tty: move drivers/serial/ to drivers/tty/serial/

The serial drivers are really just tty drivers, so move them to
drivers/tty/ to make things a bit neater overall.

This is part of the tty/serial driver movement proceedure as proposed by
Arnd Bergmann and approved by everyone involved a number of months ago.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Rogier Wolff <R.E.Wolff@bitwizard.nl>
Cc: Michael H. Warfield <mhw@wittsend.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1808 insertions, 0 deletions

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
new file mode 100644
index 000000000000..3892666b5fbd
--- /dev/null
+++ b/drivers/tty/serial/atmel_serial.c
@@ -0,0 +1,1808 @@
+/*
+ *  linux/drivers/char/atmel_serial.c
+ *
+ *  Driver for Atmel AT91 / AT32 Serial ports
+ *  Copyright (C) 2003 Rick Bronson
+ *
+ *  Based on drivers/char/serial_sa1100.c, by Deep Blue Solutions Ltd.
+ *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
+ *
+ *  DMA support added by Chip Coldwell.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+#include <linux/module.h>
+#include <linux/tty.h>
+#include <linux/ioport.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/serial.h>
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/tty_flip.h>
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+#include <linux/atmel_pdc.h>
+#include <linux/atmel_serial.h>
+#include <linux/uaccess.h>
+
+#include <asm/io.h>
+#include <asm/ioctls.h>
+
+#include <asm/mach/serial_at91.h>
+#include <mach/board.h>
+
+#ifdef CONFIG_ARM
+#include <mach/cpu.h>
+#include <mach/gpio.h>
+#endif
+
+#define PDC_BUFFER_SIZE		512
+/* Revisit: We should calculate this based on the actual port settings */
+#define PDC_RX_TIMEOUT		(3 * 10)		/* 3 bytes */
+
+#if defined(CONFIG_SERIAL_ATMEL_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/serial_core.h>
+
+static void atmel_start_rx(struct uart_port *port);
+static void atmel_stop_rx(struct uart_port *port);
+
+#ifdef CONFIG_SERIAL_ATMEL_TTYAT
+
+/* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
+ * should coexist with the 8250 driver, such as if we have an external 16C550
+ * UART. */
+#define SERIAL_ATMEL_MAJOR	204
+#define MINOR_START		154
+#define ATMEL_DEVICENAME	"ttyAT"
+
+#else
+
+/* Use device name ttyS, major 4, minor 64-68.  This is the usual serial port
+ * name, but it is legally reserved for the 8250 driver. */
+#define SERIAL_ATMEL_MAJOR	TTY_MAJOR
+#define MINOR_START		64
+#define ATMEL_DEVICENAME	"ttyS"
+
+#endif
+
+#define ATMEL_ISR_PASS_LIMIT	256
+
+/* UART registers. CR is write-only, hence no GET macro */
+#define UART_PUT_CR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_CR)
+#define UART_GET_MR(port)	__raw_readl((port)->membase + ATMEL_US_MR)
+#define UART_PUT_MR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_MR)
+#define UART_PUT_IER(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_IER)
+#define UART_PUT_IDR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_IDR)
+#define UART_GET_IMR(port)	__raw_readl((port)->membase + ATMEL_US_IMR)
+#define UART_GET_CSR(port)	__raw_readl((port)->membase + ATMEL_US_CSR)
+#define UART_GET_CHAR(port)	__raw_readl((port)->membase + ATMEL_US_RHR)
+#define UART_PUT_CHAR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_THR)
+#define UART_GET_BRGR(port)	__raw_readl((port)->membase + ATMEL_US_BRGR)
+#define UART_PUT_BRGR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_BRGR)
