tty: serial: add Freescale lpuart driver support

Add Freescale lpuart driver support. The lpuart device
can be found on Vybrid VF610 and Layerscape LS-1 SoCs.

Signed-off-by: Jingchang Lu <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/tty/serial/fsl-lpuart.txt

···
+* Freescale low power universal asynchronous receiver/transmitter (lpuart)
+
+Required properties:
+- compatible : Should be "fsl,<soc>-lpuart"
+- reg : Address and length of the register set for the device
+- interrupts : Should contain uart interrupt
+
+Example:
+
+uart0: serial@40027000 {
+	       compatible = "fsl,vf610-lpuart";
+	       reg = <0x40027000 0x1000>;
+	       interrupts = <0 61 0x00>;
+       };

drivers/tty/serial/Kconfig

···
 	  If multiple cards are present, the default limit of 32 ports may
 	  need to be increased.
 
+config SERIAL_FSL_LPUART
+	tristate "Freescale lpuart serial port support"
+	select SERIAL_CORE
+	help
+	  Support for the on-chip lpuart on some Freescale SOCs.
+
+config SERIAL_FSL_LPUART_CONSOLE
+	bool "Console on Freescale lpuart serial port"
+	depends on SERIAL_FSL_LPUART=y
+	select SERIAL_CORE_CONSOLE
+	help
+	  If you have enabled the lpuart serial port on the Freescale SoCs,
+	  you can make it the console by answering Y to this option.
+
 endmenu
 
 endif # TTY

drivers/tty/serial/Makefile

···
 obj-$(CONFIG_SERIAL_EFM32_UART) += efm32-uart.o
 obj-$(CONFIG_SERIAL_ARC)	+= arc_uart.o
 obj-$(CONFIG_SERIAL_RP2)	+= rp2.o
+obj-$(CONFIG_SERIAL_FSL_LPUART)	+= fsl_lpuart.o

