Subject: [PATCH] Add support for the nwp serial device

From: Arnd Bergmann <[email-masked]>
Date: Thu, 20 Nov 2008 15:01:23 +0100

From: Benjamin Krill <[email-masked]>

This patch adds support for the nwp serial device which is connected to
a DCR bus. It uses the of_serial device driver to determine necessary
properties from the device tree. The supported device is added as serial
port number 84.

Signed-off-by: Benjamin Krill <[email-masked]>
Signed-off-by: Arnd Bergmann <[email-masked]>
---

Since the serial drivers are still orphaned, should we merge this through
the powerpc tree?

---
 drivers/serial/Kconfig      |   11 +-
 drivers/serial/Makefile     |    1 +
 drivers/serial/nwpserial.c  |  443 +++++++++++++++++++++++++++++++++++++++++++
 drivers/serial/of_serial.c  |   18 ++
 include/linux/nwpserial.h   |   18 ++
 include/linux/serial_core.h |    3 +
 6 files changed, 493 insertions(+), 1 deletions(-)
 create mode 100644 drivers/serial/nwpserial.c
 create mode 100644 include/linux/nwpserial.h

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 579d63a..45dcc8d 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -1297,13 +1297,22 @@ config SERIAL_NETX_CONSOLE
 config SERIAL_OF_PLATFORM
 	tristate "Serial port on Open Firmware platform bus"
 	depends on PPC_OF
-	depends on SERIAL_8250
+	depends on SERIAL_8250 || SERIAL_OF_PLATFORM_NWPSERIAL
 	help
 	  If you have a PowerPC based system that has serial ports
 	  on a platform specific bus, you should enable this option.
 	  Currently, only 8250 compatible ports are supported, but
 	  others can easily be added.
 
