atmel_serial.c

 * transmit interrupt handler. (Transmit is IRQF_NODELAY safe)
 */
static void
atmel_handle_transmit(struct uart_port *port, unsigned int pending)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

	if (pending & atmel_port->tx_done_mask) {
		/* Either PDC or interrupt transmission */
		UART_PUT_IDR(port, atmel_port->tx_done_mask);
		tasklet_schedule(&atmel_port->tasklet);
	}
}

/*
 * status flags interrupt handler.
 */
static void
atmel_handle_status(struct uart_port *port, unsigned int pending,
		    unsigned int status)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

	if (pending & (ATMEL_US_RIIC | ATMEL_US_DSRIC | ATMEL_US_DCDIC
				| ATMEL_US_CTSIC)) {
		atmel_port->irq_status = status;
		tasklet_schedule(&atmel_port->tasklet);
	}
}

/*
 * Interrupt handler
 */
static irqreturn_t atmel_interrupt(int irq, void *dev_id)
{
	struct uart_port *port = dev_id;
	unsigned int status, pending, pass_counter = 0;

	do {
		status = UART_GET_CSR(port);
		pending = status & UART_GET_IMR(port);
		if (!pending)
			break;

		atmel_handle_receive(port, pending);
		atmel_handle_status(port, pending, status);
		atmel_handle_transmit(port, pending);
	} while (pass_counter++ < ATMEL_ISR_PASS_LIMIT);

	return pass_counter ? IRQ_HANDLED : IRQ_NONE;
}

static void atmel_release_tx_pdc(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;

	dma_unmap_single(port->dev,
			 pdc->dma_addr,
			 pdc->dma_size,
			 DMA_TO_DEVICE);
}

/*
 * Called from tasklet with ENDTX and TXBUFE interrupts disabled.
 */
static void atmel_tx_pdc(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	struct circ_buf *xmit = &port->state->xmit;
	struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
	int count;

	/* nothing left to transmit? */
	if (UART_GET_TCR(port))
		return;

	xmit->tail += pdc->ofs;
	xmit->tail &= UART_XMIT_SIZE - 1;

	port->icount.tx += pdc->ofs;
	pdc->ofs = 0;

	/* more to transmit - setup next transfer */

	/* disable PDC transmit */
	UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);

	if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) {
		dma_sync_single_for_device(port->dev,
					   pdc->dma_addr,
					   pdc->dma_size,
					   DMA_TO_DEVICE);

		count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
		pdc->ofs = count;

		UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
		UART_PUT_TCR(port, count);
		/* re-enable PDC transmit */
		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
		/* Enable interrupts */
		UART_PUT_IER(port, atmel_port->tx_done_mask);
	} else {
		if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
		    !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX)) {
			/* DMA done, stop TX, start RX for RS485 */
			atmel_start_rx(port);
		}
	}

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

static int atmel_prepare_tx_pdc(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
	struct circ_buf *xmit = &port->state->xmit;

	pdc->buf = xmit->buf;
	pdc->dma_addr = dma_map_single(port->dev,
					pdc->buf,
					UART_XMIT_SIZE,
					DMA_TO_DEVICE);
	pdc->dma_size = UART_XMIT_SIZE;
	pdc->ofs = 0;

	return 0;
}

static void atmel_rx_from_ring(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	struct circ_buf *ring = &atmel_port->rx_ring;
	unsigned int flg;
	unsigned int status;

	while (ring->head != ring->tail) {
		struct atmel_uart_char c;

		/* Make sure c is loaded after head. */
		smp_rmb();

		c = ((struct atmel_uart_char *)ring->buf)[ring->tail];

		ring->tail = (ring->tail + 1) & (ATMEL_SERIAL_RINGSIZE - 1);

		port->icount.rx++;
		status = c.status;
		flg = TTY_NORMAL;

