hsu: driver for Medfield High Speed UART device

This is a PCI & UART driver, which suppors both PIO and DMA mode
UART operation. It has 3 identical UART ports and one internal
DMA controller.

Current FW will export 4 pci devices for hsu: 3 uart ports and 1
dma controller, each has one IRQ line. And we need to discuss the
device model, one PCI device covering whole HSU should be a better
model, but there is a problem of how to export the 4 IRQs info

Current driver set the highest baud rate to 2746800bps, which is
easy to scale down to 115200/230400.... To suport higher baud rate,
we need add special process, change DLAB/DLH/PS/DIV/MUL registers
all together.

921600 is the highest baud rate that has been tested with Bluetooth
modem connected to HSU port 0. Will test more when there is right
BT firmware.

Current version contains several work around for A0's Silicon bugs

Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

6 files changed, 1564 insertions, 0 deletions

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index c34c217..a22e60c 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -724,6 +724,16 @@ config MRST_MAX3110_IRQ
 	help
 	  This has to be enabled after Moorestown GPIO driver is loaded
 
+config SERIAL_MFD_HSU
+	tristate "Medfield High Speed UART support"
+	depends on PCI
+	select SERIAL_CORE
+
+config SERIAL_MFD_HSU_CONSOLE
+	boolean "Medfile HSU serial console support"
+	depends on SERIAL_MFD_HSU=y
+	select SERIAL_CORE_CONSOLE
+
 config SERIAL_BFIN
 	tristate "Blackfin serial port support"
 	depends on BLACKFIN
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 424067a..1ca4fd5 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -87,3 +87,4 @@ obj-$(CONFIG_SERIAL_GRLIB_GAISLER_APBUART) += apbuart.o
 obj-$(CONFIG_SERIAL_ALTERA_JTAGUART) += altera_jtaguart.o
 obj-$(CONFIG_SERIAL_ALTERA_UART) += altera_uart.o
 obj-$(CONFIG_SERIAL_MRST_MAX3110)	+= mrst_max3110.o
+obj-$(CONFIG_SERIAL_MFD_HSU)	+= mfd.o
diff --git a/drivers/serial/mfd.c b/drivers/serial/mfd.c
new file mode 100644
index 0000000..300dcb13
--- /dev/null
+++ b/drivers/serial/mfd.c
@@ -0,0 +1,1488 @@
+/*
+ * mfd.c: driver for High Speed UART device of Intel Medfield platform
+ *
+ * Refer pxa.c, 8250.c and some other drivers in drivers/serial/
+ *
+ * (C) Copyright 2009 Intel Corporation
+ *
+ * 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; version 2
+ * of the License.
+ */
+
+
+/* Notes:
+ * 1. there should be 2 types of register access method, one for
+ *    UART ports, the other for the general purpose registers
+ *
+ * 2. It used to have a Irda port, but was defeatured recently
+ *
+ * 3. Based on the info from HSU MAS, 0/1 channel are assigned to
+ *    port0, 2/3 chan to port 1, 4/5 chan to port 3. Even number
+ *    chan will be read, odd chan for write
+ *
+ * 4. HUS supports both the 64B and 16B FIFO version, but this driver
+ *    will only use 64B version
+ *
+ * 5. In A0 stepping, UART will not support TX half empty flag, thus
+ *    need add a #ifdef judgement
+ *
+ * 6. One more bug for A0, the loopback mode won't support AFC
+ *    auto-flow control
+ *
+ * 7. HSU has some special FCR control bits, we add it to serial_reg.h
+ *
+ * 8. The RI/DSR/DCD/DTR are not pinned out, DCD & DSR are always asserted,
+ *    only when the HW is reset the DDCD and DDSR will be triggered
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/console.h>
+#include <linux/sysrq.h>
+#include <linux/serial_reg.h>
+#include <linux/circ_buf.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial_core.h>
+#include <linux/serial_mfd.h>
+#include <linux/dma-mapping.h>
+#include <linux/pci.h>
+#include <linux/io.h>
+#include <linux/debugfs.h>
+
+#define  MFD_HSU_A0_STEPPING	1
+
+#define HSU_DMA_BUF_SIZE	2048
+
+#define chan_readl(chan, offset)	readl(chan->reg + offset)
+#define chan_writel(chan, offset, val)	writel(val, chan->reg + offset)
+
+#define mfd_readl(obj, offset)		readl(obj->reg + offset)
+#define mfd_writel(obj, offset, val)	writel(val, obj->reg + offset)
+
+struct hsu_dma_buffer {
+	u8		*buf;
+	dma_addr_t	dma_addr;
+	u32		dma_size;
+	u32		ofs;
+};
+
+struct hsu_dma_chan {
+	u32	id;
+	u32	dirt;	/* to or from device */
+	struct uart_hsu_port	*uport;
+	void __iomem	*reg;
+};
+
+struct uart_hsu_port {
+	struct uart_port        port;
+	unsigned char           ier;
+	unsigned char           lcr;
+	unsigned char           mcr;
+	unsigned int            lsr_break_flag;
+	char			name[12];
+	int			index;
+	struct device		*dev;
+
+	struct hsu_dma_chan	*txc;
+	struct hsu_dma_chan	*rxc;
+	struct hsu_dma_buffer	txbuf;
+	struct hsu_dma_buffer	rxbuf;
+	int			use_dma;	/* flag for DMA/PIO */
+	int			running;
+	int			dma_tx_on;
+};
+
+/* Top level data structure of HSU */
+struct hsu_port {
+	struct pci_device	*pdev;
+
+	void __iomem	*reg;
+	unsigned long	paddr;
+	unsigned long	iolen;
+	u32		irq;
+
+	struct uart_hsu_port	port[3];
+	struct hsu_dma_chan	chans[10];
+
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *debugfs;
+#endif
+};
+
+static inline void hexdump(char *str, u8 *addr, int cnt)
+{
+	int i;
+
+	for (i = 0; i < cnt; i += 8) {
+		printk("0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x",
+			addr[i], addr[i+1], addr[i+2], addr[i+3],
+			addr[i+4], addr[i+5], addr[i+6], addr[i+7]);
+		printk("\n");
+	}
+}
+
+static inline unsigned int serial_in(struct uart_hsu_port *up, int offset)
+{
+	unsigned int val;
+
+	if (offset > UART_MSR) {
+		offset <<= 2;
+		val = readl(up->port.membase + offset);
+	} else
+		val = (unsigned int)readb(up->port.membase + offset);
+
+	return val;
+}
+
+static inline void serial_out(struct uart_hsu_port *up, int offset, int value)
+{
+	if (offset > UART_MSR) {
