drivers/tty/serial/pxa.c

// SPDX-License-Identifier: GPL-2.0+
/*
 *  Based on drivers/serial/8250.c by Russell King.
 *
 *  Author:	Nicolas Pitre
 *  Created:	Feb 20, 2003
 *  Copyright:	(C) 2003 Monta Vista Software, Inc.
 *
 * Note 1: This driver is made separate from the already too overloaded
 * 8250.c because it needs some kirks of its own and that'll make it
 * easier to add DMA support.
 *
 * Note 2: I'm too sick of device allocation policies for serial ports.
 * If someone else wants to request an "official" allocation of major/minor
 * for this driver please be my guest.  And don't forget that new hardware
 * to come from Intel might have more than 3 or 4 of those UARTs.  Let's
 * hope for a better port registration and dynamic device allocation scheme
 * with the serial core maintainer satisfaction to appear soon.
 */


#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/serial.h>
#include <linux/serial_reg.h>
#include <linux/circ_buf.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/slab.h>

#define PXA_NAME_LEN		8

struct uart_pxa_port {
	struct uart_port        port;
	unsigned char           ier;
	unsigned char           lcr;
	unsigned char           mcr;
	unsigned int            lsr_break_flag;
	struct clk		*clk;
	char			name[PXA_NAME_LEN];
};

static inline unsigned int serial_in(struct uart_pxa_port *up, int offset)
{
	offset <<= 2;
	return readl(up->port.membase + offset);
}

static inline void serial_out(struct uart_pxa_port *up, int offset, int value)
{
	offset <<= 2;
	writel(value, up->port.membase + offset);
}

static void serial_pxa_enable_ms(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

	up->ier |= UART_IER_MSI;
	serial_out(up, UART_IER, up->ier);
}

static void serial_pxa_stop_tx(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

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

static void serial_pxa_stop_rx(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

	up->ier &= ~UART_IER_RLSI;
	up->port.read_status_mask &= ~UART_LSR_DR;
	serial_out(up, UART_IER, up->ier);
}

static inline void receive_chars(struct uart_pxa_port *up, int *status)
{
	u8 ch, flag;
	int max_count = 256;

	do {
		/* work around Errata #20 according to
		 * Intel(R) PXA27x Processor Family
		 * Specification Update (May 2005)
		 *
		 * Step 2
		 * Disable the Reciever Time Out Interrupt via IER[RTOEI]
		 */
		up->ier &= ~UART_IER_RTOIE;
		serial_out(up, UART_IER, up->ier);

		ch = serial_in(up, UART_RX);
		flag = TTY_NORMAL;
		up->port.icount.rx++;

		if (unlikely(*status & (UART_LSR_BI | UART_LSR_PE |
				       UART_LSR_FE | UART_LSR_OE))) {
			/*
			 * For statistics only
			 */
			if (*status & UART_LSR_BI) {
				*status &= ~(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 (*status & UART_LSR_PE)
				up->port.icount.parity++;
			else if (*status & UART_LSR_FE)
				up->port.icount.frame++;
			if (*status & UART_LSR_OE)
				up->port.icount.overrun++;

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

#ifdef CONFIG_SERIAL_PXA_CONSOLE
			if (up->port.line == up->port.cons->index) {
				/* Recover the break flag from console xmit */
				*status |= up->lsr_break_flag;
				up->lsr_break_flag = 0;
			}
#endif
			if (*status & UART_LSR_BI) {
				flag = TTY_BREAK;
			} else if (*status & UART_LSR_PE)
				flag = TTY_PARITY;
			else if (*status & UART_LSR_FE)
				flag = TTY_FRAME;
		}

		if (uart_handle_sysrq_char(&up->port, ch))
			goto ignore_char;

		uart_insert_char(&up->port, *status, UART_LSR_OE, ch, flag);

	ignore_char:
		*status = serial_in(up, UART_LSR);
	} while ((*status & UART_LSR_DR) && (max_count-- > 0));
	tty_flip_buffer_push(&up->port.state->port);