		/*
		 * note that the error handling code is
		 * out of the main execution path
		 */
		if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME
				       | ATMEL_US_OVRE | ATMEL_US_RXBRK))) {
			if (status & ATMEL_US_RXBRK) {
				/* ignore side-effect */
				status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);

				port->icount.brk++;
				if (uart_handle_break(port))
					continue;
			}
			if (status & ATMEL_US_PARE)
				port->icount.parity++;
			if (status & ATMEL_US_FRAME)
				port->icount.frame++;
			if (status & ATMEL_US_OVRE)
				port->icount.overrun++;

			status &= port->read_status_mask;

			if (status & ATMEL_US_RXBRK)
				flg = TTY_BREAK;
			else if (status & ATMEL_US_PARE)
				flg = TTY_PARITY;
			else if (status & ATMEL_US_FRAME)
				flg = TTY_FRAME;
		}


		if (uart_handle_sysrq_char(port, c.ch))
			continue;

		uart_insert_char(port, status, ATMEL_US_OVRE, c.ch, flg);
	}

	/*
	 * Drop the lock here since it might end up calling
	 * uart_start(), which takes the lock.
	 */
	spin_unlock(&port->lock);
	tty_flip_buffer_push(&port->state->port);
	spin_lock(&port->lock);
}

static void atmel_release_rx_pdc(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	int i;

	for (i = 0; i < 2; i++) {
		struct atmel_dma_buffer *pdc = &atmel_port->pdc_rx[i];

		dma_unmap_single(port->dev,
				 pdc->dma_addr,
				 pdc->dma_size,
				 DMA_FROM_DEVICE);
		kfree(pdc->buf);
	}
}

static void atmel_rx_from_pdc(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	struct tty_port *tport = &port->state->port;
	struct atmel_dma_buffer *pdc;
	int rx_idx = atmel_port->pdc_rx_idx;
	unsigned int head;
	unsigned int tail;
	unsigned int count;

	do {
		/* Reset the UART timeout early so that we don't miss one */
		UART_PUT_CR(port, ATMEL_US_STTTO);

		pdc = &atmel_port->pdc_rx[rx_idx];
		head = UART_GET_RPR(port) - pdc->dma_addr;
		tail = pdc->ofs;

		/* If the PDC has switched buffers, RPR won't contain
		 * any address within the current buffer. Since head
		 * is unsigned, we just need a one-way comparison to
		 * find out.
		 *
		 * In this case, we just need to consume the entire
		 * buffer and resubmit it for DMA. This will clear the
		 * ENDRX bit as well, so that we can safely re-enable
		 * all interrupts below.
		 */
		head = min(head, pdc->dma_size);

		if (likely(head != tail)) {
			dma_sync_single_for_cpu(port->dev, pdc->dma_addr,
					pdc->dma_size, DMA_FROM_DEVICE);

			/*
			 * head will only wrap around when we recycle
			 * the DMA buffer, and when that happens, we
			 * explicitly set tail to 0. So head will
			 * always be greater than tail.
			 */
			count = head - tail;

			tty_insert_flip_string(tport, pdc->buf + pdc->ofs,
						count);

			dma_sync_single_for_device(port->dev, pdc->dma_addr,
					pdc->dma_size, DMA_FROM_DEVICE);

			port->icount.rx += count;
			pdc->ofs = head;
		}

		/*
		 * If the current buffer is full, we need to check if
		 * the next one contains any additional data.
		 */
		if (head >= pdc->dma_size) {
			pdc->ofs = 0;
			UART_PUT_RNPR(port, pdc->dma_addr);
			UART_PUT_RNCR(port, pdc->dma_size);

			rx_idx = !rx_idx;
			atmel_port->pdc_rx_idx = rx_idx;
		}
	} while (head >= pdc->dma_size);

	/*
	 * Drop the lock here since it might end up calling
	 * uart_start(), which takes the lock.
	 */
	spin_unlock(&port->lock);
	tty_flip_buffer_push(tport);
	spin_lock(&port->lock);

	UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
}

static int atmel_prepare_rx_pdc(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	int i;

	for (i = 0; i < 2; i++) {
		struct atmel_dma_buffer *pdc = &atmel_port->pdc_rx[i];

		pdc->buf = kmalloc(PDC_BUFFER_SIZE, GFP_KERNEL);
		if (pdc->buf == NULL) {
			if (i != 0) {
				dma_unmap_single(port->dev,
					atmel_port->pdc_rx[0].dma_addr,
					PDC_BUFFER_SIZE,
					DMA_FROM_DEVICE);
				kfree(atmel_port->pdc_rx[0].buf);
			}
			atmel_port->use_pdc_rx = 0;
			return -ENOMEM;
		}
		pdc->dma_addr = dma_map_single(port->dev,
						pdc->buf,
						PDC_BUFFER_SIZE,
						DMA_FROM_DEVICE);
		pdc->dma_size = PDC_BUFFER_SIZE;
		pdc->ofs = 0;
	}

	atmel_port->pdc_rx_idx = 0;