+#define UART_PUT_RTOR(port,v)	__raw_writel(v, (port)->membase + ATMEL_US_RTOR)
+#define UART_PUT_TTGR(port, v)	__raw_writel(v, (port)->membase + ATMEL_US_TTGR)
+
+ /* PDC registers */
+#define UART_PUT_PTCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
+#define UART_GET_PTSR(port)	__raw_readl((port)->membase + ATMEL_PDC_PTSR)
+
+#define UART_PUT_RPR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_RPR)
+#define UART_GET_RPR(port)	__raw_readl((port)->membase + ATMEL_PDC_RPR)
+#define UART_PUT_RCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_RCR)
+#define UART_PUT_RNPR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_RNPR)
+#define UART_PUT_RNCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_RNCR)
+
+#define UART_PUT_TPR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_TPR)
+#define UART_PUT_TCR(port,v)	__raw_writel(v, (port)->membase + ATMEL_PDC_TCR)
+#define UART_GET_TCR(port)	__raw_readl((port)->membase + ATMEL_PDC_TCR)
+
+static int (*atmel_open_hook)(struct uart_port *);
+static void (*atmel_close_hook)(struct uart_port *);
+
+struct atmel_dma_buffer {
+	unsigned char	*buf;
+	dma_addr_t	dma_addr;
+	unsigned int	dma_size;
+	unsigned int	ofs;
+};
+
+struct atmel_uart_char {
+	u16		status;
+	u16		ch;
+};
+
+#define ATMEL_SERIAL_RINGSIZE 1024
+
+/*
+ * We wrap our port structure around the generic uart_port.
+ */
+struct atmel_uart_port {
+	struct uart_port	uart;		/* uart */
+	struct clk		*clk;		/* uart clock */
+	int			may_wakeup;	/* cached value of device_may_wakeup for times we need to disable it */
+	u32			backup_imr;	/* IMR saved during suspend */
+	int			break_active;	/* break being received */
+
+	short			use_dma_rx;	/* enable PDC receiver */
+	short			pdc_rx_idx;	/* current PDC RX buffer */
+	struct atmel_dma_buffer	pdc_rx[2];	/* PDC receier */
+
+	short			use_dma_tx;	/* enable PDC transmitter */
+	struct atmel_dma_buffer	pdc_tx;		/* PDC transmitter */
+
+	struct tasklet_struct	tasklet;
+	unsigned int		irq_status;
+	unsigned int		irq_status_prev;
+
+	struct circ_buf		rx_ring;
+
+	struct serial_rs485	rs485;		/* rs485 settings */
+	unsigned int		tx_done_mask;
+};
+
+static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
+
+#ifdef SUPPORT_SYSRQ
+static struct console atmel_console;
+#endif
+
+static inline struct atmel_uart_port *
+to_atmel_uart_port(struct uart_port *uart)
+{
+	return container_of(uart, struct atmel_uart_port, uart);
+}
+
+#ifdef CONFIG_SERIAL_ATMEL_PDC
+static bool atmel_use_dma_rx(struct uart_port *port)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+	return atmel_port->use_dma_rx;
+}
+
+static bool atmel_use_dma_tx(struct uart_port *port)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+	return atmel_port->use_dma_tx;
+}
+#else
+static bool atmel_use_dma_rx(struct uart_port *port)
+{
+	return false;
+}
+
+static bool atmel_use_dma_tx(struct uart_port *port)
+{
+	return false;
+}
+#endif
+
+/* Enable or disable the rs485 support */
+void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	unsigned int mode;
+
+	spin_lock(&port->lock);
+
+	/* Disable interrupts */
+	UART_PUT_IDR(port, atmel_port->tx_done_mask);
+
+	mode = UART_GET_MR(port);
+
+	/* Resetting serial mode to RS232 (0x0) */
+	mode &= ~ATMEL_US_USMODE;
+
+	atmel_port->rs485 = *rs485conf;
+
+	if (rs485conf->flags & SER_RS485_ENABLED) {
+		dev_dbg(port->dev, "Setting UART to RS485\n");
+		atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
