atmel_serial.c

	quot = uart_get_divisor(port, baud);

	if (quot > 65535) {	/* BRGR is 16-bit, so switch to slower clock */
		quot /= 8;
		mode |= ATMEL_US_USCLKS_MCK_DIV8;
	}

	/* byte size */
	switch (termios->c_cflag & CSIZE) {
	case CS5:
		mode |= ATMEL_US_CHRL_5;
		break;
	case CS6:
		mode |= ATMEL_US_CHRL_6;
		break;
	case CS7:
		mode |= ATMEL_US_CHRL_7;
		break;
	default:
		mode |= ATMEL_US_CHRL_8;
		break;
	}

	/* stop bits */
	if (termios->c_cflag & CSTOPB)
		mode |= ATMEL_US_NBSTOP_2;

	/* parity */
	if (termios->c_cflag & PARENB) {
		/* Mark or Space parity */
		if (termios->c_cflag & CMSPAR) {
			if (termios->c_cflag & PARODD)
				mode |= ATMEL_US_PAR_MARK;
			else
				mode |= ATMEL_US_PAR_SPACE;
		} else if (termios->c_cflag & PARODD)
			mode |= ATMEL_US_PAR_ODD;
		else
			mode |= ATMEL_US_PAR_EVEN;
	} else
		mode |= ATMEL_US_PAR_NONE;

	spin_lock_irqsave(&port->lock, flags);

	port->read_status_mask = ATMEL_US_OVRE;
	if (termios->c_iflag & INPCK)
		port->read_status_mask |= (ATMEL_US_FRAME | ATMEL_US_PARE);
	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
		port->read_status_mask |= ATMEL_US_RXBRK;

	if (atmel_use_pdc_rx(port))
		/* need to enable error interrupts */
		atmel_uart_writel(port, ATMEL_US_IER, port->read_status_mask);

	/*
	 * Characters to ignore
	 */
	port->ignore_status_mask = 0;
	if (termios->c_iflag & IGNPAR)
		port->ignore_status_mask |= (ATMEL_US_FRAME | ATMEL_US_PARE);
	if (termios->c_iflag & IGNBRK) {
		port->ignore_status_mask |= ATMEL_US_RXBRK;
		/*
		 * If we're ignoring parity and break indicators,
		 * ignore overruns too (for real raw support).
		 */
		if (termios->c_iflag & IGNPAR)
			port->ignore_status_mask |= ATMEL_US_OVRE;
	}
	/* TODO: Ignore all characters if CREAD is set.*/

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

	/*
	 * save/disable interrupts. The tty layer will ensure that the
	 * transmitter is empty if requested by the caller, so there's
	 * no need to wait for it here.
	 */
	imr = atmel_uart_readl(port, ATMEL_US_IMR);
	atmel_uart_writel(port, ATMEL_US_IDR, -1);

	/* disable receiver and transmitter */
	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXDIS | ATMEL_US_RXDIS);

	/* mode */
	if (port->rs485.flags & SER_RS485_ENABLED) {
		atmel_uart_writel(port, ATMEL_US_TTGR,
				  port->rs485.delay_rts_after_send);
		mode |= ATMEL_US_USMODE_RS485;
	} else if (termios->c_cflag & CRTSCTS) {
		/* RS232 with hardware handshake (RTS/CTS) */
		mode |= ATMEL_US_USMODE_HWHS;
	} else {
		/* RS232 without hadware handshake */
		mode |= ATMEL_US_USMODE_NORMAL;
	}

	/* set the mode, clock divisor, parity, stop bits and data size */
	atmel_uart_writel(port, ATMEL_US_MR, mode);

	/*
	 * when switching the mode, set the RTS line state according to the
	 * new mode, otherwise keep the former state
	 */
	if ((old_mode & ATMEL_US_USMODE) != (mode & ATMEL_US_USMODE)) {
		unsigned int rts_state;

		if ((mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_HWHS) {
			/* let the hardware control the RTS line */
			rts_state = ATMEL_US_RTSDIS;
		} else {
			/* force RTS line to low level */
			rts_state = ATMEL_US_RTSEN;
		}

		atmel_uart_writel(port, ATMEL_US_CR, rts_state);
	}

	/* set the baud rate */
	atmel_uart_writel(port, ATMEL_US_BRGR, quot);
	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);