	UART_PUT_RPR(port, atmel_port->pdc_rx[0].dma_addr);
	UART_PUT_RCR(port, PDC_BUFFER_SIZE);

	UART_PUT_RNPR(port, atmel_port->pdc_rx[1].dma_addr);
	UART_PUT_RNCR(port, PDC_BUFFER_SIZE);

	return 0;
}

/*
 * tasklet handling tty stuff outside the interrupt handler.
 */
static void atmel_tasklet_func(unsigned long data)
{
	struct uart_port *port = (struct uart_port *)data;
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	unsigned int status;
	unsigned int status_change;

	/* The interrupt handler does not take the lock */
	spin_lock(&port->lock);

	atmel_port->schedule_tx(port);

	status = atmel_port->irq_status;
	status_change = status ^ atmel_port->irq_status_prev;

	if (status_change & (ATMEL_US_RI | ATMEL_US_DSR
				| ATMEL_US_DCD | ATMEL_US_CTS)) {
		/* TODO: All reads to CSR will clear these interrupts! */
		if (status_change & ATMEL_US_RI)
			port->icount.rng++;
		if (status_change & ATMEL_US_DSR)
			port->icount.dsr++;
		if (status_change & ATMEL_US_DCD)
			uart_handle_dcd_change(port, !(status & ATMEL_US_DCD));
		if (status_change & ATMEL_US_CTS)
			uart_handle_cts_change(port, !(status & ATMEL_US_CTS));

		wake_up_interruptible(&port->state->port.delta_msr_wait);

		atmel_port->irq_status_prev = status;
	}

	atmel_port->schedule_rx(port);

	spin_unlock(&port->lock);
}

static void atmel_set_ops(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

	if (atmel_use_dma_rx(port)) {
		atmel_port->prepare_rx = &atmel_prepare_rx_dma;
		atmel_port->schedule_rx = &atmel_rx_from_dma;
		atmel_port->release_rx = &atmel_release_rx_dma;
	} else if (atmel_use_pdc_rx(port)) {
		atmel_port->prepare_rx = &atmel_prepare_rx_pdc;
		atmel_port->schedule_rx = &atmel_rx_from_pdc;
		atmel_port->release_rx = &atmel_release_rx_pdc;
	} else {
		atmel_port->prepare_rx = NULL;
		atmel_port->schedule_rx = &atmel_rx_from_ring;
		atmel_port->release_rx = NULL;
	}

	if (atmel_use_dma_tx(port)) {
		atmel_port->prepare_tx = &atmel_prepare_tx_dma;
		atmel_port->schedule_tx = &atmel_tx_dma;
		atmel_port->release_tx = &atmel_release_tx_dma;
	} else if (atmel_use_pdc_tx(port)) {
		atmel_port->prepare_tx = &atmel_prepare_tx_pdc;
		atmel_port->schedule_tx = &atmel_tx_pdc;
		atmel_port->release_tx = &atmel_release_tx_pdc;
	} else {
		atmel_port->prepare_tx = NULL;
		atmel_port->schedule_tx = &atmel_tx_chars;
		atmel_port->release_tx = NULL;
	}
}

/*
 * Perform initialization and enable port for reception
 */
static int atmel_startup(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	struct tty_struct *tty = port->state->port.tty;
	int retval;

	/*
	 * Ensure that no interrupts are enabled otherwise when
	 * request_irq() is called we could get stuck trying to
	 * handle an unexpected interrupt
	 */
	UART_PUT_IDR(port, -1);

	/*
	 * Allocate the IRQ
	 */
	retval = request_irq(port->irq, atmel_interrupt, IRQF_SHARED,
			tty ? tty->name : "atmel_serial", port);
	if (retval) {
		printk("atmel_serial: atmel_startup - Can't get irq\n");
		return retval;
	}

	/*
	 * Initialize DMA (if necessary)
	 */
	if (atmel_port->prepare_rx) {
		retval = atmel_port->prepare_rx(port);
		if (retval < 0)
			atmel_set_ops(port);
	}

	if (atmel_port->prepare_tx) {
		retval = atmel_port->prepare_tx(port);
		if (retval < 0)
			atmel_set_ops(port);
	}
	/*
	 * If there is a specific "open" function (to register
	 * control line interrupts)
	 */
	if (atmel_open_hook) {
		retval = atmel_open_hook(port);
		if (retval) {
			free_irq(port->irq, port);
			return retval;
		}
	}

