Initial import

1 files changed, 2369 insertions, 0 deletions

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
new file mode 100644
index 000000000..763eb20fe
--- /dev/null
+++ b/drivers/tty/serial/amba-pl011.c
@@ -0,0 +1,2369 @@
+/*
+ *  Driver for AMBA serial ports
+ *
+ *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
+ *
+ *  Copyright 1999 ARM Limited
+ *  Copyright (C) 2000 Deep Blue Solutions Ltd.
+ *  Copyright (C) 2010 ST-Ericsson SA
+ *
+ * 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
+ *
+ * This is a generic driver for ARM AMBA-type serial ports.  They
+ * have a lot of 16550-like features, but are not register compatible.
+ * Note that although they do have CTS, DCD and DSR inputs, they do
+ * not have an RI input, nor do they have DTR or RTS outputs.  If
+ * required, these have to be supplied via some other means (eg, GPIO)
+ * and hooked into this driver.
+ */
+
+
+#if defined(CONFIG_SERIAL_AMBA_PL011_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
+#define SUPPORT_SYSRQ
+#endif
+
+#include <linux/module.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/device.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial_core.h>
+#include <linux/serial.h>
+#include <linux/amba/bus.h>
+#include <linux/amba/serial.h>
+#include <linux/clk.h>
+#include <linux/slab.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/scatterlist.h>
+#include <linux/delay.h>
+#include <linux/types.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/sizes.h>
+#include <linux/io.h>
+#include <linux/workqueue.h>
+
+#define UART_NR			14
+
+#define SERIAL_AMBA_MAJOR	204
+#define SERIAL_AMBA_MINOR	64
+#define SERIAL_AMBA_NR		UART_NR
+
+#define AMBA_ISR_PASS_LIMIT	256
+
+#define UART_DR_ERROR		(UART011_DR_OE|UART011_DR_BE|UART011_DR_PE|UART011_DR_FE)
+#define UART_DUMMY_DR_RX	(1 << 16)
+
+/* There is by now at least one vendor with differing details, so handle it */
+struct vendor_data {
+	unsigned int		ifls;
+	unsigned int		lcrh_tx;
+	unsigned int		lcrh_rx;
+	bool			oversampling;
+	bool			dma_threshold;
+	bool			cts_event_workaround;
+
+	unsigned int (*get_fifosize)(struct amba_device *dev);
+};
+
+static unsigned int get_fifosize_arm(struct amba_device *dev)
+{
+	return amba_rev(dev) < 3 ? 16 : 32;
+}
+
+static struct vendor_data vendor_arm = {
+	.ifls			= UART011_IFLS_RX4_8|UART011_IFLS_TX4_8,
+	.lcrh_tx		= UART011_LCRH,
+	.lcrh_rx		= UART011_LCRH,
+	.oversampling		= false,
+	.dma_threshold		= false,
+	.cts_event_workaround	= false,
+	.get_fifosize		= get_fifosize_arm,
+};
+
+static unsigned int get_fifosize_st(struct amba_device *dev)
+{
+	return 64;
+}
+
+static struct vendor_data vendor_st = {
+	.ifls			= UART011_IFLS_RX_HALF|UART011_IFLS_TX_HALF,
+	.lcrh_tx		= ST_UART011_LCRH_TX,
+	.lcrh_rx		= ST_UART011_LCRH_RX,
+	.oversampling		= true,
+	.dma_threshold		= true,
+	.cts_event_workaround	= true,
+	.get_fifosize		= get_fifosize_st,
+};
+
+/* Deals with DMA transactions */
+
+struct pl011_sgbuf {
+	struct scatterlist sg;
+	char *buf;
+};
+
+struct pl011_dmarx_data {
+	struct dma_chan		*chan;
+	struct completion	complete;
+	bool			use_buf_b;
+	struct pl011_sgbuf	sgbuf_a;
+	struct pl011_sgbuf	sgbuf_b;
+	dma_cookie_t		cookie;
+	bool			running;
+	struct timer_list	timer;
+	unsigned int last_residue;
+	unsigned long last_jiffies;
+	bool auto_poll_rate;
+	unsigned int poll_rate;
+	unsigned int poll_timeout;
+};
+
+struct pl011_dmatx_data {
+	struct dma_chan		*chan;
+	struct scatterlist	sg;
+	char			*buf;
+	bool			queued;
+};
+
+/*
+ * We wrap our port structure around the generic uart_port.
+ */
+struct uart_amba_port {
+	struct uart_port	port;
+	struct clk		*clk;
+	const struct vendor_data *vendor;
+	unsigned int		dmacr;		/* dma control reg */
+	unsigned int		im;		/* interrupt mask */
+	unsigned int		old_status;
+	unsigned int		fifosize;	/* vendor-specific */
+	unsigned int		lcrh_tx;	/* vendor-specific */
+	unsigned int		lcrh_rx;	/* vendor-specific */
+	unsigned int		old_cr;		/* state during shutdown */
+	struct delayed_work	tx_softirq_work;
+	bool			autorts;
+	unsigned int		tx_irq_seen;	/* 0=none, 1=1, 2=2 or more */
+	char			type[12];
+#ifdef CONFIG_DMA_ENGINE
+	/* DMA stuff */
+	bool			using_tx_dma;
+	bool			using_rx_dma;
+	struct pl011_dmarx_data dmarx;
+	struct pl011_dmatx_data	dmatx;
+	bool			dma_probed;
+#endif
+};
+
+/*
+ * Reads up to 256 characters from the FIFO or until it's empty and
+ * inserts them into the TTY layer. Returns the number of characters
+ * read from the FIFO.
+ */
+static int pl011_fifo_to_tty(struct uart_amba_port *uap)
+{
+	u16 status, ch;
+	unsigned int flag, max_count = 256;
+	int fifotaken = 0;
+
+	while (max_count--) {
+		status = readw(uap->port.membase + UART01x_FR);
+		if (status & UART01x_FR_RXFE)
+			break;
+
+		/* Take chars from the FIFO and update status */
+		ch = readw(uap->port.membase + UART01x_DR) |
+			UART_DUMMY_DR_RX;
+		flag = TTY_NORMAL;
+		uap->port.icount.rx++;
+		fifotaken++;
+
+		if (unlikely(ch & UART_DR_ERROR)) {
+			if (ch & UART011_DR_BE) {
+				ch &= ~(UART011_DR_FE | UART011_DR_PE);
+				uap->port.icount.brk++;
+				if (uart_handle_break(&uap->port))
+					continue;
+			} else if (ch & UART011_DR_PE)
+				uap->port.icount.parity++;
+			else if (ch & UART011_DR_FE)
+				uap->port.icount.frame++;
+			if (ch & UART011_DR_OE)
+				uap->port.icount.overrun++;
+
+			ch &= uap->port.read_status_mask;
+
+			if (ch & UART011_DR_BE)
+				flag = TTY_BREAK;
+			else if (ch & UART011_DR_PE)
+				flag = TTY_PARITY;
+			else if (ch & UART011_DR_FE)
+				flag = TTY_FRAME;
+		}
+
+		if (uart_handle_sysrq_char(&uap->port, ch & 255))
+			continue;
+
+		uart_insert_char(&uap->port, ch, UART011_DR_OE, ch, flag);
+	}
+
+	return fifotaken;
+}
+
+
+/*
+ * All the DMA operation mode stuff goes inside this ifdef.
+ * This assumes that you have a generic DMA device interface,
+ * no custom DMA interfaces are supported.
+ */
+#ifdef CONFIG_DMA_ENGINE
+
+#define PL011_DMA_BUFFER_SIZE PAGE_SIZE
+
+static int pl011_sgbuf_init(struct dma_chan *chan, struct pl011_sgbuf *sg,
+	enum dma_data_direction dir)
+{
+	dma_addr_t dma_addr;
+
+	sg->buf = dma_alloc_coherent(chan->device->dev,
+		PL011_DMA_BUFFER_SIZE, &dma_addr, GFP_KERNEL);
+	if (!sg->buf)
+		return -ENOMEM;
+
+	sg_init_table(&sg->sg, 1);
+	sg_set_page(&sg->sg, phys_to_page(dma_addr),
+		PL011_DMA_BUFFER_SIZE, offset_in_page(dma_addr));
+	sg_dma_address(&sg->sg) = dma_addr;
+	sg_dma_len(&sg->sg) = PL011_DMA_BUFFER_SIZE;
+
+	return 0;
+}
+
+static void pl011_sgbuf_free(struct dma_chan *chan, struct pl011_sgbuf *sg,
+	enum dma_data_direction dir)
+{
+	if (sg->buf) {
+		dma_free_coherent(chan->device->dev,
+			PL011_DMA_BUFFER_SIZE, sg->buf,
+			sg_dma_address(&sg->sg));
+	}
+}
+
+static void pl011_dma_probe(struct uart_amba_port *uap)
+{
+	/* DMA is the sole user of the platform data right now */
+	struct amba_pl011_data *plat = dev_get_platdata(uap->port.dev);
+	struct device *dev = uap->port.dev;
+	struct dma_slave_config tx_conf = {
+		.dst_addr = uap->port.mapbase + UART01x_DR,
+		.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+		.direction = DMA_MEM_TO_DEV,
+		.dst_maxburst = uap->fifosize >> 1,
+		.device_fc = false,
+	};
+	struct dma_chan *chan;
+	dma_cap_mask_t mask;
+
+	uap->dma_probed = true;
+	chan = dma_request_slave_channel_reason(dev, "tx");
+	if (IS_ERR(chan)) {
+		if (PTR_ERR(chan) == -EPROBE_DEFER) {
+			uap->dma_probed = false;
+			return;
+		}
+
+		/* We need platform data */
+		if (!plat || !plat->dma_filter) {
+			dev_info(uap->port.dev, "no DMA platform data\n");
+			return;
+		}
+
+		/* Try to acquire a generic DMA engine slave TX channel */
+		dma_cap_zero(mask);
+		dma_cap_set(DMA_SLAVE, mask);
+
+		chan = dma_request_channel(mask, plat->dma_filter,
+						plat->dma_tx_param);
+		if (!chan) {
+			dev_err(uap->port.dev, "no TX DMA channel!\n");
+			return;
+		}
+	}
+
+	dmaengine_slave_config(chan, &tx_conf);
+	uap->dmatx.chan = chan;
+
+	dev_info(uap->port.dev, "DMA channel TX %s\n",
+		 dma_chan_name(uap->dmatx.chan));
+
+	/* Optionally make use of an RX channel as well */
+	chan = dma_request_slave_channel(dev, "rx");
+
+	if (!chan && plat->dma_rx_param) {
+		chan = dma_request_channel(mask, plat->dma_filter, plat->dma_rx_param);
+
+		if (!chan) {
+			dev_err(uap->port.dev, "no RX DMA channel!\n");
+			return;
+		}
+	}
+
+	if (chan) {
+		struct dma_slave_config rx_conf = {
+			.src_addr = uap->port.mapbase + UART01x_DR,
+			.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
+			.direction = DMA_DEV_TO_MEM,
+			.src_maxburst = uap->fifosize >> 2,
+			.device_fc = false,
+		};
+		struct dma_slave_caps caps;
+
+		/*
+		 * Some DMA controllers provide information on their capabilities.
