
		spin_lock(&(up->uart_dma.tx_lock));
		serial_omap_stop_tx(&up->port);
		up->uart_dma.tx_dma_used = false;
		spin_unlock(&(up->uart_dma.tx_lock));
	} else {
		omap_stop_dma(up->uart_dma.tx_dma_channel);
		serial_omap_continue_tx(up);
	}
	up->port_activity = jiffies;
	return;
}

static void omap_serial_fill_features_erratas(struct uart_omap_port *up)
{
	u32 mvr, scheme;
	u16 revision, major, minor;

	mvr = serial_in(up, UART_OMAP_MVER);

	/* Check revision register scheme */
	scheme = mvr >> OMAP_UART_MVR_SCHEME_SHIFT;

	switch (scheme) {
	case 0: /* Legacy Scheme: OMAP2/3 */
		/* MINOR_REV[0:4], MAJOR_REV[4:7] */
		major = (mvr & OMAP_UART_LEGACY_MVR_MAJ_MASK) >>
					OMAP_UART_LEGACY_MVR_MAJ_SHIFT;
		minor = (mvr & OMAP_UART_LEGACY_MVR_MIN_MASK);
		break;
	case 1:
		/* New Scheme: OMAP4+ */
		/* MINOR_REV[0:5], MAJOR_REV[8:10] */
		major = (mvr & OMAP_UART_MVR_MAJ_MASK) >>
					OMAP_UART_MVR_MAJ_SHIFT;
		minor = (mvr & OMAP_UART_MVR_MIN_MASK);
		break;
	default:
		dev_warn(&up->pdev->dev,
			"Unknown %s revision, defaulting to highest\n",
			up->name);
		/* highest possible revision */
		major = 0xff;
		minor = 0xff;
	}

	/* normalize revision for the driver */
	revision = UART_BUILD_REVISION(major, minor);

	switch (revision) {
	case OMAP_UART_REV_46:
		up->errata |= (UART_ERRATA_i202_MDR1_ACCESS |
				UART_ERRATA_i291_DMA_FORCEIDLE);
		break;
	case OMAP_UART_REV_52:
		up->errata |= (UART_ERRATA_i202_MDR1_ACCESS |
				UART_ERRATA_i291_DMA_FORCEIDLE);
		break;
	case OMAP_UART_REV_63:
		up->errata |= UART_ERRATA_i202_MDR1_ACCESS;
		break;
	default:
		break;
	}
}

static struct omap_uart_port_info *of_get_uart_port_info(struct device *dev)
{
	struct omap_uart_port_info *omap_up_info;

	omap_up_info = devm_kzalloc(dev, sizeof(*omap_up_info), GFP_KERNEL);
	if (!omap_up_info)
		return NULL; /* out of memory */

	of_property_read_u32(dev->of_node, "clock-frequency",
					 &omap_up_info->uartclk);
	return omap_up_info;
}

static int serial_omap_probe(struct platform_device *pdev)
{
	struct uart_omap_port	*up;
	struct resource		*mem, *irq, *dma_tx, *dma_rx;
	struct omap_uart_port_info *omap_up_info = pdev->dev.platform_data;
	int ret;

	if (pdev->dev.of_node)
		omap_up_info = of_get_uart_port_info(&pdev->dev);

	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!mem) {
		dev_err(&pdev->dev, "no mem resource?\n");
		return -ENODEV;
	}

	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (!irq) {
		dev_err(&pdev->dev, "no irq resource?\n");
		return -ENODEV;
	}

	if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
				pdev->dev.driver->name)) {
		dev_err(&pdev->dev, "memory region already claimed\n");
		return -EBUSY;
	}

	dma_rx = platform_get_resource_byname(pdev, IORESOURCE_DMA, "rx");
	if (!dma_rx)
		return -ENXIO;

	dma_tx = platform_get_resource_byname(pdev, IORESOURCE_DMA, "tx");
	if (!dma_tx)
		return -ENXIO;

	if (gpio_is_valid(omap_up_info->DTR_gpio) &&
	    omap_up_info->DTR_present) {
		ret = gpio_request(omap_up_info->DTR_gpio, "omap-serial");
		if (ret < 0)
			return ret;
		ret = gpio_direction_output(omap_up_info->DTR_gpio,
					    omap_up_info->DTR_inverted);
		if (ret < 0)
			return ret;
	}