+config SERIAL_OF_PLATFORM_NWPSERIAL
+	tristate "NWP serial port driver"
+	depends on PPC_OF && PPC_DCR
+	select SERIAL_OF_PLATFORM
+	select SERIAL_CORE_CONSOLE
+	select SERIAL_CORE
+	help
+	  This driver supports the nwp serial port.
+
 config SERIAL_QE
 	tristate "Freescale QUICC Engine serial port support"
 	depends on QUICC_ENGINE
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 0c17c8d..05da19d 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -70,6 +70,7 @@ obj-$(CONFIG_SERIAL_ATMEL) += atmel_serial.o
 obj-$(CONFIG_SERIAL_UARTLITE) += uartlite.o
 obj-$(CONFIG_SERIAL_NETX) += netx-serial.o
 obj-$(CONFIG_SERIAL_OF_PLATFORM) += of_serial.o
+obj-$(CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL) += nwpserial.o
 obj-$(CONFIG_SERIAL_KS8695) += serial_ks8695.o
 obj-$(CONFIG_KGDB_SERIAL_CONSOLE) += kgdboc.o
 obj-$(CONFIG_SERIAL_QE) += ucc_uart.o
diff --git a/drivers/serial/nwpserial.c b/drivers/serial/nwpserial.c
new file mode 100644
index 0000000..5f2ecab
--- /dev/null
+++ b/drivers/serial/nwpserial.c
@@ -0,0 +1,443 @@
+/*
+ *  Serial Port driver for a NWP uart device
+ *
+ *    Copyright (C) 2008 IBM Corp., Benjamin Krill <[email-masked]>
+ *
+ *  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/console.h>
+#include <linux/serial.h>
+#include <linux/serial_reg.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/irqreturn.h>
+#include <linux/mutex.h>
+#include <linux/of_platform.h>
+#include <linux/of_device.h>
+#include <linux/nwpserial.h>
+#include <asm/prom.h>
+#include <asm/dcr.h>
+
+#define NWPSERIAL_NR               2
+
+#define NWPSERIAL_STATUS_RXVALID 0x1
+#define NWPSERIAL_STATUS_TXFULL  0x2
+
+struct nwpserial_port {
+	struct uart_port port;
+	dcr_host_t dcr_host;
+	unsigned int ier;
+	unsigned int mcr;
+};
+
+static DEFINE_MUTEX(nwpserial_mutex);
+static struct nwpserial_port nwpserial_ports[NWPSERIAL_NR];
+
+static void nwpserial_console_putchar(struct uart_port *port, int c)
+{
+	struct nwpserial_port *up = container_of(port, struct nwpserial_port, port);
+	/* check if tx buffer is full */
+	while ((dcr_read(up->dcr_host, UART_LSR) & UART_LSR_THRE) == 0)
+		cpu_relax();
+	dcr_write(up->dcr_host, UART_TX, c);
+	up->port.icount.tx++;
+}
+
+static void
+nwpserial_console_write(struct console *co, const char *s, unsigned int count)
+{
+	struct nwpserial_port *up = &nwpserial_ports[co->index];
+	unsigned long flags;
+	int locked = 1;
+
+	if (oops_in_progress)
+		locked = spin_trylock_irqsave(&up->port.lock, flags);
+	else
+		spin_lock_irqsave(&up->port.lock, flags);
+
+	/* save and disable interrupt */
+	up->ier = dcr_read(up->dcr_host, UART_IER);
+	dcr_write(up->dcr_host, UART_IER, up->ier & ~UART_IER_RDI);
+
+	uart_console_write(&up->port, s, count, nwpserial_console_putchar);
+
+	/* wait for transmitter to become emtpy */
+	while ((dcr_read(up->dcr_host, UART_LSR) & UART_LSR_THRE) == 0)
+		cpu_relax();
+
+	/* restore interrupt state */
+	dcr_write(up->dcr_host, UART_IER, up->ier);
+
+	if (locked)
+		spin_unlock_irqrestore(&up->port.lock, flags);
+}
+
+static struct uart_driver nwpserial_reg;
+static struct console nwpserial_console = {
+	.name		= "ttySQ",
+	.write		= nwpserial_console_write,
+	.device		= uart_console_device,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &nwpserial_reg,
+};
+
+/*******************************************************************************/
+
+static int nwpserial_request_port(struct uart_port *port)
+{
+	return 0;
+}
+
+static void nwpserial_release_port(struct uart_port *port)
+{
+	/* N/A */
+}
+
+static void nwpserial_config_port(struct uart_port *port, int flags)
+{
+	port->type = PORT_NWPSERIAL;
+}
+
+static irqreturn_t nwpserial_interrupt(int irq, void *dev_id)
+{
+	struct nwpserial_port *up = dev_id;//container_of(dev_id, struct nwpserial_port, port);
+	struct tty_struct *tty = up->port.info->port.tty;
+	irqreturn_t ret;
+	unsigned int iir;
+	unsigned char ch;
+
+	spin_lock(&up->port.lock);
+
