[PATCH v5 0/2] serial: Drivers for Altera UARTs

[PATCH v5 0/2] serial: Drivers for Altera UARTs

[Tobias Klauser]

This is the fifth version of the patchset to add the serial drivers for the
Altera UARTs. The following changes were made on top of the fourth version
submitted on 30 Mar 2010:

 - Fix Kconfig so altera_uart and altera_jtaguart can be properly built as
   modules. Add dependecy SERIAL_ALTERA_JTAGUART=y (instead of just
   SERIAL_ALTERA_JTAGUART) to SERIAL_ALTERA_JTAGUART_CONSOLE to prevent build
   failure when building as module (accordingly for the altera_uart driver).
   Thanks to Stephen Rothwell for the help with this.

Tobias Klauser (2):
  serial: Add driver for the Altera JTAG UART
  serial: Add driver for the Altera UART

 drivers/serial/Kconfig           |   52 ++++
 drivers/serial/Makefile          |    2 +
 drivers/serial/altera_jtaguart.c |  504 +++++++++++++++++++++++++++++++++
 drivers/serial/altera_uart.c     |  570 ++++++++++++++++++++++++++++++++++++++
 include/linux/altera_jtaguart.h  |   16 +
 include/linux/altera_uart.h      |   14 +
 include/linux/serial_core.h      |    4 +
 7 files changed, 1162 insertions(+), 0 deletions(-)
 create mode 100644 drivers/serial/altera_jtaguart.c
 create mode 100644 drivers/serial/altera_uart.c
 create mode 100644 include/linux/altera_jtaguart.h
 create mode 100644 include/linux/altera_uart.h

[PATCH 1/2] serial: Add driver for the Altera JTAG UART

[Tobias Klauser]

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 <tklauser@distanz.ch>
---
 drivers/serial/Kconfig           |   21 ++
 drivers/serial/Makefile          |    1 +
 drivers/serial/altera_jtaguart.c |  504 ++++++++++++++++++++++++++++++++++++++
 include/linux/altera_jtaguart.h  |   16 ++
 include/linux/serial_core.h      |    3 +
 5 files changed, 545 insertions(+), 0 deletions(-)
 create mode 100644 drivers/serial/altera_jtaguart.c
 create mode 100644 include/linux/altera_jtaguart.h

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 9c2e743..2a36f3f 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -1530,4 +1530,25 @@ config SERIAL_GRLIB_GAISLER_APBUART_CONSOLE
 	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
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 6aa4723..a4b748f 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -83,3 +83,4 @@ obj-$(CONFIG_KGDB_SERIAL_CONSOLE) += kgdboc.o
 obj-$(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
diff --git a/drivers/serial/altera_jtaguart.c b/drivers/serial/altera_jtaguart.c
new file mode 100644
index 0000000..f9b49b5
--- /dev/null
+++ b/drivers/serial/altera_jtaguart.c
@@ -0,0 +1,504 @@
+/*
+ * altera_jtaguart.c -- Altera JTAG 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_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 <thomas@wytron.com.tw>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);
diff --git a/include/linux/altera_jtaguart.h b/include/linux/altera_jtaguart.h
new file mode 100644
index 0000000..953b178
--- /dev/null
+++ b/include/linux/altera_jtaguart.h
@@ -0,0 +1,16 @@
+/*
+ * 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 */
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index ad83996..308863a 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -182,6 +182,9 @@
 /* Aeroflex Gaisler GRLIB APBUART */
 #define PORT_APBUART    90
 
+/* Altera UARTs */
+#define PORT_ALTERA_JTAGUART	91
+
 #ifdef __KERNEL__
 
 #include <linux/compiler.h>
-- 
1.6.3.3

[PATCH 2/2] serial: Add driver for the Altera UART

[Tobias Klauser]

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>
---
 drivers/serial/Kconfig       |   31 +++
 drivers/serial/Makefile      |    1 +
 drivers/serial/altera_uart.c |  570 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/altera_uart.h  |   14 +
 include/linux/serial_core.h  |    1 +
 5 files changed, 617 insertions(+), 0 deletions(-)
 create mode 100644 drivers/serial/altera_uart.c
 create mode 100644 include/linux/altera_uart.h

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 2a36f3f..f88fb97 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -1551,4 +1551,35 @@ 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 a4b748f..733a19a 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -84,3 +84,4 @@ 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);
diff --git a/include/linux/altera_uart.h b/include/linux/altera_uart.h
new file mode 100644
index 0000000..8d44106
--- /dev/null
+++ b/include/linux/altera_uart.h
@@ -0,0 +1,14 @@
+/*
+ * altera_uart.h -- Altera UART driver defines.
+ */
+
+#ifndef	__ALTUART_H
+#define	__ALTUART_H
+
+struct altera_uart_platform_uart {
+	unsigned long mapbase;	/* Physical address base */
+	unsigned int irq;	/* Interrupt vector */
+	unsigned int uartclk;	/* UART clock rate */
+};
+
+#endif /* __ALTUART_H */
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 308863a..f10db6e 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -184,6 +184,7 @@
 
 /* Altera UARTs */
 #define PORT_ALTERA_JTAGUART	91
+#define PORT_ALTERA_UART	92
 
 #ifdef __KERNEL__
 
-- 
1.6.3.3

Re: [Nios2-dev] [PATCH 2/2] serial: Add driver for the Altera UART

[Ian Abbott]

On Wed, 2010-05-05 at 09:35 +0100, Tobias Klauser wrote:
> Add an UART driver for the UART component available as a SOPC (System on
> Programmable Chip) component for Altera FPGAs.
[...]

