serial: Add driver for the Altera JTAG UART

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

Signed-off-by: Tobias Klauser <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/serial/Kconfig

···
 	help
 	Support for running a console on the GRLIB APBUART
 
+config SERIAL_ALTERA_JTAGUART
+	tristate "Altera JTAG UART support"
+	select SERIAL_CORE
+	help
+	  This driver supports the Altera JTAG UART port.
+
+config SERIAL_ALTERA_JTAGUART_CONSOLE
+	bool "Altera JTAG UART console support"
+	depends on SERIAL_ALTERA_JTAGUART=y
+	select SERIAL_CORE_CONSOLE
+	help
+	  Enable a Altera JTAG UART port to be the system console.
+
+config SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS
+	bool "Bypass output when no connection"
+	depends on SERIAL_ALTERA_JTAGUART_CONSOLE
+	select SERIAL_CORE_CONSOLE
+	help
+	  Bypass console output and keep going even if there is no
+	  JTAG terminal connection with the host.
+
 endmenu

drivers/serial/Makefile

···
 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

drivers/serial/altera_jtaguart.c

···
+/*
+ * altera_jtaguart.c -- Altera JTAG UART driver
+ *
+ * Based on mcf.c -- Freescale ColdFire UART driver
+ *
+ * (C) Copyright 2003-2007, Greg Ungerer <[e-mail]>
+ * (C) Copyright 2008, Thomas Chou <[e-mail]>
+ * (C) Copyright 2010, Tobias Klauser <[e-mail]>
+ *
+ * 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_jtaguart.h>
+
+#define DRV_NAME "altera_jtaguart"
+
+/*
+ * Altera JTAG UART register definitions according to the Altera JTAG UART
+ * datasheet: http://www.altera.com/literature/hb/nios2/n2cpu_nii51009.pdf
+ */
+
+#define ALTERA_JTAGUART_SIZE			8
+
+#define ALTERA_JTAGUART_DATA_REG		0
+
+#define ALTERA_JTAGUART_DATA_DATA_MSK		0x000000FF
+#define ALTERA_JTAGUART_DATA_RVALID_MSK		0x00008000
+#define ALTERA_JTAGUART_DATA_RAVAIL_MSK		0xFFFF0000
+#define ALTERA_JTAGUART_DATA_RAVAIL_OFF		16
+
+#define ALTERA_JTAGUART_CONTROL_REG		4
+
+#define ALTERA_JTAGUART_CONTROL_RE_MSK		0x00000001
+#define ALTERA_JTAGUART_CONTROL_WE_MSK		0x00000002
+#define ALTERA_JTAGUART_CONTROL_RI_MSK		0x00000100
+#define ALTERA_JTAGUART_CONTROL_RI_OFF		8
+#define ALTERA_JTAGUART_CONTROL_WI_MSK		0x00000200
+#define ALTERA_JTAGUART_CONTROL_AC_MSK		0x00000400
+#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK	0xFFFF0000
+#define ALTERA_JTAGUART_CONTROL_WSPACE_OFF	16
+
+/*
+ * Local per-uart structure.
+ */
+struct altera_jtaguart {
+	struct uart_port port;
+	unsigned int sigs;	/* Local copy of line sigs */
+	unsigned long imr;	/* Local IMR mirror */
+};
+
+static unsigned int altera_jtaguart_tx_empty(struct uart_port *port)
+{
+	return (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
+		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int altera_jtaguart_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
+}
+
+static void altera_jtaguart_set_mctrl(struct uart_port *port, unsigned int sigs)
+{
+}
+
+static void altera_jtaguart_start_tx(struct uart_port *port)
+{
+	struct altera_jtaguart *pp =
+	    container_of(port, struct altera_jtaguart, port);
+
+	pp->imr |= ALTERA_JTAGUART_CONTROL_WE_MSK;
+	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
+}
+
+static void altera_jtaguart_stop_tx(struct uart_port *port)
+{
+	struct altera_jtaguart *pp =
+	    container_of(port, struct altera_jtaguart, port);
+
+	pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
+	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
+}
+
+static void altera_jtaguart_stop_rx(struct uart_port *port)
+{
+	struct altera_jtaguart *pp =
+	    container_of(port, struct altera_jtaguart, port);
+
+	pp->imr &= ~ALTERA_JTAGUART_CONTROL_RE_MSK;
+	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
+}
+