+		if (rs485conf->flags & SER_RS485_RTS_AFTER_SEND)
+			UART_PUT_TTGR(port, rs485conf->delay_rts_after_send);
+		mode |= ATMEL_US_USMODE_RS485;
+	} else {
+		dev_dbg(port->dev, "Setting UART to RS232\n");
+		if (atmel_use_dma_tx(port))
+			atmel_port->tx_done_mask = ATMEL_US_ENDTX |
+				ATMEL_US_TXBUFE;
+		else
+			atmel_port->tx_done_mask = ATMEL_US_TXRDY;
+	}
+	UART_PUT_MR(port, mode);
+
+	/* Enable interrupts */
+	UART_PUT_IER(port, atmel_port->tx_done_mask);
+
+	spin_unlock(&port->lock);
+
+}
+
+/*
+ * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
+ */
+static u_int atmel_tx_empty(struct uart_port *port)
+{
+	return (UART_GET_CSR(port) & ATMEL_US_TXEMPTY) ? TIOCSER_TEMT : 0;
+}
+
+/*
+ * Set state of the modem control output lines
+ */
+static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
+{
+	unsigned int control = 0;
+	unsigned int mode;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+#ifdef CONFIG_ARCH_AT91RM9200
+	if (cpu_is_at91rm9200()) {
+		/*
+		 * AT91RM9200 Errata #39: RTS0 is not internally connected
+		 * to PA21. We need to drive the pin manually.
+		 */
+		if (port->mapbase == AT91RM9200_BASE_US0) {
+			if (mctrl & TIOCM_RTS)
+				at91_set_gpio_value(AT91_PIN_PA21, 0);
+			else
+				at91_set_gpio_value(AT91_PIN_PA21, 1);
+		}
+	}
+#endif
+
+	if (mctrl & TIOCM_RTS)
+		control |= ATMEL_US_RTSEN;
+	else
+		control |= ATMEL_US_RTSDIS;
+
+	if (mctrl & TIOCM_DTR)
+		control |= ATMEL_US_DTREN;
+	else
+		control |= ATMEL_US_DTRDIS;
+
+	UART_PUT_CR(port, control);
+
+	/* Local loopback mode? */
+	mode = UART_GET_MR(port) & ~ATMEL_US_CHMODE;
+	if (mctrl & TIOCM_LOOP)
+		mode |= ATMEL_US_CHMODE_LOC_LOOP;
+	else
+		mode |= ATMEL_US_CHMODE_NORMAL;
+
+	/* 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.flags & SER_RS485_RTS_AFTER_SEND)
+			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");
+	}
+	UART_PUT_MR(port, mode);
+}
+
+/*
+ * Get state of the modem control input lines
+ */
+static u_int atmel_get_mctrl(struct uart_port *port)
+{
+	unsigned int status, ret = 0;
+
+	status = UART_GET_CSR(port);
+
+	/*
+	 * The control signals are active low.
+	 */
+	if (!(status & ATMEL_US_DCD))
+		ret |= TIOCM_CD;
+	if (!(status & ATMEL_US_CTS))
+		ret |= TIOCM_CTS;
+	if (!(status & ATMEL_US_DSR))
+		ret |= TIOCM_DSR;
+	if (!(status & ATMEL_US_RI))
+		ret |= TIOCM_RI;
+
+	return ret;
+}
+
+/*
+ * Stop transmitting.
+ */
+static void atmel_stop_tx(struct uart_port *port)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+	if (atmel_use_dma_tx(port)) {
+		/* disable PDC transmit */
+		UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
+	}
+	/* Disable interrupts */
+	UART_PUT_IDR(port, atmel_port->tx_done_mask);
+
+	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		atmel_start_rx(port);
+}
+
+/*
+ * Start transmitting.
+ */
+static void atmel_start_tx(struct uart_port *port)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+	if (atmel_use_dma_tx(port)) {
+		if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
+			/* The transmitter is already running.  Yes, we
+			   really need this.*/
+			return;
+
+		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+			atmel_stop_rx(port);
+
+		/* re-enable PDC transmit */
+		UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
+	}
+	/* Enable interrupts */
+	UART_PUT_IER(port, atmel_port->tx_done_mask);
+}
+
+/*
+ * start receiving - port is in process of being opened.
