[PATCH] serial uartlite driver

Add a driver for the Xilinx uartlite serial controller used in boards with
the PPC405 core in the Xilinx V2P/V4 fpgas.

The hardware is very simple (baudrate/start/stopbits fixed and no break
support).  See the datasheet for details:

	http://www.xilinx.com/bvdocs/ipcenter/data_sheet/opb_uartlite.pdf

See http://thread.gmane.org/gmane.linux.serial/1237/ for the email thread.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Acked-by: Olof Johansson <olof@lixom.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 525 insertions, 0 deletions

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 0b71e7d18903..e936c91640b4 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -511,6 +511,25 @@ config SERIAL_IMX_CONSOLE
           your boot loader (lilo or loadlin) about how to pass options to the
           kernel at boot time.)
 
+config SERIAL_UARTLITE
+        tristate "Xilinx uartlite serial port support"
+        depends on PPC32
+        select SERIAL_CORE
+        help
+          Say Y here if you want to use the Xilinx uartlite serial controller.
+
+          To compile this driver as a module, choose M here: the
+          module will be called uartlite.ko.
+
+config SERIAL_UARTLITE_CONSOLE
+        bool "Support for console on Xilinx uartlite serial port"
+        depends on SERIAL_UARTLITE=y
+        select SERIAL_CORE_CONSOLE
+        help
+          Say Y here if you wish to use a Xilinx uartlite as the system
+          console (the system console is the device which receives all kernel
+          messages and warnings and which allows logins in single user mode).
+
 config SERIAL_SUNCORE
         bool
         depends on SPARC
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index b4d8a7c182e3..0dba0017a006 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -55,4 +55,5 @@ obj-$(CONFIG_SERIAL_VR41XX) += vr41xx_siu.o
 obj-$(CONFIG_SERIAL_SGI_IOC4) += ioc4_serial.o
 obj-$(CONFIG_SERIAL_SGI_IOC3) += ioc3_serial.o
 obj-$(CONFIG_SERIAL_ATMEL) += atmel_serial.o
+obj-$(CONFIG_SERIAL_UARTLITE) += uartlite.o
 obj-$(CONFIG_SERIAL_NETX) += netx-serial.o
diff --git a/drivers/serial/uartlite.c b/drivers/serial/uartlite.c
new file mode 100644
index 000000000000..83690653b78b
--- /dev/null
+++ b/drivers/serial/uartlite.c
@@ -0,0 +1,505 @@
+/*
+ * uartlite.c: Serial driver for Xilinx uartlite serial controller
+ *
+ * Peter Korsgaard <jacmet@sunsite.dk>
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/console.h>
+#include <linux/serial.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <asm/io.h>
+
+#define ULITE_MAJOR             204
+#define ULITE_MINOR             187
+#define ULITE_NR_UARTS          4
+
+/* For register details see datasheet:
+   http://www.xilinx.com/bvdocs/ipcenter/data_sheet/opb_uartlite.pdf
+*/
+#define ULITE_RX                0x00
+#define ULITE_TX                0x04
+#define ULITE_STATUS            0x08
+#define ULITE_CONTROL           0x0c
+
+#define ULITE_REGION            16
+
+#define ULITE_STATUS_RXVALID    0x01
+#define ULITE_STATUS_RXFULL     0x02
+#define ULITE_STATUS_TXEMPTY    0x04
+#define ULITE_STATUS_TXFULL     0x08
+#define ULITE_STATUS_IE         0x10
+#define ULITE_STATUS_OVERRUN    0x20
+#define ULITE_STATUS_FRAME      0x40
+#define ULITE_STATUS_PARITY     0x80
+
+#define ULITE_CONTROL_RST_TX    0x01
+#define ULITE_CONTROL_RST_RX    0x02
+#define ULITE_CONTROL_IE        0x10
+
+
+static struct uart_port ports[ULITE_NR_UARTS];
+
+static int ulite_receive(struct uart_port *port, int stat)
+{
+        struct tty_struct *tty = port->info->tty;
+        unsigned char ch = 0;
+        char flag = TTY_NORMAL;
+
+        if ((stat & (ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
+                     | ULITE_STATUS_FRAME)) == 0)
+                return 0;
+
+        /* stats */
+        if (stat & ULITE_STATUS_RXVALID) {
+                port->icount.rx++;
+                ch = readb(port->membase + ULITE_RX);
+
+                if (stat & ULITE_STATUS_PARITY)
+                        port->icount.parity++;
+        }
+
+        if (stat & ULITE_STATUS_OVERRUN)
