linux-zen-desktop/drivers/tty/serial/ma35d1_serial.c

// SPDX-License-Identifier: GPL-2.0+
/*
 *  MA35D1 serial driver
 *  Copyright (C) 2023 Nuvoton Technology Corp.
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/iopoll.h>
#include <linux/serial_core.h>
#include <linux/slab.h>
#include <linux/tty_flip.h>
#include <linux/units.h>

#define MA35_UART_NR		17

#define MA35_RBR_REG		0x00
#define MA35_THR_REG		0x00
#define MA35_IER_REG		0x04
#define MA35_FCR_REG		0x08
#define MA35_LCR_REG		0x0C
#define MA35_MCR_REG		0x10
#define MA35_MSR_REG		0x14
#define MA35_FSR_REG		0x18
#define MA35_ISR_REG		0x1C
#define MA35_TOR_REG		0x20
#define MA35_BAUD_REG		0x24
#define MA35_ALTCTL_REG		0x2C
#define MA35_FUN_SEL_REG	0x30
#define MA35_WKCTL_REG		0x40
#define MA35_WKSTS_REG		0x44

/* MA35_IER_REG - Interrupt Enable Register */
#define MA35_IER_RDA_IEN	BIT(0)  /* RBR Available Interrupt Enable */
#define MA35_IER_THRE_IEN	BIT(1)  /* THR Empty Interrupt Enable */
#define MA35_IER_RLS_IEN	BIT(2)  /* RX Line Status Interrupt Enable */
#define MA35_IER_RTO_IEN	BIT(4)  /* RX Time-out Interrupt Enable */
#define MA35_IER_BUFERR_IEN	BIT(5)  /* Buffer Error Interrupt Enable */
#define MA35_IER_TIME_OUT_EN	BIT(11) /* RX Buffer Time-out Counter Enable */
#define MA35_IER_AUTO_RTS	BIT(12) /* nRTS Auto-flow Control Enable */
#define MA35_IER_AUTO_CTS	BIT(13) /* nCTS Auto-flow Control Enable */

/* MA35_FCR_REG - FIFO Control Register */
#define MA35_FCR_RFR		BIT(1)  /* RX Field Software Reset */
#define MA35_FCR_TFR		BIT(2)  /* TX Field Software Reset */
#define MA35_FCR_RFITL_MASK	GENMASK(7, 4) /* RX FIFO Interrupt Trigger Level */
#define MA35_FCR_RFITL_1BYTE	FIELD_PREP(MA35_FCR_RFITL_MASK, 0)
#define MA35_FCR_RFITL_4BYTES	FIELD_PREP(MA35_FCR_RFITL_MASK, 1)
#define MA35_FCR_RFITL_8BYTES	FIELD_PREP(MA35_FCR_RFITL_MASK, 2)
#define MA35_FCR_RFITL_14BYTES	FIELD_PREP(MA35_FCR_RFITL_MASK, 3)
#define MA35_FCR_RFITL_30BYTES	FIELD_PREP(MA35_FCR_RFITL_MASK, 4)
#define MA35_FCR_RTSTL_MASK	GENMASK(19, 16) /* nRTS Trigger Level */
#define MA35_FCR_RTSTL_1BYTE	FIELD_PREP(MA35_FCR_RTSTL_MASK, 0)
#define MA35_FCR_RTSTL_4BYTES	FIELD_PREP(MA35_FCR_RTSTL_MASK, 1)
#define MA35_FCR_RTSTL_8BYTES	FIELD_PREP(MA35_FCR_RTSTL_MASK, 2)
#define MA35_FCR_RTSTL_14BYTES	FIELD_PREP(MA35_FCR_RTSTL_MASK, 3)
#define MA35_FCR_RTSTLL_30BYTES	FIELD_PREP(MA35_FCR_RTSTL_MASK, 4)