	/* work around Errata #20 according to
	 * Intel(R) PXA27x Processor Family
	 * Specification Update (May 2005)
	 *
	 * Step 6:
	 * No more data in FIFO: Re-enable RTO interrupt via IER[RTOIE]
	 */
	up->ier |= UART_IER_RTOIE;
	serial_out(up, UART_IER, up->ier);
}

static void transmit_chars(struct uart_pxa_port *up)
{
	u8 ch;

	uart_port_tx_limited(&up->port, ch, up->port.fifosize / 2,
		true,
		serial_out(up, UART_TX, ch),
		({}));
}

static void serial_pxa_start_tx(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

	if (!(up->ier & UART_IER_THRI)) {
		up->ier |= UART_IER_THRI;
		serial_out(up, UART_IER, up->ier);
	}
}

/* should hold up->port.lock */
static inline void check_modem_status(struct uart_pxa_port *up)
{
	int status;

	status = serial_in(up, UART_MSR);

	if ((status & UART_MSR_ANY_DELTA) == 0)
		return;

	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);
}

/*
 * This handles the interrupt from one port.
 */
static inline irqreturn_t serial_pxa_irq(int irq, void *dev_id)
{
	struct uart_pxa_port *up = dev_id;
	unsigned int iir, lsr;

	iir = serial_in(up, UART_IIR);
	if (iir & UART_IIR_NO_INT)
		return IRQ_NONE;
	uart_port_lock(&up->port);
	lsr = serial_in(up, UART_LSR);
	if (lsr & UART_LSR_DR)
		receive_chars(up, &lsr);
	check_modem_status(up);
	if (lsr & UART_LSR_THRE)
		transmit_chars(up);
	uart_port_unlock(&up->port);
	return IRQ_HANDLED;
}

static unsigned int serial_pxa_tx_empty(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	unsigned long flags;
	unsigned int ret;

	uart_port_lock_irqsave(&up->port, &flags);
	ret = serial_in(up, UART_LSR) & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
	uart_port_unlock_irqrestore(&up->port, flags);

	return ret;
}

static unsigned int serial_pxa_get_mctrl(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	unsigned char status;
	unsigned int ret;

	status = serial_in(up, UART_MSR);

	ret = 0;
	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_pxa_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	unsigned char mcr = 0;

	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;

	mcr |= up->mcr;

	serial_out(up, UART_MCR, mcr);
}

static void serial_pxa_break_ctl(struct uart_port *port, int break_state)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	unsigned long flags;

	uart_port_lock_irqsave(&up->port, &flags);
	if (break_state == -1)
		up->lcr |= UART_LCR_SBC;
	else
		up->lcr &= ~UART_LCR_SBC;
	serial_out(up, UART_LCR, up->lcr);
	uart_port_unlock_irqrestore(&up->port, flags);
}

static int serial_pxa_startup(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	unsigned long flags;
	int retval;

	if (port->line == 3) /* HWUART */
		up->mcr |= UART_MCR_AFE;
	else
		up->mcr = 0;

	up->port.uartclk = clk_get_rate(up->clk);

	/*
	 * Allocate the IRQ
	 */
	retval = request_irq(up->port.irq, serial_pxa_irq, 0, up->name, up);
	if (retval)
		return retval;

	/*
	 * Clear the FIFO buffers and disable them.
	 * (they will be reenabled in set_termios())
	 */
	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);

	/*
	 * Clear the interrupt registers.
	 */
	(void) serial_in(up, UART_LSR);
	(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);

	uart_port_lock_irqsave(&up->port, &flags);
	up->port.mctrl |= TIOCM_OUT2;
	serial_pxa_set_mctrl(&up->port, up->port.mctrl);
	uart_port_unlock_irqrestore(&up->port, flags);

	/*
	 * 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 | UART_IER_RTOIE | UART_IER_UUE;
	serial_out(up, UART_IER, up->ier);

	/*
	 * And clear the interrupt registers again for luck.
	 */
	(void) serial_in(up, UART_LSR);
	(void) serial_in(up, UART_RX);
	(void) serial_in(up, UART_IIR);
	(void) serial_in(up, UART_MSR);

	return 0;
}

static void serial_pxa_shutdown(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	unsigned long flags;

	free_irq(up->port.irq, up);