+		 * If the controller does, check for suitable residue processing
+		 * otherwise assime all is well.
+		 */
+		if (0 == dma_get_slave_caps(chan, &caps)) {
+			if (caps.residue_granularity ==
+					DMA_RESIDUE_GRANULARITY_DESCRIPTOR) {
+				dma_release_channel(chan);
+				dev_info(uap->port.dev,
+					"RX DMA disabled - no residue processing\n");
+				return;
+			}
+		}
+		dmaengine_slave_config(chan, &rx_conf);
+		uap->dmarx.chan = chan;
+
+		uap->dmarx.auto_poll_rate = false;
+		if (plat && plat->dma_rx_poll_enable) {
+			/* Set poll rate if specified. */
+			if (plat->dma_rx_poll_rate) {
+				uap->dmarx.auto_poll_rate = false;
+				uap->dmarx.poll_rate = plat->dma_rx_poll_rate;
+			} else {
+				/*
+				 * 100 ms defaults to poll rate if not
+				 * specified. This will be adjusted with
+				 * the baud rate at set_termios.
+				 */
+				uap->dmarx.auto_poll_rate = true;
+				uap->dmarx.poll_rate =  100;
+			}
+			/* 3 secs defaults poll_timeout if not specified. */
+			if (plat->dma_rx_poll_timeout)
+				uap->dmarx.poll_timeout =
+					plat->dma_rx_poll_timeout;
+			else
+				uap->dmarx.poll_timeout = 3000;
+		} else if (!plat && dev->of_node) {
+			uap->dmarx.auto_poll_rate = of_property_read_bool(
+						dev->of_node, "auto-poll");
+			if (uap->dmarx.auto_poll_rate) {
+				u32 x;
+
+				if (0 == of_property_read_u32(dev->of_node,
+						"poll-rate-ms", &x))
+					uap->dmarx.poll_rate = x;
+				else
+					uap->dmarx.poll_rate = 100;
+				if (0 == of_property_read_u32(dev->of_node,
+						"poll-timeout-ms", &x))
+					uap->dmarx.poll_timeout = x;
+				else
+					uap->dmarx.poll_timeout = 3000;
+			}
+		}
+		dev_info(uap->port.dev, "DMA channel RX %s\n",
+			 dma_chan_name(uap->dmarx.chan));
+	}
+}
+
+static void pl011_dma_remove(struct uart_amba_port *uap)
+{
+	if (uap->dmatx.chan)
+		dma_release_channel(uap->dmatx.chan);
+	if (uap->dmarx.chan)
+		dma_release_channel(uap->dmarx.chan);
+}
+
+/* Forward declare these for the refill routine */
+static int pl011_dma_tx_refill(struct uart_amba_port *uap);
+static void pl011_start_tx_pio(struct uart_amba_port *uap);
+
+/*
+ * The current DMA TX buffer has been sent.
+ * Try to queue up another DMA buffer.
+ */
+static void pl011_dma_tx_callback(void *data)
+{
+	struct uart_amba_port *uap = data;
+	struct pl011_dmatx_data *dmatx = &uap->dmatx;
+	unsigned long flags;
+	u16 dmacr;
+
+	spin_lock_irqsave(&uap->port.lock, flags);
+	if (uap->dmatx.queued)
+		dma_unmap_sg(dmatx->chan->device->dev, &dmatx->sg, 1,
+			     DMA_TO_DEVICE);
+
+	dmacr = uap->dmacr;
+	uap->dmacr = dmacr & ~UART011_TXDMAE;
+	writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+
+	/*
+	 * If TX DMA was disabled, it means that we've stopped the DMA for
+	 * some reason (eg, XOFF received, or we want to send an X-char.)
+	 *
+	 * Note: we need to be careful here of a potential race between DMA
+	 * and the rest of the driver - if the driver disables TX DMA while
+	 * a TX buffer completing, we must update the tx queued status to
+	 * get further refills (hence we check dmacr).
+	 */
+	if (!(dmacr & UART011_TXDMAE) || uart_tx_stopped(&uap->port) ||
+	    uart_circ_empty(&uap->port.state->xmit)) {
+		uap->dmatx.queued = false;
+		spin_unlock_irqrestore(&uap->port.lock, flags);
+		return;
+	}
+
+	if (pl011_dma_tx_refill(uap) <= 0)
+		/*
+		 * We didn't queue a DMA buffer for some reason, but we
+		 * have data pending to be sent.  Re-enable the TX IRQ.
+		 */
+		pl011_start_tx_pio(uap);
+
+	spin_unlock_irqrestore(&uap->port.lock, flags);
+}
+
+/*
+ * Try to refill the TX DMA buffer.
+ * Locking: called with port lock held and IRQs disabled.
+ * Returns:
+ *   1 if we queued up a TX DMA buffer.
+ *   0 if we didn't want to handle this by DMA
+ *  <0 on error
+ */
+static int pl011_dma_tx_refill(struct uart_amba_port *uap)
+{
+	struct pl011_dmatx_data *dmatx = &uap->dmatx;
+	struct dma_chan *chan = dmatx->chan;
+	struct dma_device *dma_dev = chan->device;
+	struct dma_async_tx_descriptor *desc;
+	struct circ_buf *xmit = &uap->port.state->xmit;
+	unsigned int count;
+
+	/*
+	 * Try to avoid the overhead involved in using DMA if the
+	 * transaction fits in the first half of the FIFO, by using
+	 * the standard interrupt handling.  This ensures that we
+	 * issue a uart_write_wakeup() at the appropriate time.
+	 */
+	count = uart_circ_chars_pending(xmit);
+	if (count < (uap->fifosize >> 1)) {
+		uap->dmatx.queued = false;
+		return 0;
+	}
+
+	/*
+	 * Bodge: don't send the last character by DMA, as this
+	 * will prevent XON from notifying us to restart DMA.
+	 */
+	count -= 1;
+
+	/* Else proceed to copy the TX chars to the DMA buffer and fire DMA */
+	if (count > PL011_DMA_BUFFER_SIZE)
+		count = PL011_DMA_BUFFER_SIZE;
+
+	if (xmit->tail < xmit->head)
+		memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], count);
+	else {
+		size_t first = UART_XMIT_SIZE - xmit->tail;
+		size_t second;
+
+		if (first > count)
+			first = count;
+		second = count - first;
+
+		memcpy(&dmatx->buf[0], &xmit->buf[xmit->tail], first);
+		if (second)
+			memcpy(&dmatx->buf[first], &xmit->buf[0], second);
+	}
+
+	dmatx->sg.length = count;
+
+	if (dma_map_sg(dma_dev->dev, &dmatx->sg, 1, DMA_TO_DEVICE) != 1) {
+		uap->dmatx.queued = false;
+		dev_dbg(uap->port.dev, "unable to map TX DMA\n");
+		return -EBUSY;
+	}
+
+	desc = dmaengine_prep_slave_sg(chan, &dmatx->sg, 1, DMA_MEM_TO_DEV,
+					     DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!desc) {
+		dma_unmap_sg(dma_dev->dev, &dmatx->sg, 1, DMA_TO_DEVICE);
+		uap->dmatx.queued = false;
+		/*
+		 * If DMA cannot be used right now, we complete this
+		 * transaction via IRQ and let the TTY layer retry.
+		 */
+		dev_dbg(uap->port.dev, "TX DMA busy\n");
+		return -EBUSY;
+	}
+
+	/* Some data to go along to the callback */
+	desc->callback = pl011_dma_tx_callback;
+	desc->callback_param = uap;
+
+	/* All errors should happen at prepare time */
+	dmaengine_submit(desc);
+
+	/* Fire the DMA transaction */
+	dma_dev->device_issue_pending(chan);
+
+	uap->dmacr |= UART011_TXDMAE;
+	writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+	uap->dmatx.queued = true;
+
+	/*
+	 * Now we know that DMA will fire, so advance the ring buffer
+	 * with the stuff we just dispatched.
+	 */
+	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
+	uap->port.icount.tx += count;
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&uap->port);
+
+	return 1;
+}
+
+/*
+ * We received a transmit interrupt without a pending X-char but with
+ * pending characters.
+ * Locking: called with port lock held and IRQs disabled.
+ * Returns:
+ *   false if we want to use PIO to transmit
+ *   true if we queued a DMA buffer
+ */
+static bool pl011_dma_tx_irq(struct uart_amba_port *uap)
+{
+	if (!uap->using_tx_dma)
+		return false;
+
+	/*
+	 * If we already have a TX buffer queued, but received a
+	 * TX interrupt, it will be because we've just sent an X-char.