+static void altera_jtaguart_break_ctl(struct uart_port *port, int break_state)
+{
+}
+
+static void altera_jtaguart_enable_ms(struct uart_port *port)
+{
+}
+
+static void altera_jtaguart_set_termios(struct uart_port *port,
+					struct ktermios *termios,
+					struct ktermios *old)
+{
+	/* Just copy the old termios settings back */
+	if (old)
+		tty_termios_copy_hw(termios, old);
+}
+
+static void altera_jtaguart_rx_chars(struct altera_jtaguart *pp)
+{
+	struct uart_port *port = &pp->port;
+	unsigned char ch, flag;
+	unsigned long status;
+
+	while ((status = readl(port->membase + ALTERA_JTAGUART_DATA_REG)) &
+	       ALTERA_JTAGUART_DATA_RVALID_MSK) {
+		ch = status & ALTERA_JTAGUART_DATA_DATA_MSK;
+		flag = TTY_NORMAL;
+		port->icount.rx++;
+
+		if (uart_handle_sysrq_char(port, ch))
+			continue;
+		uart_insert_char(port, 0, 0, ch, flag);
+	}
+
+	tty_flip_buffer_push(port->state->port.tty);
+}
+
+static void altera_jtaguart_tx_chars(struct altera_jtaguart *pp)
+{
+	struct uart_port *port = &pp->port;
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned int pending, count;
+
+	if (port->x_char) {
+		/* Send special char - probably flow control */
+		writel(port->x_char, port->membase + ALTERA_JTAGUART_DATA_REG);
+		port->x_char = 0;
+		port->icount.tx++;
+		return;
+	}
+
+	pending = uart_circ_chars_pending(xmit);
+	if (pending > 0) {
+		count = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
+				ALTERA_JTAGUART_CONTROL_WSPACE_MSK) >>
+			ALTERA_JTAGUART_CONTROL_WSPACE_OFF;
+		if (count > pending)
+			count = pending;
+		if (count > 0) {
+			pending -= count;
+			while (count--) {
+				writel(xmit->buf[xmit->tail],
+				       port->membase + ALTERA_JTAGUART_DATA_REG);
+				xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+				port->icount.tx++;
+			}
+			if (pending < WAKEUP_CHARS)
+				uart_write_wakeup(port);
+		}
+	}
+
+	if (pending == 0) {
+		pp->imr &= ~ALTERA_JTAGUART_CONTROL_WE_MSK;
+		writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
+	}
+}
+
+static irqreturn_t altera_jtaguart_interrupt(int irq, void *data)
+{
+	struct uart_port *port = data;
+	struct altera_jtaguart *pp =
+	    container_of(port, struct altera_jtaguart, port);
+	unsigned int isr;
+
+	isr = (readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) >>
+	       ALTERA_JTAGUART_CONTROL_RI_OFF) & pp->imr;
+
+	spin_lock(&port->lock);
+
+	if (isr & ALTERA_JTAGUART_CONTROL_RE_MSK)
+		altera_jtaguart_rx_chars(pp);
+	if (isr & ALTERA_JTAGUART_CONTROL_WE_MSK)
+		altera_jtaguart_tx_chars(pp);
+
+	spin_unlock(&port->lock);
+
+	return IRQ_RETVAL(isr);
+}
+
+static void altera_jtaguart_config_port(struct uart_port *port, int flags)
+{
+	port->type = PORT_ALTERA_JTAGUART;
+
+	/* Clear mask, so no surprise interrupts. */
+	writel(0, port->membase + ALTERA_JTAGUART_CONTROL_REG);
+}
+
+static int altera_jtaguart_startup(struct uart_port *port)
+{
+	struct altera_jtaguart *pp =
+	    container_of(port, struct altera_jtaguart, port);
+	unsigned long flags;
+	int ret;
+
+	ret = request_irq(port->irq, altera_jtaguart_interrupt, IRQF_DISABLED,
+			DRV_NAME, port);
+	if (ret) {
+		pr_err(DRV_NAME ": unable to attach Altera JTAG 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_JTAGUART_CONTROL_RE_MSK;
+	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return 0;
+}
+
+static void altera_jtaguart_shutdown(struct uart_port *port)
+{
+	struct altera_jtaguart *pp =
+	    container_of(port, struct altera_jtaguart, port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* Disable all interrupts now */
+	pp->imr = 0;
+	writel(pp->imr, port->membase + ALTERA_JTAGUART_CONTROL_REG);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	free_irq(port->irq, port);