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

	uart_port_lock_irqsave(&up->port, &flags);
	up->port.mctrl &= ~TIOCM_OUT2;
	serial_pxa_set_mctrl(&up->port, up->port.mctrl);
	uart_port_unlock_irqrestore(&up->port, flags);

	/*
	 * Disable break condition and FIFOs
	 */
	serial_out(up, UART_LCR, serial_in(up, UART_LCR) & ~UART_LCR_SBC);
	serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO |
				  UART_FCR_CLEAR_RCVR |
				  UART_FCR_CLEAR_XMIT);
	serial_out(up, UART_FCR, 0);
}

static void
serial_pxa_set_termios(struct uart_port *port, struct ktermios *termios,
		       const struct ktermios *old)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	unsigned char cval, fcr = 0;
	unsigned long flags;
	unsigned int baud, quot;
	unsigned int dll;

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

	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/16);
	quot = uart_get_divisor(port, baud);

	if ((up->port.uartclk / quot) < (2400 * 16))
		fcr = UART_FCR_ENABLE_FIFO | UART_FCR_PXAR1;
	else if ((up->port.uartclk / quot) < (230400 * 16))
		fcr = UART_FCR_ENABLE_FIFO | UART_FCR_PXAR8;
	else
		fcr = UART_FCR_ENABLE_FIFO | UART_FCR_PXAR32;

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

	/*
	 * Ensure the port will be enabled.
	 * This is required especially for serial console.
	 */
	up->ier |= UART_IER_UUE;

	/*
	 * 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 & (IGNBRK | 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;

	/*
	 * CTS flow control flag and 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);

	if (termios->c_cflag & CRTSCTS)
		up->mcr |= UART_MCR_AFE;
	else
		up->mcr &= ~UART_MCR_AFE;

	serial_out(up, UART_LCR, cval | UART_LCR_DLAB);	/* set DLAB */
	serial_out(up, UART_DLL, quot & 0xff);		/* LS of divisor */

	/*
	 * work around Errata #75 according to Intel(R) PXA27x Processor Family
	 * Specification Update (Nov 2005)
	 */
	dll = serial_in(up, UART_DLL);
	WARN_ON(dll != (quot & 0xff));

	serial_out(up, UART_DLM, quot >> 8);		/* MS of divisor */
	serial_out(up, UART_LCR, cval);			/* reset DLAB */
	up->lcr = cval;					/* Save LCR */
	serial_pxa_set_mctrl(&up->port, up->port.mctrl);
	serial_out(up, UART_FCR, fcr);
	uart_port_unlock_irqrestore(&up->port, flags);
}

static void
serial_pxa_pm(struct uart_port *port, unsigned int state,
	      unsigned int oldstate)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

	if (!state)
		clk_prepare_enable(up->clk);
	else
		clk_disable_unprepare(up->clk);
}

static void serial_pxa_release_port(struct uart_port *port)
{
}

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

static void serial_pxa_config_port(struct uart_port *port, int flags)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	up->port.type = PORT_PXA;
}

static int
serial_pxa_verify_port(struct uart_port *port, struct serial_struct *ser)
{
	/* we don't want the core code to modify any port params */
	return -EINVAL;
}

static const char *
serial_pxa_type(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	return up->name;
}

static struct uart_pxa_port *serial_pxa_ports[4];
static struct uart_driver serial_pxa_reg;

#ifdef CONFIG_SERIAL_PXA_CONSOLE

/*
 *	Wait for transmitter & holding register to empty
 */
static void wait_for_xmitr(struct uart_pxa_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 (!uart_lsr_tx_empty(status));