+	 * Ensure the TX DMA is enabled and the TX IRQ is disabled.
+	 */
+	if (uap->dmatx.queued) {
+		uap->dmacr |= UART011_TXDMAE;
+		writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+		uap->im &= ~UART011_TXIM;
+		writew(uap->im, uap->port.membase + UART011_IMSC);
+		return true;
+	}
+
+	/*
+	 * We don't have a TX buffer queued, so try to queue one.
+	 * If we successfully queued a buffer, mask the TX IRQ.
+	 */
+	if (pl011_dma_tx_refill(uap) > 0) {
+		uap->im &= ~UART011_TXIM;
+		writew(uap->im, uap->port.membase + UART011_IMSC);
+		return true;
+	}
+	return false;
+}
+
+/*
+ * Stop the DMA transmit (eg, due to received XOFF).
+ * Locking: called with port lock held and IRQs disabled.
+ */
+static inline void pl011_dma_tx_stop(struct uart_amba_port *uap)
+{
+	if (uap->dmatx.queued) {
+		uap->dmacr &= ~UART011_TXDMAE;
+		writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+	}
+}
+
+/*
+ * Try to start a DMA transmit, or in the case of an XON/OFF
+ * character queued for send, try to get that character out ASAP.
+ * Locking: called with port lock held and IRQs disabled.
+ * Returns:
+ *   false if we want the TX IRQ to be enabled
+ *   true if we have a buffer queued
+ */
+static inline bool pl011_dma_tx_start(struct uart_amba_port *uap)
+{
+	u16 dmacr;
+
+	if (!uap->using_tx_dma)
+		return false;
+
+	if (!uap->port.x_char) {
+		/* no X-char, try to push chars out in DMA mode */
+		bool ret = true;
+
+		if (!uap->dmatx.queued) {
+			if (pl011_dma_tx_refill(uap) > 0) {
+				uap->im &= ~UART011_TXIM;
+				writew(uap->im, uap->port.membase +
+				       UART011_IMSC);
+			} else
+				ret = false;
+		} else if (!(uap->dmacr & UART011_TXDMAE)) {
+			uap->dmacr |= UART011_TXDMAE;
+			writew(uap->dmacr,
+				       uap->port.membase + UART011_DMACR);
+		}
+		return ret;
+	}
+
+	/*
+	 * We have an X-char to send.  Disable DMA to prevent it loading
+	 * the TX fifo, and then see if we can stuff it into the FIFO.
+	 */
+	dmacr = uap->dmacr;
+	uap->dmacr &= ~UART011_TXDMAE;
+	writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+
+	if (readw(uap->port.membase + UART01x_FR) & UART01x_FR_TXFF) {
+		/*
+		 * No space in the FIFO, so enable the transmit interrupt
+		 * so we know when there is space.  Note that once we've
+		 * loaded the character, we should just re-enable DMA.
+		 */
+		return false;
+	}
+
+	writew(uap->port.x_char, uap->port.membase + UART01x_DR);
+	uap->port.icount.tx++;
+	uap->port.x_char = 0;
+
+	/* Success - restore the DMA state */
+	uap->dmacr = dmacr;
+	writew(dmacr, uap->port.membase + UART011_DMACR);
+
+	return true;
+}
+
+/*
+ * Flush the transmit buffer.
+ * Locking: called with port lock held and IRQs disabled.
+ */
+static void pl011_dma_flush_buffer(struct uart_port *port)
+__releases(&uap->port.lock)
+__acquires(&uap->port.lock)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+
+	if (!uap->using_tx_dma)
+		return;
+
+	/* Avoid deadlock with the DMA engine callback */
+	spin_unlock(&uap->port.lock);
+	dmaengine_terminate_all(uap->dmatx.chan);
+	spin_lock(&uap->port.lock);
+	if (uap->dmatx.queued) {
+		dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1,
+			     DMA_TO_DEVICE);
+		uap->dmatx.queued = false;
+		uap->dmacr &= ~UART011_TXDMAE;
+		writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+	}
+}
+
+static void pl011_dma_rx_callback(void *data);
+
+static int pl011_dma_rx_trigger_dma(struct uart_amba_port *uap)
+{
+	struct dma_chan *rxchan = uap->dmarx.chan;
+	struct pl011_dmarx_data *dmarx = &uap->dmarx;
+	struct dma_async_tx_descriptor *desc;
+	struct pl011_sgbuf *sgbuf;
+
+	if (!rxchan)
+		return -EIO;
+
+	/* Start the RX DMA job */
+	sgbuf = uap->dmarx.use_buf_b ?
+		&uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;
+	desc = dmaengine_prep_slave_sg(rxchan, &sgbuf->sg, 1,
+					DMA_DEV_TO_MEM,
+					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	/*
+	 * If the DMA engine is busy and cannot prepare a
+	 * channel, no big deal, the driver will fall back
+	 * to interrupt mode as a result of this error code.
+	 */
+	if (!desc) {
+		uap->dmarx.running = false;
+		dmaengine_terminate_all(rxchan);
+		return -EBUSY;
+	}
+
+	/* Some data to go along to the callback */
+	desc->callback = pl011_dma_rx_callback;
+	desc->callback_param = uap;
+	dmarx->cookie = dmaengine_submit(desc);
+	dma_async_issue_pending(rxchan);
+
+	uap->dmacr |= UART011_RXDMAE;
+	writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+	uap->dmarx.running = true;
+
+	uap->im &= ~UART011_RXIM;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+
+	return 0;
+}
+
+/*
+ * This is called when either the DMA job is complete, or
+ * the FIFO timeout interrupt occurred. This must be called
+ * with the port spinlock uap->port.lock held.
+ */
+static void pl011_dma_rx_chars(struct uart_amba_port *uap,
+			       u32 pending, bool use_buf_b,
+			       bool readfifo)
+{
+	struct tty_port *port = &uap->port.state->port;
+	struct pl011_sgbuf *sgbuf = use_buf_b ?
+		&uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;
+	int dma_count = 0;
+	u32 fifotaken = 0; /* only used for vdbg() */
+
+	struct pl011_dmarx_data *dmarx = &uap->dmarx;
+	int dmataken = 0;
+
+	if (uap->dmarx.poll_rate) {
+		/* The data can be taken by polling */
+		dmataken = sgbuf->sg.length - dmarx->last_residue;
+		/* Recalculate the pending size */
+		if (pending >= dmataken)
+			pending -= dmataken;
+	}
+
+	/* Pick the remain data from the DMA */
+	if (pending) {
+
+		/*
+		 * First take all chars in the DMA pipe, then look in the FIFO.
+		 * Note that tty_insert_flip_buf() tries to take as many chars
+		 * as it can.
+		 */
+		dma_count = tty_insert_flip_string(port, sgbuf->buf + dmataken,
+				pending);
+
+		uap->port.icount.rx += dma_count;
+		if (dma_count < pending)
+			dev_warn(uap->port.dev,
+				 "couldn't insert all characters (TTY is full?)\n");
+	}
+
+	/* Reset the last_residue for Rx DMA poll */
+	if (uap->dmarx.poll_rate)
+		dmarx->last_residue = sgbuf->sg.length;
+
+	/*
+	 * Only continue with trying to read the FIFO if all DMA chars have
+	 * been taken first.
+	 */
+	if (dma_count == pending && readfifo) {
+		/* Clear any error flags */
+		writew(UART011_OEIS | UART011_BEIS | UART011_PEIS | UART011_FEIS,
+		       uap->port.membase + UART011_ICR);
+
+		/*
+		 * If we read all the DMA'd characters, and we had an
+		 * incomplete buffer, that could be due to an rx error, or
+		 * maybe we just timed out. Read any pending chars and check
+		 * the error status.
+		 *
+		 * Error conditions will only occur in the FIFO, these will
+		 * trigger an immediate interrupt and stop the DMA job, so we
+		 * will always find the error in the FIFO, never in the DMA
+		 * buffer.
+		 */
+		fifotaken = pl011_fifo_to_tty(uap);
+	}
+
+	spin_unlock(&uap->port.lock);
+	dev_vdbg(uap->port.dev,
+		 "Took %d chars from DMA buffer and %d chars from the FIFO\n",
+		 dma_count, fifotaken);
+	tty_flip_buffer_push(port);
+	spin_lock(&uap->port.lock);
+}
+
+static void pl011_dma_rx_irq(struct uart_amba_port *uap)
+{
+	struct pl011_dmarx_data *dmarx = &uap->dmarx;
+	struct dma_chan *rxchan = dmarx->chan;
+	struct pl011_sgbuf *sgbuf = dmarx->use_buf_b ?
+		&dmarx->sgbuf_b : &dmarx->sgbuf_a;
+	size_t pending;
+	struct dma_tx_state state;
+	enum dma_status dmastat;
+
+	/*
+	 * Pause the transfer so we can trust the current counter,
+	 * do this before we pause the PL011 block, else we may
+	 * overflow the FIFO.
+	 */
+	if (dmaengine_pause(rxchan))
+		dev_err(uap->port.dev, "unable to pause DMA transfer\n");
+	dmastat = rxchan->device->device_tx_status(rxchan,
+						   dmarx->cookie, &state);
+	if (dmastat != DMA_PAUSED)
+		dev_err(uap->port.dev, "unable to pause DMA transfer\n");
+
+	/* Disable RX DMA - incoming data will wait in the FIFO */
+	uap->dmacr &= ~UART011_RXDMAE;
+	writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+	uap->dmarx.running = false;
+
+	pending = sgbuf->sg.length - state.residue;
+	BUG_ON(pending > PL011_DMA_BUFFER_SIZE);
+	/* Then we terminate the transfer - we now know our residue */
+	dmaengine_terminate_all(rxchan);
+
+	/*
+	 * This will take the chars we have so far and insert
+	 * into the framework.
