tilegx: Add tty serial support for TILE-Gx on-chip UART

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 708 insertions, 0 deletions

diff --git a/drivers/tty/serial/tilegx.c b/drivers/tty/serial/tilegx.c
new file mode 100644
index 00000000000..f92d7e6bd87
--- /dev/null
+++ b/drivers/tty/serial/tilegx.c
@@ -0,0 +1,708 @@
+/*
+ * Copyright 2013 Tilera Corporation. All Rights Reserved.
+ *
+ *   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, version 2.
+ *
+ *   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, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ *
+ * TILEGx UART driver.
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+#include <gxio/common.h>
+#include <gxio/iorpc_globals.h>
+#include <gxio/iorpc_uart.h>
+#include <gxio/kiorpc.h>
+
+#include <hv/drv_uart_intf.h>
+
+/*
+ * Use device name ttyS, major 4, minor 64-65.
+ * This is the usual serial port name, 8250 conventional range.
+ */
+#define TILEGX_UART_MAJOR	TTY_MAJOR
+#define TILEGX_UART_MINOR	64
+#define TILEGX_UART_NAME	"ttyS"
+#define DRIVER_NAME_STRING	"TILEGx_Serial"
+#define TILEGX_UART_REF_CLK	125000000; /* REF_CLK is always 125 MHz. */
+
+struct tile_uart_port {
+	/* UART port. */
+	struct uart_port	uart;
+
+	/* GXIO device context. */
+	gxio_uart_context_t	context;
+
+	/* UART access mutex. */
+	struct mutex		mutex;
+
+	/* CPU receiving interrupts. */
+	int			irq_cpu;
+};
+
+static struct tile_uart_port tile_uart_ports[TILEGX_UART_NR];
+static struct uart_driver tilegx_uart_driver;
+
+
+/*
+ * Read UART rx fifo, and insert the chars into tty buffer.
+ */
+static void receive_chars(struct tile_uart_port *tile_uart,
+			  struct tty_struct *tty)
+{
+	int i;
+	char c;
+	UART_FIFO_COUNT_t count;
+	gxio_uart_context_t *context = &tile_uart->context;
+	struct tty_port *port = tty->port;
+
+	count.word = gxio_uart_read(context, UART_FIFO_COUNT);
+	for (i = 0; i < count.rfifo_count; i++) {
+		c = (char)gxio_uart_read(context, UART_RECEIVE_DATA);
+		tty_insert_flip_char(port, c, TTY_NORMAL);
+	}
+}
+
+
+/*
+ * Drain the Rx FIFO, called by interrupt handler.
+ */
+static void handle_receive(struct tile_uart_port *tile_uart)
+{
+	struct tty_port *port = &tile_uart->uart.state->port;
+	struct tty_struct *tty = tty_port_tty_get(port);
+	gxio_uart_context_t *context = &tile_uart->context;
+
+	if (!tty)
+		return;
+
+	/* First read UART rx fifo. */
+	receive_chars(tile_uart, tty);
+
+	/* Reset RFIFO_WE interrupt. */
+	gxio_uart_write(context, UART_INTERRUPT_STATUS,
+			UART_INTERRUPT_MASK__RFIFO_WE_MASK);
+
+	/* Final read, if any chars comes between the first read and
+	 * the interrupt reset.
+	 */
+	receive_chars(tile_uart, tty);
+
+	spin_unlock(&tile_uart->uart.lock);
+	tty_flip_buffer_push(port);
+	spin_lock(&tile_uart->uart.lock);
+	tty_kref_put(tty);
+}
+
+
+/*
+ * Push one char to UART Write FIFO.
+ * Return 0 on success, -1 if write filo is full.
+ */
+static int tilegx_putchar(gxio_uart_context_t *context, char c)
+{
+	UART_FLAG_t flag;
+	flag.word = gxio_uart_read(context, UART_FLAG);
+	if (flag.wfifo_full)
+		return -1;
+
+	gxio_uart_write(context, UART_TRANSMIT_DATA, (unsigned long)c);
+	return 0;
+}
+
+
+/*
+ * Send chars to UART Write FIFO; called by interrupt handler.