+                port->icount.overrun++;
+
+        if (stat & ULITE_STATUS_FRAME)
+                port->icount.frame++;
+
+
+        /* drop byte with parity error if IGNPAR specificed */
+        if (stat & port->ignore_status_mask & ULITE_STATUS_PARITY)
+                stat &= ~ULITE_STATUS_RXVALID;
+
+        stat &= port->read_status_mask;
+
+        if (stat & ULITE_STATUS_PARITY)
+                flag = TTY_PARITY;
+
+
+        stat &= ~port->ignore_status_mask;
+
+        if (stat & ULITE_STATUS_RXVALID)
+                tty_insert_flip_char(tty, ch, flag);
+
+        if (stat & ULITE_STATUS_FRAME)
+                tty_insert_flip_char(tty, 0, TTY_FRAME);
+
+        if (stat & ULITE_STATUS_OVERRUN)
+                tty_insert_flip_char(tty, 0, TTY_OVERRUN);
+
+        return 1;
+}
+
+static int ulite_transmit(struct uart_port *port, int stat)
+{
+        struct circ_buf *xmit  = &port->info->xmit;
+
+        if (stat & ULITE_STATUS_TXFULL)
+                return 0;
+
+        if (port->x_char) {
+                writeb(port->x_char, port->membase + ULITE_TX);
+                port->x_char = 0;
+                port->icount.tx++;
+                return 1;
+        }
+
+        if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+                return 0;
+
+        writeb(xmit->buf[xmit->tail], port->membase + ULITE_TX);
+        xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
+        port->icount.tx++;
+
+        /* wake up */
+        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+                uart_write_wakeup(port);
+
+        return 1;
+}
+
+static irqreturn_t ulite_isr(int irq, void *dev_id)
+{
+        struct uart_port *port = (struct uart_port *)dev_id;
+        int busy;
+
+        do {
+                int stat = readb(port->membase + ULITE_STATUS);
+                busy  = ulite_receive(port, stat);
+                busy |= ulite_transmit(port, stat);
+        } while (busy);
+
+        tty_flip_buffer_push(port->info->tty);
+
+        return IRQ_HANDLED;
+}
+
+static unsigned int ulite_tx_empty(struct uart_port *port)
+{
+        unsigned long flags;
+        unsigned int ret;
+
+        spin_lock_irqsave(&port->lock, flags);
+        ret = readb(port->membase + ULITE_STATUS);
+        spin_unlock_irqrestore(&port->lock, flags);
+
+        return ret & ULITE_STATUS_TXEMPTY ? TIOCSER_TEMT : 0;
+}
+
+static unsigned int ulite_get_mctrl(struct uart_port *port)
+{
+        return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
+}
+
+static void ulite_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+        /* N/A */
+}
+
+static void ulite_stop_tx(struct uart_port *port)
+{
+        /* N/A */
+}
+
+static void ulite_start_tx(struct uart_port *port)
+{
+        ulite_transmit(port, readb(port->membase + ULITE_STATUS));
+}
+
+static void ulite_stop_rx(struct uart_port *port)
+{
+        /* don't forward any more data (like !CREAD) */
+        port->ignore_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
+                | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
+}
+
+static void ulite_enable_ms(struct uart_port *port)
+{
+        /* N/A */
+}
+
+static void ulite_break_ctl(struct uart_port *port, int ctl)
+{
+        /* N/A */
+}
+
+static int ulite_startup(struct uart_port *port)
+{
+        int ret;
+
+        ret = request_irq(port->irq, ulite_isr,
+                          IRQF_DISABLED | IRQF_SAMPLE_RANDOM, "uartlite", port);
+        if (ret)
+                return ret;
+
+        writeb(ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX,
+               port->membase + ULITE_CONTROL);
+        writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
+
+        return 0;
+}
+
+static void ulite_shutdown(struct uart_port *port)
+{
+        writeb(0, port->membase + ULITE_CONTROL);
+        readb(port->membase + ULITE_CONTROL); /* dummy */
+        free_irq(port->irq, port);
+}
+
+static void ulite_set_termios(struct uart_port *port, struct termios *termios,
+                              struct termios *old)
+{
+        unsigned long flags;
