[PATCH v2] tty: serial: Add driver for MEN's 16z135 High Speed UART.

[Johannes Thumshirn]

Add driver for MEN's 16z135 High Speed UART.

The 16z135 is a memory mapped UART Core on an MCB FPGA and has 1024 byte
deep FIFO buffers for the RX and TX path. It also has configurable FIFO
fill level IRQs and data copied to and from the hardware has to be
acknowledged.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@xxxxxx>
---
Changes since v1:
* corrected typo prot -> port
* cleared CMSPAR flag in termios
* lock men_z135_reg_{set,clear}
* use dev_warn instead of pr_err
* remove global line counter

 drivers/tty/serial/Kconfig         |  10 +
 drivers/tty/serial/Makefile        |   1 +
 drivers/tty/serial/men_z135_uart.c | 866 +++++++++++++++++++++++++++++++++++++
 include/uapi/linux/serial_core.h   |   3 +
 4 files changed, 880 insertions(+)
 create mode 100644 drivers/tty/serial/men_z135_uart.c

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 2e6d8dd..4cd81e2 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1507,6 +1507,16 @@ config SERIAL_ST_ASC_CONSOLE
 	depends on SERIAL_ST_ASC=y
 	select SERIAL_CORE_CONSOLE

+config SERIAL_MEN_Z135
+	tristate "MEN 16z135 Support"
+	depends on MCB
+	help
+	  Say yes here to enable support for the MEN 16z135 High Speed UART IP-Core
+	  on a MCB carrier.
+
+	  This driver can also be build as a module. If so, the module will be called
+	  men_z135_uart.ko
+
 endmenu

 endif # TTY
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 3680854..5f2a3f4 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -87,3 +87,4 @@ obj-$(CONFIG_SERIAL_EFM32_UART) += efm32-uart.o
 obj-$(CONFIG_SERIAL_ARC)	+= arc_uart.o
 obj-$(CONFIG_SERIAL_RP2)	+= rp2.o
 obj-$(CONFIG_SERIAL_FSL_LPUART)	+= fsl_lpuart.o
+obj-$(CONFIG_SERIAL_MEN_Z135)	+= men_z135_uart.o
diff --git a/drivers/tty/serial/men_z135_uart.c b/drivers/tty/serial/men_z135_uart.c
new file mode 100644
index 0000000..d08eb5d
--- /dev/null
+++ b/drivers/tty/serial/men_z135_uart.c
@@ -0,0 +1,866 @@
+/*
+ * MEN 16z135 High Speed UART
+ *
+ * Copyright (C) 2014 MEN Mikroelektronik GmbH (www.men.de)
+ * Author: Johannes Thumshirn <johannes.thumshirn@xxxxxx>
+ *
+ * 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.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ":" fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/serial_core.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/tty_flip.h>
+#include <linux/bitops.h>
+#include <linux/mcb.h>
+
+#define MEN_Z135_MAX_PORTS		12
+#define MEN_Z135_BASECLK		29491200
+#define MEN_Z135_FIFO_SIZE		1024
+#define MEN_Z135_NUM_MSI_VECTORS	2
+#define MEN_Z135_FIFO_WATERMARK		1020
+
+#define MEN_Z135_STAT_REG		0x0
+#define MEN_Z135_RX_RAM			0x4
+#define MEN_Z135_TX_RAM			0x400
