1 files changed, 662 insertions, 18 deletions

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 107e80722575..af821a908720 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -28,6 +28,9 @@
 #define SUPPORT_SYSRQ
 #endif
 
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/ioport.h>
 #include <linux/io.h>
@@ -78,6 +81,10 @@ static void dbg(const char *fmt, ...)
 #define S3C24XX_SERIAL_MAJOR	204
 #define S3C24XX_SERIAL_MINOR	64
 
+#define S3C24XX_TX_PIO			1
+#define S3C24XX_TX_DMA			2
+#define S3C24XX_RX_PIO			1
+#define S3C24XX_RX_DMA			2
 /* macros to change one thing to another */
 
 #define tx_enabled(port) ((port)->unused[0])
@@ -154,39 +161,272 @@ static void s3c24xx_serial_rx_disable(struct uart_port *port)
 static void s3c24xx_serial_stop_tx(struct uart_port *port)
 {
 	struct s3c24xx_uart_port *ourport = to_ourport(port);
+	struct s3c24xx_uart_dma *dma = ourport->dma;
+	struct circ_buf *xmit = &port->state->xmit;
+	struct dma_tx_state state;
+	int count;
 
-	if (tx_enabled(port)) {
-		if (s3c24xx_serial_has_interrupt_mask(port))
-			__set_bit(S3C64XX_UINTM_TXD,
-				portaddrl(port, S3C64XX_UINTM));
-		else
-			disable_irq_nosync(ourport->tx_irq);
-		tx_enabled(port) = 0;
-		if (port->flags & UPF_CONS_FLOW)
-			s3c24xx_serial_rx_enable(port);
+	if (!tx_enabled(port))
+		return;
+
+	if (s3c24xx_serial_has_interrupt_mask(port))
+		__set_bit(S3C64XX_UINTM_TXD,
+			portaddrl(port, S3C64XX_UINTM));
+	else
+		disable_irq_nosync(ourport->tx_irq);
+
+	if (dma && dma->tx_chan && ourport->tx_in_progress == S3C24XX_TX_DMA) {
+		dmaengine_pause(dma->tx_chan);
+		dmaengine_tx_status(dma->tx_chan, dma->tx_cookie, &state);
+		dmaengine_terminate_all(dma->tx_chan);
+		dma_sync_single_for_cpu(ourport->port.dev,
+			dma->tx_transfer_addr, dma->tx_size, DMA_TO_DEVICE);
+		async_tx_ack(dma->tx_desc);
+		count = dma->tx_bytes_requested - state.residue;
+		xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
+		port->icount.tx += count;
 	}
+
+	tx_enabled(port) = 0;
+	ourport->tx_in_progress = 0;
+
+	if (port->flags & UPF_CONS_FLOW)
+		s3c24xx_serial_rx_enable(port);
+
+	ourport->tx_mode = 0;
 }
 