+ */
+static void handle_transmit(struct tile_uart_port *tile_uart)
+{
+	unsigned char ch;
+	struct uart_port *port;
+	struct circ_buf *xmit;
+	gxio_uart_context_t *context = &tile_uart->context;
+
+	/* First reset WFIFO_RE interrupt. */
+	gxio_uart_write(context, UART_INTERRUPT_STATUS,
+			UART_INTERRUPT_MASK__WFIFO_RE_MASK);
+
+	port = &tile_uart->uart;
+	xmit = &port->state->xmit;
+	if (port->x_char) {
+		if (tilegx_putchar(context, port->x_char))
+			return;
+		port->x_char = 0;
+		port->icount.tx++;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+		return;
+
+	while (!uart_circ_empty(xmit)) {
+		ch = xmit->buf[xmit->tail];
+		if (tilegx_putchar(context, ch))
+			break;
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+	}
+
+	/* Reset WFIFO_RE interrupt. */
+	gxio_uart_write(context, UART_INTERRUPT_STATUS,
+			UART_INTERRUPT_MASK__WFIFO_RE_MASK);
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+}
+
+
+/*
+ * UART Interrupt handler.
+ */
+static irqreturn_t tilegx_interrupt(int irq, void *dev_id)
+{
+	unsigned long flags;
+	UART_INTERRUPT_STATUS_t intr_stat;
+	struct tile_uart_port *tile_uart;
+	gxio_uart_context_t *context;
+	struct uart_port *port = dev_id;
+	irqreturn_t ret = IRQ_NONE;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	tile_uart = container_of(port, struct tile_uart_port, uart);
+	context = &tile_uart->context;
+	intr_stat.word = gxio_uart_read(context, UART_INTERRUPT_STATUS);
+
+	if (intr_stat.rfifo_we) {
+		handle_receive(tile_uart);
+		ret = IRQ_HANDLED;
+	}
+	if (intr_stat.wfifo_re) {
+		handle_transmit(tile_uart);
+		ret = IRQ_HANDLED;
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
+	return ret;
+}
+
+
+/*
+ * Return TIOCSER_TEMT when transmitter FIFO is empty.
+ */
+static u_int tilegx_tx_empty(struct uart_port *port)
+{
+	int ret;
+	UART_FLAG_t flag;
+	struct tile_uart_port *tile_uart;
+	gxio_uart_context_t *context;
+
+	tile_uart = container_of(port, struct tile_uart_port, uart);
+	if (!mutex_trylock(&tile_uart->mutex))
+		return 0;
+	context = &tile_uart->context;
+
+	flag.word = gxio_uart_read(context, UART_FLAG);
+	ret = (flag.wfifo_empty) ? TIOCSER_TEMT : 0;
+	mutex_unlock(&tile_uart->mutex);
+
+	return ret;
+}
+
+
+/*
+ * Set state of the modem control output lines.
+ */
+static void tilegx_set_mctrl(struct uart_port *port, u_int mctrl)
+{
+	/* N/A */
+}
+
+
+/*
+ * Get state of the modem control input lines.
+ */
+static u_int tilegx_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
+}
+
+
+/*
+ * Stop transmitting.
+ */
+static void tilegx_stop_tx(struct uart_port *port)
+{
+	/* N/A */
+}
+
+
+/*
+ * Start transmitting.
+ */
+static void tilegx_start_tx(struct uart_port *port)
+{
+	unsigned char ch;
+	struct circ_buf *xmit;
+	struct tile_uart_port *tile_uart;
+	gxio_uart_context_t *context;
+
+	tile_uart = container_of(port, struct tile_uart_port, uart);
+	if (!mutex_trylock(&tile_uart->mutex))
+		return;
+	context = &tile_uart->context;
+	xmit = &port->state->xmit;
+	if (port->x_char) {
+		if (tilegx_putchar(context, port->x_char))
+			return;
+		port->x_char = 0;
+		port->icount.tx++;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
+		mutex_unlock(&tile_uart->mutex);
+		return;
+	}
+
+	while (!uart_circ_empty(xmit)) {
+		ch = xmit->buf[xmit->tail];
+		if (tilegx_putchar(context, ch))
+			break;
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	mutex_unlock(&tile_uart->mutex);
+}
+
+
+/*
+ * Stop receiving - port is in process of being closed.
+ */
+static void tilegx_stop_rx(struct uart_port *port)
+{
+	int err;
+	struct tile_uart_port *tile_uart;
+	gxio_uart_context_t *context;
+	int cpu;
+
+	tile_uart = container_of(port, struct tile_uart_port, uart);
+	if (!mutex_trylock(&tile_uart->mutex))
+		return;
+
+	context = &tile_uart->context;
+	cpu = tile_uart->irq_cpu;
+	err = gxio_uart_cfg_interrupt(context, cpu_x(cpu), cpu_y(cpu),
+				      KERNEL_PL, -1);
+	mutex_unlock(&tile_uart->mutex);
+}
+
+
+/*
+ * Enable modem status interrupts.