+#define MEN_Z135_RX_CTRL		0x800
+#define MEN_Z135_TX_CTRL		0x804
+#define MEN_Z135_CONF_REG		0x808
+#define MEN_Z135_UART_FREQ		0x80c
+#define MEN_Z135_BAUD_REG		0x810
+#define MENZ135_TIMEOUT			0x814
+
+#define MEN_Z135_MEM_SIZE		0x818
+
+#define IS_IRQ(x) ((x) & 1)
+#define IRQ_ID(x) (((x) >> 1) & 7)
+
+#define MEN_Z135_IER_RXCIEN BIT(0)		/* TX Space IRQ */
+#define MEN_Z135_IER_TXCIEN BIT(1)		/* RX Space IRQ */
+#define MEN_Z135_IER_RLSIEN BIT(2)		/* Receiver Line Status IRQ */
+#define MEN_Z135_IER_MSIEN  BIT(3)		/* Modem Status IRQ */
+#define MEN_Z135_ALL_IRQS (MEN_Z135_IER_RXCIEN		\
+				| MEN_Z135_IER_RLSIEN	\
+				| MEN_Z135_IER_MSIEN	\
+				| MEN_Z135_IER_TXCIEN)
+
+#define MEN_Z135_MCR_DTR	BIT(24)
+#define MEN_Z135_MCR_RTS	BIT(25)
+#define MEN_Z135_MCR_OUT1	BIT(26)
+#define MEN_Z135_MCR_OUT2	BIT(27)
+#define MEN_Z135_MCR_LOOP	BIT(28)
+#define MEN_Z135_MCR_RCFC	BIT(29)
+
+#define MEN_Z135_MSR_DCTS	BIT(0)
+#define MEN_Z135_MSR_DDSR	BIT(1)
+#define MEN_Z135_MSR_DRI	BIT(2)
+#define MEN_Z135_MSR_DDCD	BIT(3)
+#define MEN_Z135_MSR_CTS	BIT(4)
+#define MEN_Z135_MSR_DSR	BIT(5)
+#define MEN_Z135_MSR_RI		BIT(6)
+#define MEN_Z135_MSR_DCD	BIT(7)
+
+#define MEN_Z135_LCR_SHIFT 8	/* LCR shift mask */
+
+#define MEN_Z135_WL5 0		/* CS5 */
+#define MEN_Z135_WL6 1		/* CS6 */
+#define MEN_Z135_WL7 2		/* CS7 */
+#define MEN_Z135_WL8 3		/* CS8 */
+
+#define MEN_Z135_STB_SHIFT 2	/* Stopbits */
+#define MEN_Z135_NSTB1 0
+#define MEN_Z135_NSTB2 1
+
+#define MEN_Z135_PEN_SHIFT 3	/* Parity enable */
+#define MEN_Z135_PAR_DIS 0
+#define MEN_Z135_PAR_ENA 1
+
+#define MEN_Z135_PTY_SHIFT 4	/* Parity type */
+#define MEN_Z135_PTY_ODD 0
+#define MEN_Z135_PTY_EVN 1
+
+#define MEN_Z135_LSR_DR BIT(0)
+#define MEN_Z135_LSR_OE BIT(1)
+#define MEN_Z135_LSR_PE BIT(2)
+#define MEN_Z135_LSR_FE BIT(3)
+#define MEN_Z135_LSR_BI BIT(4)
+#define MEN_Z135_LSR_THEP BIT(5)
+#define MEN_Z135_LSR_TEXP BIT(6)
+#define MEN_Z135_LSR_RXFIFOERR BIT(7)
+
+#define MEN_Z135_IRQ_ID_MST 0
+#define MEN_Z135_IRQ_ID_TSA 1
+#define MEN_Z135_IRQ_ID_RDA 2
+#define MEN_Z135_IRQ_ID_RLS 3
+#define MEN_Z135_IRQ_ID_CTI 6
+
+#define LCR(x) (((x) >> MEN_Z135_LCR_SHIFT) & 0xff)
+
+#define BYTES_TO_ALIGN(x) ((x) & 0x3)
+
+static int line;
+
+static int txlvl = 5;
+module_param(txlvl, int, S_IRUGO);
+MODULE_PARM_DESC(txlvl, "TX IRQ trigger level 0-7, default 5 (128 byte)");
+
+static int rxlvl = 6;
+module_param(rxlvl, int, S_IRUGO);
+MODULE_PARM_DESC(rxlvl, "RX IRQ trigger level 0-7, default 6 (256 byte)");
+
+static int align;
+module_param(align, int, S_IRUGO);
+MODULE_PARM_DESC(align, "Keep hardware FIFO write pointer aligned, default 0");
+
+struct men_z135_port {
+	struct uart_port port;
+	struct mcb_device *mdev;
+	unsigned char *rxbuf;
+	u32 stat_reg;