-static void s3c24xx_serial_start_tx(struct uart_port *port)
+static void s3c24xx_serial_start_next_tx(struct s3c24xx_uart_port *ourport);
+
+static void s3c24xx_serial_tx_dma_complete(void *args)
+{
+	struct s3c24xx_uart_port *ourport = args;
+	struct uart_port *port = &ourport->port;
+	struct circ_buf *xmit = &port->state->xmit;
+	struct s3c24xx_uart_dma *dma = ourport->dma;
+	struct dma_tx_state state;
+	unsigned long flags;
+	int count;
+
+
+	dmaengine_tx_status(dma->tx_chan, dma->tx_cookie, &state);
+	count = dma->tx_bytes_requested - state.residue;
+	async_tx_ack(dma->tx_desc);
+
+	dma_sync_single_for_cpu(ourport->port.dev, dma->tx_transfer_addr,
+				dma->tx_size, DMA_TO_DEVICE);
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
+	port->icount.tx += count;
+	ourport->tx_in_progress = 0;
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	s3c24xx_serial_start_next_tx(ourport);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void enable_tx_dma(struct s3c24xx_uart_port *ourport)
+{
+	struct uart_port *port = &ourport->port;
+	u32 ucon;
+
+	/* Mask Tx interrupt */
+	if (s3c24xx_serial_has_interrupt_mask(port))
+		__set_bit(S3C64XX_UINTM_TXD,
+			  portaddrl(port, S3C64XX_UINTM));
+	else
+		disable_irq_nosync(ourport->tx_irq);
+
+	/* Enable tx dma mode */
+	ucon = rd_regl(port, S3C2410_UCON);
+	ucon &= ~(S3C64XX_UCON_TXBURST_MASK | S3C64XX_UCON_TXMODE_MASK);
+	ucon |= (dma_get_cache_alignment() >= 16) ?
+		S3C64XX_UCON_TXBURST_16 : S3C64XX_UCON_TXBURST_1;
+	ucon |= S3C64XX_UCON_TXMODE_DMA;
+	wr_regl(port,  S3C2410_UCON, ucon);
+
+	ourport->tx_mode = S3C24XX_TX_DMA;
+}
+
+static void enable_tx_pio(struct s3c24xx_uart_port *ourport)
+{
+	struct uart_port *port = &ourport->port;
+	u32 ucon, ufcon;
+
+	/* Set ufcon txtrig */
+	ourport->tx_in_progress = S3C24XX_TX_PIO;
+	ufcon = rd_regl(port, S3C2410_UFCON);
+	wr_regl(port,  S3C2410_UFCON, ufcon);
+
+	/* Enable tx pio mode */
+	ucon = rd_regl(port, S3C2410_UCON);
+	ucon &= ~(S3C64XX_UCON_TXMODE_MASK);
+	ucon |= S3C64XX_UCON_TXMODE_CPU;
+	wr_regl(port,  S3C2410_UCON, ucon);
+
+	/* Unmask Tx interrupt */
+	if (s3c24xx_serial_has_interrupt_mask(port))
+		__clear_bit(S3C64XX_UINTM_TXD,
+			    portaddrl(port, S3C64XX_UINTM));
+	else
+		enable_irq(ourport->tx_irq);
+
+	ourport->tx_mode = S3C24XX_TX_PIO;
+}
+
+static void s3c24xx_serial_start_tx_pio(struct s3c24xx_uart_port *ourport)
+{
+	if (ourport->tx_mode != S3C24XX_TX_PIO)
+		enable_tx_pio(ourport);
+}
+
+static int s3c24xx_serial_start_tx_dma(struct s3c24xx_uart_port *ourport,
+				      unsigned int count)
+{
+	struct uart_port *port = &ourport->port;
+	struct circ_buf *xmit = &port->state->xmit;
+	struct s3c24xx_uart_dma *dma = ourport->dma;
+
+
+	if (ourport->tx_mode != S3C24XX_TX_DMA)
+		enable_tx_dma(ourport);
+
+	while (xmit->tail & (dma_get_cache_alignment() - 1)) {
+		if (rd_regl(port, S3C2410_UFSTAT) & ourport->info->tx_fifofull)
+			return 0;
+		wr_regb(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+		count--;
+	}
+
+	dma->tx_size = count & ~(dma_get_cache_alignment() - 1);
+	dma->tx_transfer_addr = dma->tx_addr + xmit->tail;
+
+	dma_sync_single_for_device(ourport->port.dev, dma->tx_transfer_addr,
+				dma->tx_size, DMA_TO_DEVICE);
+
+	dma->tx_desc = dmaengine_prep_slave_single(dma->tx_chan,
+				dma->tx_transfer_addr, dma->tx_size,
+				DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT);
+	if (!dma->tx_desc) {
+		dev_err(ourport->port.dev, "Unable to get desc for Tx\n");
+		return -EIO;
+	}
+
+	dma->tx_desc->callback = s3c24xx_serial_tx_dma_complete;
+	dma->tx_desc->callback_param = ourport;
+	dma->tx_bytes_requested = dma->tx_size;
+
+	ourport->tx_in_progress = S3C24XX_TX_DMA;
+	dma->tx_cookie = dmaengine_submit(dma->tx_desc);
+	dma_async_issue_pending(dma->tx_chan);
+	return 0;
+}
+
+static void s3c24xx_serial_start_next_tx(struct s3c24xx_uart_port *ourport)
+{
+	struct uart_port *port = &ourport->port;
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned long count;
+
+	/* Get data size up to the end of buffer */
+	count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+
+	if (!count) {
+		s3c24xx_serial_stop_tx(port);
+		return;
+	}
+
+	if (!ourport->dma || !ourport->dma->tx_chan || count < port->fifosize)
+		s3c24xx_serial_start_tx_pio(ourport);
+	else
+		s3c24xx_serial_start_tx_dma(ourport, count);
+}
+
+void s3c24xx_serial_start_tx(struct uart_port *port)
 {
 	struct s3c24xx_uart_port *ourport = to_ourport(port);
+	struct circ_buf *xmit = &port->state->xmit;
 