	/* restore interrupts */
	atmel_uart_writel(port, ATMEL_US_IER, imr);

	/* CTS flow-control and modem-status interrupts */
	if (UART_ENABLE_MS(port, termios->c_cflag))
		atmel_enable_ms(port);
	else
		atmel_disable_ms(port);

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

static void atmel_set_ldisc(struct uart_port *port, struct ktermios *termios)
{
	if (termios->c_line == N_PPS) {
		port->flags |= UPF_HARDPPS_CD;
		spin_lock_irq(&port->lock);
		atmel_enable_ms(port);
		spin_unlock_irq(&port->lock);
	} else {
		port->flags &= ~UPF_HARDPPS_CD;
		if (!UART_ENABLE_MS(port, termios->c_cflag)) {
			spin_lock_irq(&port->lock);
			atmel_disable_ms(port);
			spin_unlock_irq(&port->lock);
		}
	}
}

/*
 * Return string describing the specified port
 */
static const char *atmel_type(struct uart_port *port)
{
	return (port->type == PORT_ATMEL) ? "ATMEL_SERIAL" : NULL;
}

/*
 * Release the memory region(s) being used by 'port'.
 */
static void atmel_release_port(struct uart_port *port)
{
	struct platform_device *pdev = to_platform_device(port->dev);
	int size = pdev->resource[0].end - pdev->resource[0].start + 1;

	release_mem_region(port->mapbase, size);

	if (port->flags & UPF_IOREMAP) {
		iounmap(port->membase);
		port->membase = NULL;
	}
}

/*
 * Request the memory region(s) being used by 'port'.
 */
static int atmel_request_port(struct uart_port *port)
{
	struct platform_device *pdev = to_platform_device(port->dev);
	int size = pdev->resource[0].end - pdev->resource[0].start + 1;

	if (!request_mem_region(port->mapbase, size, "atmel_serial"))
		return -EBUSY;

	if (port->flags & UPF_IOREMAP) {
		port->membase = ioremap(port->mapbase, size);
		if (port->membase == NULL) {
			release_mem_region(port->mapbase, size);
			return -ENOMEM;
		}
	}

	return 0;
}

/*
 * Configure/autoconfigure the port.
 */
static void atmel_config_port(struct uart_port *port, int flags)
{
	if (flags & UART_CONFIG_TYPE) {
		port->type = PORT_ATMEL;
		atmel_request_port(port);
	}
}

/*
 * Verify the new serial_struct (for TIOCSSERIAL).
 */
static int atmel_verify_port(struct uart_port *port, struct serial_struct *ser)
{
	int ret = 0;
	if (ser->type != PORT_UNKNOWN && ser->type != PORT_ATMEL)
		ret = -EINVAL;
	if (port->irq != ser->irq)
		ret = -EINVAL;
	if (ser->io_type != SERIAL_IO_MEM)
		ret = -EINVAL;
	if (port->uartclk / 16 != ser->baud_base)
		ret = -EINVAL;
	if (port->mapbase != (unsigned long)ser->iomem_base)
		ret = -EINVAL;
	if (port->iobase != ser->port)
		ret = -EINVAL;
	if (ser->hub6 != 0)
		ret = -EINVAL;
	return ret;
}

#ifdef CONFIG_CONSOLE_POLL
static int atmel_poll_get_char(struct uart_port *port)
{
	while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_RXRDY))
		cpu_relax();

	return atmel_uart_read_char(port);
}

static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
{
	while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY))
		cpu_relax();

	atmel_uart_write_char(port, ch);
}
#endif

static struct uart_ops atmel_pops = {
	.tx_empty	= atmel_tx_empty,
	.set_mctrl	= atmel_set_mctrl,
	.get_mctrl	= atmel_get_mctrl,
	.stop_tx	= atmel_stop_tx,
	.start_tx	= atmel_start_tx,
	.stop_rx	= atmel_stop_rx,
	.enable_ms	= atmel_enable_ms,
	.break_ctl	= atmel_break_ctl,
	.startup	= atmel_startup,
	.shutdown	= atmel_shutdown,
	.flush_buffer	= atmel_flush_buffer,
	.set_termios	= atmel_set_termios,
	.set_ldisc	= atmel_set_ldisc,
	.type		= atmel_type,
	.release_port	= atmel_release_port,
	.request_port	= atmel_request_port,
	.config_port	= atmel_config_port,
	.verify_port	= atmel_verify_port,
	.pm		= atmel_serial_pm,
#ifdef CONFIG_CONSOLE_POLL
	.poll_get_char	= atmel_poll_get_char,
	.poll_put_char	= atmel_poll_put_char,
#endif
};