+	 */
+	pl011_dma_rx_chars(uap, pending, dmarx->use_buf_b, true);
+
+	/* Switch buffer & re-trigger DMA job */
+	dmarx->use_buf_b = !dmarx->use_buf_b;
+	if (pl011_dma_rx_trigger_dma(uap)) {
+		dev_dbg(uap->port.dev, "could not retrigger RX DMA job "
+			"fall back to interrupt mode\n");
+		uap->im |= UART011_RXIM;
+		writew(uap->im, uap->port.membase + UART011_IMSC);
+	}
+}
+
+static void pl011_dma_rx_callback(void *data)
+{
+	struct uart_amba_port *uap = data;
+	struct pl011_dmarx_data *dmarx = &uap->dmarx;
+	struct dma_chan *rxchan = dmarx->chan;
+	bool lastbuf = dmarx->use_buf_b;
+	struct pl011_sgbuf *sgbuf = dmarx->use_buf_b ?
+		&dmarx->sgbuf_b : &dmarx->sgbuf_a;
+	size_t pending;
+	struct dma_tx_state state;
+	int ret;
+
+	/*
+	 * This completion interrupt occurs typically when the
+	 * RX buffer is totally stuffed but no timeout has yet
+	 * occurred. When that happens, we just want the RX
+	 * routine to flush out the secondary DMA buffer while
+	 * we immediately trigger the next DMA job.
+	 */
+	spin_lock_irq(&uap->port.lock);
+	/*
+	 * Rx data can be taken by the UART interrupts during
+	 * the DMA irq handler. So we check the residue here.
+	 */
+	rxchan->device->device_tx_status(rxchan, dmarx->cookie, &state);
+	pending = sgbuf->sg.length - state.residue;
+	BUG_ON(pending > PL011_DMA_BUFFER_SIZE);
+	/* Then we terminate the transfer - we now know our residue */
+	dmaengine_terminate_all(rxchan);
+
+	uap->dmarx.running = false;
+	dmarx->use_buf_b = !lastbuf;
+	ret = pl011_dma_rx_trigger_dma(uap);
+
+	pl011_dma_rx_chars(uap, pending, lastbuf, false);
+	spin_unlock_irq(&uap->port.lock);
+	/*
+	 * Do this check after we picked the DMA chars so we don't
+	 * get some IRQ immediately from RX.
+	 */
+	if (ret) {
+		dev_dbg(uap->port.dev, "could not retrigger RX DMA job "
+			"fall back to interrupt mode\n");
+		uap->im |= UART011_RXIM;
+		writew(uap->im, uap->port.membase + UART011_IMSC);
+	}
+}
+
+/*
+ * Stop accepting received characters, when we're shutting down or
+ * suspending this port.
+ * Locking: called with port lock held and IRQs disabled.
+ */
+static inline void pl011_dma_rx_stop(struct uart_amba_port *uap)
+{
+	/* FIXME.  Just disable the DMA enable */
+	uap->dmacr &= ~UART011_RXDMAE;
+	writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+}
+
+/*
+ * Timer handler for Rx DMA polling.
+ * Every polling, It checks the residue in the dma buffer and transfer
+ * data to the tty. Also, last_residue is updated for the next polling.
+ */
+static void pl011_dma_rx_poll(unsigned long args)
+{
+	struct uart_amba_port *uap = (struct uart_amba_port *)args;
+	struct tty_port *port = &uap->port.state->port;
+	struct pl011_dmarx_data *dmarx = &uap->dmarx;
+	struct dma_chan *rxchan = uap->dmarx.chan;
+	unsigned long flags = 0;
+	unsigned int dmataken = 0;
+	unsigned int size = 0;
+	struct pl011_sgbuf *sgbuf;
+	int dma_count;
+	struct dma_tx_state state;
+
+	sgbuf = dmarx->use_buf_b ? &uap->dmarx.sgbuf_b : &uap->dmarx.sgbuf_a;
+	rxchan->device->device_tx_status(rxchan, dmarx->cookie, &state);
+	if (likely(state.residue < dmarx->last_residue)) {
+		dmataken = sgbuf->sg.length - dmarx->last_residue;
+		size = dmarx->last_residue - state.residue;
+		dma_count = tty_insert_flip_string(port, sgbuf->buf + dmataken,
+				size);
+		if (dma_count == size)
+			dmarx->last_residue =  state.residue;
+		dmarx->last_jiffies = jiffies;
+	}
+	tty_flip_buffer_push(port);
+
+	/*
+	 * If no data is received in poll_timeout, the driver will fall back
+	 * to interrupt mode. We will retrigger DMA at the first interrupt.
+	 */
+	if (jiffies_to_msecs(jiffies - dmarx->last_jiffies)
+			> uap->dmarx.poll_timeout) {
+
+		spin_lock_irqsave(&uap->port.lock, flags);
+		pl011_dma_rx_stop(uap);
+		uap->im |= UART011_RXIM;
+		writew(uap->im, uap->port.membase + UART011_IMSC);
+		spin_unlock_irqrestore(&uap->port.lock, flags);
+
+		uap->dmarx.running = false;
+		dmaengine_terminate_all(rxchan);
+		del_timer(&uap->dmarx.timer);
+	} else {
+		mod_timer(&uap->dmarx.timer,
+			jiffies + msecs_to_jiffies(uap->dmarx.poll_rate));
+	}
+}
+
+static void pl011_dma_startup(struct uart_amba_port *uap)
+{
+	int ret;
+
+	if (!uap->dma_probed)
+		pl011_dma_probe(uap);
+
+	if (!uap->dmatx.chan)
+		return;
+
+	uap->dmatx.buf = kmalloc(PL011_DMA_BUFFER_SIZE, GFP_KERNEL | __GFP_DMA);
+	if (!uap->dmatx.buf) {
+		dev_err(uap->port.dev, "no memory for DMA TX buffer\n");
+		uap->port.fifosize = uap->fifosize;
+		return;
+	}
+
+	sg_init_one(&uap->dmatx.sg, uap->dmatx.buf, PL011_DMA_BUFFER_SIZE);
+
+	/* The DMA buffer is now the FIFO the TTY subsystem can use */
+	uap->port.fifosize = PL011_DMA_BUFFER_SIZE;
+	uap->using_tx_dma = true;
+
+	if (!uap->dmarx.chan)
+		goto skip_rx;
+
+	/* Allocate and map DMA RX buffers */
+	ret = pl011_sgbuf_init(uap->dmarx.chan, &uap->dmarx.sgbuf_a,
+			       DMA_FROM_DEVICE);
+	if (ret) {
+		dev_err(uap->port.dev, "failed to init DMA %s: %d\n",
+			"RX buffer A", ret);
+		goto skip_rx;
+	}
+
+	ret = pl011_sgbuf_init(uap->dmarx.chan, &uap->dmarx.sgbuf_b,
+			       DMA_FROM_DEVICE);
+	if (ret) {
+		dev_err(uap->port.dev, "failed to init DMA %s: %d\n",
+			"RX buffer B", ret);
+		pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_a,
+				 DMA_FROM_DEVICE);
+		goto skip_rx;
+	}
+
+	uap->using_rx_dma = true;
+
+skip_rx:
+	/* Turn on DMA error (RX/TX will be enabled on demand) */
+	uap->dmacr |= UART011_DMAONERR;
+	writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+
+	/*
+	 * ST Micro variants has some specific dma burst threshold
+	 * compensation. Set this to 16 bytes, so burst will only
+	 * be issued above/below 16 bytes.
