serial: Add driver for the Altera UART

Add an UART driver for the UART component available as a SOPC (System on
Programmable Chip) component for Altera FPGAs.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 602 insertions, 0 deletions

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index f4050e6..8b23165 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -1544,4 +1544,35 @@ config SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS
 	  Bypass console output and keep going even if there is no
 	  JTAG terminal connection with the host.
 
+config SERIAL_ALTERA_UART
+	tristate "Altera UART support"
+	select SERIAL_CORE
+	help
+	  This driver supports the Altera softcore UART port.
+
+config SERIAL_ALTERA_UART_MAXPORTS
+	int "Maximum number of Altera UART ports"
+	depends on SERIAL_ALTERA_UART
+	default 4
+	help
+	  This setting lets you define the maximum number of the Altera
+	  UART ports. The usual default varies from board to board, and
+	  this setting is a way of catering for that.
+
+config SERIAL_ALTERA_UART_BAUDRATE
+	int "Default baudrate for Altera UART ports"
+	depends on SERIAL_ALTERA_UART
+	default 115200
+	help
+	  This setting lets you define what the default baudrate is for the
+	  Altera UART ports. The usual default varies from board to board,
+	  and this setting is a way of catering for that.
+
+config SERIAL_ALTERA_UART_CONSOLE
+	bool "Altera UART console support"
+	depends on SERIAL_ALTERA_UART=y
+	select SERIAL_CORE_CONSOLE
+	help
+	  Enable a Altera UART port to be the system console.
+
 endmenu
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 7f9d225..208a855 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -83,3 +83,4 @@ obj-$(CONFIG_SERIAL_QE) += ucc_uart.o
 obj-$(CONFIG_SERIAL_TIMBERDALE)	+= timbuart.o
 obj-$(CONFIG_SERIAL_GRLIB_GAISLER_APBUART) += apbuart.o
 obj-$(CONFIG_SERIAL_ALTERA_JTAGUART) += altera_jtaguart.o
+obj-$(CONFIG_SERIAL_ALTERA_UART) += altera_uart.o
diff --git a/drivers/serial/altera_uart.c b/drivers/serial/altera_uart.c
new file mode 100644
index 0000000..bcee156
--- /dev/null
+++ b/drivers/serial/altera_uart.c
@@ -0,0 +1,570 @@
+/*
+ * altera_uart.c -- Altera UART driver
+ *
+ * Based on mcf.c -- Freescale ColdFire UART driver
+ *
+ * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com>
+ * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw>
+ * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch>
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/console.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial.h>
+#include <linux/serial_core.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/altera_uart.h>
+
+#define DRV_NAME "altera_uart"
+
+/*
+ * Altera UART register definitions according to the Nios UART datasheet:
+ * http://www.altera.com/literature/ds/ds_nios_uart.pdf
+ */
+
+#define ALTERA_UART_SIZE		32
+
+#define ALTERA_UART_RXDATA_REG		0
+#define ALTERA_UART_TXDATA_REG		4
+#define ALTERA_UART_STATUS_REG		8
+#define ALTERA_UART_CONTROL_REG		12
+#define ALTERA_UART_DIVISOR_REG		16
+#define ALTERA_UART_EOP_REG		20
+
+#define ALTERA_UART_STATUS_PE_MSK	0x0001	/* parity error */
+#define ALTERA_UART_STATUS_FE_MSK	0x0002	/* framing error */
+#define ALTERA_UART_STATUS_BRK_MSK	0x0004	/* break */
+#define ALTERA_UART_STATUS_ROE_MSK	0x0008	/* RX overrun error */
+#define ALTERA_UART_STATUS_TOE_MSK	0x0010	/* TX overrun error */