/*
 * Configure the port from the platform device resource info.
 */
static int atmel_init_port(struct atmel_uart_port *atmel_port,
				      struct platform_device *pdev)
{
	int ret;
	struct uart_port *port = &atmel_port->uart;
	struct atmel_uart_data *pdata = dev_get_platdata(&pdev->dev);

	atmel_init_property(atmel_port, pdev);
	atmel_set_ops(port);

	atmel_init_rs485(port, pdev);

	port->iotype		= UPIO_MEM;
	port->flags		= UPF_BOOT_AUTOCONF;
	port->ops		= &atmel_pops;
	port->fifosize		= 1;
	port->dev		= &pdev->dev;
	port->mapbase	= pdev->resource[0].start;
	port->irq	= pdev->resource[1].start;
	port->rs485_config	= atmel_config_rs485;

	tasklet_init(&atmel_port->tasklet, atmel_tasklet_func,
			(unsigned long)port);
	tasklet_disable(&atmel_port->tasklet);

	memset(&atmel_port->rx_ring, 0, sizeof(atmel_port->rx_ring));

	if (pdata && pdata->regs) {
		/* Already mapped by setup code */
		port->membase = pdata->regs;
	} else {
		port->flags	|= UPF_IOREMAP;
		port->membase	= NULL;
	}

	/* for console, the clock could already be configured */
	if (!atmel_port->clk) {
		atmel_port->clk = clk_get(&pdev->dev, "usart");
		if (IS_ERR(atmel_port->clk)) {
			ret = PTR_ERR(atmel_port->clk);
			atmel_port->clk = NULL;
			return ret;
		}
		ret = clk_prepare_enable(atmel_port->clk);
		if (ret) {
			clk_put(atmel_port->clk);
			atmel_port->clk = NULL;
			return ret;
		}
		port->uartclk = clk_get_rate(atmel_port->clk);
		clk_disable_unprepare(atmel_port->clk);
		/* only enable clock when USART is in use */
	}

	/* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
	if (port->rs485.flags & SER_RS485_ENABLED)
		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
	else if (atmel_use_pdc_tx(port)) {
		port->fifosize = PDC_BUFFER_SIZE;
		atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
	} else {
		atmel_port->tx_done_mask = ATMEL_US_TXRDY;
	}

	return 0;
}

struct platform_device *atmel_default_console_device;	/* the serial console device */

#ifdef CONFIG_SERIAL_ATMEL_CONSOLE
static void atmel_console_putchar(struct uart_port *port, int ch)
{
	while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_TXRDY))
		cpu_relax();
	atmel_uart_write_char(port, ch);
}

/*
 * Interrupts are disabled on entering
 */
static void atmel_console_write(struct console *co, const char *s, u_int count)
{
	struct uart_port *port = &atmel_ports[co->index].uart;
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	unsigned int status, imr;
	unsigned int pdc_tx;

	/*
	 * First, save IMR and then disable interrupts
	 */
	imr = atmel_uart_readl(port, ATMEL_US_IMR);
	atmel_uart_writel(port, ATMEL_US_IDR,
			  ATMEL_US_RXRDY | atmel_port->tx_done_mask);

	/* Store PDC transmit status and disable it */
	pdc_tx = atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN;
	atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTDIS);

	uart_console_write(port, s, count, atmel_console_putchar);

	/*
	 * Finally, wait for transmitter to become empty
	 * and restore IMR
	 */
	do {
		status = atmel_uart_readl(port, ATMEL_US_CSR);
	} while (!(status & ATMEL_US_TXRDY));

	/* Restore PDC transmit status */
	if (pdc_tx)
		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);

	/* set interrupts back the way they were */
	atmel_uart_writel(port, ATMEL_US_IER, imr);
}

/*
 * If the port was already initialised (eg, by a boot loader),
 * try to determine the current setup.
 */
static void __init atmel_console_get_options(struct uart_port *port, int *baud,
					     int *parity, int *bits)
{
	unsigned int mr, quot;

