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

3 files changed, 526 insertions, 0 deletions

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 577d2762a4f4..f4050e678460 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -1523,4 +1523,25 @@ 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 328f107346c4..7f9d225d0430 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -82,3 +82,4 @@ 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 000000000000..f9b49b5ff5e1
--- /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);