drivers/tty/serial/fsl_lpuart.c

···
+/*
+ *  Freescale lpuart serial port driver
+ *
+ *  Copyright 2012-2013 Freescale Semiconductor, Inc.
+ *
+ * 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.
+ */
+
+#if defined(CONFIG_SERIAL_FSL_LPUART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/console.h>
+#include <linux/serial_core.h>
+#include <linux/tty_flip.h>
+
+/* All registers are 8-bit width */
+#define UARTBDH			0x00
+#define UARTBDL			0x01
+#define UARTCR1			0x02
+#define UARTCR2			0x03
+#define UARTSR1			0x04
+#define UARTCR3			0x06
+#define UARTDR			0x07
+#define UARTCR4			0x0a
+#define UARTCR5			0x0b
+#define UARTMODEM		0x0d
+#define UARTPFIFO		0x10
+#define UARTCFIFO		0x11
+#define UARTSFIFO		0x12
+#define UARTTWFIFO		0x13
+#define UARTTCFIFO		0x14
+#define UARTRWFIFO		0x15
+
+#define UARTBDH_LBKDIE		0x80
+#define UARTBDH_RXEDGIE		0x40
+#define UARTBDH_SBR_MASK	0x1f
+
+#define UARTCR1_LOOPS		0x80
+#define UARTCR1_RSRC		0x20
+#define UARTCR1_M		0x10
+#define UARTCR1_WAKE		0x08
+#define UARTCR1_ILT		0x04
+#define UARTCR1_PE		0x02
+#define UARTCR1_PT		0x01
+
+#define UARTCR2_TIE		0x80
+#define UARTCR2_TCIE		0x40
+#define UARTCR2_RIE		0x20
+#define UARTCR2_ILIE		0x10
+#define UARTCR2_TE		0x08
+#define UARTCR2_RE		0x04
+#define UARTCR2_RWU		0x02
+#define UARTCR2_SBK		0x01
+
+#define UARTSR1_TDRE		0x80
+#define UARTSR1_TC		0x40
+#define UARTSR1_RDRF		0x20
+#define UARTSR1_IDLE		0x10
+#define UARTSR1_OR		0x08
+#define UARTSR1_NF		0x04
+#define UARTSR1_FE		0x02
+#define UARTSR1_PE		0x01
+
+#define UARTCR3_R8		0x80
+#define UARTCR3_T8		0x40
+#define UARTCR3_TXDIR		0x20
+#define UARTCR3_TXINV		0x10
+#define UARTCR3_ORIE		0x08
+#define UARTCR3_NEIE		0x04
+#define UARTCR3_FEIE		0x02
+#define UARTCR3_PEIE		0x01
+
+#define UARTCR4_MAEN1		0x80
+#define UARTCR4_MAEN2		0x40
+#define UARTCR4_M10		0x20
+#define UARTCR4_BRFA_MASK	0x1f
+#define UARTCR4_BRFA_OFF	0
+
+#define UARTCR5_TDMAS		0x80
+#define UARTCR5_RDMAS		0x20
+
+#define UARTMODEM_RXRTSE	0x08
+#define UARTMODEM_TXRTSPOL	0x04
+#define UARTMODEM_TXRTSE	0x02
+#define UARTMODEM_TXCTSE	0x01
+
+#define UARTPFIFO_TXFE		0x80
+#define UARTPFIFO_FIFOSIZE_MASK	0x7
+#define UARTPFIFO_TXSIZE_OFF	4
+#define UARTPFIFO_RXFE		0x08
+#define UARTPFIFO_RXSIZE_OFF	0
+
+#define UARTCFIFO_TXFLUSH	0x80
+#define UARTCFIFO_RXFLUSH	0x40
+#define UARTCFIFO_RXOFE		0x04
+#define UARTCFIFO_TXOFE		0x02
+#define UARTCFIFO_RXUFE		0x01
+
+#define UARTSFIFO_TXEMPT	0x80
+#define UARTSFIFO_RXEMPT	0x40
+#define UARTSFIFO_RXOF		0x04
+#define UARTSFIFO_TXOF		0x02
+#define UARTSFIFO_RXUF		0x01
+
+#define DRIVER_NAME	"fsl-lpuart"
+#define DEV_NAME	"ttyLP"
+#define UART_NR		6
+
+struct lpuart_port {
+	struct uart_port	port;
+	struct clk		*clk;
+	unsigned int		txfifo_size;
+	unsigned int		rxfifo_size;
+};
+
+static struct of_device_id lpuart_dt_ids[] = {
+	{
+		.compatible = "fsl,vf610-lpuart",
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, lpuart_dt_ids);
+
+static void lpuart_stop_tx(struct uart_port *port)
+{
+	unsigned char temp;
+
+	temp = readb(port->membase + UARTCR2);
+	temp &= ~(UARTCR2_TIE | UARTCR2_TCIE);
+	writeb(temp, port->membase + UARTCR2);
+}
+
+static void lpuart_stop_rx(struct uart_port *port)
+{
+	unsigned char temp;
+
+	temp = readb(port->membase + UARTCR2);
+	writeb(temp & ~UARTCR2_RE, port->membase + UARTCR2);
+}
+
+static void lpuart_enable_ms(struct uart_port *port)
+{
+}
+
+static inline void lpuart_transmit_buffer(struct lpuart_port *sport)
+{