 	if (!tx_enabled(port)) {
 		if (port->flags & UPF_CONS_FLOW)
 			s3c24xx_serial_rx_disable(port);
 
-		if (s3c24xx_serial_has_interrupt_mask(port))
-			__clear_bit(S3C64XX_UINTM_TXD,
-				portaddrl(port, S3C64XX_UINTM));
-		else
-			enable_irq(ourport->tx_irq);
 		tx_enabled(port) = 1;
+		if (!ourport->dma || !ourport->dma->tx_chan)
+			s3c24xx_serial_start_tx_pio(ourport);
+	}
+
+	if (ourport->dma && ourport->dma->tx_chan) {
+		if (!uart_circ_empty(xmit) && !ourport->tx_in_progress)
+			s3c24xx_serial_start_next_tx(ourport);
+	}
+}
+
+static void s3c24xx_uart_copy_rx_to_tty(struct s3c24xx_uart_port *ourport,
+		struct tty_port *tty, int count)
+{
+	struct s3c24xx_uart_dma *dma = ourport->dma;
+	int copied;
+
+	if (!count)
+		return;
+
+	dma_sync_single_for_cpu(ourport->port.dev, dma->rx_addr,
+				dma->rx_size, DMA_FROM_DEVICE);
+
+	ourport->port.icount.rx += count;
+	if (!tty) {
+		dev_err(ourport->port.dev, "No tty port\n");
+		return;
+	}
+	copied = tty_insert_flip_string(tty,
+			((unsigned char *)(ourport->dma->rx_buf)), count);
+	if (copied != count) {
+		WARN_ON(1);
+		dev_err(ourport->port.dev, "RxData copy to tty layer failed\n");
+	}
+}
+
+static int s3c24xx_serial_rx_fifocnt(struct s3c24xx_uart_port *ourport,
+				     unsigned long ufstat);
+
+static void uart_rx_drain_fifo(struct s3c24xx_uart_port *ourport)
+{
+	struct uart_port *port = &ourport->port;
+	struct tty_port *tty = &port->state->port;
+	unsigned int ch, ufstat;
+	unsigned int count;
+
+	ufstat = rd_regl(port, S3C2410_UFSTAT);
+	count = s3c24xx_serial_rx_fifocnt(ourport, ufstat);
+
+	if (!count)
+		return;
+
+	while (count-- > 0) {
+		ch = rd_regb(port, S3C2410_URXH);
+
+		ourport->port.icount.rx++;
+		tty_insert_flip_char(tty, ch, TTY_NORMAL);
 	}
+
+	tty_flip_buffer_push(tty);
 }
 
 static void s3c24xx_serial_stop_rx(struct uart_port *port)
 {
 	struct s3c24xx_uart_port *ourport = to_ourport(port);
+	struct s3c24xx_uart_dma *dma = ourport->dma;
+	struct tty_port *t = &port->state->port;
+	struct dma_tx_state state;
+	enum dma_status dma_status;
+	unsigned int received;
 