+	 */
+	if (uap->vendor->dma_threshold)
+		writew(ST_UART011_DMAWM_RX_16 | ST_UART011_DMAWM_TX_16,
+			       uap->port.membase + ST_UART011_DMAWM);
+
+	if (uap->using_rx_dma) {
+		if (pl011_dma_rx_trigger_dma(uap))
+			dev_dbg(uap->port.dev, "could not trigger initial "
+				"RX DMA job, fall back to interrupt mode\n");
+		if (uap->dmarx.poll_rate) {
+			init_timer(&(uap->dmarx.timer));
+			uap->dmarx.timer.function = pl011_dma_rx_poll;
+			uap->dmarx.timer.data = (unsigned long)uap;
+			mod_timer(&uap->dmarx.timer,
+				jiffies +
+				msecs_to_jiffies(uap->dmarx.poll_rate));
+			uap->dmarx.last_residue = PL011_DMA_BUFFER_SIZE;
+			uap->dmarx.last_jiffies = jiffies;
+		}
+	}
+}
+
+static void pl011_dma_shutdown(struct uart_amba_port *uap)
+{
+	if (!(uap->using_tx_dma || uap->using_rx_dma))
+		return;
+
+	/* Disable RX and TX DMA */
+	while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_BUSY)
+		barrier();
+
+	spin_lock_irq(&uap->port.lock);
+	uap->dmacr &= ~(UART011_DMAONERR | UART011_RXDMAE | UART011_TXDMAE);
+	writew(uap->dmacr, uap->port.membase + UART011_DMACR);
+	spin_unlock_irq(&uap->port.lock);
+
+	if (uap->using_tx_dma) {
+		/* In theory, this should already be done by pl011_dma_flush_buffer */
+		dmaengine_terminate_all(uap->dmatx.chan);
+		if (uap->dmatx.queued) {
+			dma_unmap_sg(uap->dmatx.chan->device->dev, &uap->dmatx.sg, 1,
+				     DMA_TO_DEVICE);
+			uap->dmatx.queued = false;
+		}
+
+		kfree(uap->dmatx.buf);
+		uap->using_tx_dma = false;
+	}
+
+	if (uap->using_rx_dma) {
+		dmaengine_terminate_all(uap->dmarx.chan);
+		/* Clean up the RX DMA */
+		pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_a, DMA_FROM_DEVICE);
+		pl011_sgbuf_free(uap->dmarx.chan, &uap->dmarx.sgbuf_b, DMA_FROM_DEVICE);
+		if (uap->dmarx.poll_rate)
+			del_timer_sync(&uap->dmarx.timer);
+		uap->using_rx_dma = false;
+	}
+}
+
+static inline bool pl011_dma_rx_available(struct uart_amba_port *uap)
+{
+	return uap->using_rx_dma;
+}
+
+static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
+{
+	return uap->using_rx_dma && uap->dmarx.running;
+}
+
+#else
+/* Blank functions if the DMA engine is not available */
+static inline void pl011_dma_probe(struct uart_amba_port *uap)
+{
+}
+
+static inline void pl011_dma_remove(struct uart_amba_port *uap)
+{
+}
+
+static inline void pl011_dma_startup(struct uart_amba_port *uap)
+{
+}
+
+static inline void pl011_dma_shutdown(struct uart_amba_port *uap)
+{
+}
+
+static inline bool pl011_dma_tx_irq(struct uart_amba_port *uap)
+{
+	return false;
+}
+
+static inline void pl011_dma_tx_stop(struct uart_amba_port *uap)
+{
+}
+
+static inline bool pl011_dma_tx_start(struct uart_amba_port *uap)
+{
+	return false;
+}
+
+static inline void pl011_dma_rx_irq(struct uart_amba_port *uap)
+{
+}
+
+static inline void pl011_dma_rx_stop(struct uart_amba_port *uap)
+{
+}
+
+static inline int pl011_dma_rx_trigger_dma(struct uart_amba_port *uap)
+{
+	return -EIO;
+}
+
+static inline bool pl011_dma_rx_available(struct uart_amba_port *uap)
+{
+	return false;
+}
+
+static inline bool pl011_dma_rx_running(struct uart_amba_port *uap)
+{
+	return false;
+}
+
+#define pl011_dma_flush_buffer	NULL
+#endif
+
+static void pl011_stop_tx(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+
+	uap->im &= ~UART011_TXIM;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	pl011_dma_tx_stop(uap);
+}
+
+static bool pl011_tx_chars(struct uart_amba_port *uap);
+
+/* Start TX with programmed I/O only (no DMA) */
+static void pl011_start_tx_pio(struct uart_amba_port *uap)
+{
+	uap->im |= UART011_TXIM;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	if (!uap->tx_irq_seen)
+		pl011_tx_chars(uap);
+}
+
+static void pl011_start_tx(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+
+	if (!pl011_dma_tx_start(uap))
+		pl011_start_tx_pio(uap);
+}
+
+static void pl011_stop_rx(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+
+	uap->im &= ~(UART011_RXIM|UART011_RTIM|UART011_FEIM|
+		     UART011_PEIM|UART011_BEIM|UART011_OEIM);
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+
+	pl011_dma_rx_stop(uap);
+}
+
+static void pl011_enable_ms(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+
+	uap->im |= UART011_RIMIM|UART011_CTSMIM|UART011_DCDMIM|UART011_DSRMIM;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+}
+
+static void pl011_rx_chars(struct uart_amba_port *uap)
+__releases(&uap->port.lock)
+__acquires(&uap->port.lock)
+{
+	pl011_fifo_to_tty(uap);
+
+	spin_unlock(&uap->port.lock);
+	tty_flip_buffer_push(&uap->port.state->port);
+	/*
+	 * If we were temporarily out of DMA mode for a while,
+	 * attempt to switch back to DMA mode again.
+	 */
+	if (pl011_dma_rx_available(uap)) {
+		if (pl011_dma_rx_trigger_dma(uap)) {
+			dev_dbg(uap->port.dev, "could not trigger RX DMA job "
+				"fall back to interrupt mode again\n");
+			uap->im |= UART011_RXIM;
+			writew(uap->im, uap->port.membase + UART011_IMSC);
+		} else {
+#ifdef CONFIG_DMA_ENGINE
+			/* Start Rx DMA poll */
+			if (uap->dmarx.poll_rate) {
+				uap->dmarx.last_jiffies = jiffies;
+				uap->dmarx.last_residue	= PL011_DMA_BUFFER_SIZE;
+				mod_timer(&uap->dmarx.timer,
+					jiffies +
+					msecs_to_jiffies(uap->dmarx.poll_rate));
+			}
+#endif
+		}
+	}
+	spin_lock(&uap->port.lock);
+}
+
+/*
+ * Transmit a character
+ *
+ * Returns true if the character was successfully queued to the FIFO.
+ * Returns false otherwise.
+ */
+static bool pl011_tx_char(struct uart_amba_port *uap, unsigned char c)
+{
+	if (readw(uap->port.membase + UART01x_FR) & UART01x_FR_TXFF)
+		return false; /* unable to transmit character */
+
+	writew(c, uap->port.membase + UART01x_DR);
+	uap->port.icount.tx++;
+
+	return true;
+}
+
+static bool pl011_tx_chars(struct uart_amba_port *uap)
+{
+	struct circ_buf *xmit = &uap->port.state->xmit;
+	int count;
+
+	if (unlikely(uap->tx_irq_seen < 2))
+		/*
+		 * Initial FIFO fill level unknown: we must check TXFF
+		 * after each write, so just try to fill up the FIFO.
+		 */
+		count = uap->fifosize;
+	else /* tx_irq_seen >= 2 */
+		/*
+		 * FIFO initially at least half-empty, so we can simply
+		 * write half the FIFO without polling TXFF.
+
+		 * Note: the *first* TX IRQ can still race with
+		 * pl011_start_tx_pio(), which can result in the FIFO
+		 * being fuller than expected in that case.
+		 */
+		count = uap->fifosize >> 1;
+
+	/*
+	 * If the FIFO is full we're guaranteed a TX IRQ at some later point,
+	 * and can't transmit immediately in any case:
+	 */
+	if (unlikely(uap->tx_irq_seen < 2 &&
+		     readw(uap->port.membase + UART01x_FR) & UART01x_FR_TXFF))
+		return false;
+
+	if (uap->port.x_char) {
+		if (!pl011_tx_char(uap, uap->port.x_char))
+			goto done;
+		uap->port.x_char = 0;
+		--count;
+	}
+	if (uart_circ_empty(xmit) || uart_tx_stopped(&uap->port)) {
+		pl011_stop_tx(&uap->port);
+		goto done;
+	}
+
+	/* If we are using DMA mode, try to send some characters. */
+	if (pl011_dma_tx_irq(uap))
+		goto done;
+
+	while (count-- > 0 && pl011_tx_char(uap, xmit->buf[xmit->tail])) {
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		if (uart_circ_empty(xmit))
+			break;
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&uap->port);
+
+	if (uart_circ_empty(xmit)) {
+		pl011_stop_tx(&uap->port);
+		goto done;
+	}
+
+	if (unlikely(!uap->tx_irq_seen))
+		schedule_delayed_work(&uap->tx_softirq_work, uap->port.timeout);
+
+done:
+	return false;
+}
+
+static void pl011_modem_status(struct uart_amba_port *uap)
+{
+	unsigned int status, delta;
+
+	status = readw(uap->port.membase + UART01x_FR) & UART01x_FR_MODEM_ANY;
+
+	delta = status ^ uap->old_status;
+	uap->old_status = status;
+
+	if (!delta)
+		return;
+
+	if (delta & UART01x_FR_DCD)
+		uart_handle_dcd_change(&uap->port, status & UART01x_FR_DCD);
+
+	if (delta & UART01x_FR_DSR)
+		uap->port.icount.dsr++;
+
+	if (delta & UART01x_FR_CTS)
+		uart_handle_cts_change(&uap->port, status & UART01x_FR_CTS);
+
+	wake_up_interruptible(&uap->port.state->port.delta_msr_wait);
+}
+
+static void pl011_tx_softirq(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct uart_amba_port *uap =
+		container_of(dwork, struct uart_amba_port, tx_softirq_work);
+
+	spin_lock(&uap->port.lock);
+	while (pl011_tx_chars(uap)) ;
+	spin_unlock(&uap->port.lock);
+}
+
+static void pl011_tx_irq_seen(struct uart_amba_port *uap)
+{
+	if (likely(uap->tx_irq_seen > 1))
+		return;
+
+	uap->tx_irq_seen++;
+	if (uap->tx_irq_seen < 2)
+		/* first TX IRQ */
+		cancel_delayed_work(&uap->tx_softirq_work);
+}
+
+static irqreturn_t pl011_int(int irq, void *dev_id)
+{
+	struct uart_amba_port *uap = dev_id;
+	unsigned long flags;