/* MA35_LCR_REG - Line Control Register */
#define	MA35_LCR_NSB		BIT(2)  /* Number of “STOP Bit” */
#define MA35_LCR_PBE		BIT(3)  /* Parity Bit Enable */
#define MA35_LCR_EPE		BIT(4)  /* Even Parity Enable */
#define MA35_LCR_SPE		BIT(5)  /* Stick Parity Enable */
#define MA35_LCR_BREAK		BIT(6)  /* Break Control */
#define MA35_LCR_WLS_MASK	GENMASK(1, 0) /* Word Length Selection */
#define MA35_LCR_WLS_5BITS	FIELD_PREP(MA35_LCR_WLS_MASK, 0)
#define MA35_LCR_WLS_6BITS	FIELD_PREP(MA35_LCR_WLS_MASK, 1)
#define MA35_LCR_WLS_7BITS	FIELD_PREP(MA35_LCR_WLS_MASK, 2)
#define MA35_LCR_WLS_8BITS	FIELD_PREP(MA35_LCR_WLS_MASK, 3)

/* MA35_MCR_REG - Modem Control Register */
#define MA35_MCR_RTS_CTRL	BIT(1)  /* nRTS Signal Control */
#define MA35_MCR_RTSACTLV	BIT(9)  /* nRTS Pin Active Level */
#define MA35_MCR_RTSSTS		BIT(13) /* nRTS Pin Status (Read Only) */

/* MA35_MSR_REG - Modem Status Register */
#define MA35_MSR_CTSDETF	BIT(0)  /* Detect nCTS State Change Flag */
#define MA35_MSR_CTSSTS		BIT(4)  /* nCTS Pin Status (Read Only) */
#define MA35_MSR_CTSACTLV	BIT(8)  /* nCTS Pin Active Level */

/* MA35_FSR_REG - FIFO Status Register */
#define MA35_FSR_RX_OVER_IF	BIT(0)  /* RX Overflow Error Interrupt Flag */
#define MA35_FSR_PEF		BIT(4)  /* Parity Error Flag*/
#define MA35_FSR_FEF		BIT(5)  /* Framing Error Flag */
#define MA35_FSR_BIF		BIT(6)  /* Break Interrupt Flag */
#define MA35_FSR_RX_EMPTY	BIT(14) /* Receiver FIFO Empty (Read Only) */
#define MA35_FSR_RX_FULL	BIT(15) /* Receiver FIFO Full (Read Only) */
#define MA35_FSR_TX_EMPTY	BIT(22) /* Transmitter FIFO Empty (Read Only) */
#define MA35_FSR_TX_FULL	BIT(23) /* Transmitter FIFO Full (Read Only) */
#define MA35_FSR_TX_OVER_IF	BIT(24) /* TX Overflow Error Interrupt Flag */
#define MA35_FSR_TE_FLAG	BIT(28) /* Transmitter Empty Flag (Read Only) */
#define MA35_FSR_RXPTR_MSK	GENMASK(13, 8) /* TX FIFO Pointer mask */
#define MA35_FSR_TXPTR_MSK	GENMASK(21, 16) /* RX FIFO Pointer mask */

/* MA35_ISR_REG - Interrupt Status Register */
#define MA35_ISR_RDA_IF		BIT(0)  /* RBR Available Interrupt Flag */
#define MA35_ISR_THRE_IF	BIT(1)  /* THR Empty Interrupt Flag */
#define MA35_ISR_RLSIF		BIT(2)  /* Receive Line Interrupt Flag */
#define MA35_ISR_MODEMIF	BIT(3)  /* MODEM Interrupt Flag */
#define MA35_ISR_RXTO_IF	BIT(4)  /* RX Time-out Interrupt Flag */
#define MA35_ISR_BUFEIF		BIT(5)  /* Buffer Error Interrupt Flag */
#define MA35_ISR_WK_IF		BIT(6)  /* UART Wake-up Interrupt Flag */
#define MA35_ISR_RDAINT		BIT(8)  /* RBR Available Interrupt Indicator */
#define MA35_ISR_THRE_INT	BIT(9)  /* THR Empty Interrupt Indicator */
#define MA35_ISR_ALL		0xFFFFFFFF