+	struct circ_buf *xmit = &sport->port.state->xmit;
+
+	while (!uart_circ_empty(xmit) &&
+		(readb(sport->port.membase + UARTTCFIFO) < sport->txfifo_size)) {
+		writeb(xmit->buf[xmit->tail], sport->port.membase + UARTDR);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		sport->port.icount.tx++;
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&sport->port);
+
+	if (uart_circ_empty(xmit))
+		lpuart_stop_tx(&sport->port);
+}
+
+static void lpuart_start_tx(struct uart_port *port)
+{
+	struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
+	unsigned char temp;
+
+	temp = readb(port->membase + UARTCR2);
+	writeb(temp | UARTCR2_TIE, port->membase + UARTCR2);
+
+	if (readb(port->membase + UARTSR1) & UARTSR1_TDRE)
+		lpuart_transmit_buffer(sport);
+}
+
+static irqreturn_t lpuart_txint(int irq, void *dev_id)
+{
+	struct lpuart_port *sport = dev_id;
+	struct circ_buf *xmit = &sport->port.state->xmit;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+	if (sport->port.x_char) {
+		writeb(sport->port.x_char, sport->port.membase + UARTDR);
+		goto out;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
+		lpuart_stop_tx(&sport->port);
+		goto out;
+	}
+
+	lpuart_transmit_buffer(sport);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&sport->port);
+
+out:
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t lpuart_rxint(int irq, void *dev_id)
+{
+	struct lpuart_port *sport = dev_id;
+	unsigned int flg, ignored = 0;
+	struct tty_port *port = &sport->port.state->port;
+	unsigned long flags;
+	unsigned char rx, sr;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	while (!(readb(sport->port.membase + UARTSFIFO) & UARTSFIFO_RXEMPT)) {
+		flg = TTY_NORMAL;
+		sport->port.icount.rx++;
+		/*
+		 * to clear the FE, OR, NF, FE, PE flags,
+		 * read SR1 then read DR
+		 */
+		sr = readb(sport->port.membase + UARTSR1);
+		rx = readb(sport->port.membase + UARTDR);
+
+		if (uart_handle_sysrq_char(&sport->port, (unsigned char)rx))
+			continue;
+
+		if (sr & (UARTSR1_PE | UARTSR1_OR | UARTSR1_FE)) {
+			if (sr & UARTSR1_PE)
+				sport->port.icount.parity++;
+			else if (sr & UARTSR1_FE)
+				sport->port.icount.frame++;
+
+			if (sr & UARTSR1_OR)
+				sport->port.icount.overrun++;
+
+			if (sr & sport->port.ignore_status_mask) {
+				if (++ignored > 100)
+					goto out;
+				continue;
+			}
+
+			sr &= sport->port.read_status_mask;
+
+			if (sr & UARTSR1_PE)
+				flg = TTY_PARITY;
+			else if (sr & UARTSR1_FE)
+				flg = TTY_FRAME;
+
+			if (sr & UARTSR1_OR)
+				flg = TTY_OVERRUN;
+
+#ifdef SUPPORT_SYSRQ
+			sport->port.sysrq = 0;
+#endif
+		}
+
+		tty_insert_flip_char(port, rx, flg);
+	}
+
+out:
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+
+	tty_flip_buffer_push(port);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t lpuart_int(int irq, void *dev_id)
+{
+	struct lpuart_port *sport = dev_id;
+	unsigned char sts;
+
+	sts = readb(sport->port.membase + UARTSR1);
+
+	if (sts & UARTSR1_RDRF)
+		lpuart_rxint(irq, dev_id);
+
+	if (sts & UARTSR1_TDRE &&
+		!(readb(sport->port.membase + UARTCR5) & UARTCR5_TDMAS))
+		lpuart_txint(irq, dev_id);
+
+	return IRQ_HANDLED;
+}
+
+/* return TIOCSER_TEMT when transmitter is not busy */
+static unsigned int lpuart_tx_empty(struct uart_port *port)
+{
+	return (readb(port->membase + UARTSR1) & UARTSR1_TC) ?
+		TIOCSER_TEMT : 0;
+}
+
+static unsigned int lpuart_get_mctrl(struct uart_port *port)
+{
+	unsigned int temp = 0;
+	unsigned char reg;
+