+	unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;
+	int handled = 0;
+	unsigned int dummy_read;
+
+	spin_lock_irqsave(&uap->port.lock, flags);
+	status = readw(uap->port.membase + UART011_MIS);
+	if (status) {
+		do {
+			if (uap->vendor->cts_event_workaround) {
+				/* workaround to make sure that all bits are unlocked.. */
+				writew(0x00, uap->port.membase + UART011_ICR);
+
+				/*
+				 * WA: introduce 26ns(1 uart clk) delay before W1C;
+				 * single apb access will incur 2 pclk(133.12Mhz) delay,
+				 * so add 2 dummy reads
+				 */
+				dummy_read = readw(uap->port.membase + UART011_ICR);
+				dummy_read = readw(uap->port.membase + UART011_ICR);
+			}
+
+			writew(status & ~(UART011_TXIS|UART011_RTIS|
+					  UART011_RXIS),
+			       uap->port.membase + UART011_ICR);
+
+			if (status & (UART011_RTIS|UART011_RXIS)) {
+				if (pl011_dma_rx_running(uap))
+					pl011_dma_rx_irq(uap);
+				else
+					pl011_rx_chars(uap);
+			}
+			if (status & (UART011_DSRMIS|UART011_DCDMIS|
+				      UART011_CTSMIS|UART011_RIMIS))
+				pl011_modem_status(uap);
+			if (status & UART011_TXIS) {
+				pl011_tx_irq_seen(uap);
+				pl011_tx_chars(uap);
+			}
+
+			if (pass_counter-- == 0)
+				break;
+
+			status = readw(uap->port.membase + UART011_MIS);
+		} while (status != 0);
+		handled = 1;
+	}
+
+	spin_unlock_irqrestore(&uap->port.lock, flags);
+
+	return IRQ_RETVAL(handled);
+}
+
+static unsigned int pl011_tx_empty(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned int status = readw(uap->port.membase + UART01x_FR);
+	return status & (UART01x_FR_BUSY|UART01x_FR_TXFF) ? 0 : TIOCSER_TEMT;
+}
+
+static unsigned int pl011_get_mctrl(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned int result = 0;
+	unsigned int status = readw(uap->port.membase + UART01x_FR);
+
+#define TIOCMBIT(uartbit, tiocmbit)	\
+	if (status & uartbit)		\
+		result |= tiocmbit
+
+	TIOCMBIT(UART01x_FR_DCD, TIOCM_CAR);
+	TIOCMBIT(UART01x_FR_DSR, TIOCM_DSR);
+	TIOCMBIT(UART01x_FR_CTS, TIOCM_CTS);
+	TIOCMBIT(UART011_FR_RI, TIOCM_RNG);
+#undef TIOCMBIT
+	return result;
+}
+
+static void pl011_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned int cr;
+
+	cr = readw(uap->port.membase + UART011_CR);
+
+#define	TIOCMBIT(tiocmbit, uartbit)		\
+	if (mctrl & tiocmbit)		\
+		cr |= uartbit;		\
+	else				\
+		cr &= ~uartbit
+
+	TIOCMBIT(TIOCM_RTS, UART011_CR_RTS);
+	TIOCMBIT(TIOCM_DTR, UART011_CR_DTR);
+	TIOCMBIT(TIOCM_OUT1, UART011_CR_OUT1);
+	TIOCMBIT(TIOCM_OUT2, UART011_CR_OUT2);
+	TIOCMBIT(TIOCM_LOOP, UART011_CR_LBE);
+
+	if (uap->autorts) {
+		/* We need to disable auto-RTS if we want to turn RTS off */
+		TIOCMBIT(TIOCM_RTS, UART011_CR_RTSEN);
+	}
+#undef TIOCMBIT
+
+	writew(cr, uap->port.membase + UART011_CR);
+}
+
+static void pl011_break_ctl(struct uart_port *port, int break_state)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned long flags;
+	unsigned int lcr_h;
+
+	spin_lock_irqsave(&uap->port.lock, flags);
+	lcr_h = readw(uap->port.membase + uap->lcrh_tx);
+	if (break_state == -1)
+		lcr_h |= UART01x_LCRH_BRK;
+	else
+		lcr_h &= ~UART01x_LCRH_BRK;
+	writew(lcr_h, uap->port.membase + uap->lcrh_tx);
+	spin_unlock_irqrestore(&uap->port.lock, flags);
+}
+
+#ifdef CONFIG_CONSOLE_POLL
+
+static void pl011_quiesce_irqs(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned char __iomem *regs = uap->port.membase;
+
+	writew(readw(regs + UART011_MIS), regs + UART011_ICR);
+	/*
+	 * There is no way to clear TXIM as this is "ready to transmit IRQ", so
+	 * we simply mask it. start_tx() will unmask it.
+	 *
+	 * Note we can race with start_tx(), and if the race happens, the
+	 * polling user might get another interrupt just after we clear it.
+	 * But it should be OK and can happen even w/o the race, e.g.
+	 * controller immediately got some new data and raised the IRQ.
+	 *
+	 * And whoever uses polling routines assumes that it manages the device
+	 * (including tx queue), so we're also fine with start_tx()'s caller
+	 * side.
+	 */
+	writew(readw(regs + UART011_IMSC) & ~UART011_TXIM, regs + UART011_IMSC);
+}
+
+static int pl011_get_poll_char(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned int status;
+
+	/*
+	 * The caller might need IRQs lowered, e.g. if used with KDB NMI
+	 * debugger.
+	 */
+	pl011_quiesce_irqs(port);
+
+	status = readw(uap->port.membase + UART01x_FR);
+	if (status & UART01x_FR_RXFE)
+		return NO_POLL_CHAR;
+
+	return readw(uap->port.membase + UART01x_DR);
+}
+
+static void pl011_put_poll_char(struct uart_port *port,
+			 unsigned char ch)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+
+	while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_TXFF)
+		barrier();
+
+	writew(ch, uap->port.membase + UART01x_DR);
+}
+
+#endif /* CONFIG_CONSOLE_POLL */
+
+static int pl011_hwinit(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	int retval;
+
+	/* Optionaly enable pins to be muxed in and configured */
+	pinctrl_pm_select_default_state(port->dev);
+
+	/*
+	 * Try to enable the clock producer.
+	 */
+	retval = clk_prepare_enable(uap->clk);
+	if (retval)
+		return retval;
+
+	uap->port.uartclk = clk_get_rate(uap->clk);
+
+	/* Clear pending error and receive interrupts */
+	writew(UART011_OEIS | UART011_BEIS | UART011_PEIS | UART011_FEIS |
+	       UART011_RTIS | UART011_RXIS, uap->port.membase + UART011_ICR);
+
+	/*
+	 * Save interrupts enable mask, and enable RX interrupts in case if
+	 * the interrupt is used for NMI entry.
+	 */
+	uap->im = readw(uap->port.membase + UART011_IMSC);
+	writew(UART011_RTIM | UART011_RXIM, uap->port.membase + UART011_IMSC);
+
+	if (dev_get_platdata(uap->port.dev)) {
+		struct amba_pl011_data *plat;
+
+		plat = dev_get_platdata(uap->port.dev);
+		if (plat->init)
+			plat->init();
+	}
+	return 0;
+}
+
+static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h)
+{
+	writew(lcr_h, uap->port.membase + uap->lcrh_rx);
+	if (uap->lcrh_rx != uap->lcrh_tx) {
+		int i;
+		/*
+		 * Wait 10 PCLKs before writing LCRH_TX register,
+		 * to get this delay write read only register 10 times
+		 */
+		for (i = 0; i < 10; ++i)
+			writew(0xff, uap->port.membase + UART011_MIS);
+		writew(lcr_h, uap->port.membase + uap->lcrh_tx);
+	}
+}
+
+static int pl011_startup(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned int cr;
+	int retval;
+
+	retval = pl011_hwinit(port);
+	if (retval)
+		goto clk_dis;
+
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+
+	/*
+	 * Allocate the IRQ
+	 */
+	retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
+	if (retval)
+		goto clk_dis;
+
+	writew(uap->vendor->ifls, uap->port.membase + UART011_IFLS);
+
+	/* Assume that TX IRQ doesn't work until we see one: */
+	uap->tx_irq_seen = 0;
+
+	spin_lock_irq(&uap->port.lock);
+
+	/* restore RTS and DTR */
+	cr = uap->old_cr & (UART011_CR_RTS | UART011_CR_DTR);
+	cr |= UART01x_CR_UARTEN | UART011_CR_RXE | UART011_CR_TXE;
+	writew(cr, uap->port.membase + UART011_CR);
+
+	spin_unlock_irq(&uap->port.lock);
+
+	/*
+	 * initialise the old status of the modem signals
+	 */
+	uap->old_status = readw(uap->port.membase + UART01x_FR) & UART01x_FR_MODEM_ANY;
+
+	/* Startup DMA */
+	pl011_dma_startup(uap);
+
+	/*
+	 * Finally, enable interrupts, only timeouts when using DMA
+	 * if initial RX DMA job failed, start in interrupt mode
+	 * as well.
+	 */
+	spin_lock_irq(&uap->port.lock);
+	/* Clear out any spuriously appearing RX interrupts */
+	 writew(UART011_RTIS | UART011_RXIS,
+		uap->port.membase + UART011_ICR);
+	uap->im = UART011_RTIM;
+	if (!pl011_dma_rx_running(uap))
+		uap->im |= UART011_RXIM;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	spin_unlock_irq(&uap->port.lock);
+
+	return 0;
+
+ clk_dis:
+	clk_disable_unprepare(uap->clk);
+	return retval;
+}
+
+static void pl011_shutdown_channel(struct uart_amba_port *uap,
+					unsigned int lcrh)
+{
+      unsigned long val;
+
+      val = readw(uap->port.membase + lcrh);
+      val &= ~(UART01x_LCRH_BRK | UART01x_LCRH_FEN);
+      writew(val, uap->port.membase + lcrh);
+}
+
+static void pl011_shutdown(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned int cr;
+
+	cancel_delayed_work_sync(&uap->tx_softirq_work);
+
+	/*
+	 * disable all interrupts
+	 */
+	spin_lock_irq(&uap->port.lock);
+	uap->im = 0;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	writew(0xffff, uap->port.membase + UART011_ICR);
+	spin_unlock_irq(&uap->port.lock);
+
+	pl011_dma_shutdown(uap);
+
+	/*
+	 * Free the interrupt
+	 */
+	free_irq(uap->port.irq, uap);
+
+	/*
+	 * disable the port
+	 * disable the port. It should not disable RTS and DTR.
+	 * Also RTS and DTR state should be preserved to restore
+	 * it during startup().