/* MA35_BAUD_REG - Baud Rate Divider Register */
#define	MA35_BAUD_MODE_MASK	GENMASK(29, 28)
#define MA35_BAUD_MODE0		FIELD_PREP(MA35_BAUD_MODE_MASK, 0)
#define MA35_BAUD_MODE1		FIELD_PREP(MA35_BAUD_MODE_MASK, 2)
#define MA35_BAUD_MODE2		FIELD_PREP(MA35_BAUD_MODE_MASK, 3)
#define	MA35_BAUD_MASK		GENMASK(15, 0)

/* MA35_ALTCTL_REG - Alternate Control/Status Register */
#define MA35_ALTCTL_RS485AUD	BIT(10) /* RS-485 Auto Direction Function */

/* MA35_FUN_SEL_REG - Function Select Register */
#define MA35_FUN_SEL_MASK	GENMASK(2, 0)
#define MA35_FUN_SEL_UART	FIELD_PREP(MA35_FUN_SEL_MASK, 0)
#define MA35_FUN_SEL_RS485	FIELD_PREP(MA35_FUN_SEL_MASK, 3)

/* The constrain for MA35D1 UART baud rate divider */
#define MA35_BAUD_DIV_MAX	0xFFFF
#define MA35_BAUD_DIV_MIN	11

/* UART FIFO depth */
#define MA35_UART_FIFO_DEPTH	32
/* UART console clock */
#define MA35_UART_CONSOLE_CLK	(24 * HZ_PER_MHZ)
/* UART register ioremap size */
#define MA35_UART_REG_SIZE	0x100
/* Rx Timeout */
#define MA35_UART_RX_TOUT	0x40

#define MA35_IER_CONFIG		(MA35_IER_RTO_IEN | MA35_IER_RDA_IEN | \
				 MA35_IER_TIME_OUT_EN | MA35_IER_BUFERR_IEN)

#define MA35_ISR_IF_CHECK	(MA35_ISR_RDA_IF | MA35_ISR_RXTO_IF | \
				 MA35_ISR_THRE_INT | MA35_ISR_BUFEIF)

#define MA35_FSR_TX_BOTH_EMPTY	(MA35_FSR_TE_FLAG | MA35_FSR_TX_EMPTY)

static struct uart_driver ma35d1serial_reg;

struct uart_ma35d1_port {
	struct uart_port port;
	struct clk *clk;
	u16 capabilities; /* port capabilities */
	u8 ier;
	u8 lcr;
	u8 mcr;
	u32 baud_rate;
	u32 console_baud_rate;
	u32 console_line;
	u32 console_int;
};

static struct uart_ma35d1_port ma35d1serial_ports[MA35_UART_NR];

static struct uart_ma35d1_port *to_ma35d1_uart_port(struct uart_port *uart)
{
	return container_of(uart, struct uart_ma35d1_port, port);
}

static u32 serial_in(struct uart_ma35d1_port *p, u32 offset)
{
	return readl_relaxed(p->port.membase + offset);
}

static void serial_out(struct uart_ma35d1_port *p, u32 offset, u32 value)
{
	writel_relaxed(value, p->port.membase + offset);
}

static void __stop_tx(struct uart_ma35d1_port *p)
{
	u32 ier;

	ier = serial_in(p, MA35_IER_REG);
	if (ier & MA35_IER_THRE_IEN)
		serial_out(p, MA35_IER_REG, ier & ~MA35_IER_THRE_IEN);
}

static void ma35d1serial_stop_tx(struct uart_port *port)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);