+		offset <<= 2;
+		writel(value, up->port.membase + offset);
+	} else {
+		unsigned char val = value & 0xff;
+		writeb(val, up->port.membase + offset);
+	}
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+#define HSU_REGS_BUFSIZE	1024
+
+static int hsu_show_regs_open(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+	return 0;
+}
+
+static ssize_t port_show_regs(struct file *file, char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	struct uart_hsu_port *up = file->private_data;
+	char *buf;
+	u32 len = 0;
+	ssize_t ret;
+
+	buf = kzalloc(HSU_REGS_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return 0;
+
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"MFD HSU port[%d] regs:\n", up->index);
+
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"=================================\n");
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"IER: \t\t0x%08x\n", serial_in(up, UART_IER));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"IIR: \t\t0x%08x\n", serial_in(up, UART_IIR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"LCR: \t\t0x%08x\n", serial_in(up, UART_LCR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"MCR: \t\t0x%08x\n", serial_in(up, UART_MCR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"LSR: \t\t0x%08x\n", serial_in(up, UART_LSR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"MSR: \t\t0x%08x\n", serial_in(up, UART_MSR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"FOR: \t\t0x%08x\n", serial_in(up, UART_FOR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"PS: \t\t0x%08x\n", serial_in(up, UART_PS));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"MUL: \t\t0x%08x\n", serial_in(up, UART_MUL));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"DIV: \t\t0x%08x\n", serial_in(up, UART_DIV));
+
+	ret =  simple_read_from_buffer(user_buf, count, ppos, buf, len);
+	kfree(buf);
+	return ret;
+}
+
+static ssize_t dma_show_regs(struct file *file, char __user *user_buf,
+				size_t count, loff_t *ppos)
+{
+	struct hsu_dma_chan *chan = file->private_data;
+	char *buf;
+	u32 len = 0;
+	ssize_t ret;
+
+	buf = kzalloc(HSU_REGS_BUFSIZE, GFP_KERNEL);
+	if (!buf)
+		return 0;
+
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"MFD HSU DMA channel [%d] regs:\n", chan->id);
+
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"=================================\n");
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"CR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_CR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"DCR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_DCR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"BSR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_BSR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"MOTSR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_MOTSR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"D0SAR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_D0SAR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"D0TSR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_D0TSR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"D0SAR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_D1SAR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"D0TSR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_D1TSR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"D0SAR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_D2SAR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"D0TSR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_D2TSR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"D0SAR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_D3SAR));
+	len += snprintf(buf + len, HSU_REGS_BUFSIZE - len,
+			"D0TSR: \t\t0x%08x\n", chan_readl(chan, HSU_CH_D3TSR));
+
+	ret =  simple_read_from_buffer(user_buf, count, ppos, buf, len);
+	kfree(buf);
+	return ret;
+}
+
+static const struct file_operations port_regs_ops = {
+	.owner		= THIS_MODULE,
+	.open		= hsu_show_regs_open,
+	.read		= port_show_regs,
+};
+
+static const struct file_operations dma_regs_ops = {
+	.owner		= THIS_MODULE,
+	.open		= hsu_show_regs_open,
+	.read		= dma_show_regs,
+};
+
+static int hsu_debugfs_init(struct hsu_port *hsu)
+{
+	int i;
+	char name[32];
+
+	hsu->debugfs = debugfs_create_dir("hsu", NULL);
+	if (!hsu->debugfs)
+		return -ENOMEM;
+
+	for (i = 0; i < 3; i++) {
+		snprintf(name, sizeof(name), "port_%d_regs", i);
+		debugfs_create_file(name, S_IFREG | S_IRUGO,
+			hsu->debugfs, (void *)(&hsu->port[i]), &port_regs_ops);
+	}
+
+	for (i = 0; i < 6; i++) {
+		snprintf(name, sizeof(name), "dma_chan_%d_regs", i);
+		debugfs_create_file(name, S_IFREG | S_IRUGO,
+			hsu->debugfs, (void *)&hsu->chans[i], &dma_regs_ops);
+	}
+
+	return 0;
+}
+
+static void hsu_debugfs_remove(struct hsu_port *hsu)
+{
+	if (hsu->debugfs)
+		debugfs_remove_recursive(hsu->debugfs);
+}
+
+#else
+static inline int hsu_debugfs_init(struct hsu_port *hsu)
+{
+	return 0;
+}
+
+static inline void hsu_debugfs_remove(struct hsu_port *hsu)
+{
+}
+#endif /* CONFIG_DEBUG_FS */
+
+static void serial_hsu_enable_ms(struct uart_port *port)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+
+	up->ier |= UART_IER_MSI;
+	serial_out(up, UART_IER, up->ier);
+}
+
+void hsu_dma_tx(struct uart_hsu_port *up)
+{
+	struct circ_buf *xmit = &up->port.state->xmit;
+	struct hsu_dma_buffer *dbuf = &up->txbuf;
+	int count;
+
+	/* test_and_set_bit may be better, but anyway it's in lock protected mode */
+	if (up->dma_tx_on)
+		return;
+
+	/* Update the circ buf info */
+	xmit->tail += dbuf->ofs;
+	xmit->tail &= UART_XMIT_SIZE - 1;
+
+	up->port.icount.tx += dbuf->ofs;
+	dbuf->ofs = 0;
+
+	/* Disable the channel */
