linux/drivers/tty/serial/efm32-uart.c

#if defined(CONFIG_SERIAL_EFM32_UART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/serial_core.h>
#include <linux/tty_flip.h>
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/of.h>
#include <linux/of_device.h>

#include <linux/platform_data/efm32-uart.h>

#define DRIVER_NAME "efm32-uart"
#define DEV_NAME "ttyefm"

#define UARTn_CTRL		0x00
#define UARTn_CTRL_SYNC		0x0001
#define UARTn_CTRL_TXBIL		0x1000

#define UARTn_FRAME		0x04
#define UARTn_FRAME_DATABITS__MASK	0x000f
#define UARTn_FRAME_DATABITS(n)		((n) - 3)
#define UARTn_FRAME_PARITY__MASK	0x0300
#define UARTn_FRAME_PARITY_NONE		0x0000
#define UARTn_FRAME_PARITY_EVEN		0x0200
#define UARTn_FRAME_PARITY_ODD		0x0300
#define UARTn_FRAME_STOPBITS_HALF	0x0000
#define UARTn_FRAME_STOPBITS_ONE	0x1000
#define UARTn_FRAME_STOPBITS_TWO	0x3000

#define UARTn_CMD		0x0c
#define UARTn_CMD_RXEN			0x0001
#define UARTn_CMD_RXDIS		0x0002
#define UARTn_CMD_TXEN			0x0004
#define UARTn_CMD_TXDIS		0x0008

#define UARTn_STATUS		0x10
#define UARTn_STATUS_TXENS		0x0002
#define UARTn_STATUS_TXC		0x0020
#define UARTn_STATUS_TXBL		0x0040
#define UARTn_STATUS_RXDATAV		0x0080

#define UARTn_CLKDIV		0x14

#define UARTn_RXDATAX		0x18
#define UARTn_RXDATAX_RXDATA__MASK	0x01ff
#define UARTn_RXDATAX_PERR		0x4000
#define UARTn_RXDATAX_FERR		0x8000
/*
 * This is a software only flag used for ignore_status_mask and
 * read_status_mask! It's used for breaks that the hardware doesn't report
 * explicitly.
 */
#define SW_UARTn_RXDATAX_BERR		0x2000

#define UARTn_TXDATA		0x34

#define UARTn_IF		0x40
#define UARTn_IF_TXC			0x0001
#define UARTn_IF_TXBL			0x0002
#define UARTn_IF_RXDATAV		0x0004
#define UARTn_IF_RXOF			0x0010

#define UARTn_IFS		0x44
#define UARTn_IFC		0x48
#define UARTn_IEN		0x4c

#define UARTn_ROUTE		0x54
#define UARTn_ROUTE_LOCATION__MASK	0x0700
#define UARTn_ROUTE_LOCATION(n)		(((n) << 8) & UARTn_ROUTE_LOCATION__MASK)
#define UARTn_ROUTE_RXPEN		0x0001
#define UARTn_ROUTE_TXPEN		0x0002

struct efm32_uart_port {
	struct uart_port port;
	unsigned int txirq;
	struct clk *clk;
	struct efm32_uart_pdata pdata;
};
#define to_efm_port(_port) container_of(_port, struct efm32_uart_port, port)
#define efm_debug(efm_port, format, arg...)			\
	dev_dbg(efm_port->port.dev, format, ##arg)

static void efm32_uart_write32(struct efm32_uart_port *efm_port,
		u32 value, unsigned offset)
{
	writel_relaxed(value, efm_port->port.membase + offset);
}

static u32 efm32_uart_read32(struct efm32_uart_port *efm_port,
		unsigned offset)
{
	return readl_relaxed(efm_port->port.membase + offset);
}

static unsigned int efm32_uart_tx_empty(struct uart_port *port)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);
	u32 status = efm32_uart_read32(efm_port, UARTn_STATUS);

	if (status & UARTn_STATUS_TXC)
		return TIOCSER_TEMT;
	else
		return 0;
}

static void efm32_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	/* sorry, neither handshaking lines nor loop functionallity */
}