+	 */
+	uap->autorts = false;
+	spin_lock_irq(&uap->port.lock);
+	cr = readw(uap->port.membase + UART011_CR);
+	uap->old_cr = cr;
+	cr &= UART011_CR_RTS | UART011_CR_DTR;
+	cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
+	writew(cr, uap->port.membase + UART011_CR);
+	spin_unlock_irq(&uap->port.lock);
+
+	/*
+	 * disable break condition and fifos
+	 */
+	pl011_shutdown_channel(uap, uap->lcrh_rx);
+	if (uap->lcrh_rx != uap->lcrh_tx)
+		pl011_shutdown_channel(uap, uap->lcrh_tx);
+
+	/*
+	 * Shut down the clock producer
+	 */
+	clk_disable_unprepare(uap->clk);
+	/* Optionally let pins go into sleep states */
+	pinctrl_pm_select_sleep_state(port->dev);
+
+	if (dev_get_platdata(uap->port.dev)) {
+		struct amba_pl011_data *plat;
+
+		plat = dev_get_platdata(uap->port.dev);
+		if (plat->exit)
+			plat->exit();
+	}
+
+	if (uap->port.ops->flush_buffer)
+		uap->port.ops->flush_buffer(port);
+}
+
+static void
+pl011_set_termios(struct uart_port *port, struct ktermios *termios,
+		     struct ktermios *old)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	unsigned int lcr_h, old_cr;
+	unsigned long flags;
+	unsigned int baud, quot, clkdiv;
+
+	if (uap->vendor->oversampling)
+		clkdiv = 8;
+	else
+		clkdiv = 16;
+
+	/*
+	 * Ask the core to calculate the divisor for us.
+	 */
+	baud = uart_get_baud_rate(port, termios, old, 0,
+				  port->uartclk / clkdiv);
+#ifdef CONFIG_DMA_ENGINE
+	/*
+	 * Adjust RX DMA polling rate with baud rate if not specified.
+	 */
+	if (uap->dmarx.auto_poll_rate)
+		uap->dmarx.poll_rate = DIV_ROUND_UP(10000000, baud);
+#endif
+
+	if (baud > port->uartclk/16)
+		quot = DIV_ROUND_CLOSEST(port->uartclk * 8, baud);
+	else
+		quot = DIV_ROUND_CLOSEST(port->uartclk * 4, baud);
+
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		lcr_h = UART01x_LCRH_WLEN_5;
+		break;
+	case CS6:
+		lcr_h = UART01x_LCRH_WLEN_6;
+		break;
+	case CS7:
+		lcr_h = UART01x_LCRH_WLEN_7;
+		break;
+	default: // CS8
+		lcr_h = UART01x_LCRH_WLEN_8;
+		break;
+	}
+	if (termios->c_cflag & CSTOPB)
+		lcr_h |= UART01x_LCRH_STP2;
+	if (termios->c_cflag & PARENB) {
+		lcr_h |= UART01x_LCRH_PEN;
+		if (!(termios->c_cflag & PARODD))
+			lcr_h |= UART01x_LCRH_EPS;
+	}
+	if (uap->fifosize > 1)
+		lcr_h |= UART01x_LCRH_FEN;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/*
+	 * Update the per-port timeout.
+	 */
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	port->read_status_mask = UART011_DR_OE | 255;
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= UART011_DR_FE | UART011_DR_PE;
+	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
+		port->read_status_mask |= UART011_DR_BE;
+
+	/*
+	 * Characters to ignore
+	 */
+	port->ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		port->ignore_status_mask |= UART011_DR_FE | UART011_DR_PE;
+	if (termios->c_iflag & IGNBRK) {
+		port->ignore_status_mask |= UART011_DR_BE;
+		/*
+		 * If we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag & IGNPAR)
+			port->ignore_status_mask |= UART011_DR_OE;
+	}
+
+	/*
+	 * Ignore all characters if CREAD is not set.
+	 */
+	if ((termios->c_cflag & CREAD) == 0)
+		port->ignore_status_mask |= UART_DUMMY_DR_RX;
+
+	if (UART_ENABLE_MS(port, termios->c_cflag))
+		pl011_enable_ms(port);
+
+	/* first, disable everything */
+	old_cr = readw(port->membase + UART011_CR);
+	writew(0, port->membase + UART011_CR);
+
+	if (termios->c_cflag & CRTSCTS) {
+		if (old_cr & UART011_CR_RTS)
+			old_cr |= UART011_CR_RTSEN;
+
+		old_cr |= UART011_CR_CTSEN;
+		uap->autorts = true;
+	} else {
+		old_cr &= ~(UART011_CR_CTSEN | UART011_CR_RTSEN);
+		uap->autorts = false;
+	}
+
+	if (uap->vendor->oversampling) {
+		if (baud > port->uartclk / 16)
+			old_cr |= ST_UART011_CR_OVSFACT;
+		else
+			old_cr &= ~ST_UART011_CR_OVSFACT;
+	}
+
+	/*
+	 * Workaround for the ST Micro oversampling variants to
+	 * increase the bitrate slightly, by lowering the divisor,
+	 * to avoid delayed sampling of start bit at high speeds,
+	 * else we see data corruption.
+	 */
+	if (uap->vendor->oversampling) {
+		if ((baud >= 3000000) && (baud < 3250000) && (quot > 1))
+			quot -= 1;
+		else if ((baud > 3250000) && (quot > 2))
+			quot -= 2;
+	}
+	/* Set baud rate */
+	writew(quot & 0x3f, port->membase + UART011_FBRD);
+	writew(quot >> 6, port->membase + UART011_IBRD);
+
+	/*
+	 * ----------v----------v----------v----------v-----
+	 * NOTE: lcrh_tx and lcrh_rx MUST BE WRITTEN AFTER
+	 * UART011_FBRD & UART011_IBRD.
+	 * ----------^----------^----------^----------^-----
+	 */
+	pl011_write_lcr_h(uap, lcr_h);
+	writew(old_cr, port->membase + UART011_CR);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *pl011_type(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+	return uap->port.type == PORT_AMBA ? uap->type : NULL;
+}
+
+/*
+ * Release the memory region(s) being used by 'port'
+ */
+static void pl011_release_port(struct uart_port *port)
+{
+	release_mem_region(port->mapbase, SZ_4K);
+}
+
+/*
+ * Request the memory region(s) being used by 'port'
+ */
+static int pl011_request_port(struct uart_port *port)
+{
+	return request_mem_region(port->mapbase, SZ_4K, "uart-pl011")
+			!= NULL ? 0 : -EBUSY;
+}
+
+/*
+ * Configure/autoconfigure the port.
+ */
+static void pl011_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE) {
+		port->type = PORT_AMBA;
+		pl011_request_port(port);
+	}
+}
+
+/*
+ * verify the new serial_struct (for TIOCSSERIAL).
+ */
+static int pl011_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	int ret = 0;
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_AMBA)
+		ret = -EINVAL;
+	if (ser->irq < 0 || ser->irq >= nr_irqs)
+		ret = -EINVAL;
+	if (ser->baud_base < 9600)
+		ret = -EINVAL;
+	return ret;
+}
+
+static struct uart_ops amba_pl011_pops = {
+	.tx_empty	= pl011_tx_empty,
+	.set_mctrl	= pl011_set_mctrl,
+	.get_mctrl	= pl011_get_mctrl,
+	.stop_tx	= pl011_stop_tx,
+	.start_tx	= pl011_start_tx,
+	.stop_rx	= pl011_stop_rx,
+	.enable_ms	= pl011_enable_ms,
+	.break_ctl	= pl011_break_ctl,
+	.startup	= pl011_startup,
+	.shutdown	= pl011_shutdown,
+	.flush_buffer	= pl011_dma_flush_buffer,
+	.set_termios	= pl011_set_termios,
+	.type		= pl011_type,
+	.release_port	= pl011_release_port,
+	.request_port	= pl011_request_port,
+	.config_port	= pl011_config_port,
+	.verify_port	= pl011_verify_port,
+#ifdef CONFIG_CONSOLE_POLL
+	.poll_init     = pl011_hwinit,
+	.poll_get_char = pl011_get_poll_char,
+	.poll_put_char = pl011_put_poll_char,
+#endif
+};
+
+static struct uart_amba_port *amba_ports[UART_NR];
+
+#ifdef CONFIG_SERIAL_AMBA_PL011_CONSOLE
+
+static void pl011_console_putchar(struct uart_port *port, int ch)
+{
+	struct uart_amba_port *uap =
+	    container_of(port, struct uart_amba_port, port);
+
+	while (readw(uap->port.membase + UART01x_FR) & UART01x_FR_TXFF)
+		barrier();
+	writew(ch, uap->port.membase + UART01x_DR);
+}
+
+static void
+pl011_console_write(struct console *co, const char *s, unsigned int count)
+{
+	struct uart_amba_port *uap = amba_ports[co->index];
+	unsigned int status, old_cr, new_cr;
+	unsigned long flags;
+	int locked = 1;
+
+	clk_enable(uap->clk);
+
+	local_irq_save(flags);
+	if (uap->port.sysrq)
+		locked = 0;
+	else if (oops_in_progress)
+		locked = spin_trylock(&uap->port.lock);
+	else
+		spin_lock(&uap->port.lock);
+
+	/*
+	 *	First save the CR then disable the interrupts
+	 */
+	old_cr = readw(uap->port.membase + UART011_CR);
+	new_cr = old_cr & ~UART011_CR_CTSEN;
+	new_cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
+	writew(new_cr, uap->port.membase + UART011_CR);
+
+	uart_console_write(&uap->port, s, count, pl011_console_putchar);
+
+	/*
+	 *	Finally, wait for transmitter to become empty
+	 *	and restore the TCR
+	 */
+	do {
+		status = readw(uap->port.membase + UART01x_FR);
+	} while (status & UART01x_FR_BUSY);
+	writew(old_cr, uap->port.membase + UART011_CR);
+
+	if (locked)
+		spin_unlock(&uap->port.lock);
+	local_irq_restore(flags);
+
+	clk_disable(uap->clk);
+}
+
+static void __init
+pl011_console_get_options(struct uart_amba_port *uap, int *baud,
+			     int *parity, int *bits)
+{
+	if (readw(uap->port.membase + UART011_CR) & UART01x_CR_UARTEN) {
+		unsigned int lcr_h, ibrd, fbrd;
+
+		lcr_h = readw(uap->port.membase + uap->lcrh_tx);
+
+		*parity = 'n';
+		if (lcr_h & UART01x_LCRH_PEN) {
+			if (lcr_h & UART01x_LCRH_EPS)
+				*parity = 'e';
+			else
+				*parity = 'o';
+		}
+
+		if ((lcr_h & 0x60) == UART01x_LCRH_WLEN_7)
+			*bits = 7;
+		else
+			*bits = 8;
+
+		ibrd = readw(uap->port.membase + UART011_IBRD);
+		fbrd = readw(uap->port.membase + UART011_FBRD);
+
+		*baud = uap->port.uartclk * 4 / (64 * ibrd + fbrd);
+
+		if (uap->vendor->oversampling) {
+			if (readw(uap->port.membase + UART011_CR)
+				  & ST_UART011_CR_OVSFACT)
+				*baud *= 2;
+		}
+	}
+}
+
+static int __init pl011_console_setup(struct console *co, char *options)
+{
+	struct uart_amba_port *uap;
+	int baud = 38400;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+	int ret;
+
+	/*
+	 * Check whether an invalid uart number has been specified, and
+	 * if so, search for the first available port that does have
+	 * console support.