+	chan_writel(up->txc, HSU_CH_CR, 0x0);
+
+	if (!uart_circ_empty(xmit) && !uart_tx_stopped(&up->port)) {
+		dma_sync_single_for_device(up->port.dev,
+					   dbuf->dma_addr,
+					   dbuf->dma_size,
+					   DMA_TO_DEVICE);
+
+		count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
+		dbuf->ofs = count;
+
+		/* Reprogram the channel */
+		chan_writel(up->txc, HSU_CH_D0SAR, dbuf->dma_addr + xmit->tail);
+		chan_writel(up->txc, HSU_CH_D0TSR, count);
+
+		/* Reenable the channel */
+		chan_writel(up->txc, HSU_CH_DCR, 0x1
+						 | (0x1 << 8)
+						 | (0x1 << 16)
+						 | (0x1 << 24));
+
+		WARN(chan_readl(up->txc, HSU_CH_CR) & 0x1,
+			"TX channel has already be started!!\n");
+		up->dma_tx_on = 1;
+		chan_writel(up->txc, HSU_CH_CR, 0x1);
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&up->port);
+}
+
+/* The buffer is already cache coherent */
+void hsu_dma_start_rx_chan(struct hsu_dma_chan *rxc, struct hsu_dma_buffer *dbuf)
+{
+	/* Need start RX dma channel here */
+	dbuf->ofs = 0;
+
+	chan_writel(rxc, HSU_CH_BSR, 32);
+	chan_writel(rxc, HSU_CH_MOTSR, 4);
+
+	chan_writel(rxc, HSU_CH_D0SAR, dbuf->dma_addr);
+	chan_writel(rxc, HSU_CH_D0TSR, dbuf->dma_size);
+	chan_writel(rxc, HSU_CH_DCR, 0x1 | (0x1 << 8)
+					 | (0x1 << 16)
+					 | (0x1 << 24)	/* timeout bit, see HSU Errata 1 */
+					 );
+	chan_writel(rxc, HSU_CH_CR, 0x3);
+}
+
+/* Protected by spin_lock_irqsave(port->lock) */
+static void serial_hsu_start_tx(struct uart_port *port)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+
+	if (up->use_dma) {
+		hsu_dma_tx(up);
+	} else if (!(up->ier & UART_IER_THRI)) {
+		up->ier |= UART_IER_THRI;
+		serial_out(up, UART_IER, up->ier);
+	}
+}
+
+static void serial_hsu_stop_tx(struct uart_port *port)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	struct hsu_dma_chan *txc = up->txc;
+
+	if (up->use_dma)
+		chan_writel(txc, HSU_CH_CR, 0x0);
+	else if (up->ier & UART_IER_THRI) {
+		up->ier &= ~UART_IER_THRI;
+		serial_out(up, UART_IER, up->ier);
+	}
+}
+
+/* This is always called in spinlock protected mode, so
+ * modify timeout timer is safe here */
+void hsu_dma_rx(struct uart_hsu_port *up, u32 int_sts)
+{
+	struct hsu_dma_buffer *dbuf = &up->rxbuf;
+	struct hsu_dma_chan *chan = up->rxc;
+	struct uart_port *port = &up->port;
+	struct tty_struct *tty = port->state->port.tty;
+	int count;
+
+	if (!tty)
+		return;
+
+	/*
+	 * first need to know how many is already transferred,
+	 * then check if its a timeout DMA irq, and return
+	 * the trail bytes out, push them up and reenable the
+	 * channel, better to use 2 descriptors at the same time
+	 */
+
+	/* timeout IRQ, need wait some time, see Errata 2 */
+	if (int_sts & 0xf00)
+		udelay(2);
+
+	/* Stop the channel */
+	chan_writel(chan, HSU_CH_CR, 0x0);
+
+	/* We can use 2 ways to calc the actual transfer len */
+	count = chan_readl(chan, HSU_CH_D0SAR) - dbuf->dma_addr;
+
+	if (!count)
+		return;
+
+	dma_sync_single_for_cpu(port->dev, dbuf->dma_addr,
+			dbuf->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.
+	 */
+	tty_insert_flip_string(tty, dbuf->buf, count);
+	port->icount.rx += count;
+
+	dma_sync_single_for_device(up->port.dev, dbuf->dma_addr,
+			dbuf->dma_size, DMA_FROM_DEVICE);
+
+	/* Reprogram the channel */
+	chan_writel(chan, HSU_CH_D0SAR, dbuf->dma_addr);
+	chan_writel(chan, HSU_CH_D0TSR, dbuf->dma_size);
+	chan_writel(chan, HSU_CH_DCR, 0x1
+					 | (0x1 << 8)
+					 | (0x1 << 16)
+					 | (0x1 << 24)	/* timeout bit, see HSU Errata 1 */
+					 );
+	chan_writel(chan, HSU_CH_CR, 0x3);
+
+	tty_flip_buffer_push(tty);
+}
+
+static void serial_hsu_stop_rx(struct uart_port *port)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	struct hsu_dma_chan *chan = up->rxc;
+
+	if (up->use_dma)
+		chan_writel(chan, HSU_CH_CR, 0x2);
+	else {
+		up->ier &= ~UART_IER_RLSI;
+		up->port.read_status_mask &= ~UART_LSR_DR;
+		serial_out(up, UART_IER, up->ier);
+	}
+}
+
+/*
+ * if there is error flag, should we just reset the FIFO or keeps
+ * working on it
+ */
+static inline void receive_chars(struct uart_hsu_port *up, int *status)
+{
+	struct tty_struct *tty = up->port.state->port.tty;
+	unsigned int ch, flag;
+	unsigned int max_count = 256;
+
+	if (!tty)
+		return;
+
+	do {
+		ch = serial_in(up, UART_RX);
+		flag = TTY_NORMAL;
+		up->port.icount.rx++;
+
+		if (unlikely(*status & (UART_LSR_BI | UART_LSR_PE |
+				       UART_LSR_FE | UART_LSR_OE))) {
+
+			dev_warn(up->dev, "We really rush into ERR/BI case"
+				"status = 0x%02x", *status);
+			/* For statistics only */
+			if (*status & UART_LSR_BI) {
+				*status &= ~(UART_LSR_FE | UART_LSR_PE);
+				up->port.icount.brk++;
+				/*
+				 * We do the SysRQ and SAK checking
+				 * here because otherwise the break
+				 * may get masked by ignore_status_mask
+				 * or read_status_mask.
+				 */
+				if (uart_handle_break(&up->port))
+					goto ignore_char;
+			} else if (*status & UART_LSR_PE)
+				up->port.icount.parity++;
+			else if (*status & UART_LSR_FE)
+				up->port.icount.frame++;
+			if (*status & UART_LSR_OE)
+				up->port.icount.overrun++;
+
+			/* Mask off conditions which should be ignored. */
+			*status &= up->port.read_status_mask;
+
+#ifdef CONFIG_SERIAL_MFD_HSU_CONSOLE
+			if (up->port.cons &&
+				up->port.cons->index == up->port.line) {
+				/* Recover the break flag from console xmit */
+				*status |= up->lsr_break_flag;
+				up->lsr_break_flag = 0;
+			}
+#endif
+			if (*status & UART_LSR_BI) {
+				flag = TTY_BREAK;
+			} else if (*status & UART_LSR_PE)
+				flag = TTY_PARITY;
+			else if (*status & UART_LSR_FE)
+				flag = TTY_FRAME;
+		}
+
+		if (uart_handle_sysrq_char(&up->port, ch))
+			goto ignore_char;
+
+		uart_insert_char(&up->port, *status, UART_LSR_OE, ch, flag);