static unsigned int efm32_uart_get_mctrl(struct uart_port *port)
{
	/* sorry, no handshaking lines available */
	return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR;
}

static void efm32_uart_stop_tx(struct uart_port *port)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);
	u32 ien = efm32_uart_read32(efm_port,  UARTn_IEN);

	efm32_uart_write32(efm_port, UARTn_CMD_TXDIS, UARTn_CMD);
	ien &= ~(UARTn_IF_TXC | UARTn_IF_TXBL);
	efm32_uart_write32(efm_port, ien, UARTn_IEN);
}

static void efm32_uart_tx_chars(struct efm32_uart_port *efm_port)
{
	struct uart_port *port = &efm_port->port;
	struct circ_buf *xmit = &port->state->xmit;

	while (efm32_uart_read32(efm_port, UARTn_STATUS) &
			UARTn_STATUS_TXBL) {
		if (port->x_char) {
			port->icount.tx++;
			efm32_uart_write32(efm_port, port->x_char,
					UARTn_TXDATA);
			port->x_char = 0;
			continue;
		}
		if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) {
			port->icount.tx++;
			efm32_uart_write32(efm_port, xmit->buf[xmit->tail],
					UARTn_TXDATA);
			xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		} else
			break;
	}

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

	if (!port->x_char && uart_circ_empty(xmit) &&
			efm32_uart_read32(efm_port, UARTn_STATUS) &
				UARTn_STATUS_TXC)
		efm32_uart_stop_tx(port);
}

static void efm32_uart_start_tx(struct uart_port *port)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);
	u32 ien;

	efm32_uart_write32(efm_port,
			UARTn_IF_TXBL | UARTn_IF_TXC, UARTn_IFC);
	ien = efm32_uart_read32(efm_port, UARTn_IEN);
	efm32_uart_write32(efm_port,
			ien | UARTn_IF_TXBL | UARTn_IF_TXC, UARTn_IEN);
	efm32_uart_write32(efm_port, UARTn_CMD_TXEN, UARTn_CMD);

	efm32_uart_tx_chars(efm_port);
}

static void efm32_uart_stop_rx(struct uart_port *port)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);

	efm32_uart_write32(efm_port, UARTn_CMD_RXDIS, UARTn_CMD);
}

static void efm32_uart_break_ctl(struct uart_port *port, int ctl)
{
	/* not possible without fiddling with gpios */
}

static void efm32_uart_rx_chars(struct efm32_uart_port *efm_port)
{
	struct uart_port *port = &efm_port->port;

	while (efm32_uart_read32(efm_port, UARTn_STATUS) &
			UARTn_STATUS_RXDATAV) {
		u32 rxdata = efm32_uart_read32(efm_port, UARTn_RXDATAX);
		int flag = 0;

		/*
		 * This is a reserved bit and I only saw it read as 0. But to be
		 * sure not to be confused too much by new devices adhere to the
		 * warning in the reference manual that reserverd bits might
		 * read as 1 in the future.
		 */
		rxdata &= ~SW_UARTn_RXDATAX_BERR;

		port->icount.rx++;

		if ((rxdata & UARTn_RXDATAX_FERR) &&
				!(rxdata & UARTn_RXDATAX_RXDATA__MASK)) {
			rxdata |= SW_UARTn_RXDATAX_BERR;
			port->icount.brk++;
			if (uart_handle_break(port))
				continue;
		} else if (rxdata & UARTn_RXDATAX_PERR)
			port->icount.parity++;
		else if (rxdata & UARTn_RXDATAX_FERR)
			port->icount.frame++;

		rxdata &= port->read_status_mask;

		if (rxdata & SW_UARTn_RXDATAX_BERR)
			flag = TTY_BREAK;
		else if (rxdata & UARTn_RXDATAX_PERR)
			flag = TTY_PARITY;
		else if (rxdata & UARTn_RXDATAX_FERR)
			flag = TTY_FRAME;
		else if (uart_handle_sysrq_char(port,
					rxdata & UARTn_RXDATAX_RXDATA__MASK))
			continue;