 	if (rx_enabled(port)) {
 		dbg("s3c24xx_serial_stop_rx: port=%p\n", port);
@@ -197,6 +437,17 @@ static void s3c24xx_serial_stop_rx(struct uart_port *port)
 			disable_irq_nosync(ourport->rx_irq);
 		rx_enabled(port) = 0;
 	}
+	if (dma && dma->rx_chan) {
+		dmaengine_pause(dma->tx_chan);
+		dma_status = dmaengine_tx_status(dma->rx_chan,
+				dma->rx_cookie, &state);
+		if (dma_status == DMA_IN_PROGRESS ||
+			dma_status == DMA_PAUSED) {
+			received = dma->rx_bytes_requested - state.residue;
+			dmaengine_terminate_all(dma->rx_chan);
+			s3c24xx_uart_copy_rx_to_tty(ourport, t, received);
+		}
+	}
 }
 
 static inline struct s3c24xx_uart_info
@@ -228,12 +479,157 @@ static int s3c24xx_serial_rx_fifocnt(struct s3c24xx_uart_port *ourport,
 	return (ufstat & info->rx_fifomask) >> info->rx_fifoshift;
 }
 
+static void s3c64xx_start_rx_dma(struct s3c24xx_uart_port *ourport);
+static void s3c24xx_serial_rx_dma_complete(void *args)
+{
+	struct s3c24xx_uart_port *ourport = args;
+	struct uart_port *port = &ourport->port;
+
+	struct s3c24xx_uart_dma *dma = ourport->dma;
+	struct tty_port *t = &port->state->port;
+	struct tty_struct *tty = tty_port_tty_get(&ourport->port.state->port);
+
+	struct dma_tx_state state;
+	unsigned long flags;
+	int received;
+
+	dmaengine_tx_status(dma->rx_chan,  dma->rx_cookie, &state);
+	received  = dma->rx_bytes_requested - state.residue;
+	async_tx_ack(dma->rx_desc);
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	if (received)
+		s3c24xx_uart_copy_rx_to_tty(ourport, t, received);
+
+	if (tty) {
+		tty_flip_buffer_push(t);
+		tty_kref_put(tty);
+	}
+
+	s3c64xx_start_rx_dma(ourport);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void s3c64xx_start_rx_dma(struct s3c24xx_uart_port *ourport)
+{
+	struct s3c24xx_uart_dma *dma = ourport->dma;
+
+	dma_sync_single_for_device(ourport->port.dev, dma->rx_addr,
+				dma->rx_size, DMA_FROM_DEVICE);
+
+	dma->rx_desc = dmaengine_prep_slave_single(dma->rx_chan,
+				dma->rx_addr, dma->rx_size, DMA_DEV_TO_MEM,
+				DMA_PREP_INTERRUPT);
+	if (!dma->rx_desc) {
+		dev_err(ourport->port.dev, "Unable to get desc for Rx\n");
+		return;
+	}
+
+	dma->rx_desc->callback = s3c24xx_serial_rx_dma_complete;
+	dma->rx_desc->callback_param = ourport;
+	dma->rx_bytes_requested = dma->rx_size;
+
+	dma->rx_cookie = dmaengine_submit(dma->rx_desc);
+	dma_async_issue_pending(dma->rx_chan);
+}
 
 /* ? - where has parity gone?? */
 #define S3C2410_UERSTAT_PARITY (0x1000)
 