+	reg = readb(port->membase + UARTMODEM);
+	if (reg & UARTMODEM_TXCTSE)
+		temp |= TIOCM_CTS;
+
+	if (reg & UARTMODEM_RXRTSE)
+		temp |= TIOCM_RTS;
+
+	return temp;
+}
+
+static void lpuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	unsigned char temp;
+
+	temp = readb(port->membase + UARTMODEM) &
+			~(UARTMODEM_RXRTSE | UARTMODEM_TXCTSE);
+
+	if (mctrl & TIOCM_RTS)
+		temp |= UARTMODEM_RXRTSE;
+
+	if (mctrl & TIOCM_CTS)
+		temp |= UARTMODEM_TXCTSE;
+
+	writeb(temp, port->membase + UARTMODEM);
+}
+
+static void lpuart_break_ctl(struct uart_port *port, int break_state)
+{
+	unsigned char temp;
+
+	temp = readb(port->membase + UARTCR2) & ~UARTCR2_SBK;
+
+	if (break_state != 0)
+		temp |= UARTCR2_SBK;
+
+	writeb(temp, port->membase + UARTCR2);
+}
+
+static void lpuart_setup_watermark(struct lpuart_port *sport)
+{
+	unsigned char val, cr2;
+
+	cr2 = readb(sport->port.membase + UARTCR2);
+	cr2 &= ~(UARTCR2_TIE | UARTCR2_TCIE | UARTCR2_TE |
+			UARTCR2_RIE | UARTCR2_RE);
+	writeb(cr2, sport->port.membase + UARTCR2);
+
+	/* determine FIFO size and enable FIFO mode */
+	val = readb(sport->port.membase + UARTPFIFO);
+
+	sport->txfifo_size = 0x1 << (((val >> UARTPFIFO_TXSIZE_OFF) &
+		UARTPFIFO_FIFOSIZE_MASK) + 1);
+
+	sport->rxfifo_size = 0x1 << (((val >> UARTPFIFO_RXSIZE_OFF) &
+		UARTPFIFO_FIFOSIZE_MASK) + 1);
+
+	writeb(val | UARTPFIFO_TXFE | UARTPFIFO_RXFE,
+			sport->port.membase + UARTPFIFO);
+
+	/* flush Tx and Rx FIFO */
+	writeb(UARTCFIFO_TXFLUSH | UARTCFIFO_RXFLUSH,
+			sport->port.membase + UARTCFIFO);
+
+	writeb(2, sport->port.membase + UARTTWFIFO);
+	writeb(1, sport->port.membase + UARTRWFIFO);
+}
+
+static int lpuart_startup(struct uart_port *port)
+{
+	struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
+	int ret;
+	unsigned long flags;
+	unsigned char temp;
+
+	ret = devm_request_irq(port->dev, port->irq, lpuart_int, 0,
+				DRIVER_NAME, sport);
+	if (ret)
+		return ret;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	lpuart_setup_watermark(sport);
+
+	temp = readb(sport->port.membase + UARTCR2);
+	temp |= (UARTCR2_RIE | UARTCR2_TIE | UARTCR2_RE | UARTCR2_TE);
+	writeb(temp, sport->port.membase + UARTCR2);
+
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+	return 0;
+}
+
+static void lpuart_shutdown(struct uart_port *port)
+{
+	struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
+	unsigned char temp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* disable Rx/Tx and interrupts */
+	temp = readb(port->membase + UARTCR2);
+	temp &= ~(UARTCR2_TE | UARTCR2_RE |
+			UARTCR2_TIE | UARTCR2_TCIE | UARTCR2_RIE);
+	writeb(temp, port->membase + UARTCR2);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	devm_free_irq(port->dev, port->irq, sport);
+}
+
+static void
+lpuart_set_termios(struct uart_port *port, struct ktermios *termios,
+		   struct ktermios *old)
+{
+	struct lpuart_port *sport = container_of(port, struct lpuart_port, port);
+	unsigned long flags;
+	unsigned char cr1, old_cr1, old_cr2, cr4, bdh, modem;
+	unsigned int  baud;
+	unsigned int old_csize = old ? old->c_cflag & CSIZE : CS8;
+	unsigned int sbr, brfa;
+
+	cr1 = old_cr1 = readb(sport->port.membase + UARTCR1);
+	old_cr2 = readb(sport->port.membase + UARTCR2);
+	cr4 = readb(sport->port.membase + UARTCR4);
+	bdh = readb(sport->port.membase + UARTBDH);
+	modem = readb(sport->port.membase + UARTMODEM);
+	/*
+	 * only support CS8 and CS7, and for CS7 must enable PE.
+	 * supported mode:
+	 *  - (7,e/o,1)