> +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);
> +}

Those four functions shouldn't grab port->lock because the caller in
serial_core.c grabs it before calling them.

> +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);
> +}

Either the interrupt routine should grab port->lock (see equivalent
function in altera_jtaguart.c for an example), or this could be done
lower down in altera_uart_rx_chars() and altera_uart_tx_chars(). (It's
less messing about to do it here in the interrupt routine though.)

> +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;
> +       }
> +}

I'd suggest calling udelay(1) in each iteration of the loop.  Perhaps
the second loop is overkill.

I was also going to suggest using the port->lock spin lock, but I'm not
sure about the policy regarding that for console output (the 8250 driver
console output doesn't use the spin lock for example).

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-

Re: [Nios2-dev] [PATCH 1/2] serial: Add driver for the Altera JTAG UART

[Ian Abbott]

On Wed, 2010-05-05 at 09:35 +0100, Tobias Klauser wrote:
> 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 <tklauser@distanz.ch>
[...]
> +#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

I was originally responsible for adding the spin locks to these console
putc functions, but I'm not sure what the policy is regarding that, as
the 8250 driver doesn't use them for console output for example.

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-

Re: [Nios2-dev] [PATCH 2/2] serial: Add driver for the Altera UART

[Ian Abbott]

On 06/05/10 11:44, Ian Abbott wrote:
> On Wed, 2010-05-05 at 09:35 +0100, Tobias Klauser wrote:
>> Add an UART driver for the UART component available as a SOPC (System on
>> Programmable Chip) component for Altera FPGAs.
> [...]
> 
>> +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);
>> +}
> 
> Those four functions shouldn't grab port->lock because the caller in
> serial_core.c grabs it before calling them.

Oh, and that also applies to altera_uart_set_mctrl() - the caller grabs
port->lock before calling it.

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-

Re: [Nios2-dev] [PATCH 2/2] serial: Add driver for the Altera UART

[Ian Abbott]

On 06/05/10 12:09, Ian Abbott wrote:
> On 06/05/10 11:44, Ian Abbott wrote:
>> Those four functions shouldn't grab port->lock because the caller in
>> serial_core.c grabs it before calling them.
> 
> Oh, and that also applies to altera_uart_set_mctrl() - the caller grabs
> port->lock before calling it.

And altera_uart_get_mctrl().

(And for completeness, altera_uart_enable_ms() but the current
implementation doesn't grab it anyway as it's just an empty function.)

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-

Re: [Nios2-dev] [PATCH 1/2] serial: Add driver for the Altera JTAG UART

[Alan Cox]

> I was originally responsible for adding the spin locks to these console
> putc functions, but I'm not sure what the policy is regarding that, as
> the 8250 driver doesn't use them for console output for example.

For the console it depends if you need them for internal consistency as I
understand the codebase. For the core stuff it currently protects
port->port.tty against a hangup which would drop the tty under you.

Re: [Nios2-dev] [PATCH 2/2] serial: Add driver for the Altera UART

[Tobias Klauser]

Hi Ian,

Thanks a lot for your review. Please see my notes below.

On 05/06/2010 12:44 PM, Ian Abbott wrote:
> On Wed, 2010-05-05 at 09:35 +0100, Tobias Klauser wrote:
>> Add an UART driver for the UART component available as a SOPC (System on
>> Programmable Chip) component for Altera FPGAs.
> [...]
> 
>> +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);
>> +}
> 
> Those four functions shouldn't grab port->lock because the caller in
> serial_core.c grabs it before calling them.

Agreed, I removed the lock grabbing from altera_uart_stop_rx,
altera_uart_stop_tx, altera_uart_start_tx, altera_uart_set_mctrl and
altera_uart_get_mctrl (as suggested in the original message and the two
followups).

I also noticed, that altera_uart_break_ctl takes the lock which might be
not necessary as the caller in serial_core.c already takes port->mutex
which should be enough. Or am I wrong?

>> +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);
>> +}
> 
> Either the interrupt routine should grab port->lock (see equivalent
> function in altera_jtaguart.c for an example), or this could be done
> lower down in altera_uart_rx_chars() and altera_uart_tx_chars(). (It's
> less messing about to do it here in the interrupt routine though.)

I added the lock to the interrupt routine (similar to altera_jtaguart.c).

>> +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;
>> +       }
>> +}
> 
> I'd suggest calling udelay(1) in each iteration of the loop.  Perhaps
> the second loop is overkill.

Those seem to come from mcf.c on which this driver was based. I added
the udelay to the first loop and dropped the second loop which indeed
isn't needed here. I also replace the first loop with the equivalent
construct from altera_uart_tx_chars.

> I was also going to suggest using the port->lock spin lock, but I'm not
> sure about the policy regarding that for console output (the 8250 driver
> console output doesn't use the spin lock for example).

As I understood from Alan's comment on altera_jtaguart.c the lock is
needed to protect port->port.tty so I'll add it in altera_uart.c too.

Cheers,
Tobias

Re: [Nios2-dev] [PATCH 2/2] serial: Add driver for the Altera UART

[Ian Abbott]

Hi Tobias,

On 06/05/10 13:03, Tobias Klauser wrote:
> I also noticed, that altera_uart_break_ctl takes the lock which might be
> not necessary as the caller in serial_core.c already takes port->mutex
> which should be enough. Or am I wrong?

It's not enough.  The spin lock is needed to protect modification of
pp->imr and writing this modified value to the control register.  Not
all paths that modify pp->imr and the control register grab port->mutex
beforehand (for example, the interrupt routine doesn't and can't).

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@mev.co.uk>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-