+#define ALTERA_UART_STATUS_TMT_MSK	0x0020	/* TX shift register state */
+#define ALTERA_UART_STATUS_TRDY_MSK	0x0040	/* TX ready */
+#define ALTERA_UART_STATUS_RRDY_MSK	0x0080	/* RX ready */
+#define ALTERA_UART_STATUS_E_MSK	0x0100	/* exception condition */
+#define ALTERA_UART_STATUS_DCTS_MSK	0x0400	/* CTS logic-level change */
+#define ALTERA_UART_STATUS_CTS_MSK	0x0800	/* CTS logic state */
+#define ALTERA_UART_STATUS_EOP_MSK	0x1000	/* EOP written/read */
+
+						/* Enable interrupt on... */
+#define ALTERA_UART_CONTROL_PE_MSK	0x0001	/* ...parity error */
+#define ALTERA_UART_CONTROL_FE_MSK	0x0002	/* ...framing error */
+#define ALTERA_UART_CONTROL_BRK_MSK	0x0004	/* ...break */
+#define ALTERA_UART_CONTROL_ROE_MSK	0x0008	/* ...RX overrun */
+#define ALTERA_UART_CONTROL_TOE_MSK	0x0010	/* ...TX overrun */
+#define ALTERA_UART_CONTROL_TMT_MSK	0x0020	/* ...TX shift register empty */
+#define ALTERA_UART_CONTROL_TRDY_MSK	0x0040	/* ...TX ready */
+#define ALTERA_UART_CONTROL_RRDY_MSK	0x0080	/* ...RX ready */
+#define ALTERA_UART_CONTROL_E_MSK	0x0100	/* ...exception*/
+
+#define ALTERA_UART_CONTROL_TRBK_MSK	0x0200	/* TX break */
+#define ALTERA_UART_CONTROL_DCTS_MSK	0x0400	/* Interrupt on CTS change */
+#define ALTERA_UART_CONTROL_RTS_MSK	0x0800	/* RTS signal */
+#define ALTERA_UART_CONTROL_EOP_MSK	0x1000	/* Interrupt on EOP */
+
+/*
+ * Local per-uart structure.
+ */
+struct altera_uart {
+	struct uart_port port;
+	unsigned int sigs;	/* Local copy of line sigs */
+	unsigned short imr;	/* Local IMR mirror */
+};
+
+static unsigned int altera_uart_tx_empty(struct uart_port *port)
+{
+	return (readl(port->membase + ALTERA_UART_STATUS_REG) &
+		ALTERA_UART_STATUS_TMT_MSK) ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int altera_uart_get_mctrl(struct uart_port *port)
+{
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+	unsigned long flags;
+	unsigned int sigs;
+
+	spin_lock_irqsave(&port->lock, flags);
+	sigs =
+	    (readl(port->membase + ALTERA_UART_STATUS_REG) &
+	     ALTERA_UART_STATUS_CTS_MSK) ? TIOCM_CTS : 0;
+	sigs |= (pp->sigs & TIOCM_RTS);
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return sigs;
+}
+
+static void altera_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
+{
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	pp->sigs = sigs;
+	if (sigs & TIOCM_RTS)
+		pp->imr |= ALTERA_UART_CONTROL_RTS_MSK;
+	else
+		pp->imr &= ~ALTERA_UART_CONTROL_RTS_MSK;
+	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void altera_uart_start_tx(struct uart_port *port)
+{
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	pp->imr |= ALTERA_UART_CONTROL_TRDY_MSK;
+	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void altera_uart_stop_tx(struct uart_port *port)
+{
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
+	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void altera_uart_stop_rx(struct uart_port *port)
+{
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	pp->imr &= ~ALTERA_UART_CONTROL_RRDY_MSK;
+	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void altera_uart_break_ctl(struct uart_port *port, int break_state)
+{
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	if (break_state == -1)
+		pp->imr |= ALTERA_UART_CONTROL_TRBK_MSK;
+	else
+		pp->imr &= ~ALTERA_UART_CONTROL_TRBK_MSK;
+	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void altera_uart_enable_ms(struct uart_port *port)