+	 *  - (8,n,1)
+	 *  - (8,m/s,1)
+	 *  - (8,e/o,1)
+	 */
+	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) == CS8 ||
+		(termios->c_cflag & CSIZE) == CS7)
+		cr1 = old_cr1 & ~UARTCR1_M;
+
+	if (termios->c_cflag & CMSPAR) {
+		if ((termios->c_cflag & CSIZE) != CS8) {
+			termios->c_cflag &= ~CSIZE;
+			termios->c_cflag |= CS8;
+		}
+		cr1 |= UARTCR1_M;
+	}
+
+	if (termios->c_cflag & CRTSCTS) {
+		modem |= (UARTMODEM_RXRTSE | UARTMODEM_TXCTSE);
+	} else {
+		termios->c_cflag &= ~CRTSCTS;
+		modem &= ~(UARTMODEM_RXRTSE | UARTMODEM_TXCTSE);
+	}
+
+	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)) {
+		if (termios->c_cflag & CMSPAR) {
+			cr1 &= ~UARTCR1_PE;
+			cr1 |= UARTCR1_M;
+		} else {
+			cr1 |= UARTCR1_PE;
+			if ((termios->c_cflag & CSIZE) == CS8)
+				cr1 |= UARTCR1_M;
+			if (termios->c_cflag & PARODD)
+				cr1 |= UARTCR1_PT;
+			else
+				cr1 &= ~UARTCR1_PT;
+		}
+	}
+
+	/* ask the core to calculate the divisor */
+	baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16);
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+
+	sport->port.read_status_mask = 0;
+	if (termios->c_iflag & INPCK)
+		sport->port.read_status_mask |=	(UARTSR1_FE | UARTSR1_PE);
+	if (termios->c_iflag & (BRKINT | PARMRK))
+		sport->port.read_status_mask |= UARTSR1_FE;
+
+	/* characters to ignore */
+	sport->port.ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		sport->port.ignore_status_mask |= UARTSR1_PE;
+	if (termios->c_iflag & IGNBRK) {
+		sport->port.ignore_status_mask |= UARTSR1_FE;
+		/*
+		 * if we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag & IGNPAR)
+			sport->port.ignore_status_mask |= UARTSR1_OR;
+	}
+
+	/* update the per-port timeout */
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	/* wait transmit engin complete */
+	while (!(readb(sport->port.membase + UARTSR1) & UARTSR1_TC))
+		barrier();
+
+	/* disable transmit and receive */
+	writeb(old_cr2 & ~(UARTCR2_TE | UARTCR2_RE),
+			sport->port.membase + UARTCR2);
+
+	sbr = sport->port.uartclk / (16 * baud);
+	brfa = ((sport->port.uartclk - (16 * sbr * baud)) * 2) / baud;
+	bdh &= ~UARTBDH_SBR_MASK;
+	bdh |= (sbr >> 8) & 0x1F;
+	cr4 &= ~UARTCR4_BRFA_MASK;
+	brfa &= UARTCR4_BRFA_MASK;
+	writeb(cr4 | brfa, sport->port.membase + UARTCR4);
+	writeb(bdh, sport->port.membase + UARTBDH);
+	writeb(sbr & 0xFF, sport->port.membase + UARTBDL);
+	writeb(cr1, sport->port.membase + UARTCR1);
+	writeb(modem, sport->port.membase + UARTMODEM);
+
+	/* restore control register */
+	writeb(old_cr2, sport->port.membase + UARTCR2);
+
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+}
+
+static const char *lpuart_type(struct uart_port *port)
+{
+	return "FSL_LPUART";
+}
+
+static void lpuart_release_port(struct uart_port *port)
+{
+	/* nothing to do */
+}
+
+static int lpuart_request_port(struct uart_port *port)
+{
+	return  0;
+}
+
+/* configure/autoconfigure the port */
+static void lpuart_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE)
+		port->type = PORT_LPUART;
+}
+
+static int lpuart_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	int ret = 0;
+
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_LPUART)
+		ret = -EINVAL;
+	if (port->irq != ser->irq)
+		ret = -EINVAL;
+	if (ser->io_type != UPIO_MEM)
+		ret = -EINVAL;
+	if (port->uartclk / 16 != ser->baud_base)
+		ret = -EINVAL;
+	if (port->iobase != ser->port)
+		ret = -EINVAL;
+	if (ser->hub6 != 0)
+		ret = -EINVAL;
+	return ret;
+}
+
+static struct uart_ops lpuart_pops = {