	__stop_tx(up);
}

static void transmit_chars(struct uart_ma35d1_port *up)
{
	u32 count;
	u8 ch;

	if (uart_tx_stopped(&up->port)) {
		ma35d1serial_stop_tx(&up->port);
		return;
	}
	count = MA35_UART_FIFO_DEPTH - FIELD_GET(MA35_FSR_TXPTR_MSK,
						 serial_in(up, MA35_FSR_REG));
	uart_port_tx_limited(&up->port, ch, count,
			     !(serial_in(up, MA35_FSR_REG) & MA35_FSR_TX_FULL),
			     serial_out(up, MA35_THR_REG, ch),
			     ({}));
}

static void ma35d1serial_start_tx(struct uart_port *port)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);
	u32 ier;

	ier = serial_in(up, MA35_IER_REG);
	serial_out(up, MA35_IER_REG, ier & ~MA35_IER_THRE_IEN);
	transmit_chars(up);
	serial_out(up, MA35_IER_REG, ier | MA35_IER_THRE_IEN);
}

static void ma35d1serial_stop_rx(struct uart_port *port)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);
	u32 ier;

	ier = serial_in(up, MA35_IER_REG);
	ier &= ~MA35_IER_RDA_IEN;
	serial_out(up, MA35_IER_REG, ier);
}

static void receive_chars(struct uart_ma35d1_port *up)
{
	int max_count = 256;
	u8 ch, flag;
	u32 fsr;

	fsr = serial_in(up, MA35_FSR_REG);
	do {
		flag = TTY_NORMAL;
		up->port.icount.rx++;

		if (unlikely(fsr & (MA35_FSR_BIF | MA35_FSR_FEF |
				    MA35_FSR_PEF | MA35_FSR_RX_OVER_IF))) {
			if (fsr & MA35_FSR_BIF) {
				up->port.icount.brk++;
				if (uart_handle_break(&up->port))
					continue;
			}
			if (fsr & MA35_FSR_FEF)
				up->port.icount.frame++;
			if (fsr & MA35_FSR_PEF)
				up->port.icount.parity++;
			if (fsr & MA35_FSR_RX_OVER_IF)
				up->port.icount.overrun++;

			serial_out(up, MA35_FSR_REG,
				   fsr & (MA35_FSR_BIF | MA35_FSR_FEF |
					  MA35_FSR_PEF | MA35_FSR_RX_OVER_IF));
			if (fsr & MA35_FSR_BIF)
				flag = TTY_BREAK;
			else if (fsr & MA35_FSR_PEF)
				flag = TTY_PARITY;
			else if (fsr & MA35_FSR_FEF)
				flag = TTY_FRAME;
		}

		ch = serial_in(up, MA35_RBR_REG);
		if (uart_handle_sysrq_char(&up->port, ch))
			continue;

		spin_lock(&up->port.lock);
		uart_insert_char(&up->port, fsr, MA35_FSR_RX_OVER_IF, ch, flag);
		spin_unlock(&up->port.lock);

		fsr = serial_in(up, MA35_FSR_REG);
	} while (!(fsr & MA35_FSR_RX_EMPTY) && (max_count-- > 0));

	spin_lock(&up->port.lock);
	tty_flip_buffer_push(&up->port.state->port);
	spin_unlock(&up->port.lock);
}

static irqreturn_t ma35d1serial_interrupt(int irq, void *dev_id)
{
	struct uart_port *port = dev_id;
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);
	u32 isr, fsr;

	isr = serial_in(up, MA35_ISR_REG);
	fsr = serial_in(up, MA35_FSR_REG);

	if (!(isr & MA35_ISR_IF_CHECK))
		return IRQ_NONE;

	if (isr & (MA35_ISR_RDA_IF | MA35_ISR_RXTO_IF))
		receive_chars(up);
	if (isr & MA35_ISR_THRE_INT)
		transmit_chars(up);
	if (fsr & MA35_FSR_TX_OVER_IF)
		serial_out(up, MA35_FSR_REG, MA35_FSR_TX_OVER_IF);

	return IRQ_HANDLED;
}

static u32 ma35d1serial_tx_empty(struct uart_port *port)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);
	u32 fsr;

	fsr = serial_in(up, MA35_FSR_REG);
	if ((fsr & MA35_FSR_TX_BOTH_EMPTY) == MA35_FSR_TX_BOTH_EMPTY)
		return TIOCSER_TEMT;
	else
		return 0;
}