+ */
+static void atmel_start_rx(struct uart_port *port)
+{
+	UART_PUT_CR(port, ATMEL_US_RSTSTA);  /* reset status and receiver */
+
+	if (atmel_use_dma_rx(port)) {
+		/* enable PDC controller */
+		UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+			port->read_status_mask);
+		UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
+	} else {
+		UART_PUT_IER(port, ATMEL_US_RXRDY);
+	}
+}
+
+/*
+ * Stop receiving - port is in process of being closed.
+ */
+static void atmel_stop_rx(struct uart_port *port)
+{
+	if (atmel_use_dma_rx(port)) {
+		/* disable PDC receive */
+		UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
+		UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
+			port->read_status_mask);
+	} else {
+		UART_PUT_IDR(port, ATMEL_US_RXRDY);
+	}
+}
+
+/*
+ * Enable modem status interrupts
+ */
+static void atmel_enable_ms(struct uart_port *port)
+{
+	UART_PUT_IER(port, ATMEL_US_RIIC | ATMEL_US_DSRIC
+			| ATMEL_US_DCDIC | ATMEL_US_CTSIC);
+}
+
+/*
+ * Control the transmission of a break signal
+ */
+static void atmel_break_ctl(struct uart_port *port, int break_state)
+{
+	if (break_state != 0)
+		UART_PUT_CR(port, ATMEL_US_STTBRK);	/* start break */
+	else
+		UART_PUT_CR(port, ATMEL_US_STPBRK);	/* stop break */
+}
+
+/*
+ * Stores the incoming character in the ring buffer
+ */
+static void
+atmel_buffer_rx_char(struct uart_port *port, unsigned int status,
+		     unsigned int ch)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	struct circ_buf *ring = &atmel_port->rx_ring;
+	struct atmel_uart_char *c;
+
+	if (!CIRC_SPACE(ring->head, ring->tail, ATMEL_SERIAL_RINGSIZE))
+		/* Buffer overflow, ignore char */
+		return;
+
+	c = &((struct atmel_uart_char *)ring->buf)[ring->head];
+	c->status	= status;
+	c->ch		= ch;
+
+	/* Make sure the character is stored before we update head. */
+	smp_wmb();
+
+	ring->head = (ring->head + 1) & (ATMEL_SERIAL_RINGSIZE - 1);
+}
+
+/*
+ * Deal with parity, framing and overrun errors.
+ */
+static void atmel_pdc_rxerr(struct uart_port *port, unsigned int status)
+{
+	/* clear error */
+	UART_PUT_CR(port, ATMEL_US_RSTSTA);
+
+	if (status & ATMEL_US_RXBRK) {
+		/* ignore side-effect */
+		status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);
+		port->icount.brk++;
+	}
+	if (status & ATMEL_US_PARE)
+		port->icount.parity++;
+	if (status & ATMEL_US_FRAME)
+		port->icount.frame++;
+	if (status & ATMEL_US_OVRE)
+		port->icount.overrun++;
+}
+
+/*
+ * Characters received (called from interrupt handler)
+ */
+static void atmel_rx_chars(struct uart_port *port)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	unsigned int status, ch;
+
+	status = UART_GET_CSR(port);
+	while (status & ATMEL_US_RXRDY) {
+		ch = UART_GET_CHAR(port);
+
+		/*
+		 * 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)
+			     || atmel_port->break_active)) {
+
+			/* clear error */
+			UART_PUT_CR(port, ATMEL_US_RSTSTA);
+
+			if (status & ATMEL_US_RXBRK
+			    && !atmel_port->break_active) {
+				atmel_port->break_active = 1;
+				UART_PUT_IER(port, ATMEL_US_RXBRK);
+			} else {
+				/*
+				 * This is either the end-of-break
+				 * condition or we've received at
+				 * least one character without RXBRK
+				 * being set. In both cases, the next
+				 * RXBRK will indicate start-of-break.