+ */
+static void tilegx_enable_ms(struct uart_port *port)
+{
+	/* N/A */
+}
+
+/*
+ * Control the transmission of a break signal.
+ */
+static void tilegx_break_ctl(struct uart_port *port, int break_state)
+{
+	/* N/A */
+}
+
+
+/*
+ * Perform initialization and enable port for reception.
+ */
+static int tilegx_startup(struct uart_port *port)
+{
+	struct tile_uart_port *tile_uart;
+	gxio_uart_context_t *context;
+	int ret = 0;
+	int cpu = raw_smp_processor_id();  /* pick an arbitrary cpu */
+
+	tile_uart = container_of(port, struct tile_uart_port, uart);
+	if (mutex_lock_interruptible(&tile_uart->mutex))
+		return -EBUSY;
+	context = &tile_uart->context;
+
+	/* Now open the hypervisor device if we haven't already. */
+	if (context->fd < 0) {
+		UART_INTERRUPT_MASK_t intr_mask;
+
+		/* Initialize UART device. */
+		ret = gxio_uart_init(context, port->line);
+		if (ret) {
+			ret = -ENXIO;
+			goto err;
+		}
+
+		/* Create our IRQs. */
+		port->irq = create_irq();
+		if (port->irq < 0)
+			goto err_uart_dest;
+		tile_irq_activate(port->irq, TILE_IRQ_PERCPU);
+
+		/* Register our IRQs. */
+		ret = request_irq(port->irq, tilegx_interrupt, 0,
+				  tilegx_uart_driver.driver_name, port);
+		if (ret)
+			goto err_dest_irq;
+
+		/* Request that the hardware start sending us interrupts. */
+		tile_uart->irq_cpu = cpu;
+		ret = gxio_uart_cfg_interrupt(context, cpu_x(cpu), cpu_y(cpu),
+					      KERNEL_PL, port->irq);
+		if (ret)
+			goto err_free_irq;
+
+		/* Enable UART Tx/Rx Interrupt. */
+		intr_mask.word = gxio_uart_read(context, UART_INTERRUPT_MASK);
+		intr_mask.wfifo_re = 0;
+		intr_mask.rfifo_we = 0;
+		gxio_uart_write(context, UART_INTERRUPT_MASK, intr_mask.word);
+
+		/* Reset the Tx/Rx interrupt in case it's set. */
+		gxio_uart_write(context, UART_INTERRUPT_STATUS,
+				UART_INTERRUPT_MASK__WFIFO_RE_MASK |
+				UART_INTERRUPT_MASK__RFIFO_WE_MASK);
+	}
+
+	mutex_unlock(&tile_uart->mutex);
+	return ret;
+
+err_free_irq:
+	free_irq(port->irq, port);
+err_dest_irq:
+	destroy_irq(port->irq);
+err_uart_dest:
+	gxio_uart_destroy(context);
+	ret = -ENXIO;
+err:
+	mutex_unlock(&tile_uart->mutex);
+	return ret;
+}
+
+
+/*
+ * Release kernel resources if it is the last close, disable the port,
+ * free IRQ and close the port.
+ */
+static void tilegx_shutdown(struct uart_port *port)
+{
+	int err;
+	UART_INTERRUPT_MASK_t intr_mask;
+	struct tile_uart_port *tile_uart;
+	gxio_uart_context_t *context;
+	int cpu;
+
+	tile_uart = container_of(port, struct tile_uart_port, uart);
+	if (mutex_lock_interruptible(&tile_uart->mutex))
+		return;
+	context = &tile_uart->context;
+
+	/* Disable UART Tx/Rx Interrupt. */
+	intr_mask.word = gxio_uart_read(context, UART_INTERRUPT_MASK);
+	intr_mask.wfifo_re = 1;
+	intr_mask.rfifo_we = 1;
+	gxio_uart_write(context, UART_INTERRUPT_MASK, intr_mask.word);
+
+	/* Request that the hardware stop sending us interrupts. */
+	cpu = tile_uart->irq_cpu;
+	err = gxio_uart_cfg_interrupt(context, cpu_x(cpu), cpu_y(cpu),
+				      KERNEL_PL, -1);
+
+	if (port->irq > 0) {
+		free_irq(port->irq, port);
+		destroy_irq(port->irq);
+		port->irq = 0;
+	}
+
+	gxio_uart_destroy(context);
+
+	mutex_unlock(&tile_uart->mutex);
+}
+
+
+/*
+ * Flush the buffer.