static u32 ma35d1serial_get_mctrl(struct uart_port *port)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);
	u32 status;
	u32 ret = 0;

	status = serial_in(up, MA35_MSR_REG);
	if (!(status & MA35_MSR_CTSSTS))
		ret |= TIOCM_CTS;
	return ret;
}

static void ma35d1serial_set_mctrl(struct uart_port *port, u32 mctrl)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);
	u32 mcr, msr, ier;

	mcr = serial_in(up, MA35_MCR_REG);
	mcr &= ~MA35_MCR_RTS_CTRL;

	if (mctrl & TIOCM_RTS)
		mcr |= MA35_MCR_RTSACTLV;
	else
		mcr &= ~MA35_MCR_RTSACTLV;

	if (up->mcr & UART_MCR_AFE) {
		ier = serial_in(up, MA35_IER_REG);
		ier |= MA35_IER_AUTO_RTS | MA35_IER_AUTO_CTS;
		serial_out(up, MA35_IER_REG, ier);
		up->port.flags |= UPF_HARD_FLOW;
	} else {
		ier = serial_in(up, MA35_IER_REG);
		ier &= ~(MA35_IER_AUTO_RTS | MA35_IER_AUTO_CTS);
		serial_out(up, MA35_IER_REG, ier);
		up->port.flags &= ~UPF_HARD_FLOW;
	}

	msr = serial_in(up, MA35_MSR_REG);
	msr |= MA35_MSR_CTSACTLV;
	serial_out(up, MA35_MSR_REG, msr);
	serial_out(up, MA35_MCR_REG, mcr);
}

static void ma35d1serial_break_ctl(struct uart_port *port, int break_state)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);
	unsigned long flags;
	u32 lcr;

	spin_lock_irqsave(&up->port.lock, flags);
	lcr = serial_in(up, MA35_LCR_REG);
	if (break_state != 0)
		lcr |= MA35_LCR_BREAK;
	else
		lcr &= ~MA35_LCR_BREAK;
	serial_out(up, MA35_LCR_REG, lcr);
	spin_unlock_irqrestore(&up->port.lock, flags);
}

static int ma35d1serial_startup(struct uart_port *port)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);
	u32 fcr;
	int retval;

	/* Reset FIFO */
	serial_out(up, MA35_FCR_REG, MA35_FCR_TFR | MA35_FCR_RFR);

	/* Clear pending interrupts */
	serial_out(up, MA35_ISR_REG, MA35_ISR_ALL);

	retval = request_irq(port->irq, ma35d1serial_interrupt, 0,
			     dev_name(port->dev), port);
	if (retval) {
		dev_err(up->port.dev, "request irq failed.\n");
		return retval;
	}

	fcr = serial_in(up, MA35_FCR_REG);
	fcr |= MA35_FCR_RFITL_4BYTES | MA35_FCR_RTSTL_8BYTES;
	serial_out(up, MA35_FCR_REG, fcr);
	serial_out(up, MA35_LCR_REG, MA35_LCR_WLS_8BITS);
	serial_out(up, MA35_TOR_REG, MA35_UART_RX_TOUT);
	serial_out(up, MA35_IER_REG, MA35_IER_CONFIG);
	return 0;
}

static void ma35d1serial_shutdown(struct uart_port *port)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);

	serial_out(up, MA35_IER_REG, 0);
	free_irq(port->irq, port);
}

static void ma35d1serial_set_termios(struct uart_port *port,
				     struct ktermios *termios,
				     const struct ktermios *old)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);
	unsigned long flags;
	u32 baud, quot;
	u32 lcr = 0;

	lcr = UART_LCR_WLEN(tty_get_char_size(termios->c_cflag));

	if (termios->c_cflag & CSTOPB)
		lcr |= MA35_LCR_NSB;
	if (termios->c_cflag & PARENB)
		lcr |= MA35_LCR_PBE;
	if (!(termios->c_cflag & PARODD))
		lcr |= MA35_LCR_EPE;
	if (termios->c_cflag & CMSPAR)
		lcr |= MA35_LCR_SPE;

	baud = uart_get_baud_rate(port, termios, old,
				  port->uartclk / MA35_BAUD_DIV_MAX,
				  port->uartclk / MA35_BAUD_DIV_MIN);