+	spinlock_t lock;
+};
+#define to_men_z135(port) container_of((port), struct men_z135_port, port)
+
+/**
+ * men_z135_reg_set() - Set value in register
+ * @uart: The UART port
+ * @addr: Register address
+ * @val: value to set
+ */
+static inline void men_z135_reg_set(struct men_z135_port *uart,
+				u32 addr, u32 val)
+{
+	struct uart_port *port = &uart->port;
+	unsigned long flags;
+	u32 reg;
+
+	spin_lock_irqsave(&uart->lock, flags);
+
+	reg = ioread32(port->membase + addr);
+	reg |= val;
+	iowrite32(reg, port->membase + addr);
+
+	spin_unlock_irqrestore(&uart->lock, flags);
+}
+
+/**
+ * men_z135_reg_clr() - Unset value in register
+ * @uart: The UART port
+ * @addr: Register address
+ * @val: value to clear
+ */
+static inline void men_z135_reg_clr(struct men_z135_port *uart,
+				u32 addr, u32 val)
+{
+	struct uart_port *port = &uart->port;
+	unsigned long flags;
+	u32 reg;
+
+	spin_lock_irqsave(&uart->lock, flags);
+
+	reg = ioread32(port->membase + addr);
+	reg &= ~val;
+	iowrite32(reg, port->membase + addr);
+
+	spin_unlock_irqrestore(&uart->lock, flags);
+}
+
+/**
+ * men_z135_handle_modem_status() - Handle change of modem status
+ * @port: The UART port
+ *
+ * Handle change of modem status register. This is done by reading the "delta"
+ * versions of DCD (Data Carrier Detect) and CTS (Clear To Send).
+ */
+static void men_z135_handle_modem_status(struct men_z135_port *uart)
+{
+	if (uart->stat_reg & MEN_Z135_MSR_DDCD)
+		uart_handle_dcd_change(&uart->port,
+				uart->stat_reg & ~MEN_Z135_MSR_DCD);
+	if (uart->stat_reg & MEN_Z135_MSR_DCTS)
+		uart_handle_cts_change(&uart->port,
+				uart->stat_reg & ~MEN_Z135_MSR_CTS);
+}
+
+static void men_z135_handle_lsr(struct men_z135_port *uart)
+{
+	struct uart_port *port = &uart->port;
+	u8 lsr;
+
+	lsr = (uart->stat_reg >> 16) & 0xff;
+
+	if (lsr & MEN_Z135_LSR_OE)
+		port->icount.overrun++;
+	if (lsr & MEN_Z135_LSR_PE)
+		port->icount.parity++;
+	if (lsr & MEN_Z135_LSR_FE)
+		port->icount.frame++;
+	if (lsr & MEN_Z135_LSR_BI) {
+		port->icount.brk++;
+		uart_handle_break(port);
+	}
+}
+
+/**
+ * get_rx_fifo_content() - Get the number of bytes in RX FIFO
+ * @uart: The UART port
+ *
+ * Read RXC register from hardware and return current FIFO fill size.
+ */
+static u16 get_rx_fifo_content(struct men_z135_port *uart)
+{
+	struct uart_port *port = &uart->port;
+	u32 stat_reg;
+	u16 rxc;
+	u8 rxc_lo;
+	u8 rxc_hi;
+
+	stat_reg = ioread32(port->membase + MEN_Z135_STAT_REG);
+	rxc_lo = stat_reg >> 24;
+	rxc_hi = (stat_reg & 0xC0) >> 6;
+
+	rxc = rxc_lo | (rxc_hi << 8);
+
+	return rxc;
+}
+
+/**
+ * men_z135_handle_rx() - RX tasklet routine
+ * @arg: Pointer to struct men_z135_port
+ *
+ * Copy from RX FIFO and acknowledge number of bytes copied.