+        unsigned int baud;
+
+        spin_lock_irqsave(&port->lock, flags);
+
+        port->read_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
+                | ULITE_STATUS_TXFULL;
+
+        if (termios->c_iflag & INPCK)
+                port->read_status_mask |=
+                        ULITE_STATUS_PARITY | ULITE_STATUS_FRAME;
+
+        port->ignore_status_mask = 0;
+        if (termios->c_iflag & IGNPAR)
+                port->ignore_status_mask |= ULITE_STATUS_PARITY
+                        | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
+
+        /* ignore all characters if CREAD is not set */
+        if ((termios->c_cflag & CREAD) == 0)
+                port->ignore_status_mask |=
+                        ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
+                        | ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
+
+        /* update timeout */
+        baud = uart_get_baud_rate(port, termios, old, 0, 460800);
+        uart_update_timeout(port, termios->c_cflag, baud);
+
+        spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *ulite_type(struct uart_port *port)
+{
+        return port->type == PORT_UARTLITE ? "uartlite" : NULL;
+}
+
+static void ulite_release_port(struct uart_port *port)
+{
+        release_mem_region(port->mapbase, ULITE_REGION);
+        iounmap(port->membase);
+        port->membase = 0;
+}
+
+static int ulite_request_port(struct uart_port *port)
+{
+        if (!request_mem_region(port->mapbase, ULITE_REGION, "uartlite")) {
+                dev_err(port->dev, "Memory region busy\n");
+                return -EBUSY;
+        }
+
+        port->membase = ioremap(port->mapbase, ULITE_REGION);
+        if (!port->membase) {
+                dev_err(port->dev, "Unable to map registers\n");
+                release_mem_region(port->mapbase, ULITE_REGION);
+                return -EBUSY;
+        }
+
+        return 0;
+}
+
+static void ulite_config_port(struct uart_port *port, int flags)
+{
+        ulite_request_port(port);
+        port->type = PORT_UARTLITE;
+}
+
+static int ulite_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 ulite_ops = {
+        .tx_empty       = ulite_tx_empty,
+        .set_mctrl      = ulite_set_mctrl,
+        .get_mctrl      = ulite_get_mctrl,
+        .stop_tx        = ulite_stop_tx,
+        .start_tx       = ulite_start_tx,
+        .stop_rx        = ulite_stop_rx,
+        .enable_ms      = ulite_enable_ms,
+        .break_ctl      = ulite_break_ctl,
+        .startup        = ulite_startup,
+        .shutdown       = ulite_shutdown,
+        .set_termios    = ulite_set_termios,
+        .type           = ulite_type,
+        .release_port   = ulite_release_port,
+        .request_port   = ulite_request_port,
+        .config_port    = ulite_config_port,
+        .verify_port    = ulite_verify_port
+};
+
+#ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
+static void ulite_console_wait_tx(struct uart_port *port)
+{
+        int i;
+
+        /* wait up to 10ms for the character(s) to be sent */
+        for (i = 0; i < 10000; i++) {
+                if (readb(port->membase + ULITE_STATUS) & ULITE_STATUS_TXEMPTY)
+                        break;
+                udelay(1);
+        }
+}
+
+static void ulite_console_putchar(struct uart_port *port, int ch)
+{
+        ulite_console_wait_tx(port);
+        writeb(ch, port->membase + ULITE_TX);
+}
+
+static void ulite_console_write(struct console *co, const char *s,
+                                unsigned int count)
+{
+        struct uart_port *port = &ports[co->index];
+        unsigned long flags;
+        unsigned int ier;
+        int locked = 1;
+
+        if (oops_in_progress) {
+                locked = spin_trylock_irqsave(&port->lock, flags);
+        } else
+                spin_lock_irqsave(&port->lock, flags);
+
+        /* save and disable interrupt */
+        ier = readb(port->membase + ULITE_STATUS) & ULITE_STATUS_IE;
+        writeb(0, port->membase + ULITE_CONTROL);
+
+        uart_console_write(port, s, count, ulite_console_putchar);
+
+        ulite_console_wait_tx(port);