+ */
+static void tilegx_flush_buffer(struct uart_port *port)
+{
+	/* N/A */
+}
+
+
+/*
+ * Change the port parameters.
+ */
+static void tilegx_set_termios(struct uart_port *port,
+			       struct ktermios *termios, struct ktermios *old)
+{
+	int err;
+	UART_DIVISOR_t divisor;
+	UART_TYPE_t type;
+	unsigned int baud;
+	struct tile_uart_port *tile_uart;
+	gxio_uart_context_t *context;
+
+	tile_uart = container_of(port, struct tile_uart_port, uart);
+	if (!mutex_trylock(&tile_uart->mutex))
+		return;
+	context = &tile_uart->context;
+
+	/* Open the hypervisor device if we haven't already. */
+	if (context->fd < 0) {
+		err = gxio_uart_init(context, port->line);
+		if (err) {
+			mutex_unlock(&tile_uart->mutex);
+			return;
+		}
+	}
+
+	divisor.word = gxio_uart_read(context, UART_DIVISOR);
+	type.word = gxio_uart_read(context, UART_TYPE);
+
+	/* Divisor. */
+	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
+	divisor.divisor = uart_get_divisor(port, baud);
+
+	/* Byte size. */
+	if ((termios->c_cflag & CSIZE) == CS7)
+		type.dbits = UART_TYPE__DBITS_VAL_SEVEN_DBITS;
+	else
+		type.dbits = UART_TYPE__DBITS_VAL_EIGHT_DBITS;
+
+	/* Parity. */
+	if (termios->c_cflag & PARENB) {
+		/* Mark or Space parity. */
+		if (termios->c_cflag & CMSPAR)
+			if (termios->c_cflag & PARODD)
+				type.ptype = UART_TYPE__PTYPE_VAL_MARK;
+			else
+				type.ptype = UART_TYPE__PTYPE_VAL_SPACE;
+		else if (termios->c_cflag & PARODD)
+			type.ptype = UART_TYPE__PTYPE_VAL_ODD;
+		else
+			type.ptype = UART_TYPE__PTYPE_VAL_EVEN;
+	} else
+		type.ptype = UART_TYPE__PTYPE_VAL_NONE;
+
+	/* Stop bits. */
+	if (termios->c_cflag & CSTOPB)
+		type.sbits = UART_TYPE__SBITS_VAL_TWO_SBITS;
+	else
+		type.sbits = UART_TYPE__SBITS_VAL_ONE_SBITS;
+
+	/* Set the uart paramters. */
+	gxio_uart_write(context, UART_DIVISOR, divisor.word);
+	gxio_uart_write(context, UART_TYPE, type.word);
+
+	mutex_unlock(&tile_uart->mutex);
+}
+
+
+/*
+ * Return string describing the specified port.
+ */
+static const char *tilegx_type(struct uart_port *port)
+{
+	return port->type == PORT_TILEGX ? DRIVER_NAME_STRING : NULL;
+}
+
+
+/*
+ * Release the resources being used by 'port'.
+ */
+static void tilegx_release_port(struct uart_port *port)
+{
+	/* Nothing to release. */
+}
+
+
+/*
+ * Request the resources being used by 'port'.
+ */
+static int tilegx_request_port(struct uart_port *port)
+{
+	/* Always present. */
+	return 0;
+}
+
+
+/*
+ * Configure/autoconfigure the port.
+ */
+static void tilegx_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE)
+		port->type = PORT_TILEGX;
+}
+
+
+/*
+ * Verify the new serial_struct (for TIOCSSERIAL).
+ */
+static int tilegx_verify_port(struct uart_port *port,
+			      struct serial_struct *ser)
+{
+	if ((ser->type != PORT_UNKNOWN) && (ser->type != PORT_TILEGX))
+		return -EINVAL;
+
+	return 0;
+}
+
+#ifdef CONFIG_CONSOLE_POLL
+
+/*
+ * Console polling routines for writing and reading from the uart while
+ * in an interrupt or debug context.