+ */
+static void men_z135_handle_rx(struct men_z135_port *uart)
+{
+	struct uart_port *port = &uart->port;
+	struct tty_port *tport = &port->state->port;
+	int copied;
+	u16 size;
+	int room;
+
+	size = get_rx_fifo_content(uart);
+
+	if (size == 0)
+		return;
+
+	/* Avoid accidently accessing TX FIFO instead of RX FIFO. Last
+	 * longword in RX FIFO cannot be read.(0x004-0x3FF)
+	 */
+	if (size > MEN_Z135_FIFO_WATERMARK)
+		size = MEN_Z135_FIFO_WATERMARK;
+
+	room = tty_buffer_request_room(tport, size);
+	if (room != size)
+		dev_warn(&uart->mdev->dev,
+			"Not enough room in flip buffer, truncating to %d\n",
+			room);
+
+	if (room == 0)
+		return;
+
+	memcpy_fromio(uart->rxbuf, port->membase + MEN_Z135_RX_RAM, room);
+	/* Be sure to first copy all data and then acknowledge it */
+	mb();
+	iowrite32(room, port->membase +  MEN_Z135_RX_CTRL);
+
+	copied = tty_insert_flip_string(tport, uart->rxbuf, room);
+	if (copied != room)
+		dev_warn(&uart->mdev->dev,
+			"Only copied %d instead of %d bytes\n",
+			copied, room);
+
+	port->icount.rx += copied;
+
+	tty_flip_buffer_push(tport);
+
+}
+
+/**
+ * men_z135_handle_tx() - TX tasklet routine
+ * @arg: Pointer to struct men_z135_port
+ *
+ */
+static void men_z135_handle_tx(struct men_z135_port *uart)
+{
+	struct uart_port *port = &uart->port;
+	struct circ_buf *xmit = &port->state->xmit;
+	u32 txc;
+	u32 wptr;
+	int qlen;
+	int n;
+	int txfree;
+	int head;
+	int tail;
+	int s;
+
+	if (uart_circ_empty(xmit))
+		goto out;
+
+	if (uart_tx_stopped(port))
+		goto out;
+
+	if (port->x_char)
+		goto out;
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	/* calculate bytes to copy */
+	qlen = uart_circ_chars_pending(xmit);
+	if (qlen <= 0)
+		goto out;
+
+	wptr = ioread32(port->membase + MEN_Z135_TX_CTRL);
+	txc = (wptr >> 16) & 0x3ff;
+	wptr &= 0x3ff;
+
+	if (txc > MEN_Z135_FIFO_WATERMARK)
+		txc = MEN_Z135_FIFO_WATERMARK;
+
+	txfree = MEN_Z135_FIFO_WATERMARK - txc;
+	if (txfree <= 0) {
+		pr_err("Not enough room in TX FIFO have %d, need %d\n",
+			txfree, qlen);
+		goto irq_en;
+	}
+
+	/* if we're not aligned, it's better to copy only 1 or 2 bytes and
+	 * then the rest.
+	 */
+	if (align && qlen >= 3 && BYTES_TO_ALIGN(wptr))
+		n = 4 - BYTES_TO_ALIGN(wptr);
+	else if (qlen > txfree)
+		n = txfree;
+	else
+		n = qlen;
+
+	if (n <= 0)
+		goto irq_en;
+
+	head = xmit->head & (UART_XMIT_SIZE - 1);
+	tail = xmit->tail & (UART_XMIT_SIZE - 1);
+
+	s = ((head >= tail) ? head : UART_XMIT_SIZE) - tail;
+	n = min(n, s);
+
+	memcpy_toio(port->membase + MEN_Z135_TX_RAM, &xmit->buf[xmit->tail], n);
+	xmit->tail = (xmit->tail + n) & (UART_XMIT_SIZE - 1);
+	mmiowb();
+
+	iowrite32(n & 0x3ff, port->membase + MEN_Z135_TX_CTRL);
+
+	port->icount.tx += n;
+
+irq_en:
+	if (!uart_circ_empty(xmit))
+		men_z135_reg_set(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_TXCIEN);
+	else
+		men_z135_reg_clr(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_TXCIEN);
+
+out:
+	return;
+
+}
+
+/**
+ * men_z135_intr() - Handle legacy IRQs
+ * @irq: The IRQ number
+ * @data: Pointer to UART port
+ *
+ * Check IIR register to see which tasklet to start.