+	ignore_char:
+		*status = serial_in(up, UART_LSR);
+	} while ((*status & UART_LSR_DR) && max_count--);
+	tty_flip_buffer_push(tty);
+}
+
+static void transmit_chars(struct uart_hsu_port *up)
+{
+	struct circ_buf *xmit = &up->port.state->xmit;
+	int count;
+	int i = 0; /* for debug use */
+
+	if (up->port.x_char) {
+		serial_out(up, UART_TX, up->port.x_char);
+		up->port.icount.tx++;
+		up->port.x_char = 0;
+		return;
+	}
+	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
+		serial_hsu_stop_tx(&up->port);
+		return;
+	}
+
+#ifndef MFD_HSU_A0_STEPPING
+	count = up->port.fifosize / 2;
+#else
+	/*
+	 * A0 only supports fully empty IRQ, and the first char written
+	 * into it won't clear the EMPT bit, so we may need be cautious
+	 * by useing a shorter buffer
+	 */
+	/* count = up->port.fifosize; */
+	count = up->port.fifosize - 4;
+#endif
+	do {
+		serial_out(up, UART_TX, xmit->buf[xmit->tail]);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		i++;
+
+		up->port.icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+	} while (--count > 0);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(&up->port);
+
+	if (uart_circ_empty(xmit))
+		serial_hsu_stop_tx(&up->port);
+}
+
+static inline void check_modem_status(struct uart_hsu_port *up)
+{
+	int status;
+
+	status = serial_in(up, UART_MSR);
+
+	if ((status & UART_MSR_ANY_DELTA) == 0)
+		return;
+
+	if (status & UART_MSR_TERI)
+		up->port.icount.rng++;
+	if (status & UART_MSR_DDSR)
+		up->port.icount.dsr++;
+	/* We may only get DDCD when HW init and reset */
+	if (status & UART_MSR_DDCD)
+		uart_handle_dcd_change(&up->port, status & UART_MSR_DCD);
+	/* will start/stop_tx accordingly */
+	if (status & UART_MSR_DCTS)
+		uart_handle_cts_change(&up->port, status & UART_MSR_CTS);
+
+	wake_up_interruptible(&up->port.state->port.delta_msr_wait);
+}
+
+/*
+ * This handles the interrupt from one port.
+ */
+static irqreturn_t port_irq(int irq, void *dev_id)
+{
+	struct uart_hsu_port *up = dev_id;
+	unsigned int iir, lsr;
+	unsigned long flags;
+
+	if (unlikely(!up->running))
+		return IRQ_NONE;
+
+	if (up->use_dma) {
+		lsr = serial_in(up, UART_LSR);
+		if (unlikely(lsr & (UART_LSR_BI | UART_LSR_PE |
+				       UART_LSR_FE | UART_LSR_OE)))
+			dev_warn(up->dev,
+				"Got lsr irq while using DMA, lsr = 0x%2x\n",
+				lsr);
+		check_modem_status(up);
+		return IRQ_HANDLED;
+	}
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	iir = serial_in(up, UART_IIR);
+	if (iir & UART_IIR_NO_INT) {
+		spin_unlock_irqrestore(&up->port.lock, flags);
+		return IRQ_NONE;
+	}
+
+	lsr = serial_in(up, UART_LSR);
+
+	if (lsr & UART_LSR_DR)
+		receive_chars(up, &lsr);
+
+	/* lsr will be renewed during the receive_chars */
+	if (lsr & UART_LSR_THRE)
+		transmit_chars(up);
+
+	spin_unlock_irqrestore(&up->port.lock, flags);
+	return IRQ_HANDLED;
+}
+
+static inline void dma_chan_irq(struct hsu_dma_chan *chan)
+{
+	struct uart_hsu_port *up = chan->uport;
+	unsigned long flags;
+	u32 int_sts;
+
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	if (!up->use_dma || !up->running)
+		goto exit;
+
+	/*
+	 * No matter what situation, need read clear the IRQ status
+	 * There is a bug, see Errata 5, HSD 2900918
+	 */
+	int_sts = chan_readl(chan, HSU_CH_SR);
+
+	/* Rx channel */
+	if (chan->dirt == DMA_FROM_DEVICE)
+		hsu_dma_rx(up, int_sts);
+
+	/* Tx channel */
+	if (chan->dirt == DMA_TO_DEVICE) {
+		/* dma for irq should be done */
+		chan_writel(chan, HSU_CH_CR, 0x0);
+		up->dma_tx_on = 0;
+		hsu_dma_tx(up);
+	}
+
+exit:
+	spin_unlock_irqrestore(&up->port.lock, flags);
+	return;
+}
+
+static irqreturn_t dma_irq(int irq, void *dev_id)
+{
+	struct hsu_port *hsu = dev_id;
+	u32 int_sts, i;
+
+	int_sts = mfd_readl(hsu, HSU_GBL_DMAISR);
+
+	/* Currently we only have 6 channels may be used */
+	for (i = 0; i < 6; i++) {
+		if (int_sts & 0x1)
+			dma_chan_irq(&hsu->chans[i]);
+		int_sts >>= 1;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static unsigned int serial_hsu_tx_empty(struct uart_port *port)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	unsigned long flags;
+	unsigned int ret;
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	ret = serial_in(up, UART_LSR) & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
+	spin_unlock_irqrestore(&up->port.lock, flags);
+
+	return ret;
+}
+
+static unsigned int serial_hsu_get_mctrl(struct uart_port *port)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	unsigned char status;
+	unsigned int ret;
+
+	status = serial_in(up, UART_MSR);
+
+	ret = 0;
+	if (status & UART_MSR_DCD)
+		ret |= TIOCM_CAR;
+	if (status & UART_MSR_RI)
+		ret |= TIOCM_RNG;
+	if (status & UART_MSR_DSR)
+		ret |= TIOCM_DSR;
+	if (status & UART_MSR_CTS)
+		ret |= TIOCM_CTS;
+	return ret;
+}
+
+static void serial_hsu_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	unsigned char mcr = 0;
+
+	if (mctrl & TIOCM_RTS)
+		mcr |= UART_MCR_RTS;
+	if (mctrl & TIOCM_DTR)
+		mcr |= UART_MCR_DTR;
+	if (mctrl & TIOCM_OUT1)
+		mcr |= UART_MCR_OUT1;
+	if (mctrl & TIOCM_OUT2)
+		mcr |= UART_MCR_OUT2;
+	if (mctrl & TIOCM_LOOP)
+		mcr |= UART_MCR_LOOP;
+
+	mcr |= up->mcr;
+
+	serial_out(up, UART_MCR, mcr);
+}
+
+static void serial_hsu_break_ctl(struct uart_port *port, int break_state)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	if (break_state == -1)
+		up->lcr |= UART_LCR_SBC;
+	else
+		up->lcr &= ~UART_LCR_SBC;
+	serial_out(up, UART_LCR, up->lcr);
+	spin_unlock_irqrestore(&up->port.lock, flags);
+}
+
+/*
+ * What special to do:
+ * 1. chose the 64B fifo mode
+ * 2. make sure not to select half empty mode for A0 stepping
+ * 3. start dma or pio depends on configuration
+ * 4. we only allocate dma memory when needed