-static irqreturn_t
-s3c24xx_serial_rx_chars(int irq, void *dev_id)
+static void enable_rx_dma(struct s3c24xx_uart_port *ourport)
+{
+	struct uart_port *port = &ourport->port;
+	unsigned int ucon;
+
+	/* set Rx mode to DMA mode */
+	ucon = rd_regl(port, S3C2410_UCON);
+	ucon &= ~(S3C64XX_UCON_RXBURST_MASK |
+			S3C64XX_UCON_TIMEOUT_MASK |
+			S3C64XX_UCON_EMPTYINT_EN |
+			S3C64XX_UCON_DMASUS_EN |
+			S3C64XX_UCON_TIMEOUT_EN |
+			S3C64XX_UCON_RXMODE_MASK);
+	ucon |= S3C64XX_UCON_RXBURST_16 |
+			0xf << S3C64XX_UCON_TIMEOUT_SHIFT |
+			S3C64XX_UCON_EMPTYINT_EN |
+			S3C64XX_UCON_TIMEOUT_EN |
+			S3C64XX_UCON_RXMODE_DMA;
+	wr_regl(port, S3C2410_UCON, ucon);
+
+	ourport->rx_mode = S3C24XX_RX_DMA;
+}
+
+static void enable_rx_pio(struct s3c24xx_uart_port *ourport)
+{
+	struct uart_port *port = &ourport->port;
+	unsigned int ucon;
+
+	/* set Rx mode to DMA mode */
+	ucon = rd_regl(port, S3C2410_UCON);
+	ucon &= ~(S3C64XX_UCON_TIMEOUT_MASK |
+			S3C64XX_UCON_EMPTYINT_EN |
+			S3C64XX_UCON_DMASUS_EN |
+			S3C64XX_UCON_TIMEOUT_EN |
+			S3C64XX_UCON_RXMODE_MASK);
+	ucon |= 0xf << S3C64XX_UCON_TIMEOUT_SHIFT |
+			S3C64XX_UCON_TIMEOUT_EN |
+			S3C64XX_UCON_RXMODE_CPU;
+	wr_regl(port, S3C2410_UCON, ucon);
+
+	ourport->rx_mode = S3C24XX_RX_PIO;
+}
+
+static irqreturn_t s3c24xx_serial_rx_chars_dma(int irq, void *dev_id)
+{
+	unsigned int utrstat, ufstat, received;
+	struct s3c24xx_uart_port *ourport = dev_id;
+	struct uart_port *port = &ourport->port;
+	struct s3c24xx_uart_dma *dma = ourport->dma;
+	struct tty_struct *tty = tty_port_tty_get(&ourport->port.state->port);
+	struct tty_port *t = &port->state->port;
+	unsigned long flags;
+	struct dma_tx_state state;
+
+	utrstat = rd_regl(port, S3C2410_UTRSTAT);
+	ufstat = rd_regl(port, S3C2410_UFSTAT);
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	if (!(utrstat & S3C2410_UTRSTAT_TIMEOUT)) {
+		s3c64xx_start_rx_dma(ourport);
+		if (ourport->rx_mode == S3C24XX_RX_PIO)
+			enable_rx_dma(ourport);
+		goto finish;
+	}
+
+	if (ourport->rx_mode == S3C24XX_RX_DMA) {
+		dmaengine_pause(dma->rx_chan);
+		dmaengine_tx_status(dma->rx_chan, dma->rx_cookie, &state);
+		dmaengine_terminate_all(dma->rx_chan);
+		received = dma->rx_bytes_requested - state.residue;
+		s3c24xx_uart_copy_rx_to_tty(ourport, t, received);
+
+		enable_rx_pio(ourport);
+	}
+
+	uart_rx_drain_fifo(ourport);
+
+	if (tty) {
+		tty_flip_buffer_push(t);
+		tty_kref_put(tty);
+	}
+
+	wr_regl(port, S3C2410_UTRSTAT, S3C2410_UTRSTAT_TIMEOUT);
+
+finish:
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t s3c24xx_serial_rx_chars_pio(int irq, void *dev_id)
 {
 	struct s3c24xx_uart_port *ourport = dev_id;
 	struct uart_port *port = &ourport->port;
@@ -324,16 +720,33 @@ out:
 	return IRQ_HANDLED;
 }
 
