serial: Added Timberdale UART driver

Driver for the UART found in the Timberdale FPGA

Signed-off-by: Richard Röjfors <richard.rojfors.ext@mocean-labs.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 520 insertions, 0 deletions

diff --git a/drivers/serial/timbuart.c b/drivers/serial/timbuart.c
new file mode 100644
index 000000000000..30ba3c4cc180
--- /dev/null
+++ b/drivers/serial/timbuart.c
@@ -0,0 +1,520 @@
+/*
+ * timbuart.c timberdale FPGA UART driver
+ * Copyright (c) 2009 Intel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/* Supports:
+ * Timberdale FPGA UART
+ */
+
+#include <linux/pci.h>
+#include <linux/interrupt.h>
+#include <linux/serial_core.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/ioport.h>
+
+#include "timbuart.h"
+
+struct timbuart_port {
+        struct uart_port        port;
+        struct tasklet_struct   tasklet;
+        int                     usedma;
+        u8                      last_ier;
+        struct platform_device  *dev;
+};
+
+static int baudrates[] = {9600, 19200, 38400, 57600, 115200, 230400, 460800,
+        921600, 1843200, 3250000};
+
+static void timbuart_mctrl_check(struct uart_port *port, u8 isr, u8 *ier);
+
+static irqreturn_t timbuart_handleinterrupt(int irq, void *devid);
+
+static void timbuart_stop_rx(struct uart_port *port)
+{
+        /* spin lock held by upper layer, disable all RX interrupts */
+        u8 ier = ioread8(port->membase + TIMBUART_IER) & ~RXFLAGS;
+        iowrite8(ier, port->membase + TIMBUART_IER);
+}
+
+static void timbuart_stop_tx(struct uart_port *port)
+{
+        /* spinlock held by upper layer, disable TX interrupt */
+        u8 ier = ioread8(port->membase + TIMBUART_IER) & ~TXBAE;
+        iowrite8(ier, port->membase + TIMBUART_IER);
+}
+
+static void timbuart_start_tx(struct uart_port *port)
+{
+        struct timbuart_port *uart =
+                container_of(port, struct timbuart_port, port);
+
+        /* do not transfer anything here -> fire off the tasklet */
+        tasklet_schedule(&uart->tasklet);
+}
+
+static void timbuart_flush_buffer(struct uart_port *port)
+{
+        u8 ctl = ioread8(port->membase + TIMBUART_CTRL) | TIMBUART_CTRL_FLSHTX;
+
+        iowrite8(ctl, port->membase + TIMBUART_CTRL);
+        iowrite8(TXBF, port->membase + TIMBUART_ISR);
+}
+
+static void timbuart_rx_chars(struct uart_port *port)
+{
+        struct tty_struct *tty = port->info->port.tty;
+
+        while (ioread8(port->membase + TIMBUART_ISR) & RXDP) {
+                u8 ch = ioread8(port->membase + TIMBUART_RXFIFO);
+                port->icount.rx++;
+                tty_insert_flip_char(tty, ch, TTY_NORMAL);
+        }
+
+        spin_unlock(&port->lock);
+        tty_flip_buffer_push(port->info->port.tty);
+        spin_lock(&port->lock);
+
+        dev_dbg(port->dev, "%s - total read %d bytes\n",
+                __func__, port->icount.rx);
+}
+
+static void timbuart_tx_chars(struct uart_port *port)
+{
+        struct circ_buf *xmit = &port->info->xmit;
+
+        while (!(ioread8(port->membase + TIMBUART_ISR) & TXBF) &&
+                !uart_circ_empty(xmit)) {
+                iowrite8(xmit->buf[xmit->tail],
+                        port->membase + TIMBUART_TXFIFO);
+                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+                port->icount.tx++;
+        }
+
+        dev_dbg(port->dev,
+                "%s - total written %d bytes, CTL: %x, RTS: %x, baud: %x\n",
+                 __func__,
+                port->icount.tx,
+                ioread8(port->membase + TIMBUART_CTRL),
+                port->mctrl & TIOCM_RTS,
+                ioread8(port->membase + TIMBUART_BAUDRATE));
+}
+
+static void timbuart_handle_tx_port(struct uart_port *port, u8 isr, u8 *ier)
+{
+        struct timbuart_port *uart =
+                container_of(port, struct timbuart_port, port);
+        struct circ_buf *xmit = &port->info->xmit;
+
+        if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+                return;
+
+        if (port->x_char)
+                return;
+
+        if (isr & TXFLAGS) {
+                timbuart_tx_chars(port);
+                /* clear all TX interrupts */
+                iowrite8(TXFLAGS, port->membase + TIMBUART_ISR);
+
+                if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+                        uart_write_wakeup(port);
+        } else
+                /* Re-enable any tx interrupt */
+                *ier |= uart->last_ier & TXFLAGS;
+
+        /* enable interrupts if there are chars in the transmit buffer,
+         * Or if we delivered some bytes and want the almost empty interrupt
+         * we wake up the upper layer later when we got the interrupt
+         * to give it some time to go out...