+ */
+static int serial_hsu_startup(struct uart_port *port)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	unsigned long flags;
+
+	/*
+	 * Clear the FIFO buffers and disable them.
+	 * (they will be reenabled in set_termios())
+	 */
+	serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO);
+	serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO |
+			UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
+	serial_out(up, UART_FCR, 0);
+
+	/* Clear the interrupt registers. */
+	(void) serial_in(up, UART_LSR);
+	(void) serial_in(up, UART_RX);
+	(void) serial_in(up, UART_IIR);
+	(void) serial_in(up, UART_MSR);
+
+	/* Now, initialize the UART, default is 8n1 */
+	serial_out(up, UART_LCR, UART_LCR_WLEN8);
+
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	up->port.mctrl |= TIOCM_OUT2;
+	serial_hsu_set_mctrl(&up->port, up->port.mctrl);
+
+	/*
+	 * Finally, enable interrupts.  Note: Modem status interrupts
+	 * are set via set_termios(), which will be occurring imminently
+	 * anyway, so we don't enable them here.
+	 */
+	if (!up->use_dma)
+		up->ier = UART_IER_RLSI | UART_IER_RDI | UART_IER_RTOIE;
+	else
+		up->ier = 0;
+	serial_out(up, UART_IER, up->ier);
+
+	spin_unlock_irqrestore(&up->port.lock, flags);
+
+	/* DMA init */
+	/* When use DMA, TX/RX's FIFO and IRQ should be disabled */
+	if (up->use_dma) {
+		struct hsu_dma_buffer *dbuf;
+		struct circ_buf *xmit = &port->state->xmit;
+
+		up->dma_tx_on = 0;
+
+		/* First allocate the RX buffer */
+		dbuf = &up->rxbuf;
+		dbuf->buf = kzalloc(HSU_DMA_BUF_SIZE, GFP_KERNEL);
+		if (!dbuf->buf) {
+			up->use_dma = 0;
+			goto exit;
+		}
+		dbuf->dma_addr = dma_map_single(port->dev,
+						dbuf->buf,
+						HSU_DMA_BUF_SIZE,
+						DMA_FROM_DEVICE);
+		dbuf->dma_size = HSU_DMA_BUF_SIZE;
+
+		/* Start the RX channel right now */
+		hsu_dma_start_rx_chan(up->rxc, dbuf);
+
+		/* Next init the TX DMA */
+		dbuf = &up->txbuf;
+		dbuf->buf = xmit->buf;
+		dbuf->dma_addr = dma_map_single(port->dev,
+					       dbuf->buf,
+					       UART_XMIT_SIZE,
+					       DMA_TO_DEVICE);
+		dbuf->dma_size = UART_XMIT_SIZE;
+
+		/* This should not be changed all around */
+		chan_writel(up->txc, HSU_CH_BSR, 32);
+		chan_writel(up->txc, HSU_CH_MOTSR, 4);
+		dbuf->ofs = 0;
+	}
+
+exit:
+	 /* And clear the interrupt registers again for luck. */
+	(void) serial_in(up, UART_LSR);
+	(void) serial_in(up, UART_RX);
+	(void) serial_in(up, UART_IIR);
+	(void) serial_in(up, UART_MSR);
+
+	up->running = 1;
+	return 0;
+}
+
+static void serial_hsu_shutdown(struct uart_port *port)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	unsigned long flags;
+
+	/* Disable interrupts from this port */
+	up->ier = 0;
+	serial_out(up, UART_IER, 0);
+	up->running = 0;
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	up->port.mctrl &= ~TIOCM_OUT2;
+	serial_hsu_set_mctrl(&up->port, up->port.mctrl);
+	spin_unlock_irqrestore(&up->port.lock, flags);
+
+	/* Disable break condition and FIFOs */
+	serial_out(up, UART_LCR, serial_in(up, UART_LCR) & ~UART_LCR_SBC);
+	serial_out(up, UART_FCR, UART_FCR_ENABLE_FIFO |
+				  UART_FCR_CLEAR_RCVR |
+				  UART_FCR_CLEAR_XMIT);
+	serial_out(up, UART_FCR, 0);
+}
+
+static void
+serial_hsu_set_termios(struct uart_port *port, struct ktermios *termios,
+		       struct ktermios *old)
+{
+	struct uart_hsu_port *up =
+			container_of(port, struct uart_hsu_port, port);
+	struct tty_struct *tty = port->state->port.tty;
+	unsigned char cval, fcr = 0;
+	unsigned long flags;
+	unsigned int baud, quot;
+	u32 mul = 0x3600;
+	u32 ps = 0x10;
+
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		cval = UART_LCR_WLEN5;
+		break;
+	case CS6:
+		cval = UART_LCR_WLEN6;
+		break;
+	case CS7:
+		cval = UART_LCR_WLEN7;
+		break;
+	default:
+	case CS8:
+		cval = UART_LCR_WLEN8;
+		break;
+	}
+
+	/* CMSPAR isn't supported by this driver */
+	if (tty)
+		tty->termios->c_cflag &= ~CMSPAR;
+
+	if (termios->c_cflag & CSTOPB)
+		cval |= UART_LCR_STOP;
+	if (termios->c_cflag & PARENB)
+		cval |= UART_LCR_PARITY;
+	if (!(termios->c_cflag & PARODD))
+		cval |= UART_LCR_EPAR;
+
+	/*
+	 * For those basic low baud rate we can get the direct
+	 * scalar from 2746800, like 115200 = 2746800/24, for those
+	 * higher baud rate, we have to handle them case by case,
+	 * but DIV reg is never touched as its default value 0x3d09
+	 */
+	baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
+	quot = uart_get_divisor(port, baud);
+
+	switch (baud) {
+	case 3500000:
+		mul = 0x3345;
+		ps = 0xC;
+		quot = 1;
+		break;
+	case 2500000:
+		mul = 0x2710;
+		ps = 0x10;
+		quot = 1;
+		break;
+	case 18432000:
+		mul = 0x2400;
+		ps = 0x10;
+		quot = 1;
+		break;
+	case 1500000:
+		mul = 0x1D4C;
+		ps = 0xc;
+		quot = 1;
+		break;
+	default:
+		;
+	}
+
+	if ((up->port.uartclk / quot) < (2400 * 16))
+		fcr = UART_FCR_ENABLE_FIFO | UART_FCR_HSU_64_1B;
+	else if ((up->port.uartclk / quot) < (230400 * 16))
+		fcr = UART_FCR_ENABLE_FIFO | UART_FCR_HSU_64_16B;
+	else
+		fcr = UART_FCR_ENABLE_FIFO | UART_FCR_HSU_64_32B;
+
+	fcr |= UART_FCR_HSU_64B_FIFO;
+#ifdef MFD_HSU_A0_STEPPING
+	/* A0 doesn't support half empty IRQ */
+	fcr |= UART_FCR_FULL_EMPT_TXI;
+#endif
+
+	/*
+	 * Ok, we're now changing the port state.  Do it with
+	 * interrupts disabled.
+	 */
+	spin_lock_irqsave(&up->port.lock, flags);
+
+	/* Update the per-port timeout */
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	up->port.read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
+	if (termios->c_iflag & INPCK)
+		up->port.read_status_mask |= UART_LSR_FE | UART_LSR_PE;
+	if (termios->c_iflag & (BRKINT | PARMRK))
+		up->port.read_status_mask |= UART_LSR_BI;
+
+	/* Characters to ignore */