+
+static irqreturn_t s3c24xx_serial_rx_chars(int irq, void *dev_id)
+{
+	struct s3c24xx_uart_port *ourport = dev_id;
+
+	if (ourport->dma && ourport->dma->rx_chan)
+		return s3c24xx_serial_rx_chars_dma(irq, dev_id);
+	return s3c24xx_serial_rx_chars_pio(irq, dev_id);
+}
+
 static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
 {
 	struct s3c24xx_uart_port *ourport = id;
 	struct uart_port *port = &ourport->port;
 	struct circ_buf *xmit = &port->state->xmit;
 	unsigned long flags;
-	int count = port->fifosize;
+	int count;
 
 	spin_lock_irqsave(&port->lock, flags);
 
+	count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+
+	if (ourport->dma && ourport->dma->tx_chan && count >= port->fifosize) {
+		s3c24xx_serial_start_tx_dma(ourport, count);
+		goto out;
+	}
+
 	if (port->x_char) {
 		wr_regb(port, S3C2410_UTXH, port->x_char);
 		port->icount.tx++;
@@ -352,6 +765,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
 
 	/* try and drain the buffer... */
 
+	count = port->fifosize;
 	while (!uart_circ_empty(xmit) && count-- > 0) {
 		if (rd_regl(port, S3C2410_UFSTAT) & ourport->info->tx_fifofull)
 			break;
@@ -453,6 +867,93 @@ static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state)
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
+static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
+{
+	struct s3c24xx_uart_dma	*dma = p->dma;
+	dma_cap_mask_t mask;
+	unsigned long flags;
+
+	/* Default slave configuration parameters */
+	dma->rx_conf.direction		= DMA_DEV_TO_MEM;
+	dma->rx_conf.src_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma->rx_conf.src_addr		= p->port.mapbase + S3C2410_URXH;
+	dma->rx_conf.src_maxburst	= 16;
+
+	dma->tx_conf.direction		= DMA_MEM_TO_DEV;
+	dma->tx_conf.dst_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma->tx_conf.dst_addr		= p->port.mapbase + S3C2410_UTXH;
+	if (dma_get_cache_alignment() >= 16)
+		dma->tx_conf.dst_maxburst = 16;
+	else
+		dma->tx_conf.dst_maxburst = 1;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
+
+	dma->rx_chan = dma_request_slave_channel_compat(mask, dma->fn,
+					dma->rx_param, p->port.dev, "rx");
+	if (!dma->rx_chan)
+		return -ENODEV;
+
+	dmaengine_slave_config(dma->rx_chan, &dma->rx_conf);
+
+	dma->tx_chan = dma_request_slave_channel_compat(mask, dma->fn,
+					dma->tx_param, p->port.dev, "tx");
+	if (!dma->tx_chan) {
+		dma_release_channel(dma->rx_chan);
+		return -ENODEV;
+	}
+
+	dmaengine_slave_config(dma->tx_chan, &dma->tx_conf);
+
+	/* RX buffer */
+	dma->rx_size = PAGE_SIZE;
+
+	dma->rx_buf = kmalloc(dma->rx_size, GFP_KERNEL);
+
+	if (!dma->rx_buf) {
+		dma_release_channel(dma->rx_chan);
+		dma_release_channel(dma->tx_chan);
+		return -ENOMEM;
+	}
+
+	dma->rx_addr = dma_map_single(dma->rx_chan->device->dev, dma->rx_buf,
+				dma->rx_size, DMA_FROM_DEVICE);
+
+	spin_lock_irqsave(&p->port.lock, flags);
+
+	/* TX buffer */
+	dma->tx_addr = dma_map_single(dma->tx_chan->device->dev,
+				p->port.state->xmit.buf,
+				UART_XMIT_SIZE, DMA_TO_DEVICE);
+
+	spin_unlock_irqrestore(&p->port.lock, flags);
+
+	return 0;
+}
+
+static void s3c24xx_serial_release_dma(struct s3c24xx_uart_port *p)
+{
+	struct s3c24xx_uart_dma	*dma = p->dma;
+
+	if (dma->rx_chan) {
+		dmaengine_terminate_all(dma->rx_chan);
+		dma_unmap_single(dma->rx_chan->device->dev, dma->rx_addr,
+				dma->rx_size, DMA_FROM_DEVICE);
+		kfree(dma->rx_buf);
+		dma_release_channel(dma->rx_chan);
+		dma->rx_chan = NULL;
+	}
+
+	if (dma->tx_chan) {
+		dmaengine_terminate_all(dma->tx_chan);
+		dma_unmap_single(dma->tx_chan->device->dev, dma->tx_addr,
+				UART_XMIT_SIZE, DMA_TO_DEVICE);
+		dma_release_channel(dma->tx_chan);
+		dma->tx_chan = NULL;
+	}
+}
+
 static void s3c24xx_serial_shutdown(struct uart_port *port)
 {
 	struct s3c24xx_uart_port *ourport = to_ourport(port);
@@ -478,6 +979,11 @@ static void s3c24xx_serial_shutdown(struct uart_port *port)
 		wr_regl(port, S3C64XX_UINTP, 0xf);
 		wr_regl(port, S3C64XX_UINTM, 0xf);
 	}
+
+	if (ourport->dma)
+		s3c24xx_serial_release_dma(ourport);
+
+	ourport->tx_in_progress = 0;
 }
 