	/*
	 * If the baud rate generator isn't running, the port wasn't
	 * initialized by the boot loader.
	 */
	quot = atmel_uart_readl(port, ATMEL_US_BRGR) & ATMEL_US_CD;
	if (!quot)
		return;

	mr = atmel_uart_readl(port, ATMEL_US_MR) & ATMEL_US_CHRL;
	if (mr == ATMEL_US_CHRL_8)
		*bits = 8;
	else
		*bits = 7;

	mr = atmel_uart_readl(port, ATMEL_US_MR) & ATMEL_US_PAR;
	if (mr == ATMEL_US_PAR_EVEN)
		*parity = 'e';
	else if (mr == ATMEL_US_PAR_ODD)
		*parity = 'o';

	/*
	 * The serial core only rounds down when matching this to a
	 * supported baud rate. Make sure we don't end up slightly
	 * lower than one of those, as it would make us fall through
	 * to a much lower baud rate than we really want.
	 */
	*baud = port->uartclk / (16 * (quot - 1));
}

static int __init atmel_console_setup(struct console *co, char *options)
{
	int ret;
	struct uart_port *port = &atmel_ports[co->index].uart;
	int baud = 115200;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	if (port->membase == NULL) {
		/* Port not initialized yet - delay setup */
		return -ENODEV;
	}

	ret = clk_prepare_enable(atmel_ports[co->index].clk);
	if (ret)
		return ret;

	atmel_uart_writel(port, ATMEL_US_IDR, -1);
	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
	atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);

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

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

static struct uart_driver atmel_uart;

static struct console atmel_console = {
	.name		= ATMEL_DEVICENAME,
	.write		= atmel_console_write,
	.device		= uart_console_device,
	.setup		= atmel_console_setup,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
	.data		= &atmel_uart,
};

#define ATMEL_CONSOLE_DEVICE	(&atmel_console)

/*
 * Early console initialization (before VM subsystem initialized).
 */
static int __init atmel_console_init(void)
{
	int ret;
	if (atmel_default_console_device) {
		struct atmel_uart_data *pdata =
			dev_get_platdata(&atmel_default_console_device->dev);
		int id = pdata->num;
		struct atmel_uart_port *atmel_port = &atmel_ports[id];

		atmel_port->backup_imr = 0;
		atmel_port->uart.line = id;

		add_preferred_console(ATMEL_DEVICENAME, id, NULL);
		ret = atmel_init_port(atmel_port, atmel_default_console_device);
		if (ret)
			return ret;
		register_console(&atmel_console);
	}

	return 0;
}

console_initcall(atmel_console_init);

/*
 * Late console initialization.
 */
static int __init atmel_late_console_init(void)
{
	if (atmel_default_console_device
	    && !(atmel_console.flags & CON_ENABLED))
		register_console(&atmel_console);

	return 0;
}

core_initcall(atmel_late_console_init);

static inline bool atmel_is_console_port(struct uart_port *port)
{
	return port->cons && port->cons->index == port->line;
}

#else
#define ATMEL_CONSOLE_DEVICE	NULL

static inline bool atmel_is_console_port(struct uart_port *port)
{
	return false;
}
#endif

static struct uart_driver atmel_uart = {
	.owner		= THIS_MODULE,
	.driver_name	= "atmel_serial",
	.dev_name	= ATMEL_DEVICENAME,
	.major		= SERIAL_ATMEL_MAJOR,
	.minor		= MINOR_START,
	.nr		= ATMEL_MAX_UART,
	.cons		= ATMEL_CONSOLE_DEVICE,
};

#ifdef CONFIG_PM
static bool atmel_serial_clk_will_stop(void)
{
#ifdef CONFIG_ARCH_AT91
	return at91_suspend_entering_slow_clock();
#else
	return false;
#endif
}

static int atmel_serial_suspend(struct platform_device *pdev,
				pm_message_t state)
{
	struct uart_port *port = platform_get_drvdata(pdev);
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

	if (atmel_is_console_port(port) && console_suspend_enabled) {
		/* Drain the TX shifter */
		while (!(atmel_uart_readl(port, ATMEL_US_CSR) &
			 ATMEL_US_TXEMPTY))
			cpu_relax();
	}