+ */
+static irqreturn_t men_z135_intr(int irq, void *data)
+{
+	struct men_z135_port *uart = (struct men_z135_port *)data;
+	struct uart_port *port = &uart->port;
+	int irq_id;
+
+	uart->stat_reg = ioread32(port->membase + MEN_Z135_STAT_REG);
+	/* IRQ pending is low active */
+	if (IS_IRQ(uart->stat_reg))
+		return IRQ_NONE;
+
+	irq_id = IRQ_ID(uart->stat_reg);
+	switch (irq_id) {
+	case MEN_Z135_IRQ_ID_MST:
+		men_z135_handle_modem_status(uart);
+		break;
+	case MEN_Z135_IRQ_ID_TSA:
+		men_z135_handle_tx(uart);
+		break;
+	case MEN_Z135_IRQ_ID_CTI:
+		dev_dbg(&uart->mdev->dev, "Character Timeout Indication\n");
+		/* Fallthrough */
+	case MEN_Z135_IRQ_ID_RDA:
+		/* Reading data clears RX IRQ */
+		men_z135_handle_rx(uart);
+		break;
+	case MEN_Z135_IRQ_ID_RLS:
+		men_z135_handle_lsr(uart);
+		break;
+	default:
+		dev_warn(&uart->mdev->dev, "Unknown IRQ id %d\n", irq_id);
+		return IRQ_NONE;
+	}
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * men_z135_request_irq() - Request IRQ for 16z135 core
+ * @uart: z135 private uart port structure
+ *
+ * Request an IRQ for 16z135 to use. First try using MSI, if it fails
+ * fall back to using legacy interrupts.
+ */
+static int men_z135_request_irq(struct men_z135_port *uart)
+{
+	struct device *dev = &uart->mdev->dev;
+	struct uart_port *port = &uart->port;
+	int err = 0;
+
+	err = request_irq(port->irq, men_z135_intr, IRQF_SHARED,
+			"men_z135_intr", uart);
+	if (err)
+		dev_err(dev, "Error %d getting interrupt\n", err);
+
+	return err;
+}
+
+/**
+ * men_z135_tx_empty() - Handle tx_empty call
+ * @port: The UART port
+ *
+ * This function tests whether the TX FIFO and shifter for the port
+ * described by @port is empty.
+ */
+static unsigned int men_z135_tx_empty(struct uart_port *port)
+{
+	u32 wptr;
+	u16 txc;
+
+	wptr = ioread32(port->membase + MEN_Z135_TX_CTRL);
+	txc = (wptr >> 16) & 0x3ff;
+
+	if (txc == 0)
+		return TIOCSER_TEMT;
+	else
+		return 0;
+}
+
+/**
+ * men_z135_set_mctrl() - Set modem control lines
+ * @port: The UART port
+ * @mctrl: The modem control lines
+ *
+ * This function sets the modem control lines for a port described by @port
+ * to the state described by @mctrl
+ */
+static void men_z135_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	struct men_z135_port *uart = to_men_z135(port);
+	u32 conf_reg = 0;
+
+	if (mctrl & TIOCM_RTS)
+		conf_reg |= MEN_Z135_MCR_RTS;
+	if (mctrl & TIOCM_DTR)
+		conf_reg |= MEN_Z135_MCR_DTR;
+	if (mctrl & TIOCM_OUT1)
+		conf_reg |= MEN_Z135_MCR_OUT1;
+	if (mctrl & TIOCM_OUT2)
+		conf_reg |= MEN_Z135_MCR_OUT2;
+	if (mctrl & TIOCM_LOOP)
+		conf_reg |= MEN_Z135_MCR_LOOP;
+
+	men_z135_reg_set(uart, MEN_Z135_CONF_REG, conf_reg);
+}
+
+/**
+ * men_z135_get_mctrl() - Get modem control lines
+ * @port: The UART port
+ *
+ * Retruns the current state of modem control inputs.