+{
+}
+
+static void altera_uart_set_termios(struct uart_port *port,
+				    struct ktermios *termios,
+				    struct ktermios *old)
+{
+	unsigned long flags;
+	unsigned int baud, baudclk;
+
+	baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
+	baudclk = port->uartclk / baud;
+
+	if (old)
+		tty_termios_copy_hw(termios, old);
+	tty_termios_encode_baud_rate(termios, baud, baud);
+
+	spin_lock_irqsave(&port->lock, flags);
+	writel(baudclk, port->membase + ALTERA_UART_DIVISOR_REG);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void altera_uart_rx_chars(struct altera_uart *pp)
+{
+	struct uart_port *port = &pp->port;
+	unsigned char ch, flag;
+	unsigned short status;
+
+	while ((status = readl(port->membase + ALTERA_UART_STATUS_REG)) &
+	       ALTERA_UART_STATUS_RRDY_MSK) {
+		ch = readl(port->membase + ALTERA_UART_RXDATA_REG);
+		flag = TTY_NORMAL;
+		port->icount.rx++;
+
+		if (status & ALTERA_UART_STATUS_E_MSK) {
+			writel(status, port->membase + ALTERA_UART_STATUS_REG);
+
+			if (status & ALTERA_UART_STATUS_BRK_MSK) {
+				port->icount.brk++;
+				if (uart_handle_break(port))
+					continue;
+			} else if (status & ALTERA_UART_STATUS_PE_MSK) {
+				port->icount.parity++;
+			} else if (status & ALTERA_UART_STATUS_ROE_MSK) {
+				port->icount.overrun++;
+			} else if (status & ALTERA_UART_STATUS_FE_MSK) {
+				port->icount.frame++;
+			}
+
+			status &= port->read_status_mask;
+
+			if (status & ALTERA_UART_STATUS_BRK_MSK)
+				flag = TTY_BREAK;
+			else if (status & ALTERA_UART_STATUS_PE_MSK)
+				flag = TTY_PARITY;
+			else if (status & ALTERA_UART_STATUS_FE_MSK)
+				flag = TTY_FRAME;
+		}
+
+		if (uart_handle_sysrq_char(port, ch))
+			continue;
+		uart_insert_char(port, status, ALTERA_UART_STATUS_ROE_MSK, ch,
+				 flag);
+	}
+
+	tty_flip_buffer_push(port->state->port.tty);
+}
+
+static void altera_uart_tx_chars(struct altera_uart *pp)
+{
+	struct uart_port *port = &pp->port;
+	struct circ_buf *xmit = &port->state->xmit;
+
+	if (port->x_char) {
+		/* Send special char - probably flow control */
+		writel(port->x_char, port->membase + ALTERA_UART_TXDATA_REG);
+		port->x_char = 0;
+		port->icount.tx++;
+		return;
+	}
+
+	while (readl(port->membase + ALTERA_UART_STATUS_REG) &
+	       ALTERA_UART_STATUS_TRDY_MSK) {
+		if (xmit->head == xmit->tail)
+			break;
+		writel(xmit->buf[xmit->tail],
+		       port->membase + ALTERA_UART_TXDATA_REG);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (xmit->head == xmit->tail) {
+		pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
+		writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
+	}
+}
+
+static irqreturn_t altera_uart_interrupt(int irq, void *data)
+{
+	struct uart_port *port = data;
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+	unsigned int isr;
+
+	isr = readl(port->membase + ALTERA_UART_STATUS_REG) & pp->imr;
+	if (isr & ALTERA_UART_STATUS_RRDY_MSK)
+		altera_uart_rx_chars(pp);
+	if (isr & ALTERA_UART_STATUS_TRDY_MSK)
+		altera_uart_tx_chars(pp);
+	return IRQ_RETVAL(isr);
+}
+
+static void altera_uart_config_port(struct uart_port *port, int flags)
+{
+	port->type = PORT_ALTERA_UART;
+
+	/* Clear mask, so no surprise interrupts. */
+	writel(0, port->membase + ALTERA_UART_CONTROL_REG);
+	/* Clear status register */
+	writel(0, port->membase + ALTERA_UART_STATUS_REG);