+         */
+        if (!uart_circ_empty(xmit))
+                *ier |= TXBAE;
+
+        dev_dbg(port->dev, "%s - leaving\n", __func__);
+}
+
+void timbuart_handle_rx_port(struct uart_port *port, u8 isr, u8 *ier)
+{
+        if (isr & RXFLAGS) {
+                /* Some RX status is set */
+                if (isr & RXBF) {
+                        u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
+                                TIMBUART_CTRL_FLSHRX;
+                        iowrite8(ctl, port->membase + TIMBUART_CTRL);
+                        port->icount.overrun++;
+                } else if (isr & (RXDP))
+                        timbuart_rx_chars(port);
+
+                /* ack all RX interrupts */
+                iowrite8(RXFLAGS, port->membase + TIMBUART_ISR);
+        }
+
+        /* always have the RX interrupts enabled */
+        *ier |= RXBAF | RXBF | RXTT;
+
+        dev_dbg(port->dev, "%s - leaving\n", __func__);
+}
+
+void timbuart_tasklet(unsigned long arg)
+{
+        struct timbuart_port *uart = (struct timbuart_port *)arg;
+        u8 isr, ier = 0;
+
+        spin_lock(&uart->port.lock);
+
+        isr = ioread8(uart->port.membase + TIMBUART_ISR);
+        dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr);
+
+        if (!uart->usedma)
+                timbuart_handle_tx_port(&uart->port, isr, &ier);
+
+        timbuart_mctrl_check(&uart->port, isr, &ier);
+
+        if (!uart->usedma)
+                timbuart_handle_rx_port(&uart->port, isr, &ier);
+
+        iowrite8(ier, uart->port.membase + TIMBUART_IER);
+
+        spin_unlock(&uart->port.lock);
+        dev_dbg(uart->port.dev, "%s leaving\n", __func__);
+}
+
+static unsigned int timbuart_tx_empty(struct uart_port *port)
+{
+        u8 isr = ioread8(port->membase + TIMBUART_ISR);
+
+        return (isr & TXBAE) ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int timbuart_get_mctrl(struct uart_port *port)
+{
+        u8 cts = ioread8(port->membase + TIMBUART_CTRL);
+        dev_dbg(port->dev, "%s - cts %x\n", __func__, cts);
+
+        if (cts & TIMBUART_CTRL_CTS)
+                return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
+        else
+                return TIOCM_DSR | TIOCM_CAR;
+}
+
+static void timbuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+        dev_dbg(port->dev, "%s - %x\n", __func__, mctrl);
+
+        if (mctrl & TIOCM_RTS)
+                iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
+        else
+                iowrite8(TIMBUART_CTRL_RTS, port->membase + TIMBUART_CTRL);
+}
+
+static void timbuart_mctrl_check(struct uart_port *port, u8 isr, u8 *ier)
+{
+        unsigned int cts;
+
+        if (isr & CTS_DELTA) {
+                /* ack */
+                iowrite8(CTS_DELTA, port->membase + TIMBUART_ISR);
+                cts = timbuart_get_mctrl(port);
+                uart_handle_cts_change(port, cts & TIOCM_CTS);
+                wake_up_interruptible(&port->info->delta_msr_wait);
+        }
+
+        *ier |= CTS_DELTA;
+}
+
+static void timbuart_enable_ms(struct uart_port *port)
+{
+        /* N/A */
+}
+
+static void timbuart_break_ctl(struct uart_port *port, int ctl)
+{
+        /* N/A */
+}
+
+static int timbuart_startup(struct uart_port *port)
+{
+        struct timbuart_port *uart =
+                container_of(port, struct timbuart_port, port);
+
+        dev_dbg(port->dev, "%s\n", __func__);
+
+        iowrite8(TIMBUART_CTRL_FLSHRX, port->membase + TIMBUART_CTRL);
+        iowrite8(0xff, port->membase + TIMBUART_ISR);