+ */
+static unsigned int men_z135_get_mctrl(struct uart_port *port)
+{
+	unsigned int mctrl = 0;
+	u32 stat_reg;
+	u8 msr;
+
+	stat_reg = ioread32(port->membase + MEN_Z135_STAT_REG);
+
+	msr = ~((stat_reg >> 8) & 0xff);
+
+	if (msr & MEN_Z135_MSR_CTS)
+		mctrl |= TIOCM_CTS;
+	if (msr & MEN_Z135_MSR_DSR)
+		mctrl |= TIOCM_DSR;
+	if (msr & MEN_Z135_MSR_RI)
+		mctrl |= TIOCM_RI;
+	if (msr & MEN_Z135_MSR_DCD)
+		mctrl |= TIOCM_CAR;
+
+	return mctrl;
+}
+
+/**
+ * men_z135_stop_tx() - Stop transmitting characters
+ * @port: The UART port
+ *
+ * Stop transmitting characters. This might be due to CTS line becomming
+ * inactive or the tty layer indicating we want to stop transmission due to
+ * an XOFF character.
+ */
+static void men_z135_stop_tx(struct uart_port *port)
+{
+	struct men_z135_port *uart = to_men_z135(port);
+
+	men_z135_reg_clr(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_TXCIEN);
+}
+
+/**
+ * men_z135_start_tx() - Start transmitting characters
+ * @port: The UART port
+ *
+ * Start transmitting character. This actually doesn't transmit anything, but
+ * fires off the TX tasklet.
+ */
+static void men_z135_start_tx(struct uart_port *port)
+{
+	struct men_z135_port *uart = to_men_z135(port);
+
+	men_z135_handle_tx(uart);
+}
+
+/**
+ * men_z135_stop_rx() - Stop receiving characters
+ * @port: The UART port
+ *
+ * Stop receiving characters; the port is in the process of being closed.
+ */
+static void men_z135_stop_rx(struct uart_port *port)
+{
+	struct men_z135_port *uart = to_men_z135(port);
+
+	men_z135_reg_clr(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_RXCIEN);
+}
+
+/**
+ * men_z135_enable_ms() - Enable Modem Status
+ * port:
+ *
+ * Enable Modem Status IRQ.
+ */
+static void men_z135_enable_ms(struct uart_port *port)
+{
+	struct men_z135_port *uart = to_men_z135(port);
+
+	men_z135_reg_set(uart, MEN_Z135_CONF_REG, MEN_Z135_IER_MSIEN);
+}
+
+static int men_z135_startup(struct uart_port *port)
+{
+	struct men_z135_port *uart = to_men_z135(port);
+	int err;
+	u32 conf_reg = 0;
+
+	err = men_z135_request_irq(uart);
+	if (err)
+		return -ENODEV;
+
+	conf_reg = ioread32(port->membase + MEN_Z135_CONF_REG);
+
+	conf_reg |= MEN_Z135_ALL_IRQS;
+	conf_reg &= ~(0xff << 16);
+	conf_reg |= (txlvl << 16);
+	conf_reg |= (rxlvl << 20);
+
+	iowrite32(conf_reg, port->membase + MEN_Z135_CONF_REG);
+
+	return 0;
+}
+
+static void men_z135_shutdown(struct uart_port *port)
+{
+	struct men_z135_port *uart = to_men_z135(port);
+	u32 conf_reg = 0;
+
+	conf_reg |= MEN_Z135_ALL_IRQS;
+
+	men_z135_reg_clr(uart, MEN_Z135_CONF_REG, conf_reg);
+
+	free_irq(uart->port.irq, uart);
+}
+
+static void men_z135_set_termios(struct uart_port *port,
+				struct ktermios *termios,
+				struct ktermios *old)
+{
+	unsigned int baud;
+	u32 conf_reg;
+	u32 bd_reg;
+	u32 uart_freq;
+	u8 lcr;
+
+	conf_reg = ioread32(port->membase + MEN_Z135_CONF_REG);
+	lcr = LCR(conf_reg);
+
+	/* byte size */
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		lcr |= MEN_Z135_WL5;
+		break;
+	case CS6:
+		lcr |= MEN_Z135_WL6;