	/* Save current CSR for comparison in atmel_tasklet_func() */
	atmel_port->irq_status_prev = UART_GET_CSR(port);
	atmel_port->irq_status = atmel_port->irq_status_prev;

	/*
	 * Finally, enable the serial port
	 */
	UART_PUT_CR(port, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
	/* enable xmit & rcvr */
	UART_PUT_CR(port, ATMEL_US_TXEN | ATMEL_US_RXEN);

	if (atmel_use_pdc_rx(port)) {
		/* set UART timeout */
		UART_PUT_RTOR(port, PDC_RX_TIMEOUT);
		UART_PUT_CR(port, ATMEL_US_STTTO);

		UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
		/* enable PDC controller */
		UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
	} else if (atmel_use_dma_rx(port)) {
		UART_PUT_RTOR(port, PDC_RX_TIMEOUT);
		UART_PUT_CR(port, ATMEL_US_STTTO);

		UART_PUT_IER(port, ATMEL_US_TIMEOUT);
	} else {
		/* enable receive only */
		UART_PUT_IER(port, ATMEL_US_RXRDY);
	}

	return 0;
}

/*
 * Disable the port
 */
static void atmel_shutdown(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
	/*
	 * Ensure everything is stopped.
	 */
	atmel_stop_rx(port);
	atmel_stop_tx(port);

	/*
	 * Shut-down the DMA.
	 */
	if (atmel_port->release_rx)
		atmel_port->release_rx(port);
	if (atmel_port->release_tx)
		atmel_port->release_tx(port);

	/*
	 * Disable all interrupts, port and break condition.
	 */
	UART_PUT_CR(port, ATMEL_US_RSTSTA);
	UART_PUT_IDR(port, -1);

	/*
	 * Free the interrupt
	 */
	free_irq(port->irq, port);

	/*
	 * If there is a specific "close" function (to unregister
	 * control line interrupts)
	 */
	if (atmel_close_hook)
		atmel_close_hook(port);
}

/*
 * Flush any TX data submitted for DMA. Called when the TX circular
 * buffer is reset.
 */
static void atmel_flush_buffer(struct uart_port *port)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

	if (atmel_use_pdc_tx(port)) {
		UART_PUT_TCR(port, 0);
		atmel_port->pdc_tx.ofs = 0;
	}
}

/*
 * Power / Clock management.
 */
static void atmel_serial_pm(struct uart_port *port, unsigned int state,
			    unsigned int oldstate)
{
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

	switch (state) {
	case 0:
		/*
		 * Enable the peripheral clock for this serial port.
		 * This is called on uart_open() or a resume event.
		 */
		clk_prepare_enable(atmel_port->clk);

		/* re-enable interrupts if we disabled some on suspend */
		UART_PUT_IER(port, atmel_port->backup_imr);
		break;
	case 3:
		/* Back up the interrupt mask and disable all interrupts */
		atmel_port->backup_imr = UART_GET_IMR(port);
		UART_PUT_IDR(port, -1);

		/*
		 * Disable the peripheral clock for this serial port.
		 * This is called on uart_close() or a suspend event.
		 */
		clk_disable_unprepare(atmel_port->clk);
		break;
	default:
		printk(KERN_ERR "atmel_serial: unknown pm %d\n", state);
	}
}

/*
 * Change the port parameters
 */
static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
			      struct ktermios *old)
{
	unsigned long flags;
	unsigned int mode, imr, quot, baud;
	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

	/* Get current mode register */
	mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
					| ATMEL_US_NBSTOP | ATMEL_US_PAR
					| ATMEL_US_USMODE);

	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
	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;

	/* hardware handshake (RTS/CTS) */
	if (termios->c_cflag & CRTSCTS)
		mode |= ATMEL_US_USMODE_HWHS;
	else
		mode |= ATMEL_US_USMODE_NORMAL;

	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 & (BRKINT | PARMRK))
		port->read_status_mask |= ATMEL_US_RXBRK;

	if (atmel_use_pdc_rx(port))
		/* need to enable error interrupts */
		UART_PUT_IER(port, 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 = UART_GET_IMR(port);
	UART_PUT_IDR(port, -1);

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

	/* Resetting serial mode to RS232 (0x0) */
	mode &= ~ATMEL_US_USMODE;