+	up->port.ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		up->port.ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
+	if (termios->c_iflag & IGNBRK) {
+		up->port.ignore_status_mask |= UART_LSR_BI;
+		/*
+		 * If we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag & IGNPAR)
+			up->port.ignore_status_mask |= UART_LSR_OE;
+	}
+
+	/* Ignore all characters if CREAD is not set */
+	if ((termios->c_cflag & CREAD) == 0)
+		up->port.ignore_status_mask |= UART_LSR_DR;
+
+	/*
+	 * CTS flow control flag and modem status interrupts, disable
+	 * MSI by default
+	 */
+	up->ier &= ~UART_IER_MSI;
+	if (UART_ENABLE_MS(&up->port, termios->c_cflag))
+		up->ier |= UART_IER_MSI;
+
+	serial_out(up, UART_IER, up->ier);
+
+	if (termios->c_cflag & CRTSCTS)
+		up->mcr |= UART_MCR_AFE | UART_MCR_RTS;
+	else
+		up->mcr &= ~UART_MCR_AFE;
+
+	serial_out(up, UART_LCR, cval | UART_LCR_DLAB);	/* set DLAB */
+	serial_out(up, UART_DLL, quot & 0xff);		/* LS of divisor */
+	serial_out(up, UART_DLM, quot >> 8);		/* MS of divisor */
+	serial_out(up, UART_LCR, cval);			/* reset DLAB */
+	serial_out(up, UART_MUL, mul);			/* set MUL */
+	serial_out(up, UART_PS, ps);			/* set PS */
+	up->lcr = cval;					/* Save LCR */
+	serial_hsu_set_mctrl(&up->port, up->port.mctrl);
+	serial_out(up, UART_FCR, fcr);
+	spin_unlock_irqrestore(&up->port.lock, flags);
+}
+
+static void
+serial_hsu_pm(struct uart_port *port, unsigned int state,
+	      unsigned int oldstate)
+{
+}
+
+static void serial_hsu_release_port(struct uart_port *port)
+{
+}
+
+static int serial_hsu_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+static void serial_hsu_config_port(struct uart_port *port, int flags)
+{
+#if 0
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	up->port.type = PORT_MFD;
+#endif
+}
+
+static int
+serial_hsu_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	/* We don't want the core code to modify any port params */
+	return -EINVAL;
+}
+
+static const char *
+serial_hsu_type(struct uart_port *port)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+	return up->name;
+}
+
+/* Mainly for uart console use */
+static struct uart_hsu_port *serial_hsu_ports[3];
+static struct uart_driver serial_hsu_reg;
+
+#ifdef CONFIG_SERIAL_MFD_HSU_CONSOLE
+
+#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
+
+/* Wait for transmitter & holding register to empty */
+static inline void wait_for_xmitr(struct uart_hsu_port *up)
+{
+	unsigned int status, tmout = 1000;
+
+	/* Wait up to 1ms for the character to be sent. */
+	do {
+		status = serial_in(up, UART_LSR);
+
+		if (status & UART_LSR_BI)
+			up->lsr_break_flag = UART_LSR_BI;
+
+		if (--tmout == 0)
+			break;
+		udelay(1);
+	} while (!(status & BOTH_EMPTY));
+
+	/* Wait up to 1s for flow control if necessary */
+	if (up->port.flags & UPF_CONS_FLOW) {
+		tmout = 1000000;
+		while (--tmout &&
+		       ((serial_in(up, UART_MSR) & UART_MSR_CTS) == 0))
+			udelay(1);
+	}
+}
+
+static void serial_hsu_console_putchar(struct uart_port *port, int ch)
+{
+	struct uart_hsu_port *up =
+		container_of(port, struct uart_hsu_port, port);
+
+	wait_for_xmitr(up);
+	serial_out(up, UART_TX, ch);
+}
+
+/*
+ * Print a string to the serial port trying not to disturb
+ * any possible real use of the port...
+ *
+ *	The console_lock must be held when we get here.
+ */
+static void
+serial_hsu_console_write(struct console *co, const char *s, unsigned int count)
+{
+	struct uart_hsu_port *up = serial_hsu_ports[co->index];
+	unsigned long flags;
+	unsigned int ier;
+	int locked = 1;
+
+	local_irq_save(flags);
+	if (up->port.sysrq)
+		locked = 0;
+	else if (oops_in_progress) {
+		locked = spin_trylock(&up->port.lock);
+	} else
+		spin_lock(&up->port.lock);
+
+	/* First save the IER then disable the interrupts */
+	ier = serial_in(up, UART_IER);
+	serial_out(up, UART_IER, 0);
+
+	uart_console_write(&up->port, s, count, serial_hsu_console_putchar);
+
+	/*
+	 * Finally, wait for transmitter to become empty
+	 * and restore the IER
+	 */
+	wait_for_xmitr(up);
+	serial_out(up, UART_IER, ier);
+
+	if (locked)
+		spin_unlock(&up->port.lock);
+	local_irq_restore(flags);
+}
+
+static struct console serial_hsu_console;
+
+static int __init
+serial_hsu_console_setup(struct console *co, char *options)
+{
+	struct uart_hsu_port *up;
+	int baud = 115200;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+	int ret;
+
+	if (co->index == -1 || co->index >= serial_hsu_reg.nr)
+		co->index = 0;
+	up = serial_hsu_ports[co->index];
+	if (!up)
+		return -ENODEV;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	ret = uart_set_options(&up->port, co, baud, parity, bits, flow);
+
+	return ret;
+}
+
+static struct console serial_hsu_console = {
+	.name		= "ttyMFD",
+	.write		= serial_hsu_console_write,
+	.device		= uart_console_device,
+	.setup		= serial_hsu_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= 2,
+	.data		= &serial_hsu_reg,
+};
+#endif
+
+struct uart_ops serial_hsu_pops = {
+	.tx_empty	= serial_hsu_tx_empty,
+	.set_mctrl	= serial_hsu_set_mctrl,
+	.get_mctrl	= serial_hsu_get_mctrl,
+	.stop_tx	= serial_hsu_stop_tx,
+	.start_tx	= serial_hsu_start_tx,
+	.stop_rx	= serial_hsu_stop_rx,
+	.enable_ms	= serial_hsu_enable_ms,
+	.break_ctl	= serial_hsu_break_ctl,
+	.startup	= serial_hsu_startup,
+	.shutdown	= serial_hsu_shutdown,
+	.set_termios	= serial_hsu_set_termios,
+	.pm		= serial_hsu_pm,
+	.type		= serial_hsu_type,
+	.release_port	= serial_hsu_release_port,
+	.request_port	= serial_hsu_request_port,
+	.config_port	= serial_hsu_config_port,
+	.verify_port	= serial_hsu_verify_port,
+};
+
+static struct uart_driver serial_hsu_reg = {
+	.owner		= THIS_MODULE,
+	.driver_name	= "MFD serial",