		if ((rxdata & port->ignore_status_mask) == 0)
			tty_insert_flip_char(&port->state->port,
					rxdata & UARTn_RXDATAX_RXDATA__MASK, flag);
	}
}

static irqreturn_t efm32_uart_rxirq(int irq, void *data)
{
	struct efm32_uart_port *efm_port = data;
	u32 irqflag = efm32_uart_read32(efm_port, UARTn_IF);
	int handled = IRQ_NONE;
	struct uart_port *port = &efm_port->port;
	struct tty_port *tport = &port->state->port;

	spin_lock(&port->lock);

	if (irqflag & UARTn_IF_RXDATAV) {
		efm32_uart_write32(efm_port, UARTn_IF_RXDATAV, UARTn_IFC);
		efm32_uart_rx_chars(efm_port);

		handled = IRQ_HANDLED;
	}

	if (irqflag & UARTn_IF_RXOF) {
		efm32_uart_write32(efm_port, UARTn_IF_RXOF, UARTn_IFC);
		port->icount.overrun++;
		tty_insert_flip_char(tport, 0, TTY_OVERRUN);

		handled = IRQ_HANDLED;
	}

	spin_unlock(&port->lock);

	tty_flip_buffer_push(tport);

	return handled;
}

static irqreturn_t efm32_uart_txirq(int irq, void *data)
{
	struct efm32_uart_port *efm_port = data;
	u32 irqflag = efm32_uart_read32(efm_port, UARTn_IF);

	/* TXBL doesn't need to be cleared */
	if (irqflag & UARTn_IF_TXC)
		efm32_uart_write32(efm_port, UARTn_IF_TXC, UARTn_IFC);

	if (irqflag & (UARTn_IF_TXC | UARTn_IF_TXBL)) {
		efm32_uart_tx_chars(efm_port);
		return IRQ_HANDLED;
	} else
		return IRQ_NONE;
}

static int efm32_uart_startup(struct uart_port *port)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);
	int ret;

	ret = clk_enable(efm_port->clk);
	if (ret) {
		efm_debug(efm_port, "failed to enable clk\n");
		goto err_clk_enable;
	}
	port->uartclk = clk_get_rate(efm_port->clk);

	/* Enable pins at configured location */
	efm32_uart_write32(efm_port,
			UARTn_ROUTE_LOCATION(efm_port->pdata.location) |
			UARTn_ROUTE_RXPEN | UARTn_ROUTE_TXPEN,
			UARTn_ROUTE);

	ret = request_irq(port->irq, efm32_uart_rxirq, 0,
			DRIVER_NAME, efm_port);
	if (ret) {
		efm_debug(efm_port, "failed to register rxirq\n");
		goto err_request_irq_rx;
	}

	/* disable all irqs */
	efm32_uart_write32(efm_port, 0, UARTn_IEN);

	ret = request_irq(efm_port->txirq, efm32_uart_txirq, 0,
			DRIVER_NAME, efm_port);
	if (ret) {
		efm_debug(efm_port, "failed to register txirq\n");
		free_irq(port->irq, efm_port);
err_request_irq_rx:

		clk_disable(efm_port->clk);
	} else {
		efm32_uart_write32(efm_port,
				UARTn_IF_RXDATAV | UARTn_IF_RXOF, UARTn_IEN);
		efm32_uart_write32(efm_port, UARTn_CMD_RXEN, UARTn_CMD);
	}

err_clk_enable:
	return ret;
}

static void efm32_uart_shutdown(struct uart_port *port)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);

	efm32_uart_write32(efm_port, 0, UARTn_IEN);
	free_irq(port->irq, efm_port);

	clk_disable(efm_port->clk);
}

static void efm32_uart_set_termios(struct uart_port *port,
		struct ktermios *new, struct ktermios *old)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);
	unsigned long flags;
	unsigned baud;
	u32 clkdiv;
	u32 frame = 0;