+	 */
+	if (co->index >= UART_NR)
+		co->index = 0;
+	uap = amba_ports[co->index];
+	if (!uap)
+		return -ENODEV;
+
+	/* Allow pins to be muxed in and configured */
+	pinctrl_pm_select_default_state(uap->port.dev);
+
+	ret = clk_prepare(uap->clk);
+	if (ret)
+		return ret;
+
+	if (dev_get_platdata(uap->port.dev)) {
+		struct amba_pl011_data *plat;
+
+		plat = dev_get_platdata(uap->port.dev);
+		if (plat->init)
+			plat->init();
+	}
+
+	uap->port.uartclk = clk_get_rate(uap->clk);
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+	else
+		pl011_console_get_options(uap, &baud, &parity, &bits);
+
+	return uart_set_options(&uap->port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver amba_reg;
+static struct console amba_console = {
+	.name		= "ttyAMA",
+	.write		= pl011_console_write,
+	.device		= uart_console_device,
+	.setup		= pl011_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &amba_reg,
+};
+
+#define AMBA_CONSOLE	(&amba_console)
+
+static void pl011_putc(struct uart_port *port, int c)
+{
+	while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF)
+		;
+	writeb(c, port->membase + UART01x_DR);
+	while (readl(port->membase + UART01x_FR) & UART01x_FR_BUSY)
+		;
+}
+
+static void pl011_early_write(struct console *con, const char *s, unsigned n)
+{
+	struct earlycon_device *dev = con->data;
+
+	uart_console_write(&dev->port, s, n, pl011_putc);
+}
+
+static int __init pl011_early_console_setup(struct earlycon_device *device,
+					    const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	device->con->write = pl011_early_write;
+	return 0;
+}
+EARLYCON_DECLARE(pl011, pl011_early_console_setup);
+OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup);
+
+#else
+#define AMBA_CONSOLE	NULL
+#endif
+
+static struct uart_driver amba_reg = {
+	.owner			= THIS_MODULE,
+	.driver_name		= "ttyAMA",
+	.dev_name		= "ttyAMA",
+	.major			= SERIAL_AMBA_MAJOR,
+	.minor			= SERIAL_AMBA_MINOR,
+	.nr			= UART_NR,
+	.cons			= AMBA_CONSOLE,
+};
+
+static int pl011_probe_dt_alias(int index, struct device *dev)
+{
+	struct device_node *np;
+	static bool seen_dev_with_alias = false;
+	static bool seen_dev_without_alias = false;
+	int ret = index;
+
+	if (!IS_ENABLED(CONFIG_OF))
+		return ret;
+
+	np = dev->of_node;
+	if (!np)
+		return ret;
+
+	ret = of_alias_get_id(np, "serial");
+	if (IS_ERR_VALUE(ret)) {
+		seen_dev_without_alias = true;
+		ret = index;
+	} else {
+		seen_dev_with_alias = true;
+		if (ret >= ARRAY_SIZE(amba_ports) || amba_ports[ret] != NULL) {
+			dev_warn(dev, "requested serial port %d  not available.\n", ret);
+			ret = index;
+		}
+	}
+
+	if (seen_dev_with_alias && seen_dev_without_alias)
+		dev_warn(dev, "aliased and non-aliased serial devices found in device tree. Serial port enumeration may be unpredictable.\n");
+
+	return ret;
+}
+
+static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
+{
+	struct uart_amba_port *uap;
+	struct vendor_data *vendor = id->data;
+	void __iomem *base;
+	int i, ret;
+
+	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
+		if (amba_ports[i] == NULL)
+			break;
+
+	if (i == ARRAY_SIZE(amba_ports))
+		return -EBUSY;
+
+	uap = devm_kzalloc(&dev->dev, sizeof(struct uart_amba_port),
+			   GFP_KERNEL);
+	if (uap == NULL)
+		return -ENOMEM;
+
+	i = pl011_probe_dt_alias(i, &dev->dev);
+
+	base = devm_ioremap(&dev->dev, dev->res.start,
+			    resource_size(&dev->res));
+	if (!base)
+		return -ENOMEM;
+
+	uap->clk = devm_clk_get(&dev->dev, NULL);
+	if (IS_ERR(uap->clk))
+		return PTR_ERR(uap->clk);
+
+	uap->vendor = vendor;
+	uap->lcrh_rx = vendor->lcrh_rx;
+	uap->lcrh_tx = vendor->lcrh_tx;
+	uap->old_cr = 0;
+	uap->fifosize = vendor->get_fifosize(dev);
+	uap->port.dev = &dev->dev;
+	uap->port.mapbase = dev->res.start;
+	uap->port.membase = base;
+	uap->port.iotype = UPIO_MEM;
+	uap->port.irq = dev->irq[0];
+	uap->port.fifosize = uap->fifosize;
+	uap->port.ops = &amba_pl011_pops;
+	uap->port.flags = UPF_BOOT_AUTOCONF;
+	uap->port.line = i;
+	INIT_DELAYED_WORK(&uap->tx_softirq_work, pl011_tx_softirq);
+
+	/* Ensure interrupts from this UART are masked and cleared */
+	writew(0, uap->port.membase + UART011_IMSC);
+	writew(0xffff, uap->port.membase + UART011_ICR);
+
+	snprintf(uap->type, sizeof(uap->type), "PL011 rev%u", amba_rev(dev));
+
+	amba_ports[i] = uap;
+
+	amba_set_drvdata(dev, uap);
+
+	if (!amba_reg.state) {
+		ret = uart_register_driver(&amba_reg);
+		if (ret < 0) {
+			dev_err(&dev->dev,
+				"Failed to register AMBA-PL011 driver\n");
+			return ret;
+		}
+	}
+
+	ret = uart_add_one_port(&amba_reg, &uap->port);
+	if (ret) {
+		amba_ports[i] = NULL;
+		uart_unregister_driver(&amba_reg);
+	}
+
+	return ret;
+}
+
+static int pl011_remove(struct amba_device *dev)
+{
+	struct uart_amba_port *uap = amba_get_drvdata(dev);
+	bool busy = false;
+	int i;
+
+	uart_remove_one_port(&amba_reg, &uap->port);
+
+	for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
+		if (amba_ports[i] == uap)
+			amba_ports[i] = NULL;
+		else if (amba_ports[i])
+			busy = true;
+
+	pl011_dma_remove(uap);
+	if (!busy)
+		uart_unregister_driver(&amba_reg);
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int pl011_suspend(struct device *dev)
+{
+	struct uart_amba_port *uap = dev_get_drvdata(dev);
+
+	if (!uap)
+		return -EINVAL;
+
+	return uart_suspend_port(&amba_reg, &uap->port);
+}
+
+static int pl011_resume(struct device *dev)
+{
+	struct uart_amba_port *uap = dev_get_drvdata(dev);
+
+	if (!uap)
+		return -EINVAL;
+
+	return uart_resume_port(&amba_reg, &uap->port);
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(pl011_dev_pm_ops, pl011_suspend, pl011_resume);
+
+static struct amba_id pl011_ids[] = {
+	{
+		.id	= 0x00041011,
+		.mask	= 0x000fffff,
+		.data	= &vendor_arm,
+	},
+	{
+		.id	= 0x00380802,
+		.mask	= 0x00ffffff,
+		.data	= &vendor_st,
+	},
+	{ 0, 0 },
+};
+
+MODULE_DEVICE_TABLE(amba, pl011_ids);
+
+static struct amba_driver pl011_driver = {
+	.drv = {
+		.name	= "uart-pl011",
+		.pm	= &pl011_dev_pm_ops,
+	},
+	.id_table	= pl011_ids,
+	.probe		= pl011_probe,
+	.remove		= pl011_remove,
+};
+
+static int __init pl011_init(void)
+{
+	printk(KERN_INFO "Serial: AMBA PL011 UART driver\n");
+
+	return amba_driver_register(&pl011_driver);
+}
+
+static void __exit pl011_exit(void)
+{
+	amba_driver_unregister(&pl011_driver);
+}
+
+/*
+ * While this can be a module, if builtin it's most likely the console
+ * So let's leave module_exit but move module_init to an earlier place
+ */
+arch_initcall(pl011_init);
+module_exit(pl011_exit);
+
+MODULE_AUTHOR("ARM Ltd/Deep Blue Solutions Ltd");
+MODULE_DESCRIPTION("ARM AMBA serial port driver");
+MODULE_LICENSE("GPL");