+	.tx_empty	= lpuart_tx_empty,
+	.set_mctrl	= lpuart_set_mctrl,
+	.get_mctrl	= lpuart_get_mctrl,
+	.stop_tx	= lpuart_stop_tx,
+	.start_tx	= lpuart_start_tx,
+	.stop_rx	= lpuart_stop_rx,
+	.enable_ms	= lpuart_enable_ms,
+	.break_ctl	= lpuart_break_ctl,
+	.startup	= lpuart_startup,
+	.shutdown	= lpuart_shutdown,
+	.set_termios	= lpuart_set_termios,
+	.type		= lpuart_type,
+	.request_port	= lpuart_request_port,
+	.release_port	= lpuart_release_port,
+	.config_port	= lpuart_config_port,
+	.verify_port	= lpuart_verify_port,
+};
+
+static struct lpuart_port *lpuart_ports[UART_NR];
+
+#ifdef CONFIG_SERIAL_FSL_LPUART_CONSOLE
+static void lpuart_console_putchar(struct uart_port *port, int ch)
+{
+	while (!(readb(port->membase + UARTSR1) & UARTSR1_TDRE))
+		barrier();
+
+	writeb(ch, port->membase + UARTDR);
+}
+
+static void
+lpuart_console_write(struct console *co, const char *s, unsigned int count)
+{
+	struct lpuart_port *sport = lpuart_ports[co->index];
+	unsigned char  old_cr2, cr2;
+
+	/* first save CR2 and then disable interrupts */
+	cr2 = old_cr2 = readb(sport->port.membase + UARTCR2);
+	cr2 |= (UARTCR2_TE |  UARTCR2_RE);
+	cr2 &= ~(UARTCR2_TIE | UARTCR2_TCIE | UARTCR2_RIE);
+	writeb(cr2, sport->port.membase + UARTCR2);
+
+	uart_console_write(&sport->port, s, count, lpuart_console_putchar);
+
+	/* wait for transmitter finish complete and restore CR2 */
+	while (!(readb(sport->port.membase + UARTSR1) & UARTSR1_TC))
+		barrier();
+
+	writeb(old_cr2, sport->port.membase + UARTCR2);
+}
+
+/*
+ * if the port was already initialised (eg, by a boot loader),
+ * try to determine the current setup.
+ */
+static void __init
+lpuart_console_get_options(struct lpuart_port *sport, int *baud,
+			   int *parity, int *bits)
+{
+	unsigned char cr, bdh, bdl, brfa;
+	unsigned int sbr, uartclk, baud_raw;
+
+	cr = readb(sport->port.membase + UARTCR2);
+	cr &= UARTCR2_TE | UARTCR2_RE;
+	if (!cr)
+		return;
+
+	/* ok, the port was enabled */
+
+	cr = readb(sport->port.membase + UARTCR1);
+
+	*parity = 'n';
+	if (cr & UARTCR1_PE) {
+		if (cr & UARTCR1_PT)
+			*parity = 'o';
+		else
+			*parity = 'e';
+	}
+
+	if (cr & UARTCR1_M)
+		*bits = 9;
+	else
+		*bits = 8;
+
+	bdh = readb(sport->port.membase + UARTBDH);
+	bdh &= UARTBDH_SBR_MASK;
+	bdl = readb(sport->port.membase + UARTBDL);
+	sbr = bdh;
+	sbr <<= 8;
+	sbr |= bdl;
+	brfa = readb(sport->port.membase + UARTCR4);
+	brfa &= UARTCR4_BRFA_MASK;
+
+	uartclk = clk_get_rate(sport->clk);
+	/*
+	 * baud = mod_clk/(16*(sbr[13]+(brfa)/32)
+	 */
+	baud_raw = uartclk / (16 * (sbr + brfa / 32));
+
+	if (*baud != baud_raw)
+		printk(KERN_INFO "Serial: Console lpuart rounded baud rate"
+				"from %d to %d\n", baud_raw, *baud);
+}
+
+static int __init lpuart_console_setup(struct console *co, char *options)
+{
+	struct lpuart_port *sport;
+	int baud = 115200;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	/*
+	 * 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(lpuart_ports))
+		co->index = 0;
+
+	sport = lpuart_ports[co->index];
+	if (sport == NULL)
+		return -ENODEV;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+	else
+		lpuart_console_get_options(sport, &baud, &parity, &bits);
+
+	lpuart_setup_watermark(sport);
+
+	return uart_set_options(&sport->port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver lpuart_reg;
+static struct console lpuart_console = {
+	.name		= DEV_NAME,
+	.write		= lpuart_console_write,
+	.device		= uart_console_device,