	/* Wait up to 1s for flow control if necessary */
	if (up->port.flags & UPF_CONS_FLOW) {
		tmout = 1000000;
		while (--tmout &&
		       ((serial_in(up, UART_MSR) & UART_MSR_CTS) == 0))
			udelay(1);
	}
}

static void serial_pxa_console_putchar(struct uart_port *port, unsigned char ch)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

	wait_for_xmitr(up);
	serial_out(up, UART_TX, 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
serial_pxa_console_write(struct console *co, const char *s, unsigned int count)
{
	struct uart_pxa_port *up = serial_pxa_ports[co->index];
	unsigned int ier;
	unsigned long flags;
	int locked = 1;

	clk_enable(up->clk);
	local_irq_save(flags);
	if (up->port.sysrq)
		locked = 0;
	else if (oops_in_progress)
		locked = uart_port_trylock(&up->port);
	else
		uart_port_lock(&up->port);

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

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

	/*
	 *	Finally, wait for transmitter to become empty
	 *	and restore the IER
	 */
	wait_for_xmitr(up);
	serial_out(up, UART_IER, ier);

	if (locked)
		uart_port_unlock(&up->port);
	local_irq_restore(flags);
	clk_disable(up->clk);

}

#ifdef CONFIG_CONSOLE_POLL
/*
 * Console polling routines for writing and reading from the uart while
 * in an interrupt or debug context.
 */

static int serial_pxa_get_poll_char(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
	unsigned char lsr = serial_in(up, UART_LSR);

	while (!(lsr & UART_LSR_DR))
		lsr = serial_in(up, UART_LSR);

	return serial_in(up, UART_RX);
}


static void serial_pxa_put_poll_char(struct uart_port *port,
			 unsigned char c)
{
	unsigned int ier;
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

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

	wait_for_xmitr(up);
	/*
	 *	Send the character out.
	 */
	serial_out(up, UART_TX, c);

	/*
	 *	Finally, wait for transmitter to become empty
	 *	and restore the IER
	 */
	wait_for_xmitr(up);
	serial_out(up, UART_IER, ier);
}

#endif /* CONFIG_CONSOLE_POLL */

static int __init
serial_pxa_console_setup(struct console *co, char *options)
{
	struct uart_pxa_port *up;
	int baud = 9600;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	if (co->index == -1 || co->index >= serial_pxa_reg.nr)
		co->index = 0;
	up = serial_pxa_ports[co->index];
	if (!up)
		return -ENODEV;

	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_pxa_console = {
	.name		= "ttyS",
	.write		= serial_pxa_console_write,
	.device		= uart_console_device,
	.setup		= serial_pxa_console_setup,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
	.data		= &serial_pxa_reg,
};

#define PXA_CONSOLE	&serial_pxa_console
#else
#define PXA_CONSOLE	NULL
#endif

static const struct uart_ops serial_pxa_pops = {
	.tx_empty	= serial_pxa_tx_empty,
	.set_mctrl	= serial_pxa_set_mctrl,
	.get_mctrl	= serial_pxa_get_mctrl,
	.stop_tx	= serial_pxa_stop_tx,
	.start_tx	= serial_pxa_start_tx,
	.stop_rx	= serial_pxa_stop_rx,
	.enable_ms	= serial_pxa_enable_ms,
	.break_ctl	= serial_pxa_break_ctl,
	.startup	= serial_pxa_startup,
	.shutdown	= serial_pxa_shutdown,
	.set_termios	= serial_pxa_set_termios,
	.pm		= serial_pxa_pm,
	.type		= serial_pxa_type,
	.release_port	= serial_pxa_release_port,
	.request_port	= serial_pxa_request_port,
	.config_port	= serial_pxa_config_port,
	.verify_port	= serial_pxa_verify_port,
#if defined(CONFIG_CONSOLE_POLL) && defined(CONFIG_SERIAL_PXA_CONSOLE)
	.poll_get_char = serial_pxa_get_poll_char,
	.poll_put_char = serial_pxa_put_poll_char,
#endif
};

static struct uart_driver serial_pxa_reg = {
	.owner		= THIS_MODULE,
	.driver_name	= "PXA serial",
	.dev_name	= "ttyS",
	.major		= TTY_MAJOR,
	.minor		= 64,
	.nr		= 4,
	.cons		= PXA_CONSOLE,
};