+
+        /* restore interrupt state */
+        if (ier)
+                writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);
+
+        if (locked)
+                spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static int __init ulite_console_setup(struct console *co, char *options)
+{
+        struct uart_port *port;
+        int baud = 9600;
+        int bits = 8;
+        int parity = 'n';
+        int flow = 'n';
+
+        if (co->index < 0 || co->index >= ULITE_NR_UARTS)
+                return -EINVAL;
+
+        port = &ports[co->index];
+
+        /* not initialized yet? */
+        if (!port->membase)
+                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 ulite_uart_driver;
+
+static struct console ulite_console = {
+        .name   = "ttyUL",
+        .write  = ulite_console_write,
+        .device = uart_console_device,
+        .setup  = ulite_console_setup,
+        .flags  = CON_PRINTBUFFER,
+        .index  = -1, /* Specified on the cmdline (e.g. console=ttyUL0 ) */
+        .data   = &ulite_uart_driver,
+};
+
+static int __init ulite_console_init(void)
+{
+        register_console(&ulite_console);
+        return 0;
+}
+
+console_initcall(ulite_console_init);
+
+#endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
+
+static struct uart_driver ulite_uart_driver = {
+        .owner          = THIS_MODULE,
+        .driver_name    = "uartlite",
+        .dev_name       = "ttyUL",
+        .major          = ULITE_MAJOR,
+        .minor          = ULITE_MINOR,
+        .nr             = ULITE_NR_UARTS,
+#ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
+        .cons           = &ulite_console,
+#endif
+};
+
+static int __devinit ulite_probe(struct platform_device *pdev)
+{
+        struct resource *res, *res2;
+        struct uart_port *port;
+
+        if (pdev->id < 0 || pdev->id >= ULITE_NR_UARTS)
+                return -EINVAL;
+
+        if (ports[pdev->id].membase)
+                return -EBUSY;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (!res)
+                return -ENODEV;
+
+        res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+        if (!res2)
+                return -ENODEV;
+
+        port = &ports[pdev->id];
+
+        port->fifosize  = 16;
+        port->regshift  = 2;
+        port->iotype    = UPIO_MEM;
+        port->iobase    = 1; /* mark port in use */
+        port->mapbase   = res->start;
+        port->membase   = 0;
+        port->ops       = &ulite_ops;
+        port->irq       = res2->start;
+        port->flags     = UPF_BOOT_AUTOCONF;
+        port->dev       = &pdev->dev;
+        port->type      = PORT_UNKNOWN;
+        port->line      = pdev->id;
+
+        uart_add_one_port(&ulite_uart_driver, port);
+        platform_set_drvdata(pdev, port);
+
+        return 0;
+}
+
+static int ulite_remove(struct platform_device *pdev)
+{
+        struct uart_port *port = platform_get_drvdata(pdev);
+
+        platform_set_drvdata(pdev, NULL);
+
+        if (port)
+                uart_remove_one_port(&ulite_uart_driver, port);
+
+        /* mark port as free */
+        port->membase = 0;
+
+        return 0;
+}
+
+static struct platform_driver ulite_platform_driver = {
+        .probe  = ulite_probe,
+        .remove = ulite_remove,
+        .driver = {
+                   .owner = THIS_MODULE,
+                   .name  = "uartlite",
+                   },
+};
+
+int __init ulite_init(void)
+{
+        int ret;
+
+        ret = uart_register_driver(&ulite_uart_driver);
+        if (ret)
+                return ret;
+
+        ret = platform_driver_register(&ulite_platform_driver);
+        if (ret)
+                uart_unregister_driver(&ulite_uart_driver);
+
+        return ret;
+}
+
+void __exit ulite_exit(void)
+{
+        platform_driver_unregister(&ulite_platform_driver);
+        uart_unregister_driver(&ulite_uart_driver);
+}
+
+module_init(ulite_init);
+module_exit(ulite_exit);
+
+MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
+MODULE_DESCRIPTION("Xilinx uartlite serial driver");
+MODULE_LICENSE("GPL");