	/* no modem control lines */
	new->c_cflag &= ~(CRTSCTS | CMSPAR);

	baud = uart_get_baud_rate(port, new, old,
			DIV_ROUND_CLOSEST(port->uartclk, 16 * 8192),
			DIV_ROUND_CLOSEST(port->uartclk, 16));

	switch (new->c_cflag & CSIZE) {
	case CS5:
		frame |= UARTn_FRAME_DATABITS(5);
		break;
	case CS6:
		frame |= UARTn_FRAME_DATABITS(6);
		break;
	case CS7:
		frame |= UARTn_FRAME_DATABITS(7);
		break;
	case CS8:
		frame |= UARTn_FRAME_DATABITS(8);
		break;
	}

	if (new->c_cflag & CSTOPB)
		/* the receiver only verifies the first stop bit */
		frame |= UARTn_FRAME_STOPBITS_TWO;
	else
		frame |= UARTn_FRAME_STOPBITS_ONE;

	if (new->c_cflag & PARENB) {
		if (new->c_cflag & PARODD)
			frame |= UARTn_FRAME_PARITY_ODD;
		else
			frame |= UARTn_FRAME_PARITY_EVEN;
	} else
		frame |= UARTn_FRAME_PARITY_NONE;

	/*
	 * the 6 lowest bits of CLKDIV are dc, bit 6 has value 0.25.
	 * port->uartclk <= 14e6, so 4 * port->uartclk doesn't overflow.
	 */
	clkdiv = (DIV_ROUND_CLOSEST(4 * port->uartclk, 16 * baud) - 4) << 6;

	spin_lock_irqsave(&port->lock, flags);

	efm32_uart_write32(efm_port,
			UARTn_CMD_TXDIS | UARTn_CMD_RXDIS, UARTn_CMD);

	port->read_status_mask = UARTn_RXDATAX_RXDATA__MASK;
	if (new->c_iflag & INPCK)
		port->read_status_mask |=
			UARTn_RXDATAX_FERR | UARTn_RXDATAX_PERR;
	if (new->c_iflag & (IGNBRK | BRKINT | PARMRK))
		port->read_status_mask |= SW_UARTn_RXDATAX_BERR;

	port->ignore_status_mask = 0;
	if (new->c_iflag & IGNPAR)
		port->ignore_status_mask |=
			UARTn_RXDATAX_FERR | UARTn_RXDATAX_PERR;
	if (new->c_iflag & IGNBRK)
		port->ignore_status_mask |= SW_UARTn_RXDATAX_BERR;

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

	efm32_uart_write32(efm_port, UARTn_CTRL_TXBIL, UARTn_CTRL);
	efm32_uart_write32(efm_port, frame, UARTn_FRAME);
	efm32_uart_write32(efm_port, clkdiv, UARTn_CLKDIV);

	efm32_uart_write32(efm_port, UARTn_CMD_TXEN | UARTn_CMD_RXEN,
			UARTn_CMD);

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

static const char *efm32_uart_type(struct uart_port *port)
{
	return port->type == PORT_EFMUART ? "efm32-uart" : NULL;
}

static void efm32_uart_release_port(struct uart_port *port)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);

	clk_unprepare(efm_port->clk);
	clk_put(efm_port->clk);
	iounmap(port->membase);
}

static int efm32_uart_request_port(struct uart_port *port)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);
	int ret;

	port->membase = ioremap(port->mapbase, 60);
	if (!efm_port->port.membase) {
		ret = -ENOMEM;
		efm_debug(efm_port, "failed to remap\n");
		goto err_ioremap;
	}

	efm_port->clk = clk_get(port->dev, NULL);
	if (IS_ERR(efm_port->clk)) {
		ret = PTR_ERR(efm_port->clk);
		efm_debug(efm_port, "failed to get clock\n");
		goto err_clk_get;
	}