+				 */
+				UART_PUT_IDR(port, ATMEL_US_RXBRK);
+				status &= ~ATMEL_US_RXBRK;
+				atmel_port->break_active = 0;
+			}
+		}
+
+		atmel_buffer_rx_char(port, status, ch);
+		status = UART_GET_CSR(port);
+	}
+
+	tasklet_schedule(&atmel_port->tasklet);
+}
+
+/*
+ * Transmit characters (called from tasklet with TXRDY interrupt
+ * disabled)
+ */
+static void atmel_tx_chars(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+	if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
+		UART_PUT_CHAR(port, port->x_char);
+		port->icount.tx++;
+		port->x_char = 0;
+	}
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+		return;
+
+	while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
+		UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (!uart_circ_empty(xmit))
+		/* Enable interrupts */
+		UART_PUT_IER(port, atmel_port->tx_done_mask);
+}
+
+/*
+ * receive interrupt handler.
+ */
+static void
+atmel_handle_receive(struct uart_port *port, unsigned int pending)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+
+	if (atmel_use_dma_rx(port)) {
+		/*
+		 * PDC receive. Just schedule the tasklet and let it
+		 * figure out the details.
+		 *
+		 * TODO: We're not handling error flags correctly at
+		 * the moment.
+		 */
+		if (pending & (ATMEL_US_ENDRX | ATMEL_US_TIMEOUT)) {
+			UART_PUT_IDR(port, (ATMEL_US_ENDRX
+						| ATMEL_US_TIMEOUT));
+			tasklet_schedule(&atmel_port->tasklet);
+		}
+
+		if (pending & (ATMEL_US_RXBRK | ATMEL_US_OVRE |
+				ATMEL_US_FRAME | ATMEL_US_PARE))
+			atmel_pdc_rxerr(port, pending);
+	}
+
+	/* Interrupt receive */
+	if (pending & ATMEL_US_RXRDY)
+		atmel_rx_chars(port);
+	else if (pending & ATMEL_US_RXBRK) {
+		/*
+		 * End of break detected. If it came along with a
+		 * character, atmel_rx_chars will handle it.
+		 */
+		UART_PUT_CR(port, ATMEL_US_RSTSTA);
+		UART_PUT_IDR(port, ATMEL_US_RXBRK);
+		atmel_port->break_active = 0;
+	}
+}
+
+/*
+ * 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;
+}
+
+/*
+ * Called from tasklet with ENDTX and TXBUFE interrupts disabled.
+ */
+static void atmel_tx_dma(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) {
+			/* 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 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.tty);
+	spin_lock(&port->lock);
+}
+
+static void atmel_rx_from_dma(struct uart_port *port)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	struct tty_struct *tty = port->state->port.tty;
+	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(tty, 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(tty);
+	spin_lock(&port->lock);
+
+	UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
+}
+
+/*
+ * 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);
+
+	if (atmel_use_dma_tx(port))
+		atmel_tx_dma(port);
+	else
+		atmel_tx_chars(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;
+	}
+
+	if (atmel_use_dma_rx(port))
+		atmel_rx_from_dma(port);
+	else
+		atmel_rx_from_ring(port);
+
+	spin_unlock(&port->lock);
+}
+
+/*
+ * 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_use_dma_rx(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);
+				}
+				free_irq(port->irq, port);
+				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);
+	}
+	if (atmel_use_dma_tx(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;
+	}
+
+	/*
+	 * 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_dma_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 {
+		/* 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_use_dma_rx(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);
+		}
+	}
+	if (atmel_use_dma_tx(port)) {
+		struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
+
+		dma_unmap_single(port->dev,
+				 pdc->dma_addr,
+				 pdc->dma_size,
+				 DMA_TO_DEVICE);
+	}
+
+	/*
+	 * 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_dma_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_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(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)
+