	/* MA35D1 UART baud rate equation: baudrate = UART_CLK / (quot + 2) */
	quot = (port->uartclk / baud) - 2;

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

	up->port.read_status_mask = MA35_FSR_RX_OVER_IF;
	if (termios->c_iflag & INPCK)
		up->port.read_status_mask |= MA35_FSR_FEF | MA35_FSR_PEF;
	if (termios->c_iflag & (BRKINT | PARMRK))
		up->port.read_status_mask |= MA35_FSR_BIF;

	/* Characteres to ignore */
	up->port.ignore_status_mask = 0;
	if (termios->c_iflag & IGNPAR)
		up->port.ignore_status_mask |= MA35_FSR_FEF | MA35_FSR_PEF;
	if (termios->c_iflag & IGNBRK) {
		up->port.ignore_status_mask |= MA35_FSR_BIF;
		/*
		 * 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 |= MA35_FSR_RX_OVER_IF;
	}
	if (termios->c_cflag & CRTSCTS)
		up->mcr |= UART_MCR_AFE;
	else
		up->mcr &= ~UART_MCR_AFE;

	uart_update_timeout(port, termios->c_cflag, baud);

	ma35d1serial_set_mctrl(&up->port, up->port.mctrl);

	serial_out(up, MA35_BAUD_REG, MA35_BAUD_MODE2 | FIELD_PREP(MA35_BAUD_MASK, quot));

	serial_out(up, MA35_LCR_REG, lcr);

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

static const char *ma35d1serial_type(struct uart_port *port)
{
	return "ma35d1-uart";
}

static void ma35d1serial_config_port(struct uart_port *port, int flags)
{
	/*
	 * Driver core for serial ports forces a non-zero value for port type.
	 * Write an arbitrary value here to accommodate the serial core driver,
	 * as ID part of UAPI is redundant.
	 */
	port->type = 1;
}

static int ma35d1serial_verify_port(struct uart_port *port, struct serial_struct *ser)
{
	if (port->type != PORT_UNKNOWN && ser->type != 1)
		return -EINVAL;

	return 0;
}

static const struct uart_ops ma35d1serial_ops = {
	.tx_empty     = ma35d1serial_tx_empty,
	.set_mctrl    = ma35d1serial_set_mctrl,
	.get_mctrl    = ma35d1serial_get_mctrl,
	.stop_tx      = ma35d1serial_stop_tx,
	.start_tx     = ma35d1serial_start_tx,
	.stop_rx      = ma35d1serial_stop_rx,
	.break_ctl    = ma35d1serial_break_ctl,
	.startup      = ma35d1serial_startup,
	.shutdown     = ma35d1serial_shutdown,
	.set_termios  = ma35d1serial_set_termios,
	.type         = ma35d1serial_type,
	.config_port  = ma35d1serial_config_port,
	.verify_port  = ma35d1serial_verify_port,
};

static const struct of_device_id ma35d1_serial_of_match[] = {
	{ .compatible = "nuvoton,ma35d1-uart" },
	{},
};
MODULE_DEVICE_TABLE(of, ma35d1_serial_of_match);