	ret = clk_prepare(efm_port->clk);
	if (ret) {
		clk_put(efm_port->clk);
err_clk_get:

		iounmap(port->membase);
err_ioremap:
		return ret;
	}
	return 0;
}

static void efm32_uart_config_port(struct uart_port *port, int type)
{
	if (type & UART_CONFIG_TYPE &&
			!efm32_uart_request_port(port))
		port->type = PORT_EFMUART;
}

static int efm32_uart_verify_port(struct uart_port *port,
		struct serial_struct *serinfo)
{
	int ret = 0;

	if (serinfo->type != PORT_UNKNOWN && serinfo->type != PORT_EFMUART)
		ret = -EINVAL;

	return ret;
}

static const struct uart_ops efm32_uart_pops = {
	.tx_empty = efm32_uart_tx_empty,
	.set_mctrl = efm32_uart_set_mctrl,
	.get_mctrl = efm32_uart_get_mctrl,
	.stop_tx = efm32_uart_stop_tx,
	.start_tx = efm32_uart_start_tx,
	.stop_rx = efm32_uart_stop_rx,
	.break_ctl = efm32_uart_break_ctl,
	.startup = efm32_uart_startup,
	.shutdown = efm32_uart_shutdown,
	.set_termios = efm32_uart_set_termios,
	.type = efm32_uart_type,
	.release_port = efm32_uart_release_port,
	.request_port = efm32_uart_request_port,
	.config_port = efm32_uart_config_port,
	.verify_port = efm32_uart_verify_port,
};

static struct efm32_uart_port *efm32_uart_ports[5];

#ifdef CONFIG_SERIAL_EFM32_UART_CONSOLE
static void efm32_uart_console_putchar(struct uart_port *port, int ch)
{
	struct efm32_uart_port *efm_port = to_efm_port(port);
	unsigned int timeout = 0x400;
	u32 status;

	while (1) {
		status = efm32_uart_read32(efm_port, UARTn_STATUS);

		if (status & UARTn_STATUS_TXBL)
			break;
		if (!timeout--)
			return;
	}
	efm32_uart_write32(efm_port, ch, UARTn_TXDATA);
}

static void efm32_uart_console_write(struct console *co, const char *s,
		unsigned int count)
{
	struct efm32_uart_port *efm_port = efm32_uart_ports[co->index];
	u32 status = efm32_uart_read32(efm_port, UARTn_STATUS);
	unsigned int timeout = 0x400;

	if (!(status & UARTn_STATUS_TXENS))
		efm32_uart_write32(efm_port, UARTn_CMD_TXEN, UARTn_CMD);

	uart_console_write(&efm_port->port, s, count,
			efm32_uart_console_putchar);

	/* Wait for the transmitter to become empty */
	while (1) {
		u32 status = efm32_uart_read32(efm_port, UARTn_STATUS);
		if (status & UARTn_STATUS_TXC)
			break;
		if (!timeout--)
			break;
	}

	if (!(status & UARTn_STATUS_TXENS))
		efm32_uart_write32(efm_port, UARTn_CMD_TXDIS, UARTn_CMD);
}

static void efm32_uart_console_get_options(struct efm32_uart_port *efm_port,
		int *baud, int *parity, int *bits)
{
	u32 ctrl = efm32_uart_read32(efm_port, UARTn_CTRL);
	u32 route, clkdiv, frame;

	if (ctrl & UARTn_CTRL_SYNC)
		/* not operating in async mode */
		return;

	route = efm32_uart_read32(efm_port, UARTn_ROUTE);
	if (!(route & UARTn_ROUTE_TXPEN))
		/* tx pin not routed */
		return;

	clkdiv = efm32_uart_read32(efm_port, UARTn_CLKDIV);