+	.setup		= lpuart_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &lpuart_reg,
+};
+
+#define LPUART_CONSOLE	(&lpuart_console)
+#else
+#define LPUART_CONSOLE	NULL
+#endif
+
+static struct uart_driver lpuart_reg = {
+	.owner		= THIS_MODULE,
+	.driver_name	= DRIVER_NAME,
+	.dev_name	= DEV_NAME,
+	.nr		= ARRAY_SIZE(lpuart_ports),
+	.cons		= LPUART_CONSOLE,
+};
+
+static int lpuart_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct lpuart_port *sport;
+	struct resource *res;
+	int ret;
+
+	sport = devm_kzalloc(&pdev->dev, sizeof(*sport), GFP_KERNEL);
+	if (!sport)
+		return -ENOMEM;
+
+	pdev->dev.coherent_dma_mask = 0;
+
+	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;
+	}
+	sport->port.line = ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	sport->port.mapbase = res->start;
+	sport->port.membase = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(sport->port.membase))
+		return PTR_ERR(sport->port.membase);
+
+	sport->port.dev = &pdev->dev;
+	sport->port.type = PORT_LPUART;
+	sport->port.iotype = UPIO_MEM;
+	sport->port.irq = platform_get_irq(pdev, 0);
+	sport->port.ops = &lpuart_pops;
+	sport->port.flags = UPF_BOOT_AUTOCONF;
+
+	sport->clk = devm_clk_get(&pdev->dev, "ipg");
+	if (IS_ERR(sport->clk)) {
+		ret = PTR_ERR(sport->clk);
+		dev_err(&pdev->dev, "failed to get uart clk: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(sport->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable uart clk: %d\n", ret);
+		return ret;
+	}
+
+	sport->port.uartclk = clk_get_rate(sport->clk);
+
+	lpuart_ports[sport->port.line] = sport;
+
+	platform_set_drvdata(pdev, &sport->port);
+
+	ret = uart_add_one_port(&lpuart_reg, &sport->port);
+	if (ret) {
+		clk_disable_unprepare(sport->clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int lpuart_remove(struct platform_device *pdev)
+{
+	struct lpuart_port *sport = platform_get_drvdata(pdev);
+
+	uart_remove_one_port(&lpuart_reg, &sport->port);
+
+	clk_disable_unprepare(sport->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int lpuart_suspend(struct device *dev)
+{
+	struct lpuart_port *sport = dev_get_drvdata(dev);
+
+	uart_suspend_port(&lpuart_reg, &sport->port);
+
+	return 0;
+}
+
+static int lpuart_resume(struct device *dev)
+{
+	struct lpuart_port *sport = dev_get_drvdata(dev);
+
+	uart_resume_port(&lpuart_reg, &sport->port);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(lpuart_pm_ops, lpuart_suspend, lpuart_resume);
+
+static struct platform_driver lpuart_driver = {
+	.probe		= lpuart_probe,
+	.remove		= lpuart_remove,
+	.driver		= {
+		.name	= "fsl-lpuart",
+		.owner	= THIS_MODULE,
+		.of_match_table = lpuart_dt_ids,
+		.pm	= &lpuart_pm_ops,
+	},
+};
+
+static int __init lpuart_serial_init(void)
+{
+	int ret;
+
+	pr_info("serial: Freescale lpuart driver\n");
+
+	ret = uart_register_driver(&lpuart_reg);
+	if (ret)
+		return ret;
+
+	ret = platform_driver_register(&lpuart_driver);
+	if (ret)
+		uart_unregister_driver(&lpuart_reg);
+
+	return 0;
+}
+
+static void __exit lpuart_serial_exit(void)
+{
+	platform_driver_unregister(&lpuart_driver);
+	uart_unregister_driver(&lpuart_reg);
+}
+
+module_init(lpuart_serial_init);
+module_exit(lpuart_serial_exit);
+
+MODULE_DESCRIPTION("Freescale lpuart serial port driver");
+MODULE_LICENSE("GPL v2");

include/uapi/linux/serial_core.h

···
 /* Rocketport EXPRESS/INFINITY */
 #define PORT_RP2	102
 
+/* Freescale lpuart */
+#define PORT_LPUART	103
+
 #endif /* _UAPILINUX_SERIAL_CORE_H */