#ifdef CONFIG_SERIAL_NUVOTON_MA35D1_CONSOLE

static struct device_node *ma35d1serial_uart_nodes[MA35_UART_NR];

static void wait_for_xmitr(struct uart_ma35d1_port *up)
{
	unsigned int reg = 0;

	read_poll_timeout_atomic(serial_in, reg, reg & MA35_FSR_TX_EMPTY,
				 1, 10000, false,
				 up, MA35_FSR_REG);
}

static void ma35d1serial_console_putchar(struct uart_port *port, unsigned char ch)
{
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);

	wait_for_xmitr(up);
	serial_out(up, MA35_THR_REG, ch);
}

/*
 *  Print a string to the serial port trying not to disturb
 *  any possible real use of the port...
 *
 *  The console_lock must be held when we get here.
 */
static void ma35d1serial_console_write(struct console *co, const char *s, u32 count)
{
	struct uart_ma35d1_port *up = &ma35d1serial_ports[co->index];
	unsigned long flags;
	int locked = 1;
	u32 ier;

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

	/*
	 *  First save the IER then disable the interrupts
	 */
	ier = serial_in(up, MA35_IER_REG);
	serial_out(up, MA35_IER_REG, 0);

	uart_console_write(&up->port, s, count, ma35d1serial_console_putchar);

	wait_for_xmitr(up);
	serial_out(up, MA35_IER_REG, ier);

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

static int __init ma35d1serial_console_setup(struct console *co, char *options)
{
	struct device_node *np;
	struct uart_ma35d1_port *p;
	u32 val32[4];
	struct uart_port *port;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	if ((co->index < 0) || (co->index >= MA35_UART_NR)) {
		pr_debug("Console Port%x out of range\n", co->index);
		return -EINVAL;
	}

	np = ma35d1serial_uart_nodes[co->index];
	p = &ma35d1serial_ports[co->index];
	if (!np || !p)
		return -ENODEV;

	if (of_property_read_u32_array(np, "reg", val32, ARRAY_SIZE(val32)) != 0)
		return -EINVAL;

	p->port.iobase = val32[1];
	p->port.membase = ioremap(p->port.iobase, MA35_UART_REG_SIZE);
	if (!p->port.membase)
		return -ENOMEM;

	p->port.ops = &ma35d1serial_ops;
	p->port.line = 0;
	p->port.uartclk = MA35_UART_CONSOLE_CLK;

	port = &ma35d1serial_ports[co->index].port;

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

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

static struct console ma35d1serial_console = {
	.name    = "ttyNVT",
	.write   = ma35d1serial_console_write,
	.device  = uart_console_device,
	.setup   = ma35d1serial_console_setup,
	.flags   = CON_PRINTBUFFER | CON_ENABLED,
	.index   = -1,
	.data    = &ma35d1serial_reg,
};

static void ma35d1serial_console_init_port(void)
{
	u32 i = 0;
	struct device_node *np;

	for_each_matching_node(np, ma35d1_serial_of_match) {
		if (ma35d1serial_uart_nodes[i] == NULL) {
			of_node_get(np);
			ma35d1serial_uart_nodes[i] = np;
			i++;
			if (i == MA35_UART_NR)
				break;
		}
	}
}

static int __init ma35d1serial_console_init(void)
{
	ma35d1serial_console_init_port();
	register_console(&ma35d1serial_console);
	return 0;
}
console_initcall(ma35d1serial_console_init);

#define MA35D1SERIAL_CONSOLE    (&ma35d1serial_console)
#else
#define MA35D1SERIAL_CONSOLE    NULL
#endif

static struct uart_driver ma35d1serial_reg = {
	.owner        = THIS_MODULE,
	.driver_name  = "serial",
	.dev_name     = "ttyNVT",
	.major        = TTY_MAJOR,
	.minor        = 64,
	.cons         = MA35D1SERIAL_CONSOLE,
	.nr           = MA35_UART_NR,
};