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

	if (gpio_is_valid(omap_up_info->DTR_gpio) &&
	    omap_up_info->DTR_present) {
		up->DTR_gpio = omap_up_info->DTR_gpio;
		up->DTR_inverted = omap_up_info->DTR_inverted;
	} else
		up->DTR_gpio = -EINVAL;
	up->DTR_active = 0;

	up->pdev = pdev;
	up->port.dev = &pdev->dev;
	up->port.type = PORT_OMAP;
	up->port.iotype = UPIO_MEM;
	up->port.irq = irq->start;

	up->port.regshift = 2;
	up->port.fifosize = 64;
	up->port.ops = &serial_omap_pops;

	if (pdev->dev.of_node)
		up->port.line = of_alias_get_id(pdev->dev.of_node, "serial");
	else
		up->port.line = pdev->id;

	if (up->port.line < 0) {
		dev_err(&pdev->dev, "failed to get alias/pdev id, errno %d\n",
								up->port.line);
		ret = -ENODEV;
		goto err_port_line;
	}

	sprintf(up->name, "OMAP UART%d", up->port.line);
	up->port.mapbase = mem->start;
	up->port.membase = devm_ioremap(&pdev->dev, mem->start,
						resource_size(mem));
	if (!up->port.membase) {
		dev_err(&pdev->dev, "can't ioremap UART\n");
		ret = -ENOMEM;
		goto err_ioremap;
	}

	up->port.flags = omap_up_info->flags;
	up->port.uartclk = omap_up_info->uartclk;
	if (!up->port.uartclk) {
		up->port.uartclk = DEFAULT_CLK_SPEED;
		dev_warn(&pdev->dev, "No clock speed specified: using default:"
						"%d\n", DEFAULT_CLK_SPEED);
	}
	up->uart_dma.uart_base = mem->start;

	if (omap_up_info->dma_enabled) {
		up->uart_dma.uart_dma_tx = dma_tx->start;
		up->uart_dma.uart_dma_rx = dma_rx->start;
		up->use_dma = 1;
		up->uart_dma.rx_buf_size = omap_up_info->dma_rx_buf_size;
		up->uart_dma.rx_timeout = omap_up_info->dma_rx_timeout;
		up->uart_dma.rx_poll_rate = omap_up_info->dma_rx_poll_rate;
		spin_lock_init(&(up->uart_dma.tx_lock));
		spin_lock_init(&(up->uart_dma.rx_lock));
		up->uart_dma.tx_dma_channel = OMAP_UART_DMA_CH_FREE;
		up->uart_dma.rx_dma_channel = OMAP_UART_DMA_CH_FREE;
	}

	up->latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
	up->calc_latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
	pm_qos_add_request(&up->pm_qos_request,
		PM_QOS_CPU_DMA_LATENCY, up->latency);
	serial_omap_uart_wq = create_singlethread_workqueue(up->name);
	INIT_WORK(&up->qos_work, serial_omap_uart_qos_work);

	pm_runtime_use_autosuspend(&pdev->dev);
	pm_runtime_set_autosuspend_delay(&pdev->dev,
			omap_up_info->autosuspend_timeout);

	pm_runtime_irq_safe(&pdev->dev);
	pm_runtime_enable(&pdev->dev);
	pm_runtime_get_sync(&pdev->dev);

	omap_serial_fill_features_erratas(up);

	ui[up->port.line] = up;
	serial_omap_add_console_port(up);

	ret = uart_add_one_port(&serial_omap_reg, &up->port);
	if (ret != 0)
		goto err_add_port;

	pm_runtime_put(&pdev->dev);
	platform_set_drvdata(pdev, up);
	return 0;

err_add_port:
	pm_runtime_put(&pdev->dev);
	pm_runtime_disable(&pdev->dev);
err_ioremap:
err_port_line:
	dev_err(&pdev->dev, "[UART%d]: failure [%s]: %d\n",
				pdev->id, __func__, ret);
	return ret;
}

static int serial_omap_remove(struct platform_device *dev)
{
	struct uart_omap_port *up = platform_get_drvdata(dev);

	if (up) {
		pm_runtime_disable(&up->pdev->dev);
		uart_remove_one_port(&serial_omap_reg, &up->port);
		pm_qos_remove_request(&up->pm_qos_request);
	}

	platform_set_drvdata(dev, NULL);
	return 0;
}

/*
 * Work Around for Errata i202 (2430, 3430, 3630, 4430 and 4460)
 * The access to uart register after MDR1 Access
 * causes UART to corrupt data.
 *
 * Need a delay =
 * 5 L4 clock cycles + 5 UART functional clock cycle (@48MHz = ~0.2uS)
 * give 10 times as much
 */
static void serial_omap_mdr1_errataset(struct uart_omap_port *up, u8 mdr1)
{
	u8 timeout = 255;

	serial_out(up, UART_OMAP_MDR1, mdr1);
	udelay(2);
	serial_out(up, UART_FCR, up->fcr | UART_FCR_CLEAR_XMIT |
			UART_FCR_CLEAR_RCVR);
	/*
	 * Wait for FIFO to empty: when empty, RX_FIFO_E bit is 0 and
	 * TX_FIFO_E bit is 1.
	 */
	while (UART_LSR_THRE != (serial_in(up, UART_LSR) &
				(UART_LSR_THRE | UART_LSR_DR))) {
		timeout--;
		if (!timeout) {
			/* Should *never* happen. we warn and carry on */
			dev_crit(&up->pdev->dev, "Errata i202: timedout %x\n",
						serial_in(up, UART_LSR));
			break;
		}
		udelay(1);
	}
}