+        /* Enable all but TX interrupts */
+        iowrite8(RXBAF | RXBF | RXTT | CTS_DELTA,
+                port->membase + TIMBUART_IER);
+
+        return request_irq(port->irq, timbuart_handleinterrupt, IRQF_SHARED,
+                "timb-uart", uart);
+}
+
+static void timbuart_shutdown(struct uart_port *port)
+{
+        struct timbuart_port *uart =
+                container_of(port, struct timbuart_port, port);
+        dev_dbg(port->dev, "%s\n", __func__);
+        free_irq(port->irq, uart);
+        iowrite8(0, port->membase + TIMBUART_IER);
+}
+
+static int get_bindex(int baud)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(baudrates); i++)
+                if (baud == baudrates[i])
+                        return i;
+
+        return -1;
+}
+
+static void timbuart_set_termios(struct uart_port *port,
+        struct ktermios *termios,
+        struct ktermios *old)
+{
+        unsigned int baud;
+        short bindex;
+        unsigned long flags;
+
+        baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
+        bindex = get_bindex(baud);
+        dev_dbg(port->dev, "%s - bindex %d\n", __func__, bindex);
+
+        if (bindex < 0) {
+                printk(KERN_ALERT "timbuart: Unsupported baud rate\n");
+        } else {
+                spin_lock_irqsave(&port->lock, flags);
+                iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE);
+                uart_update_timeout(port, termios->c_cflag, baud);
+                spin_unlock_irqrestore(&port->lock, flags);
+        }
+}
+
+static const char *timbuart_type(struct uart_port *port)
+{
+        return port->type == PORT_UNKNOWN ? "timbuart" : NULL;
+}
+
+/* We do not request/release mappings of the registers here,
+ * currently it's done in the proble function.
+ */
+static void timbuart_release_port(struct uart_port *port)
+{
+        struct platform_device *pdev = to_platform_device(port->dev);
+        int size =
+                resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
+
+        if (port->flags & UPF_IOREMAP) {
+                iounmap(port->membase);
+                port->membase = NULL;
+        }
+
+        release_mem_region(port->mapbase, size);
+}
+
+static int timbuart_request_port(struct uart_port *port)
+{
+        struct platform_device *pdev = to_platform_device(port->dev);
+        int size =
+                resource_size(platform_get_resource(pdev, IORESOURCE_MEM, 0));
+
+        if (!request_mem_region(port->mapbase, size, "timb-uart"))
+                return -EBUSY;
+
+        if (port->flags & UPF_IOREMAP) {
+                port->membase = ioremap(port->mapbase, size);
+                if (port->membase == NULL) {
+                        release_mem_region(port->mapbase, size);
+                        return -ENOMEM;
+                }
+        }
+
+        return 0;
+}
+
+static irqreturn_t timbuart_handleinterrupt(int irq, void *devid)
+{
+        struct timbuart_port *uart = (struct timbuart_port *)devid;
+
+        if (ioread8(uart->port.membase + TIMBUART_IPR)) {
+                uart->last_ier = ioread8(uart->port.membase + TIMBUART_IER);
+
+                /* disable interrupts, the tasklet enables them again */
+                iowrite8(0, uart->port.membase + TIMBUART_IER);
+
+                /* fire off bottom half */
+                tasklet_schedule(&uart->tasklet);
+
+                return IRQ_HANDLED;
+        } else
+                return IRQ_NONE;
+}
+
+/*
+ * Configure/autoconfigure the port.