+}
+
+static const char *altera_jtaguart_type(struct uart_port *port)
+{
+	return (port->type == PORT_ALTERA_JTAGUART) ? "Altera JTAG UART" : NULL;
+}
+
+static int altera_jtaguart_request_port(struct uart_port *port)
+{
+	/* UARTs always present */
+	return 0;
+}
+
+static void altera_jtaguart_release_port(struct uart_port *port)
+{
+	/* Nothing to release... */
+}
+
+static int altera_jtaguart_verify_port(struct uart_port *port,
+				       struct serial_struct *ser)
+{
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_ALTERA_JTAGUART)
+		return -EINVAL;
+	return 0;
+}
+
+/*
+ *	Define the basic serial functions we support.
+ */
+static struct uart_ops altera_jtaguart_ops = {
+	.tx_empty	= altera_jtaguart_tx_empty,
+	.get_mctrl	= altera_jtaguart_get_mctrl,
+	.set_mctrl	= altera_jtaguart_set_mctrl,
+	.start_tx	= altera_jtaguart_start_tx,
+	.stop_tx	= altera_jtaguart_stop_tx,
+	.stop_rx	= altera_jtaguart_stop_rx,
+	.enable_ms	= altera_jtaguart_enable_ms,
+	.break_ctl	= altera_jtaguart_break_ctl,
+	.startup	= altera_jtaguart_startup,
+	.shutdown	= altera_jtaguart_shutdown,
+	.set_termios	= altera_jtaguart_set_termios,
+	.type		= altera_jtaguart_type,
+	.request_port	= altera_jtaguart_request_port,
+	.release_port	= altera_jtaguart_release_port,
+	.config_port	= altera_jtaguart_config_port,
+	.verify_port	= altera_jtaguart_verify_port,
+};
+
+#define ALTERA_JTAGUART_MAXPORTS 1
+static struct altera_jtaguart altera_jtaguart_ports[ALTERA_JTAGUART_MAXPORTS];
+
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
+
+int __init early_altera_jtaguart_setup(struct altera_jtaguart_platform_uart
+				       *platp)
+{
+	struct uart_port *port;
+	int i;
+
+	for (i = 0; i < ALTERA_JTAGUART_MAXPORTS && platp[i].mapbase; i++) {
+		port = &altera_jtaguart_ports[i].port;
+
+		port->line = i;
+		port->type = PORT_ALTERA_JTAGUART;
+		port->mapbase = platp[i].mapbase;
+		port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE);
+		port->iotype = SERIAL_IO_MEM;
+		port->irq = platp[i].irq;
+		port->flags = ASYNC_BOOT_AUTOCONF;
+		port->ops = &altera_jtaguart_ops;
+	}
+
+	return 0;
+}
+
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
+static void altera_jtaguart_console_putc(struct console *co, const char c)
+{
+	struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
+	unsigned long status;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	while (((status = readl(port->membase + ALTERA_JTAGUART_CONTROL_REG)) &
+		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
+		if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0) {
+			spin_unlock_irqrestore(&port->lock, flags);
+			return;	/* no connection activity */
+		}
+		spin_unlock_irqrestore(&port->lock, flags);
+		cpu_relax();
+		spin_lock_irqsave(&port->lock, flags);
+	}
+	writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+#else
+static void altera_jtaguart_console_putc(struct console *co, const char c)
+{
+	struct uart_port *port = &(altera_jtaguart_ports + co->index)->port;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	while ((readl(port->membase + ALTERA_JTAGUART_CONTROL_REG) &
+		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
+		spin_unlock_irqrestore(&port->lock, flags);
+		cpu_relax();
+		spin_lock_irqsave(&port->lock, flags);
+	}
+	writel(c, port->membase + ALTERA_JTAGUART_DATA_REG);
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+#endif
+
+static void altera_jtaguart_console_write(struct console *co, const char *s,
+					  unsigned int count)
+{
+	for (; count; count--, s++) {
+		altera_jtaguart_console_putc(co, *s);
+		if (*s == '\n')
+			altera_jtaguart_console_putc(co, '\r');
+	}
+}
+
+static int __init altera_jtaguart_console_setup(struct console *co,