#ifdef CONFIG_PM_RUNTIME
static void serial_omap_restore_context(struct uart_omap_port *up)
{
	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
		serial_omap_mdr1_errataset(up, UART_OMAP_MDR1_DISABLE);
	else
		serial_out(up, UART_OMAP_MDR1, UART_OMAP_MDR1_DISABLE);

	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); /* Config B mode */
	serial_out(up, UART_EFR, UART_EFR_ECB);
	serial_out(up, UART_LCR, 0x0); /* Operational mode */
	serial_out(up, UART_IER, 0x0);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); /* Config B mode */
	serial_out(up, UART_DLL, up->dll);
	serial_out(up, UART_DLM, up->dlh);
	serial_out(up, UART_LCR, 0x0); /* Operational mode */
	serial_out(up, UART_IER, up->ier);
	serial_out(up, UART_FCR, up->fcr);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
	serial_out(up, UART_MCR, up->mcr);
	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); /* Config B mode */
	serial_out(up, UART_OMAP_SCR, up->scr);
	serial_out(up, UART_EFR, up->efr);
	serial_out(up, UART_LCR, up->lcr);
	if (up->errata & UART_ERRATA_i202_MDR1_ACCESS)
		serial_omap_mdr1_errataset(up, up->mdr1);
	else
		serial_out(up, UART_OMAP_MDR1, up->mdr1);
}

static int serial_omap_runtime_suspend(struct device *dev)
{
	struct uart_omap_port *up = dev_get_drvdata(dev);
	struct omap_uart_port_info *pdata = dev->platform_data;

	if (!up)
		return -EINVAL;

	if (!pdata || !pdata->enable_wakeup)
		return 0;

	if (pdata->get_context_loss_count)
		up->context_loss_cnt = pdata->get_context_loss_count(dev);

	if (device_may_wakeup(dev)) {
		if (!up->wakeups_enabled) {
			pdata->enable_wakeup(up->pdev, true);
			up->wakeups_enabled = true;
		}
	} else {
		if (up->wakeups_enabled) {
			pdata->enable_wakeup(up->pdev, false);
			up->wakeups_enabled = false;
		}
	}

	/* Errata i291 */
	if (up->use_dma && pdata->set_forceidle &&
			(up->errata & UART_ERRATA_i291_DMA_FORCEIDLE))
		pdata->set_forceidle(up->pdev);

	up->latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
	schedule_work(&up->qos_work);

	return 0;
}

static int serial_omap_runtime_resume(struct device *dev)
{
	struct uart_omap_port *up = dev_get_drvdata(dev);
	struct omap_uart_port_info *pdata = dev->platform_data;

	if (up && pdata) {
		if (pdata->get_context_loss_count) {
			u32 loss_cnt = pdata->get_context_loss_count(dev);

			if (up->context_loss_cnt != loss_cnt)
				serial_omap_restore_context(up);
		}

		/* Errata i291 */
		if (up->use_dma && pdata->set_noidle &&
				(up->errata & UART_ERRATA_i291_DMA_FORCEIDLE))
			pdata->set_noidle(up->pdev);

		up->latency = up->calc_latency;
		schedule_work(&up->qos_work);
	}

	return 0;
}
#endif

static const struct dev_pm_ops serial_omap_dev_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(serial_omap_suspend, serial_omap_resume)
	SET_RUNTIME_PM_OPS(serial_omap_runtime_suspend,
				serial_omap_runtime_resume, NULL)
};

#if defined(CONFIG_OF)
static const struct of_device_id omap_serial_of_match[] = {
	{ .compatible = "ti,omap2-uart" },
	{ .compatible = "ti,omap3-uart" },
	{ .compatible = "ti,omap4-uart" },
	{},
};
MODULE_DEVICE_TABLE(of, omap_serial_of_match);
#endif

static struct platform_driver serial_omap_driver = {
	.probe          = serial_omap_probe,
	.remove         = serial_omap_remove,
	.driver		= {
		.name	= DRIVER_NAME,
		.pm	= &serial_omap_dev_pm_ops,
		.of_match_table = of_match_ptr(omap_serial_of_match),
	},
};

static int __init serial_omap_init(void)
{
	int ret;

	ret = uart_register_driver(&serial_omap_reg);
	if (ret != 0)
		return ret;
	ret = platform_driver_register(&serial_omap_driver);
	if (ret != 0)
		uart_unregister_driver(&serial_omap_reg);
	return ret;
}

static void __exit serial_omap_exit(void)
{
	platform_driver_unregister(&serial_omap_driver);
	uart_unregister_driver(&serial_omap_reg);
}

module_init(serial_omap_init);
module_exit(serial_omap_exit);

MODULE_DESCRIPTION("OMAP High Speed UART driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Texas Instruments Inc");