 static int s3c24xx_serial_startup(struct uart_port *port)
@@ -529,12 +1035,21 @@ err:
 static int s3c64xx_serial_startup(struct uart_port *port)
 {
 	struct s3c24xx_uart_port *ourport = to_ourport(port);
+	unsigned long flags;
+	unsigned int ufcon;
 	int ret;
 
 	dbg("s3c64xx_serial_startup: port=%p (%08llx,%p)\n",
 	    port, (unsigned long long)port->mapbase, port->membase);
 
 	wr_regl(port, S3C64XX_UINTM, 0xf);
+	if (ourport->dma) {
+		ret = s3c24xx_serial_request_dma(ourport);
+		if (ret < 0) {
+			dev_warn(port->dev, "DMA request failed\n");
+			return ret;
+		}
+	}
 
 	ret = request_irq(port->irq, s3c64xx_serial_handle_irq, IRQF_SHARED,
 			  s3c24xx_serial_portname(port), ourport);
@@ -549,8 +1064,20 @@ static int s3c64xx_serial_startup(struct uart_port *port)
 	tx_enabled(port) = 0;
 	ourport->tx_claimed = 1;
 
+	spin_lock_irqsave(&port->lock, flags);
+
+	ufcon = rd_regl(port, S3C2410_UFCON);
+	ufcon |= S3C2410_UFCON_RESETRX | S3C2410_UFCON_RESETTX |
+			S5PV210_UFCON_RXTRIG8;
+	wr_regl(port, S3C2410_UFCON, ufcon);
+
+	enable_rx_pio(ourport);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
 	/* Enable Rx Interrupt */
 	__clear_bit(S3C64XX_UINTM_RXD, portaddrl(port, S3C64XX_UINTM));
+
 	dbg("s3c64xx_serial_startup ok\n");
 	return ret;
 }
@@ -1209,6 +1736,18 @@ static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport,
 	ret = platform_get_irq(platdev, 1);
 	if (ret > 0)
 		ourport->tx_irq = ret;
+	/*
+	 * DMA is currently supported only on DT platforms, if DMA properties
+	 * are specified.
+	 */
+	if (platdev->dev.of_node && of_find_property(platdev->dev.of_node,
+						     "dmas", NULL)) {
+		ourport->dma = devm_kzalloc(port->dev,
+					    sizeof(*ourport->dma),
+					    GFP_KERNEL);
+		if (!ourport->dma)
+			return -ENOMEM;
+	}
 
 	ourport->clk	= clk_get(&platdev->dev, "uart");
 	if (IS_ERR(ourport->clk)) {
@@ -1857,6 +2396,111 @@ static struct platform_driver samsung_serial_driver = {
 
 module_platform_driver(samsung_serial_driver);
 