+}
+
+static int altera_uart_startup(struct uart_port *port)
+{
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+	unsigned long flags;
+	int ret;
+
+	ret = request_irq(port->irq, altera_uart_interrupt, IRQF_DISABLED,
+			DRV_NAME, port);
+	if (ret) {
+		pr_err(DRV_NAME ": unable to attach Altera UART %d "
+		       "interrupt vector=%d\n", port->line, port->irq);
+		return ret;
+	}
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* Enable RX interrupts now */
+	pp->imr = ALTERA_UART_CONTROL_RRDY_MSK;
+	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return 0;
+}
+
+static void altera_uart_shutdown(struct uart_port *port)
+{
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* Disable all interrupts now */
+	pp->imr = 0;
+	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	free_irq(port->irq, port);
+}
+
+static const char *altera_uart_type(struct uart_port *port)
+{
+	return (port->type == PORT_ALTERA_UART) ? "Altera UART" : NULL;
+}
+
+static int altera_uart_request_port(struct uart_port *port)
+{
+	/* UARTs always present */
+	return 0;
+}
+
+static void altera_uart_release_port(struct uart_port *port)
+{
+	/* Nothing to release... */
+}
+
+static int altera_uart_verify_port(struct uart_port *port,
+				   struct serial_struct *ser)
+{
+	if ((ser->type != PORT_UNKNOWN) && (ser->type != PORT_ALTERA_UART))
+		return -EINVAL;
+	return 0;
+}
+
+/*
+ *	Define the basic serial functions we support.
+ */
+static struct uart_ops altera_uart_ops = {
+	.tx_empty	= altera_uart_tx_empty,
+	.get_mctrl	= altera_uart_get_mctrl,
+	.set_mctrl	= altera_uart_set_mctrl,
+	.start_tx	= altera_uart_start_tx,
+	.stop_tx	= altera_uart_stop_tx,
+	.stop_rx	= altera_uart_stop_rx,
+	.enable_ms	= altera_uart_enable_ms,
+	.break_ctl	= altera_uart_break_ctl,
+	.startup	= altera_uart_startup,
+	.shutdown	= altera_uart_shutdown,
+	.set_termios	= altera_uart_set_termios,
+	.type		= altera_uart_type,
+	.request_port	= altera_uart_request_port,
+	.release_port	= altera_uart_release_port,
+	.config_port	= altera_uart_config_port,
+	.verify_port	= altera_uart_verify_port,
+};
+
+static struct altera_uart altera_uart_ports[CONFIG_SERIAL_ALTERA_UART_MAXPORTS];
+
+#if defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
+
+int __init early_altera_uart_setup(struct altera_uart_platform_uart *platp)
+{
+	struct uart_port *port;
+	int i;
+
+	for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS && platp[i].mapbase; i++) {
+		port = &altera_uart_ports[i].port;
+
+		port->line = i;
+		port->type = PORT_ALTERA_UART;
+		port->mapbase = platp[i].mapbase;
+		port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
+		port->iotype = SERIAL_IO_MEM;
+		port->irq = platp[i].irq;
+		port->uartclk = platp[i].uartclk;
+		port->flags = ASYNC_BOOT_AUTOCONF;
+		port->ops = &altera_uart_ops;
+	}
+
+	return 0;
+}
+
+static void altera_uart_console_putc(struct console *co, const char c)
+{
+	struct uart_port *port = &(altera_uart_ports + co->index)->port;
+	int i;
+
+	for (i = 0; i < 0x10000; i++) {
+		if (readl(port->membase + ALTERA_UART_STATUS_REG) &
+		    ALTERA_UART_STATUS_TRDY_MSK)
+			break;
+	}
+	writel(c, port->membase + ALTERA_UART_TXDATA_REG);
+	for (i = 0; i < 0x10000; i++) {
+		if (readl(port->membase + ALTERA_UART_STATUS_REG) &
+		    ALTERA_UART_STATUS_TRDY_MSK)
+			break;
+	}
+}
+
+static void altera_uart_console_write(struct console *co, const char *s,