+	.dev_name	= "ttyMFD",
+	.major		= TTY_MAJOR,
+	.minor		= 128,
+	.nr		= 3,
+};
+
+#ifdef CONFIG_PM
+static int serial_hsu_suspend(struct pci_dev *pdev, pm_message_t state)
+{
+	struct uart_hsu_port *up;
+
+	up = pci_get_drvdata(pdev);
+	if (!up)
+		return 0;
+
+	uart_suspend_port(&serial_hsu_reg, &up->port);
+
+        return 0;
+}
+
+static int serial_hsu_resume(struct pci_dev *pdev)
+{
+	struct uart_hsu_port *up;
+
+	up = pci_get_drvdata(pdev);
+	if (!up)
+		return 0;
+	uart_resume_port(&serial_hsu_reg, &up->port);
+	return 0;
+}
+#else
+#define serial_hsu_suspend	NULL
+#define serial_hsu_resume	NULL
+#endif
+
+/* temp global pointer before we settle down on using one or four PCI dev */
+static struct hsu_port *phsu;
+
+static int serial_hsu_probe(struct pci_dev *pdev,
+				const struct pci_device_id *ent)
+{
+	struct uart_hsu_port *uport;
+	int index, ret;
+
+	printk(KERN_INFO "HSU: found PCI Serial controller(ID: %04x:%04x)\n",
+		pdev->vendor, pdev->device);
+
+	switch (pdev->device) {
+	case 0x081B:
+		index = 0;
+		break;
+	case 0x081C:
+		index = 1;
+		break;
+	case 0x081D:
+		index = 2;
+		break;
+	case 0x081E:
+		/* internal DMA controller */
+		index = 3;
+		break;
+	default:
+		dev_err(&pdev->dev, "HSU: out of index!");
+		return -ENODEV;
+	}
+
+	ret = pci_enable_device(pdev);
+	if (ret)
+		return ret;
+
+	if (index == 3) {
+		/* DMA controller */
+		ret = request_irq(pdev->irq, dma_irq, 0, "hsu_dma", phsu);
+		if (ret) {
+			dev_err(&pdev->dev, "can not get IRQ\n");
+			goto err_disable;
+		}
+		pci_set_drvdata(pdev, phsu);
+	} else {
+		/* UART port 0~2 */
+		uport = &phsu->port[index];
+		uport->port.irq = pdev->irq;
+		uport->port.dev = &pdev->dev;
+		uport->dev = &pdev->dev;
+
+		ret = request_irq(pdev->irq, port_irq, 0, uport->name, uport);
+		if (ret) {
+			dev_err(&pdev->dev, "can not get IRQ\n");
+			goto err_disable;
+		}
+		uart_add_one_port(&serial_hsu_reg, &uport->port);
+
+#ifdef CONFIG_SERIAL_MFD_HSU_CONSOLE
+		if (index == 2) {
+			register_console(&serial_hsu_console);
+			uport->port.cons = &serial_hsu_console;
+		}
+#endif
+		pci_set_drvdata(pdev, uport);
+	}
+
+	return 0;
+
+err_disable:
+	pci_disable_device(pdev);
+	return ret;
+}
+
+static void hsu_global_init(void)
+{
+	struct hsu_port *hsu;
+	struct uart_hsu_port *uport;
+	struct hsu_dma_chan *dchan;
+	int i, ret;
+
+	hsu = kzalloc(sizeof(struct hsu_port), GFP_KERNEL);
+	if (!hsu)
+		return;
+
+	/* Get basic io resource and map it */
+	hsu->paddr = 0xffa28000;
+	hsu->iolen = 0x1000;
+
+	if (!(request_mem_region(hsu->paddr, hsu->iolen, "HSU global")))
+		pr_warning("HSU: error in request mem region\n");
+
+	hsu->reg = ioremap_nocache((unsigned long)hsu->paddr, hsu->iolen);
+	if (!hsu->reg) {
+		pr_err("HSU: error in ioremap\n");
+		ret = -ENOMEM;
+		goto err_free_region;
+	}
+
+	/* Initialise the 3 UART ports */
+	uport = hsu->port;
+	for (i = 0; i < 3; i++) {
+		uport->port.type = PORT_MFD;
+		uport->port.iotype = UPIO_MEM;
+		uport->port.mapbase = (resource_size_t)hsu->paddr
+					+ HSU_PORT_REG_OFFSET
+					+ i * HSU_PORT_REG_LENGTH;
+		uport->port.membase = hsu->reg + HSU_PORT_REG_OFFSET
+					+ i * HSU_PORT_REG_LENGTH;
+
+		sprintf(uport->name, "hsu_port%d", i);
+		uport->port.fifosize = 64;
+		uport->port.ops = &serial_hsu_pops;
+		uport->port.line = i;
+		uport->port.flags = UPF_IOREMAP;
+		/* make the maxim support rate to 2746800 bps */
+		uport->port.uartclk = 115200 * 24 * 16;
+
+		uport->running = 0;
+		uport->txc = &hsu->chans[i * 2];
+		uport->rxc = &hsu->chans[i * 2 + 1];
+
+		serial_hsu_ports[i] = uport;
+		uport->index = i;
+		uport++;
+	}
+
+	/* Initialise 6 dma channels */
+	dchan = hsu->chans;
+	for (i = 0; i < 6; i++) {
+		dchan->id = i;
+		dchan->dirt = (i & 0x1) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+		dchan->uport = &hsu->port[i/2];
+		dchan->reg = hsu->reg + HSU_DMA_CHANS_REG_OFFSET +
+				i * HSU_DMA_CHANS_REG_LENGTH;
+		dchan++;
+	}
+
+	phsu = hsu;
+
+	hsu_debugfs_init(hsu);
+	return;
+
+err_free_region:
+	release_mem_region(hsu->paddr, hsu->iolen);
+	kfree(hsu);
+	return;
+}
+
+static void serial_hsu_remove(struct pci_dev *pdev)
+{
+	struct hsu_port *hsu;
+	int i;
+
+	hsu = pci_get_drvdata(pdev);
+	if (!hsu)
+		return;
+
+	for (i = 0; i < 3; i++)
+		uart_remove_one_port(&serial_hsu_reg, &hsu->port[i].port);
+
+	pci_set_drvdata(pdev, NULL);
+	free_irq(hsu->irq, hsu);
+	pci_disable_device(pdev);
+}
+
+/* First 3 are UART ports, and the 4th is the DMA */
+static const struct pci_device_id pci_ids[] __devinitdata = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x081B) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x081C) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x081D) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x081E) },
+	{},
+};
+
+static struct pci_driver hsu_pci_driver = {
+	.name =		"HSU serial",
+	.id_table =	pci_ids,
+	.probe =	serial_hsu_probe,
+	.remove =	__devexit_p(serial_hsu_remove),
+	.suspend =	serial_hsu_suspend,
+	.resume	=	serial_hsu_resume,
+};
+
+static int __init hsu_pci_init(void)
+{
+	int ret;
+
+	hsu_global_init();
+
+	ret = uart_register_driver(&serial_hsu_reg);
+	if (ret)
+		return ret;
+
+	return pci_register_driver(&hsu_pci_driver);
+}
+
+static void __exit hsu_pci_exit(void)
+{
+	pci_unregister_driver(&hsu_pci_driver);
+	uart_unregister_driver(&serial_hsu_reg);
+
+	hsu_debugfs_remove(phsu);
+
+	kfree(phsu);
+}
+
+module_init(hsu_pci_init);
+module_exit(hsu_pci_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:medfield-hsu");
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 9ddc866..f8fce35 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -189,6 +189,8 @@
 /* MAX3107 */
 #define PORT_MAX3107	94
 