	/* we can not wake up if we're running on slow clock */
	atmel_port->may_wakeup = device_may_wakeup(&pdev->dev);
	if (atmel_serial_clk_will_stop()) {
		unsigned long flags;

		spin_lock_irqsave(&atmel_port->lock_suspended, flags);
		atmel_port->suspended = true;
		spin_unlock_irqrestore(&atmel_port->lock_suspended, flags);
		device_set_wakeup_enable(&pdev->dev, 0);
	}

	uart_suspend_port(&atmel_uart, port);

	return 0;
}

static int atmel_serial_resume(struct platform_device *pdev)
{
	struct uart_port *port = platform_get_drvdata(pdev);
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	unsigned long flags;

	spin_lock_irqsave(&atmel_port->lock_suspended, flags);
	if (atmel_port->pending) {
		atmel_handle_receive(port, atmel_port->pending);
		atmel_handle_status(port, atmel_port->pending,
				    atmel_port->pending_status);
		atmel_handle_transmit(port, atmel_port->pending);
		atmel_port->pending = 0;
	}
	atmel_port->suspended = false;
	spin_unlock_irqrestore(&atmel_port->lock_suspended, flags);

	uart_resume_port(&atmel_uart, port);
	device_set_wakeup_enable(&pdev->dev, atmel_port->may_wakeup);

	return 0;
}
#else
#define atmel_serial_suspend NULL
#define atmel_serial_resume NULL
#endif

static void atmel_serial_probe_fifos(struct atmel_uart_port *atmel_port,
				     struct platform_device *pdev)
{
	atmel_port->fifo_size = 0;
	atmel_port->rts_low = 0;
	atmel_port->rts_high = 0;

	if (of_property_read_u32(pdev->dev.of_node,
				 "atmel,fifo-size",
				 &atmel_port->fifo_size))
		return;

	if (!atmel_port->fifo_size)
		return;

	if (atmel_port->fifo_size < ATMEL_MIN_FIFO_SIZE) {
		atmel_port->fifo_size = 0;
		dev_err(&pdev->dev, "Invalid FIFO size\n");
		return;
	}

	/*
	 * 0 <= rts_low <= rts_high <= fifo_size
	 * Once their CTS line asserted by the remote peer, some x86 UARTs tend
	 * to flush their internal TX FIFO, commonly up to 16 data, before
	 * actually stopping to send new data. So we try to set the RTS High
	 * Threshold to a reasonably high value respecting this 16 data
	 * empirical rule when possible.
	 */
	atmel_port->rts_high = max_t(int, atmel_port->fifo_size >> 1,
			       atmel_port->fifo_size - ATMEL_RTS_HIGH_OFFSET);
	atmel_port->rts_low  = max_t(int, atmel_port->fifo_size >> 2,
			       atmel_port->fifo_size - ATMEL_RTS_LOW_OFFSET);

	dev_info(&pdev->dev, "Using FIFO (%u data)\n",
		 atmel_port->fifo_size);
	dev_dbg(&pdev->dev, "RTS High Threshold : %2u data\n",
		atmel_port->rts_high);
	dev_dbg(&pdev->dev, "RTS Low Threshold  : %2u data\n",
		atmel_port->rts_low);
}

static int atmel_serial_probe(struct platform_device *pdev)
{
	struct atmel_uart_port *atmel_port;
	struct device_node *np = pdev->dev.of_node;
	struct atmel_uart_data *pdata = dev_get_platdata(&pdev->dev);
	void *data;
	int ret = -ENODEV;
	bool rs485_enabled;

	BUILD_BUG_ON(ATMEL_SERIAL_RINGSIZE & (ATMEL_SERIAL_RINGSIZE - 1));

	if (np)
		ret = of_alias_get_id(np, "serial");
	else
		if (pdata)
			ret = pdata->num;

	if (ret < 0)
		/* port id not found in platform data nor device-tree aliases:
		 * auto-enumerate it */
		ret = find_first_zero_bit(atmel_ports_in_use, ATMEL_MAX_UART);

	if (ret >= ATMEL_MAX_UART) {
		ret = -ENODEV;
		goto err;
	}

	if (test_and_set_bit(ret, atmel_ports_in_use)) {
		/* port already in use */
		ret = -EBUSY;
		goto err;
	}

	atmel_port = &atmel_ports[ret];
	atmel_port->backup_imr = 0;
	atmel_port->uart.line = ret;
	atmel_serial_probe_fifos(atmel_port, pdev);