+				      unsigned int count)
+{
+	for (; count; count--, s++) {
+		altera_uart_console_putc(co, *s);
+		if (*s == '\n')
+			altera_uart_console_putc(co, '\r');
+	}
+}
+
+static int __init altera_uart_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port;
+	int baud = CONFIG_SERIAL_ALTERA_UART_BAUDRATE;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (co->index < 0 || co->index >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
+		return -EINVAL;
+	port = &altera_uart_ports[co->index].port;
+	if (port->membase == 0)
+		return -ENODEV;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver altera_uart_driver;
+
+static struct console altera_uart_console = {
+	.name	= "ttyS",
+	.write	= altera_uart_console_write,
+	.device	= uart_console_device,
+	.setup	= altera_uart_console_setup,
+	.flags	= CON_PRINTBUFFER,
+	.index	= -1,
+	.data	= &altera_uart_driver,
+};
+
+static int __init altera_uart_console_init(void)
+{
+	register_console(&altera_uart_console);
+	return 0;
+}
+
+console_initcall(altera_uart_console_init);
+
+#define	ALTERA_UART_CONSOLE	(&altera_uart_console)
+
+#else
+
+#define	ALTERA_UART_CONSOLE	NULL
+
+#endif /* CONFIG_ALTERA_UART_CONSOLE */
+
+/*
+ *	Define the altera_uart UART driver structure.
+ */
+static struct uart_driver altera_uart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= DRV_NAME,
+	.dev_name	= "ttyS",
+	.major		= TTY_MAJOR,
+	.minor		= 64,
+	.nr		= CONFIG_SERIAL_ALTERA_UART_MAXPORTS,
+	.cons		= ALTERA_UART_CONSOLE,
+};
+
+static int __devinit altera_uart_probe(struct platform_device *pdev)
+{
+	struct altera_uart_platform_uart *platp = pdev->dev.platform_data;
+	struct uart_port *port;
+	int i;
+
+	for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS && platp[i].mapbase; i++) {
+		port = &altera_uart_ports[i].port;
+
+		port->line = i;
+		port->type = PORT_ALTERA_UART;
+		port->mapbase = platp[i].mapbase;
+		port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
+		port->iotype = SERIAL_IO_MEM;
+		port->irq = platp[i].irq;
+		port->uartclk = platp[i].uartclk;
+		port->ops = &altera_uart_ops;
+		port->flags = ASYNC_BOOT_AUTOCONF;
+
+		uart_add_one_port(&altera_uart_driver, port);
+	}
+
+	return 0;
+}
+
+static int altera_uart_remove(struct platform_device *pdev)
+{
+	struct uart_port *port;
+	int i;
+
+	for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS; i++) {
+		port = &altera_uart_ports[i].port;
+		if (port)
+			uart_remove_one_port(&altera_uart_driver, port);
+	}
+
+	return 0;
+}
+
+static struct platform_driver altera_uart_platform_driver = {
+	.probe	= altera_uart_probe,
+	.remove	= __devexit_p(altera_uart_remove),
+	.driver	= {
+		.name	= DRV_NAME,
+		.owner	= THIS_MODULE,
+		.pm	= NULL,
+	},
+};
+
+static int __init altera_uart_init(void)
+{
+	int rc;
+
+	rc = uart_register_driver(&altera_uart_driver);
+	if (rc)
+		return rc;
+	rc = platform_driver_register(&altera_uart_platform_driver);
+	if (rc) {
+		uart_unregister_driver(&altera_uart_driver);
+		return rc;
+	}
+	return 0;
+}
+
+static void __exit altera_uart_exit(void)
+{
+	platform_driver_unregister(&altera_uart_platform_driver);
+	uart_unregister_driver(&altera_uart_driver);
+}
+
+module_init(altera_uart_init);
+module_exit(altera_uart_exit);
+
+MODULE_DESCRIPTION("Altera UART driver");
+MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);