/*
 * Register a set of serial devices attached to a platform device.
 * The list is terminated with a zero flags entry, which means we expect
 * all entries to have at least UPF_BOOT_AUTOCONF set.
 */
static int ma35d1serial_probe(struct platform_device *pdev)
{
	struct resource *res_mem;
	struct uart_ma35d1_port *up;
	int ret = 0;

	if (pdev->dev.of_node) {
		ret = of_alias_get_id(pdev->dev.of_node, "serial");
		if (ret < 0) {
			dev_err(&pdev->dev, "failed to get alias/pdev id, errno %d\n", ret);
			return ret;
		}
	}
	up = &ma35d1serial_ports[ret];
	up->port.line = ret;
	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res_mem)
		return -ENODEV;

	up->port.iobase = res_mem->start;
	up->port.membase = ioremap(up->port.iobase, MA35_UART_REG_SIZE);
	up->port.ops = &ma35d1serial_ops;

	spin_lock_init(&up->port.lock);

	up->clk = of_clk_get(pdev->dev.of_node, 0);
	if (IS_ERR(up->clk)) {
		ret = PTR_ERR(up->clk);
		dev_err(&pdev->dev, "failed to get core clk: %d\n", ret);
		goto err_iounmap;
	}

	ret = clk_prepare_enable(up->clk);
	if (ret)
		goto err_iounmap;

	if (up->port.line != 0)
		up->port.uartclk = clk_get_rate(up->clk);

	ret = platform_get_irq(pdev, 0);
	if (ret < 0)
		goto err_clk_disable;

	up->port.irq = ret;
	up->port.dev = &pdev->dev;
	up->port.flags = UPF_BOOT_AUTOCONF;

	platform_set_drvdata(pdev, up);

	ret = uart_add_one_port(&ma35d1serial_reg, &up->port);
	if (ret < 0)
		goto err_free_irq;

	return 0;

err_free_irq:
	free_irq(up->port.irq, &up->port);

err_clk_disable:
	clk_disable_unprepare(up->clk);

err_iounmap:
	iounmap(up->port.membase);
	return ret;
}

/*
 * Remove serial ports registered against a platform device.
 */
static int ma35d1serial_remove(struct platform_device *dev)
{
	struct uart_port *port = platform_get_drvdata(dev);
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);

	uart_remove_one_port(&ma35d1serial_reg, port);
	clk_disable_unprepare(up->clk);
	return 0;
}

static int ma35d1serial_suspend(struct platform_device *dev, pm_message_t state)
{
	struct uart_port *port = platform_get_drvdata(dev);
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);

	uart_suspend_port(&ma35d1serial_reg, &up->port);
	if (up->port.line == 0) {
		up->console_baud_rate = serial_in(up, MA35_BAUD_REG);
		up->console_line = serial_in(up, MA35_LCR_REG);
		up->console_int = serial_in(up, MA35_IER_REG);
	}
	return 0;
}

static int ma35d1serial_resume(struct platform_device *dev)
{
	struct uart_port *port = platform_get_drvdata(dev);
	struct uart_ma35d1_port *up = to_ma35d1_uart_port(port);

	if (up->port.line == 0) {
		serial_out(up, MA35_BAUD_REG, up->console_baud_rate);
		serial_out(up, MA35_LCR_REG, up->console_line);
		serial_out(up, MA35_IER_REG, up->console_int);
	}
	uart_resume_port(&ma35d1serial_reg, &up->port);
	return 0;
}

static struct platform_driver ma35d1serial_driver = {
	.probe      = ma35d1serial_probe,
	.remove     = ma35d1serial_remove,
	.suspend    = ma35d1serial_suspend,
	.resume     = ma35d1serial_resume,
	.driver     = {
		.name   = "ma35d1-uart",
		.owner  = THIS_MODULE,
		.of_match_table = of_match_ptr(ma35d1_serial_of_match),
	},
};

static int __init ma35d1serial_init(void)
{
	int ret;

	ret = uart_register_driver(&ma35d1serial_reg);
	if (ret)
		return ret;

	ret = platform_driver_register(&ma35d1serial_driver);
	if (ret)
		uart_unregister_driver(&ma35d1serial_reg);

	return ret;
}

static void __exit ma35d1serial_exit(void)
{
	platform_driver_unregister(&ma35d1serial_driver);
	uart_unregister_driver(&ma35d1serial_reg);
}

module_init(ma35d1serial_init);
module_exit(ma35d1serial_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MA35D1 serial driver");