	*baud = DIV_ROUND_CLOSEST(4 * efm_port->port.uartclk,
			16 * (4 + (clkdiv >> 6)));

	frame = efm32_uart_read32(efm_port, UARTn_FRAME);
	switch (frame & UARTn_FRAME_PARITY__MASK) {
	case UARTn_FRAME_PARITY_ODD:
		*parity = 'o';
		break;
	case UARTn_FRAME_PARITY_EVEN:
		*parity = 'e';
		break;
	default:
		*parity = 'n';
	}

	*bits = (frame & UARTn_FRAME_DATABITS__MASK) -
			UARTn_FRAME_DATABITS(4) + 4;

	efm_debug(efm_port, "get_opts: options=%d%c%d\n",
			*baud, *parity, *bits);
}

static int efm32_uart_console_setup(struct console *co, char *options)
{
	struct efm32_uart_port *efm_port;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';
	int ret;

	if (co->index < 0 || co->index >= ARRAY_SIZE(efm32_uart_ports)) {
		unsigned i;
		for (i = 0; i < ARRAY_SIZE(efm32_uart_ports); ++i) {
			if (efm32_uart_ports[i]) {
				pr_warn("efm32-console: fall back to console index %u (from %hhi)\n",
						i, co->index);
				co->index = i;
				break;
			}
		}
	}

	efm_port = efm32_uart_ports[co->index];
	if (!efm_port) {
		pr_warn("efm32-console: No port at %d\n", co->index);
		return -ENODEV;
	}

	ret = clk_prepare(efm_port->clk);
	if (ret) {
		dev_warn(efm_port->port.dev,
				"console: clk_prepare failed: %d\n", ret);
		return ret;
	}

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

	if (options)
		uart_parse_options(options, &baud, &parity, &bits, &flow);
	else
		efm32_uart_console_get_options(efm_port,
				&baud, &parity, &bits);

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

static struct uart_driver efm32_uart_reg;

static struct console efm32_uart_console = {
	.name = DEV_NAME,
	.write = efm32_uart_console_write,
	.device = uart_console_device,
	.setup = efm32_uart_console_setup,
	.flags = CON_PRINTBUFFER,
	.index = -1,
	.data = &efm32_uart_reg,
};

#else
#define efm32_uart_console (*(struct console *)NULL)
#endif /* ifdef CONFIG_SERIAL_EFM32_UART_CONSOLE / else */

static struct uart_driver efm32_uart_reg = {
	.owner = THIS_MODULE,
	.driver_name = DRIVER_NAME,
	.dev_name = DEV_NAME,
	.nr = ARRAY_SIZE(efm32_uart_ports),
	.cons = &efm32_uart_console,
};

static int efm32_uart_probe_dt(struct platform_device *pdev,
		struct efm32_uart_port *efm_port)
{
	struct device_node *np = pdev->dev.of_node;
	u32 location;
	int ret;

	if (!np)
		return 1;

	ret = of_property_read_u32(np, "energymicro,location", &location);

	if (ret)
		/* fall back to wrongly namespaced property */
		ret = of_property_read_u32(np, "efm32,location", &location);

	if (ret)
		/* fall back to old and (wrongly) generic property "location" */
		ret = of_property_read_u32(np, "location", &location);

	if (!ret) {
		if (location > 5) {
			dev_err(&pdev->dev, "invalid location\n");
			return -EINVAL;
		}
		efm_debug(efm_port, "using location %u\n", location);
		efm_port->pdata.location = location;
	} else {
		efm_debug(efm_port, "fall back to location 0\n");
	}

	ret = of_alias_get_id(np, "serial");
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to get alias id: %d\n", ret);
		return ret;
	} else {
		efm_port->port.line = ret;
		return 0;
	}

}

static int efm32_uart_probe(struct platform_device *pdev)
{
	struct efm32_uart_port *efm_port;
	struct resource *res;
	unsigned int line;
	int ret;

	efm_port = kzalloc(sizeof(*efm_port), GFP_KERNEL);
	if (!efm_port) {
		dev_dbg(&pdev->dev, "failed to allocate private data\n");
		return -ENOMEM;
	}