+		break;
+	case CS7:
+		lcr |= MEN_Z135_WL7;
+		break;
+	case CS8:
+		lcr |= MEN_Z135_WL8;
+		break;
+	}
+
+	/* stop bits */
+	if (termios->c_cflag & CSTOPB)
+		lcr |= MEN_Z135_NSTB2 << MEN_Z135_STB_SHIFT;
+
+	/* parity */
+	if (termios->c_cflag & PARENB) {
+		lcr |= MEN_Z135_PAR_ENA << MEN_Z135_PEN_SHIFT;
+
+		if (termios->c_cflag & PARODD)
+			lcr |= MEN_Z135_PTY_ODD << MEN_Z135_PTY_SHIFT;
+		else
+			lcr |= MEN_Z135_PTY_EVN << MEN_Z135_PTY_SHIFT;
+	} else
+		lcr |= MEN_Z135_PAR_DIS << MEN_Z135_PEN_SHIFT;
+
+	termios->c_cflag &= ~CMSPAR; /* Mark/Space parity is not supported */
+
+	conf_reg |= lcr << MEN_Z135_LCR_SHIFT;
+	iowrite32(conf_reg, port->membase + MEN_Z135_CONF_REG);
+
+	uart_freq = ioread32(port->membase + MEN_Z135_UART_FREQ);
+	if (uart_freq == 0)
+		uart_freq = MEN_Z135_BASECLK;
+
+	baud = uart_get_baud_rate(port, termios, old, 0, uart_freq / 16);
+
+	spin_lock(&port->lock);
+	if (tty_termios_baud_rate(termios))
+		tty_termios_encode_baud_rate(termios, baud, baud);
+
+	bd_reg = uart_freq / (4 * baud);
+	iowrite32(bd_reg, port->membase + MEN_Z135_BAUD_REG);
+
+	uart_update_timeout(port, termios->c_cflag, baud);
+	spin_unlock(&port->lock);
+}
+
+static const char *men_z135_type(struct uart_port *port)
+{
+	return KBUILD_MODNAME;
+}
+
+static void men_z135_release_port(struct uart_port *port)
+{
+	iounmap(port->membase);
+	port->membase = NULL;
+
+	release_mem_region(port->mapbase, MEN_Z135_MEM_SIZE);
+}
+
+static int men_z135_request_port(struct uart_port *port)
+{
+	int size = MEN_Z135_MEM_SIZE;
+
+	if (!request_mem_region(port->mapbase, size, "men_z135_port"))
+		return -EBUSY;
+
+	port->membase = ioremap(port->mapbase, MEN_Z135_MEM_SIZE);
+	if (port->membase == NULL) {
+		release_mem_region(port->mapbase, MEN_Z135_MEM_SIZE);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void men_z135_config_port(struct uart_port *port, int type)
+{
+	port->type = PORT_MEN_Z135;
+	men_z135_request_port(port);
+}
+
+static int men_z135_verify_port(struct uart_port *port,
+				struct serial_struct *serinfo)
+{
+	return -EINVAL;
+}
+
+static struct uart_ops men_z135_ops = {
+	.tx_empty = men_z135_tx_empty,
+	.set_mctrl = men_z135_set_mctrl,
+	.get_mctrl = men_z135_get_mctrl,
+	.stop_tx = men_z135_stop_tx,
+	.start_tx = men_z135_start_tx,
+	.stop_rx = men_z135_stop_rx,
+	.enable_ms = men_z135_enable_ms,
+	.startup = men_z135_startup,
+	.shutdown = men_z135_shutdown,
+	.set_termios = men_z135_set_termios,
+	.type = men_z135_type,
+	.release_port = men_z135_release_port,
+	.request_port = men_z135_request_port,
+	.config_port = men_z135_config_port,
+	.verify_port = men_z135_verify_port,
+};
+
+static struct uart_driver men_z135_driver = {
+	.owner = THIS_MODULE,
+	.driver_name = KBUILD_MODNAME,
+	.dev_name = "ttyHSU",
+	.major = 0,
+	.minor = 0,
+	.nr = MEN_Z135_MAX_PORTS,
+};
+
+/**
+ * men_z135_probe() - Probe a z135 instance
+ * @mdev: The MCB device
+ * @id: The MCB device ID
+ *
+ * men_z135_probe does the basic setup of hardware resources and registers the
+ * new uart port to the tty layer.