	spin_lock_init(&atmel_port->lock_suspended);

	ret = atmel_init_port(atmel_port, pdev);
	if (ret)
		goto err_clear_bit;

	atmel_port->gpios = mctrl_gpio_init(&atmel_port->uart, 0);
	if (IS_ERR(atmel_port->gpios)) {
		ret = PTR_ERR(atmel_port->gpios);
		goto err_clear_bit;
	}

	if (!atmel_use_pdc_rx(&atmel_port->uart)) {
		ret = -ENOMEM;
		data = kmalloc(sizeof(struct atmel_uart_char)
				* ATMEL_SERIAL_RINGSIZE, GFP_KERNEL);
		if (!data)
			goto err_alloc_ring;
		atmel_port->rx_ring.buf = data;
	}

	rs485_enabled = atmel_port->uart.rs485.flags & SER_RS485_ENABLED;

	ret = uart_add_one_port(&atmel_uart, &atmel_port->uart);
	if (ret)
		goto err_add_port;

#ifdef CONFIG_SERIAL_ATMEL_CONSOLE
	if (atmel_is_console_port(&atmel_port->uart)
			&& ATMEL_CONSOLE_DEVICE->flags & CON_ENABLED) {
		/*
		 * The serial core enabled the clock for us, so undo
		 * the clk_prepare_enable() in atmel_console_setup()
		 */
		clk_disable_unprepare(atmel_port->clk);
	}
#endif

	device_init_wakeup(&pdev->dev, 1);
	platform_set_drvdata(pdev, atmel_port);

	/*
	 * The peripheral clock has been disabled by atmel_init_port():
	 * enable it before accessing I/O registers
	 */
	clk_prepare_enable(atmel_port->clk);

	if (rs485_enabled) {
		atmel_uart_writel(&atmel_port->uart, ATMEL_US_MR,
				  ATMEL_US_USMODE_NORMAL);
		atmel_uart_writel(&atmel_port->uart, ATMEL_US_CR,
				  ATMEL_US_RTSEN);
	}

	/*
	 * Get port name of usart or uart
	 */
	atmel_get_ip_name(&atmel_port->uart);

	/*
	 * The peripheral clock can now safely be disabled till the port
	 * is used
	 */
	clk_disable_unprepare(atmel_port->clk);

	return 0;

err_add_port:
	kfree(atmel_port->rx_ring.buf);
	atmel_port->rx_ring.buf = NULL;
err_alloc_ring:
	if (!atmel_is_console_port(&atmel_port->uart)) {
		clk_put(atmel_port->clk);
		atmel_port->clk = NULL;
	}
err_clear_bit:
	clear_bit(atmel_port->uart.line, atmel_ports_in_use);
err:
	return ret;
}

/*
 * Even if the driver is not modular, it makes sense to be able to
 * unbind a device: there can be many bound devices, and there are
 * situations where dynamic binding and unbinding can be useful.
 *
 * For example, a connected device can require a specific firmware update
 * protocol that needs bitbanging on IO lines, but use the regular serial
 * port in the normal case.
 */
static int atmel_serial_remove(struct platform_device *pdev)
{
	struct uart_port *port = platform_get_drvdata(pdev);
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	int ret = 0;

	tasklet_kill(&atmel_port->tasklet);

	device_init_wakeup(&pdev->dev, 0);

	ret = uart_remove_one_port(&atmel_uart, port);

	kfree(atmel_port->rx_ring.buf);

	/* "port" is allocated statically, so we shouldn't free it */

	clear_bit(port->line, atmel_ports_in_use);

	clk_put(atmel_port->clk);
	atmel_port->clk = NULL;

	return ret;
}

static struct platform_driver atmel_serial_driver = {
	.probe		= atmel_serial_probe,
	.remove		= atmel_serial_remove,
	.suspend	= atmel_serial_suspend,
	.resume		= atmel_serial_resume,
	.driver		= {
		.name			= "atmel_usart",
		.of_match_table		= of_match_ptr(atmel_serial_dt_ids),
	},
};

static int __init atmel_serial_init(void)
{
	int ret;

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

	ret = platform_driver_register(&atmel_serial_driver);
	if (ret)
		uart_unregister_driver(&atmel_uart);

	return ret;
}
device_initcall(atmel_serial_init);