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
		ret = -ENODEV;
		dev_dbg(&pdev->dev, "failed to determine base address\n");
		goto err_get_base;
	}

	if (resource_size(res) < 60) {
		ret = -EINVAL;
		dev_dbg(&pdev->dev, "memory resource too small\n");
		goto err_too_small;
	}

	ret = platform_get_irq(pdev, 0);
	if (ret <= 0) {
		dev_dbg(&pdev->dev, "failed to get rx irq\n");
		goto err_get_rxirq;
	}

	efm_port->port.irq = ret;

	ret = platform_get_irq(pdev, 1);
	if (ret <= 0)
		ret = efm_port->port.irq + 1;

	efm_port->txirq = ret;

	efm_port->port.dev = &pdev->dev;
	efm_port->port.mapbase = res->start;
	efm_port->port.type = PORT_EFMUART;
	efm_port->port.iotype = UPIO_MEM32;
	efm_port->port.fifosize = 2;
	efm_port->port.ops = &efm32_uart_pops;
	efm_port->port.flags = UPF_BOOT_AUTOCONF;

	ret = efm32_uart_probe_dt(pdev, efm_port);
	if (ret > 0) {
		/* not created by device tree */
		const struct efm32_uart_pdata *pdata = dev_get_platdata(&pdev->dev);

		efm_port->port.line = pdev->id;

		if (pdata)
			efm_port->pdata = *pdata;
	} else if (ret < 0)
		goto err_probe_dt;

	line = efm_port->port.line;

	if (line >= 0 && line < ARRAY_SIZE(efm32_uart_ports))
		efm32_uart_ports[line] = efm_port;

	ret = uart_add_one_port(&efm32_uart_reg, &efm_port->port);
	if (ret) {
		dev_dbg(&pdev->dev, "failed to add port: %d\n", ret);

		if (line >= 0 && line < ARRAY_SIZE(efm32_uart_ports))
			efm32_uart_ports[line] = NULL;
err_probe_dt:
err_get_rxirq:
err_too_small:
err_get_base:
		kfree(efm_port);
	} else {
		platform_set_drvdata(pdev, efm_port);
		dev_dbg(&pdev->dev, "\\o/\n");
	}

	return ret;
}

static int efm32_uart_remove(struct platform_device *pdev)
{
	struct efm32_uart_port *efm_port = platform_get_drvdata(pdev);
	unsigned int line = efm_port->port.line;

	uart_remove_one_port(&efm32_uart_reg, &efm_port->port);

	if (line >= 0 && line < ARRAY_SIZE(efm32_uart_ports))
		efm32_uart_ports[line] = NULL;

	kfree(efm_port);

	return 0;
}

static const struct of_device_id efm32_uart_dt_ids[] = {
	{
		.compatible = "energymicro,efm32-uart",
	}, {
		/* doesn't follow the "vendor,device" scheme, don't use */
		.compatible = "efm32,uart",
	}, {
		/* sentinel */
	}
};
MODULE_DEVICE_TABLE(of, efm32_uart_dt_ids);

static struct platform_driver efm32_uart_driver = {
	.probe = efm32_uart_probe,
	.remove = efm32_uart_remove,

	.driver = {
		.name = DRIVER_NAME,
		.of_match_table = efm32_uart_dt_ids,
	},
};

static int __init efm32_uart_init(void)
{
	int ret;

	ret = uart_register_driver(&efm32_uart_reg);
	if (ret)
		return ret;

	ret = platform_driver_register(&efm32_uart_driver);
	if (ret)
		uart_unregister_driver(&efm32_uart_reg);

	pr_info("EFM32 UART/USART driver\n");

	return ret;
}
module_init(efm32_uart_init);

static void __exit efm32_uart_exit(void)
{
	platform_driver_unregister(&efm32_uart_driver);
	uart_unregister_driver(&efm32_uart_reg);
}
module_exit(efm32_uart_exit);

MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>");
MODULE_DESCRIPTION("EFM32 UART/USART driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);