+	/* check if the uart was the interrupt source. */
+	iir = dcr_read(up->dcr_host, UART_IIR);
+	if (!iir) {
+		ret = IRQ_NONE;
+		goto out;
+	}
+
+	do {
+		up->port.icount.rx++;
+		ch = dcr_read(up->dcr_host, UART_RX);
+		if (up->port.ignore_status_mask != NWPSERIAL_STATUS_RXVALID)
+			tty_insert_flip_char(tty, ch, TTY_NORMAL);
+	} while (dcr_read(up->dcr_host, UART_RX) & UART_LSR_DR);
+
+	tty_flip_buffer_push(tty);
+	ret = IRQ_HANDLED;
+
+out:
+	spin_unlock(&up->port.lock);
+	return ret;
+}
+
+static int nwpserial_startup(struct uart_port *port)
+{
+	struct nwpserial_port *up = container_of(port, struct nwpserial_port, port);
+	int err;
+
+	/* disable flow control by default */
+	up->mcr = dcr_read(up->dcr_host, UART_MCR) & ~UART_MCR_AFE;
+	dcr_write(up->dcr_host, UART_MCR, up->mcr);
+
+	/* register interrupt handler */
+	err = request_irq(up->port.irq, nwpserial_interrupt,
+	                        IRQF_SHARED, "nwpserial", up);
+	if (err) {
+		free_irq(up->port.irq, port);
+		return err;
+	}
+
+	/* enable interrupts */
+	up->ier = UART_IER_RDI;
+	dcr_write(up->dcr_host, UART_IER, up->ier);
+
+	/* enable receiving */
+	up->port.ignore_status_mask &= ~NWPSERIAL_STATUS_RXVALID;
+
+	return 0;
+}
+
+static void nwpserial_shutdown(struct uart_port *port)
+{
+	struct nwpserial_port *up = container_of(port, struct nwpserial_port, port);
+
+	/* disable receiving */
+	up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;
+
+	/* disable interrupts from this port */
+	up->ier = 0;
+	dcr_write(up->dcr_host, UART_IER, up->ier);
+
+	/* free irq */
+	free_irq(up->port.irq, port);
+}
+
+static int nwpserial_verify_port(struct uart_port *port, struct serial_struct *ser)
+{
+	return -EINVAL;
+}
+
+static const char *nwpserial_type(struct uart_port *port)
+{
+	return port->type == PORT_NWPSERIAL ? "nwpserial" : NULL;
+}
+
+static void nwpserial_set_termios(struct uart_port *port, struct ktermios *termios,
+                                struct ktermios *old)
+{
+	struct nwpserial_port *up = container_of(port, struct nwpserial_port, port);
+
+	up->port.read_status_mask = NWPSERIAL_STATUS_RXVALID | NWPSERIAL_STATUS_TXFULL;
+
+	up->port.ignore_status_mask = 0;
+	/* ignore all characters if CREAD is not set */
+	if ((termios->c_cflag & CREAD) == 0)
+		up->port.ignore_status_mask |= NWPSERIAL_STATUS_RXVALID;
+}
+
+static void nwpserial_break_ctl(struct uart_port *port, int ctl)
+{
+	/* N/A */
+}
+
+static void nwpserial_enable_ms(struct uart_port *port)
+{
+	/* N/A */
+}
+
+static void nwpserial_stop_rx(struct uart_port *port)
+{
+	struct nwpserial_port *up = container_of(port, struct nwpserial_port, port);
+	/* don't forward any more data (like !CREAD) */
+	up->port.ignore_status_mask = NWPSERIAL_STATUS_RXVALID;
+}
+
+static void nwpserial_putchar(struct nwpserial_port *up, unsigned char c)
+{
+	/* check if tx buffer is full */
+	while ((dcr_read(up->dcr_host, UART_LSR) & UART_LSR_THRE) == 0)
+		cpu_relax();
+	dcr_write(up->dcr_host, UART_TX, c);
+	up->port.icount.tx++;
+}
+
+static void nwpserial_start_tx(struct uart_port *port)
+{
+	struct nwpserial_port *up = container_of(port, struct nwpserial_port, port);
+	struct circ_buf *xmit  = &up->port.info->xmit;
+
+	if (port->x_char) {
+		nwpserial_putchar(up, up->port.x_char);
+		port->x_char = 0;
+	}
+
+	while (!(uart_circ_empty(xmit) || uart_tx_stopped(&up->port))) {
+		nwpserial_putchar(up, xmit->buf[xmit->tail]);
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
+	}
+}
+
+static unsigned int nwpserial_get_mctrl(struct uart_port *port)
+{
+	return 0;
+}
+
+static void nwpserial_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	/* N/A */
+}
+
+static void nwpserial_stop_tx(struct uart_port *port)
+{
+	/* N/A */
+}
+
+static unsigned int nwpserial_tx_empty(struct uart_port *port)
+{
+	struct nwpserial_port *up = container_of(port, struct nwpserial_port, port);
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&up->port.lock, flags);
+	ret = dcr_read(up->dcr_host, UART_LSR);