+#ifdef CONFIG_SERIAL_SAMSUNG_CONSOLE
+/*
+ * Early console.
+ */
+
+struct samsung_early_console_data {
+	u32 txfull_mask;
+};
+
+static void samsung_early_busyuart(struct uart_port *port)
+{
+	while (!(readl(port->membase + S3C2410_UTRSTAT) & S3C2410_UTRSTAT_TXFE))
+		;
+}
+
+static void samsung_early_busyuart_fifo(struct uart_port *port)
+{
+	struct samsung_early_console_data *data = port->private_data;
+
+	while (readl(port->membase + S3C2410_UFSTAT) & data->txfull_mask)
+		;
+}
+
+static void samsung_early_putc(struct uart_port *port, int c)
+{
+	if (readl(port->membase + S3C2410_UFCON) & S3C2410_UFCON_FIFOMODE)
+		samsung_early_busyuart_fifo(port);
+	else
+		samsung_early_busyuart(port);
+
+	writeb(c, port->membase + S3C2410_UTXH);
+}
+
+static void samsung_early_write(struct console *con, const char *s, unsigned n)
+{
+	struct earlycon_device *dev = con->data;
+
+	uart_console_write(&dev->port, s, n, samsung_early_putc);
+}
+
+static int __init samsung_early_console_setup(struct earlycon_device *device,
+					      const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	device->con->write = samsung_early_write;
+	return 0;
+}
+
+/* S3C2410 */
+static struct samsung_early_console_data s3c2410_early_console_data = {
+	.txfull_mask = S3C2410_UFSTAT_TXFULL,
+};
+
+static int __init s3c2410_early_console_setup(struct earlycon_device *device,
+					      const char *opt)
+{
+	device->port.private_data = &s3c2410_early_console_data;
+	return samsung_early_console_setup(device, opt);
+}
+OF_EARLYCON_DECLARE(s3c2410, "samsung,s3c2410-uart",
+			s3c2410_early_console_setup);
+EARLYCON_DECLARE(s3c2410, s3c2410_early_console_setup);
+
+/* S3C2412, S3C2440, S3C64xx */
+static struct samsung_early_console_data s3c2440_early_console_data = {
+	.txfull_mask = S3C2440_UFSTAT_TXFULL,
+};
+
+static int __init s3c2440_early_console_setup(struct earlycon_device *device,
+					      const char *opt)
+{
+	device->port.private_data = &s3c2440_early_console_data;
+	return samsung_early_console_setup(device, opt);
+}
+OF_EARLYCON_DECLARE(s3c2412, "samsung,s3c2412-uart",
+			s3c2440_early_console_setup);
+OF_EARLYCON_DECLARE(s3c2440, "samsung,s3c2440-uart",
+			s3c2440_early_console_setup);
+OF_EARLYCON_DECLARE(s3c6400, "samsung,s3c6400-uart",
+			s3c2440_early_console_setup);
+EARLYCON_DECLARE(s3c2412, s3c2440_early_console_setup);
+EARLYCON_DECLARE(s3c2440, s3c2440_early_console_setup);
+EARLYCON_DECLARE(s3c6400, s3c2440_early_console_setup);
+
+/* S5PV210, EXYNOS */
+static struct samsung_early_console_data s5pv210_early_console_data = {
+	.txfull_mask = S5PV210_UFSTAT_TXFULL,
+};
+
+static int __init s5pv210_early_console_setup(struct earlycon_device *device,
+					      const char *opt)
+{
+	device->port.private_data = &s5pv210_early_console_data;
+	return samsung_early_console_setup(device, opt);
+}
+OF_EARLYCON_DECLARE(s5pv210, "samsung,s5pv210-uart",
+			s5pv210_early_console_setup);
+OF_EARLYCON_DECLARE(exynos4210, "samsung,exynos4210-uart",
+			s5pv210_early_console_setup);
+EARLYCON_DECLARE(s5pv210, s5pv210_early_console_setup);
+EARLYCON_DECLARE(exynos4210, s5pv210_early_console_setup);
+#endif
+
 MODULE_ALIAS("platform:samsung-uart");
 MODULE_DESCRIPTION("Samsung SoC Serial port driver");
 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");