	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
		dev_dbg(port->dev, "Setting UART to RS485\n");
		if ((atmel_port->rs485.delay_rts_after_send) > 0)
			UART_PUT_TTGR(port,
					atmel_port->rs485.delay_rts_after_send);
		mode |= ATMEL_US_USMODE_RS485;
	} else {
		dev_dbg(port->dev, "Setting UART to RS232\n");
	}

	/* set the parity, stop bits and data size */
	UART_PUT_MR(port, mode);

	/* set the baud rate */
	UART_PUT_BRGR(port, quot);
	UART_PUT_CR(port, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
	UART_PUT_CR(port, ATMEL_US_TXEN | ATMEL_US_RXEN);

	/* restore interrupts */
	UART_PUT_IER(port, imr);

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

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

static void atmel_set_ldisc(struct uart_port *port, int new)
{
	if (new == N_PPS) {
		port->flags |= UPF_HARDPPS_CD;
		atmel_enable_ms(port);
	} else {
		port->flags &= ~UPF_HARDPPS_CD;
	}
}

/*
 * 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 ((void *)port->mapbase != 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 (!(UART_GET_CSR(port) & ATMEL_US_RXRDY))
		cpu_relax();

	return UART_GET_CHAR(port);
}

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

	UART_PUT_CHAR(port, ch);
}
#endif

static int
atmel_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
{
	struct serial_rs485 rs485conf;

	switch (cmd) {
	case TIOCSRS485:
		if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg,
					sizeof(rs485conf)))
			return -EFAULT;

		atmel_config_rs485(port, &rs485conf);
		break;

	case TIOCGRS485:
		if (copy_to_user((struct serial_rs485 *) arg,
					&(to_atmel_uart_port(port)->rs485),
					sizeof(rs485conf)))
			return -EFAULT;
		break;

	default:
		return -ENOIOCTLCMD;
	}
	return 0;
}



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,
	.ioctl		= atmel_ioctl,
#ifdef CONFIG_CONSOLE_POLL
	.poll_get_char	= atmel_poll_get_char,
	.poll_put_char	= atmel_poll_put_char,
#endif
};

static void atmel_of_init_port(struct atmel_uart_port *atmel_port,
					 struct device_node *np)
{
	u32 rs485_delay[2];

	/* DMA/PDC usage specification */
	if (of_get_property(np, "atmel,use-dma-rx", NULL)) {
		if (of_get_property(np, "dmas", NULL)) {
			atmel_port->use_dma_rx	= true;
			atmel_port->use_pdc_rx	= false;
		} else {
			atmel_port->use_dma_rx	= false;
			atmel_port->use_pdc_rx	= true;
		}
	} else {
		atmel_port->use_dma_rx	= false;
		atmel_port->use_pdc_rx	= false;
	}

	if (of_get_property(np, "atmel,use-dma-tx", NULL)) {
		if (of_get_property(np, "dmas", NULL)) {
			atmel_port->use_dma_tx	= true;
			atmel_port->use_pdc_tx	= false;
		} else {
			atmel_port->use_dma_tx	= false;
			atmel_port->use_pdc_tx	= true;
		}
	} else {
		atmel_port->use_dma_tx	= false;
		atmel_port->use_pdc_tx	= false;
	}

	/* rs485 properties */
	if (of_property_read_u32_array(np, "rs485-rts-delay",
					    rs485_delay, 2) == 0) {
		struct serial_rs485 *rs485conf = &atmel_port->rs485;

		rs485conf->delay_rts_before_send = rs485_delay[0];
		rs485conf->delay_rts_after_send = rs485_delay[1];
		rs485conf->flags = 0;

		if (of_get_property(np, "rs485-rx-during-tx", NULL))
			rs485conf->flags |= SER_RS485_RX_DURING_TX;

		if (of_get_property(np, "linux,rs485-enabled-at-boot-time", NULL))
			rs485conf->flags |= SER_RS485_ENABLED;
	}
}

/*
 * 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 = pdev->dev.platform_data;

	if (pdev->dev.of_node) {
		atmel_of_init_port(atmel_port, pdev->dev.of_node);
	} else {
		atmel_port->use_pdc_rx	= pdata->use_dma_rx;
		atmel_port->use_pdc_tx	= pdata->use_dma_tx;
		atmel_port->use_dma_rx	= false;
		atmel_port->use_dma_tx	= false;
		atmel_port->rs485	= pdata->rs485;
	}

	atmel_set_ops(port);

	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;

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

	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 (atmel_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;
	}