+/* High Speed UART for Medfield */
+#define PORT_MFD	95
 
 #ifdef __KERNEL__
 
diff --git a/include/linux/serial_mfd.h b/include/linux/serial_mfd.h
new file mode 100644
index 0000000..2b071e0
--- /dev/null
+++ b/include/linux/serial_mfd.h
@@ -0,0 +1,47 @@
+#ifndef _SERIAL_MFD_H_
+#define _SERIAL_MFD_H_
+
+/* HW register offset definition */
+#define UART_FOR	0x08
+#define UART_PS		0x0C
+#define UART_MUL	0x0D
+#define UART_DIV	0x0E
+
+#define HSU_GBL_IEN	0x0
+#define HSU_GBL_IST	0x4
+
+#define HSU_GBL_INT_BIT_PORT0	0x0
+#define HSU_GBL_INT_BIT_PORT1	0x1
+#define HSU_GBL_INT_BIT_PORT2	0x2
+#define HSU_GBL_INT_BIT_IRI	0x3
+#define HSU_GBL_INT_BIT_HDLC	0x4
+#define HSU_GBL_INT_BIT_DMA	0x5
+
+#define HSU_GBL_ISR	0x8
+#define HSU_GBL_DMASR	0x400
+#define HSU_GBL_DMAISR	0x404
+
+#define HSU_PORT_REG_OFFSET	0x80
+#define HSU_PORT0_REG_OFFSET	0x80
+#define HSU_PORT1_REG_OFFSET	0x100
+#define HSU_PORT2_REG_OFFSET	0x180
+#define HSU_PORT_REG_LENGTH	0x80
+
+#define HSU_DMA_CHANS_REG_OFFSET	0x500
+#define HSU_DMA_CHANS_REG_LENGTH	0x40
+
+#define HSU_CH_SR		0x0	/* channel status reg */
+#define HSU_CH_CR		0x4	/* control reg */
+#define HSU_CH_DCR		0x8	/* descriptor control reg */
+#define HSU_CH_BSR		0x10	/* max fifo buffer size reg */
+#define HSU_CH_MOTSR		0x14	/* minimum ocp transfer size */
+#define HSU_CH_D0SAR		0x20	/* desc 0 start addr */
+#define HSU_CH_D0TSR		0x24	/* desc 0 transfer size */
+#define HSU_CH_D1SAR		0x28
+#define HSU_CH_D1TSR		0x2C
+#define HSU_CH_D2SAR		0x30
+#define HSU_CH_D2TSR		0x34
+#define HSU_CH_D3SAR		0x38
+#define HSU_CH_D3TSR		0x3C
+
+#endif
diff --git a/include/linux/serial_reg.h b/include/linux/serial_reg.h
index cf9327c..c7a0ce1 100644
--- a/include/linux/serial_reg.h
+++ b/include/linux/serial_reg.h
@@ -221,8 +221,24 @@
 #define UART_FCR_PXAR16	0x80	/* receive FIFO threshold = 16 */
 #define UART_FCR_PXAR32	0xc0	/* receive FIFO threshold = 32 */
 
+/*
+ * Intel MID on-chip HSU (High Speed UART) defined bits
+ */
+#define UART_FCR_HSU_64_1B	0x00	/* receive FIFO treshold = 1 */
+#define UART_FCR_HSU_64_16B	0x40	/* receive FIFO treshold = 16 */
+#define UART_FCR_HSU_64_32B	0x80	/* receive FIFO treshold = 32 */
+#define UART_FCR_HSU_64_56B	0xc0	/* receive FIFO treshold = 56 */
+
+#define UART_FCR_HSU_16_1B	0x00	/* receive FIFO treshold = 1 */
+#define UART_FCR_HSU_16_4B	0x40	/* receive FIFO treshold = 4 */
+#define UART_FCR_HSU_16_8B	0x80	/* receive FIFO treshold = 8 */
+#define UART_FCR_HSU_16_14B	0xc0	/* receive FIFO treshold = 14 */
 
+#define UART_FCR_HSU_64B_FIFO	0x20	/* chose 64 bytes FIFO */
+#define UART_FCR_HSU_16B_FIFO	0x00	/* chose 16 bytes FIFO */
 
+#define UART_FCR_HALF_EMPT_TXI	0x00	/* trigger TX_EMPT IRQ for half empty */
+#define UART_FCR_FULL_EMPT_TXI	0x08	/* trigger TX_EMPT IRQ for full empty */
 
 /*
  * These register definitions are for the 16C950