+ */
+
+static int tilegx_poll_get_char(struct uart_port *port)
+{
+	UART_FIFO_COUNT_t count;
+	gxio_uart_context_t *context;
+	struct tile_uart_port *tile_uart;
+
+	tile_uart = container_of(port, struct tile_uart_port, uart);
+	context = &tile_uart->context;
+	count.word = gxio_uart_read(context, UART_FIFO_COUNT);
+	if (count.rfifo_count == 0)
+		return NO_POLL_CHAR;
+	return (char)gxio_uart_read(context, UART_RECEIVE_DATA);
+}
+
+static void tilegx_poll_put_char(struct uart_port *port, unsigned char c)
+{
+	gxio_uart_context_t *context;
+	struct tile_uart_port *tile_uart;
+
+	tile_uart = container_of(port, struct tile_uart_port, uart);
+	context = &tile_uart->context;
+	gxio_uart_write(context, UART_TRANSMIT_DATA, (unsigned long)c);
+}
+
+#endif /* CONFIG_CONSOLE_POLL */
+
+
+static const struct uart_ops tilegx_ops = {
+	.tx_empty	= tilegx_tx_empty,
+	.set_mctrl	= tilegx_set_mctrl,
+	.get_mctrl	= tilegx_get_mctrl,
+	.stop_tx	= tilegx_stop_tx,
+	.start_tx	= tilegx_start_tx,
+	.stop_rx	= tilegx_stop_rx,
+	.enable_ms	= tilegx_enable_ms,
+	.break_ctl	= tilegx_break_ctl,
+	.startup	= tilegx_startup,
+	.shutdown	= tilegx_shutdown,
+	.flush_buffer	= tilegx_flush_buffer,
+	.set_termios	= tilegx_set_termios,
+	.type		= tilegx_type,
+	.release_port	= tilegx_release_port,
+	.request_port	= tilegx_request_port,
+	.config_port	= tilegx_config_port,
+	.verify_port	= tilegx_verify_port,
+#ifdef CONFIG_CONSOLE_POLL
+	.poll_get_char	= tilegx_poll_get_char,
+	.poll_put_char	= tilegx_poll_put_char,
+#endif
+};
+
+
+static void tilegx_init_ports(void)
+{
+	int i;
+	struct uart_port *port;
+
+	for (i = 0; i < TILEGX_UART_NR; i++) {
+		port = &tile_uart_ports[i].uart;
+		port->ops = &tilegx_ops;
+		port->line = i;
+		port->type = PORT_TILEGX;
+		port->uartclk = TILEGX_UART_REF_CLK;
+		port->flags = UPF_BOOT_AUTOCONF;
+
+		tile_uart_ports[i].context.fd = -1;
+		mutex_init(&tile_uart_ports[i].mutex);
+	}
+}
+
+
+static struct uart_driver tilegx_uart_driver = {
+	.owner		= THIS_MODULE,
+	.driver_name	= DRIVER_NAME_STRING,
+	.dev_name	= TILEGX_UART_NAME,
+	.major		= TILEGX_UART_MAJOR,
+	.minor		= TILEGX_UART_MINOR,
+	.nr		= TILEGX_UART_NR,
+};
+
+
+static int __init tilegx_init(void)
+{
+	int i;
+	int ret;
+	struct tty_driver *tty_drv;
+
+	ret = uart_register_driver(&tilegx_uart_driver);
+	if (ret)
+		return ret;
+	tty_drv = tilegx_uart_driver.tty_driver;
+	tty_drv->init_termios.c_cflag = B115200 | CS8 | CREAD | HUPCL | CLOCAL;
+	tty_drv->init_termios.c_ispeed = 115200;
+	tty_drv->init_termios.c_ospeed = 115200;
+
+	tilegx_init_ports();
+
+	for (i = 0; i < TILEGX_UART_NR; i++) {
+		struct uart_port *port = &tile_uart_ports[i].uart;
+		ret = uart_add_one_port(&tilegx_uart_driver, port);
+	}
+
+	return 0;
+}
+
+
+static void __exit tilegx_exit(void)
+{
+	int i;
+	struct uart_port *port;
+
+	for (i = 0; i < TILEGX_UART_NR; i++) {
+		port = &tile_uart_ports[i].uart;
+		uart_remove_one_port(&tilegx_uart_driver, port);
+	}
+
+	uart_unregister_driver(&tilegx_uart_driver);
+}
+
+
+module_init(tilegx_init);
+module_exit(tilegx_exit);
+
+MODULE_AUTHOR("Tilera Corporation");
+MODULE_DESCRIPTION("TILEGx serial port driver");
+MODULE_LICENSE("GPL");