+						char *options)
+{
+	struct uart_port *port;
+
+	if (co->index < 0 || co->index >= ALTERA_JTAGUART_MAXPORTS)
+		return -EINVAL;
+	port = &altera_jtaguart_ports[co->index].port;
+	if (port->membase == 0)
+		return -ENODEV;
+	return 0;
+}
+
+static struct uart_driver altera_jtaguart_driver;
+
+static struct console altera_jtaguart_console = {
+	.name	= "ttyJ",
+	.write	= altera_jtaguart_console_write,
+	.device	= uart_console_device,
+	.setup	= altera_jtaguart_console_setup,
+	.flags	= CON_PRINTBUFFER,
+	.index	= -1,
+	.data	= &altera_jtaguart_driver,
+};
+
+static int __init altera_jtaguart_console_init(void)
+{
+	register_console(&altera_jtaguart_console);
+	return 0;
+}
+
+console_initcall(altera_jtaguart_console_init);
+
+#define	ALTERA_JTAGUART_CONSOLE	(&altera_jtaguart_console)
+
+#else
+
+#define	ALTERA_JTAGUART_CONSOLE	NULL
+
+#endif /* CONFIG_ALTERA_JTAGUART_CONSOLE */
+
+static struct uart_driver altera_jtaguart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= "altera_jtaguart",
+	.dev_name	= "ttyJ",
+	.major		= ALTERA_JTAGUART_MAJOR,
+	.minor		= ALTERA_JTAGUART_MINOR,
+	.nr		= ALTERA_JTAGUART_MAXPORTS,
+	.cons		= ALTERA_JTAGUART_CONSOLE,
+};
+
+static int __devinit altera_jtaguart_probe(struct platform_device *pdev)
+{
+	struct altera_jtaguart_platform_uart *platp = pdev->dev.platform_data;
+	struct uart_port *port;
+	int i;
+
+	for (i = 0; i < ALTERA_JTAGUART_MAXPORTS && platp[i].mapbase; i++) {
+		port = &altera_jtaguart_ports[i].port;
+
+		port->line = i;
+		port->type = PORT_ALTERA_JTAGUART;
+		port->mapbase = platp[i].mapbase;
+		port->membase = ioremap(port->mapbase, ALTERA_JTAGUART_SIZE);
+		port->iotype = SERIAL_IO_MEM;
+		port->irq = platp[i].irq;
+		port->ops = &altera_jtaguart_ops;
+		port->flags = ASYNC_BOOT_AUTOCONF;
+
+		uart_add_one_port(&altera_jtaguart_driver, port);
+	}
+
+	return 0;
+}
+
+static int __devexit altera_jtaguart_remove(struct platform_device *pdev)
+{
+	struct uart_port *port;
+	int i;
+
+	for (i = 0; i < ALTERA_JTAGUART_MAXPORTS; i++) {
+		port = &altera_jtaguart_ports[i].port;
+		if (port)
+			uart_remove_one_port(&altera_jtaguart_driver, port);
+	}
+
+	return 0;
+}
+
+static struct platform_driver altera_jtaguart_platform_driver = {
+	.probe	= altera_jtaguart_probe,
+	.remove	= __devexit_p(altera_jtaguart_remove),
+	.driver	= {
+		.name	= DRV_NAME,
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init altera_jtaguart_init(void)
+{
+	int rc;
+
+	rc = uart_register_driver(&altera_jtaguart_driver);
+	if (rc)
+		return rc;
+	rc = platform_driver_register(&altera_jtaguart_platform_driver);
+	if (rc) {
+		uart_unregister_driver(&altera_jtaguart_driver);
+		return rc;
+	}
+	return 0;
+}
+
+static void __exit altera_jtaguart_exit(void)
+{
+	platform_driver_unregister(&altera_jtaguart_platform_driver);
+	uart_unregister_driver(&altera_jtaguart_driver);
+}
+
+module_init(altera_jtaguart_init);
+module_exit(altera_jtaguart_exit);
+
+MODULE_DESCRIPTION("Altera JTAG UART driver");
+MODULE_AUTHOR("Thomas Chou <[e-mail]>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);

include/linux/altera_jtaguart.h

···
+/*
+ * altera_jtaguart.h -- Altera JTAG UART driver defines.
+ */
+
+#ifndef	__ALTJUART_H
+#define	__ALTJUART_H
+
+#define ALTERA_JTAGUART_MAJOR	204
+#define ALTERA_JTAGUART_MINOR	186
+
+struct altera_jtaguart_platform_uart {
+	unsigned long mapbase;	/* Physical address base */
+	unsigned int irq;	/* Interrupt vector */
+};
+
+#endif /* __ALTJUART_H */

include/linux/serial_core.h

···
 /* Aeroflex Gaisler GRLIB APBUART */
 #define PORT_APBUART    90
 
+/* Altera UARTs */
+#define PORT_ALTERA_JTAGUART	91
+
 #ifdef __KERNEL__
 
 #include <linux/compiler.h>