+ */
+static void timbuart_config_port(struct uart_port *port, int flags)
+{
+        if (flags & UART_CONFIG_TYPE) {
+                port->type = PORT_TIMBUART;
+                timbuart_request_port(port);
+        }
+}
+
+static int timbuart_verify_port(struct uart_port *port,
+        struct serial_struct *ser)
+{
+        /* we don't want the core code to modify any port params */
+        return -EINVAL;
+}
+
+static struct uart_ops timbuart_ops = {
+        .tx_empty = timbuart_tx_empty,
+        .set_mctrl = timbuart_set_mctrl,
+        .get_mctrl = timbuart_get_mctrl,
+        .stop_tx = timbuart_stop_tx,
+        .start_tx = timbuart_start_tx,
+        .flush_buffer = timbuart_flush_buffer,
+        .stop_rx = timbuart_stop_rx,
+        .enable_ms = timbuart_enable_ms,
+        .break_ctl = timbuart_break_ctl,
+        .startup = timbuart_startup,
+        .shutdown = timbuart_shutdown,
+        .set_termios = timbuart_set_termios,
+        .type = timbuart_type,
+        .release_port = timbuart_release_port,
+        .request_port = timbuart_request_port,
+        .config_port = timbuart_config_port,
+        .verify_port = timbuart_verify_port
+};
+
+static struct uart_driver timbuart_driver = {
+        .owner = THIS_MODULE,
+        .driver_name = "timberdale_uart",
+        .dev_name = "ttyTU",
+        .major = TIMBUART_MAJOR,
+        .minor = TIMBUART_MINOR,
+        .nr = 1
+};
+
+static int timbuart_probe(struct platform_device *dev)
+{
+        int err;
+        struct timbuart_port *uart;
+        struct resource *iomem;
+
+        dev_dbg(&dev->dev, "%s\n", __func__);
+
+        uart = kzalloc(sizeof(*uart), GFP_KERNEL);
+        if (!uart) {
+                err = -EINVAL;
+                goto err_mem;
+        }
+
+        uart->usedma = 0;
+
+        uart->port.uartclk = 3250000 * 16;
+        uart->port.fifosize  = TIMBUART_FIFO_SIZE;
+        uart->port.regshift  = 2;
+        uart->port.iotype  = UPIO_MEM;
+        uart->port.ops = &timbuart_ops;
+        uart->port.irq = 0;
+        uart->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP;
+        uart->port.line  = 0;
+        uart->port.dev  = &dev->dev;
+
+        iomem = platform_get_resource(dev, IORESOURCE_MEM, 0);
+        if (!iomem) {
+                err = -ENOMEM;
+                goto err_register;
+        }
+        uart->port.mapbase = iomem->start;
+        uart->port.membase = NULL;
+
+        uart->port.irq = platform_get_irq(dev, 0);
+        if (uart->port.irq < 0) {
+                err = -EINVAL;
+                goto err_register;
+        }
+
+        tasklet_init(&uart->tasklet, timbuart_tasklet, (unsigned long)uart);
+
+        err = uart_register_driver(&timbuart_driver);
+        if (err)
+                goto err_register;
+
+        err = uart_add_one_port(&timbuart_driver, &uart->port);
+        if (err)
+                goto err_add_port;
+
+        platform_set_drvdata(dev, uart);
+
+        return 0;
+
+err_add_port:
+        uart_unregister_driver(&timbuart_driver);
+err_register:
+        kfree(uart);
+err_mem:
+        printk(KERN_ERR "timberdale: Failed to register Timberdale UART: %d\n",
+                err);
+
+        return err;
+}
+
+static int timbuart_remove(struct platform_device *dev)
+{
+        struct timbuart_port *uart = platform_get_drvdata(dev);
+
+        tasklet_kill(&uart->tasklet);
+        uart_remove_one_port(&timbuart_driver, &uart->port);
+        uart_unregister_driver(&timbuart_driver);
+        kfree(uart);
+
+        return 0;
+}
+
+static struct platform_driver timbuart_platform_driver = {
+        .driver = {
+                .name   = "timb-uart",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = timbuart_probe,
+        .remove         = timbuart_remove,
+};
+
+/*--------------------------------------------------------------------------*/
+
+static int __init timbuart_init(void)
+{
+        return platform_driver_register(&timbuart_platform_driver);
+}
+
+static void __exit timbuart_exit(void)
+{
+        platform_driver_unregister(&timbuart_platform_driver);
+}
+
+module_init(timbuart_init);
+module_exit(timbuart_exit);
+
+MODULE_DESCRIPTION("Timberdale UART driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:timb-uart");
+