+ */
+static int men_z135_probe(struct mcb_device *mdev,
+			const struct mcb_device_id *id)
+{
+	struct men_z135_port *uart;
+	struct resource *mem;
+	struct device *dev;
+	int err;
+
+	dev = &mdev->dev;
+
+	uart = devm_kzalloc(dev, sizeof(struct men_z135_port), GFP_KERNEL);
+	if (!uart)
+		return -ENOMEM;
+
+	uart->rxbuf = (unsigned char *)__get_free_page(GFP_KERNEL);
+	if (!uart->rxbuf)
+		return -ENOMEM;
+
+	mem = &mdev->mem;
+
+	mcb_set_drvdata(mdev, uart);
+
+	uart->port.uartclk = MEN_Z135_BASECLK * 16;
+	uart->port.fifosize = MEN_Z135_FIFO_SIZE;
+	uart->port.iotype = UPIO_MEM;
+	uart->port.ops = &men_z135_ops;
+	uart->port.irq = mcb_get_irq(mdev);
+	uart->port.iotype = UPIO_MEM;
+	uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
+	uart->port.line = line++;
+	uart->port.dev = dev;
+	uart->port.type = PORT_MEN_Z135;
+	uart->port.mapbase = mem->start;
+	uart->port.membase = NULL;
+	uart->mdev = mdev;
+
+	spin_lock_init(&uart->port.lock);
+	spin_lock_init(&uart->lock);
+
+	err = uart_add_one_port(&men_z135_driver, &uart->port);
+	if (err)
+		goto err;
+
+	return 0;
+
+err:
+	free_page((unsigned long) uart->rxbuf);
+	dev_err(dev, "Failed to add UART: %d\n", err);
+
+	return err;
+}
+
+/**
+ * men_z135_remove() - Remove a z135 instance from the system
+ *
+ * @mdev: The MCB device
+ */
+static void men_z135_remove(struct mcb_device *mdev)
+{
+	struct men_z135_port *uart = mcb_get_drvdata(mdev);
+
+	line--;
+	uart_remove_one_port(&men_z135_driver, &uart->port);
+	free_page((unsigned long) uart->rxbuf);
+}
+
+static const struct mcb_device_id men_z135_ids[] = {
+	{ .device = 0x87 },
+};
+MODULE_DEVICE_TABLE(mcb, men_z135_ids);
+
+static struct mcb_driver mcb_driver = {
+	.driver = {
+		.name = "z135-uart",
+		.owner = THIS_MODULE,
+	},
+	.probe = men_z135_probe,
+	.remove = men_z135_remove,
+	.id_table = men_z135_ids,
+};
+
+/**
+ * men_z135_init() - Driver Registration Routine
+ *
+ * men_z135_init is the first routine called when the driver is loaded. All it
+ * does is register with the legacy MEN Chameleon subsystem.
+ */
+static int __init men_z135_init(void)
+{
+	int err;
+
+	err = uart_register_driver(&men_z135_driver);
+	if (err) {
+		pr_err("Failed to register UART: %d\n", err);
+		return err;
+	}
+
+	err = mcb_register_driver(&mcb_driver);
+	if  (err) {
+		pr_err("Failed to register MCB driver: %d\n", err);
+		uart_unregister_driver(&men_z135_driver);
+		return err;
+	}
+
+	return 0;
+}
+module_init(men_z135_init);
+
+/**
+ * men_z135_exit() - Driver Exit Routine
+ *
+ * men_z135_exit is called just before the driver is removed from memory.
+ */
+static void __exit men_z135_exit(void)
+{
+	mcb_unregister_driver(&mcb_driver);
+	uart_unregister_driver(&men_z135_driver);
+}
+module_exit(men_z135_exit);
+
+MODULE_AUTHOR("Johannes Thumshirn <johannes.thumshirn@xxxxxx>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MEN 16z135 High Speed UART");
+MODULE_ALIAS("mcb:16z135");
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index b47dba2..e1a7b66 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -238,4 +238,7 @@
 /* Tilera TILE-Gx UART */
 #define PORT_TILEGX	106

+/* MEN 16z135 UART */
+#define PORT_MEN_Z135	107
+
 #endif /* _UAPILINUX_SERIAL_CORE_H */
--
1.9.2

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