#ifdef CONFIG_PM
static int serial_pxa_suspend(struct device *dev)
{
        struct uart_pxa_port *sport = dev_get_drvdata(dev);

        if (sport)
                uart_suspend_port(&serial_pxa_reg, &sport->port);

        return 0;
}

static int serial_pxa_resume(struct device *dev)
{
        struct uart_pxa_port *sport = dev_get_drvdata(dev);

        if (sport)
                uart_resume_port(&serial_pxa_reg, &sport->port);

        return 0;
}

static const struct dev_pm_ops serial_pxa_pm_ops = {
	.suspend	= serial_pxa_suspend,
	.resume		= serial_pxa_resume,
};
#endif

static const struct of_device_id serial_pxa_dt_ids[] = {
	{ .compatible = "mrvl,pxa-uart", },
	{ .compatible = "mrvl,mmp-uart", },
	{}
};

static int serial_pxa_probe_dt(struct platform_device *pdev,
			       struct uart_pxa_port *sport)
{
	struct device_node *np = pdev->dev.of_node;
	int ret;

	if (!np)
		return 1;

	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;
	return 0;
}

static int serial_pxa_probe(struct platform_device *dev)
{
	struct uart_pxa_port *sport;
	struct resource *mmres;
	int ret;
	int irq;

	mmres = platform_get_resource(dev, IORESOURCE_MEM, 0);
	if (!mmres)
		return -ENODEV;

	irq = platform_get_irq(dev, 0);
	if (irq < 0)
		return irq;

	sport = kzalloc(sizeof(struct uart_pxa_port), GFP_KERNEL);
	if (!sport)
		return -ENOMEM;

	sport->clk = clk_get(&dev->dev, NULL);
	if (IS_ERR(sport->clk)) {
		ret = PTR_ERR(sport->clk);
		goto err_free;
	}

	ret = clk_prepare(sport->clk);
	if (ret) {
		clk_put(sport->clk);
		goto err_free;
	}

	sport->port.type = PORT_PXA;
	sport->port.iotype = UPIO_MEM;
	sport->port.mapbase = mmres->start;
	sport->port.irq = irq;
	sport->port.fifosize = 64;
	sport->port.ops = &serial_pxa_pops;
	sport->port.dev = &dev->dev;
	sport->port.flags = UPF_IOREMAP | UPF_BOOT_AUTOCONF;
	sport->port.uartclk = clk_get_rate(sport->clk);
	sport->port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_PXA_CONSOLE);

	ret = serial_pxa_probe_dt(dev, sport);
	if (ret > 0)
		sport->port.line = dev->id;
	else if (ret < 0)
		goto err_clk;
	if (sport->port.line >= ARRAY_SIZE(serial_pxa_ports)) {
		dev_err(&dev->dev, "serial%d out of range\n", sport->port.line);
		ret = -EINVAL;
		goto err_clk;
	}
	snprintf(sport->name, PXA_NAME_LEN - 1, "UART%d", sport->port.line + 1);

	sport->port.membase = ioremap(mmres->start, resource_size(mmres));
	if (!sport->port.membase) {
		ret = -ENOMEM;
		goto err_clk;
	}

	serial_pxa_ports[sport->port.line] = sport;

	uart_add_one_port(&serial_pxa_reg, &sport->port);
	platform_set_drvdata(dev, sport);

	return 0;

 err_clk:
	clk_unprepare(sport->clk);
	clk_put(sport->clk);
 err_free:
	kfree(sport);
	return ret;
}

static struct platform_driver serial_pxa_driver = {
        .probe          = serial_pxa_probe,

	.driver		= {
	        .name	= "pxa2xx-uart",
#ifdef CONFIG_PM
		.pm	= &serial_pxa_pm_ops,
#endif
		.suppress_bind_attrs = true,
		.of_match_table = serial_pxa_dt_ids,
	},
};


/* 8250 driver for PXA serial ports should be used */
static int __init serial_pxa_init(void)
{
	int ret;

	ret = uart_register_driver(&serial_pxa_reg);
	if (ret != 0)
		return ret;

	ret = platform_driver_register(&serial_pxa_driver);
	if (ret != 0)
		uart_unregister_driver(&serial_pxa_reg);

	return ret;
}
device_initcall(serial_pxa_init);