+	spin_unlock_irqrestore(&up->port.lock, flags);
+
+	return ret & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
+}
+
+static struct uart_ops nwpserial_pops = {
+	.tx_empty     = nwpserial_tx_empty,
+	.set_mctrl    = nwpserial_set_mctrl,
+	.get_mctrl    = nwpserial_get_mctrl,
+	.stop_tx      = nwpserial_stop_tx,
+	.start_tx     = nwpserial_start_tx,
+	.stop_rx      = nwpserial_stop_rx,
+	.enable_ms    = nwpserial_enable_ms,
+	.break_ctl    = nwpserial_break_ctl,
+	.startup      = nwpserial_startup,
+	.shutdown     = nwpserial_shutdown,
+	.set_termios  = nwpserial_set_termios,
+	.type         = nwpserial_type,
+	.release_port = nwpserial_release_port,
+	.request_port = nwpserial_request_port,
+	.config_port  = nwpserial_config_port,
+	.verify_port  = nwpserial_verify_port,
+};
+
+static struct uart_driver nwpserial_reg = {
+	.owner       = THIS_MODULE,
+	.driver_name = "nwpserial",
+	.dev_name    = "ttySQ",
+	.major       = TTY_MAJOR,
+	.minor       = 68,
+	.nr          = NWPSERIAL_NR,
+	.cons        = &nwpserial_console,
+};
+
+int
+nwpserial_register_port(struct uart_port *port)
+{
+	struct nwpserial_port *up = NULL;
+	int ret = -1;
+	int i;
+	static int first = 1;
+	int dcr_len;
+	int dcr_base;
+	struct device_node *dn;
+
+	mutex_lock(&nwpserial_mutex);
+
+	dn = to_of_device(port->dev)->node;
+	if (dn == NULL)
+		goto out;
+
+	/* get dcr base. */
+	dcr_base = dcr_resource_start(dn, 0);
+
+	/* find matching entry */
+	for (i = 0; i < NWPSERIAL_NR; i++)
+		if (nwpserial_ports[i].port.iobase == dcr_base) {
+			up = &nwpserial_ports[i];
+			break;
+		}
+
+	/* we didn't find a mtching entry, search for a free port */
+	if (up == NULL)
+		for (i = 0; i < NWPSERIAL_NR; i++)
+			if (nwpserial_ports[i].port.type == PORT_UNKNOWN &&
+				nwpserial_ports[i].port.iobase == 0) {
+				up = &nwpserial_ports[i];
+				break;
+			}
+
+	if (up == NULL) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	if (first)
+		uart_register_driver(&nwpserial_reg);
+	first = 0;
+
+	up->port.membase      = port->membase;
+	up->port.irq          = port->irq;
+	up->port.uartclk      = port->uartclk;
+	up->port.fifosize     = port->fifosize;
+	up->port.regshift     = port->regshift;
+	up->port.iotype       = port->iotype;
+	up->port.flags        = port->flags;
+	up->port.mapbase      = port->mapbase;
+	up->port.private_data = port->private_data;
+
+	if (port->dev)
+		up->port.dev = port->dev;
+
+	if (up->port.iobase != dcr_base) {
+		up->port.ops          = &nwpserial_pops;
+		up->port.fifosize     = 16;
+
+		spin_lock_init(&up->port.lock);
+
+		up->port.iobase = dcr_base;
+		dcr_len = dcr_resource_len(dn, 0);
+
+		up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
+		if (!DCR_MAP_OK(up->dcr_host)) {
+			printk("Cannot map DCR resources for NWPSERIAL");
+			goto out;
+		}
+	}
+
+	ret = uart_add_one_port(&nwpserial_reg, &up->port);
+	if (ret == 0)
+		ret = up->port.line;
+
+out:
+	mutex_unlock(&nwpserial_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(nwpserial_register_port);
+
+void nwpserial_unregister_port(int line)
+{
+	struct nwpserial_port *up = &nwpserial_ports[line];
+	mutex_lock(&nwpserial_mutex);
+	uart_remove_one_port(&nwpserial_reg, &up->port);
+
+	up->port.type = PORT_UNKNOWN;
+
+	mutex_unlock(&nwpserial_mutex);
+}
+EXPORT_SYMBOL(nwpserial_unregister_port);
+
+static int __init nwpserial_console_init(void)
+{
+	struct nwpserial_port *up = NULL;
+	struct device_node *dn;
+	const char *name;
+	int dcr_base;
+	int dcr_len;
+	int i;
+
+	/* search for a free port */
+	for (i = 0; i < NWPSERIAL_NR; i++)
+		if (nwpserial_ports[i].port.type == PORT_UNKNOWN) {
+			up = &nwpserial_ports[i];
+			break;
+		}
+
+	if (up == NULL)
+		return -1;
+
+	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
+	if (name == NULL)
+		return -1;
+
+	dn = of_find_node_by_path(name);
+	if (!dn)
+		return -1;
+
+	spin_lock_init(&up->port.lock);
+	up->port.ops = &nwpserial_pops;
+	up->port.type = PORT_NWPSERIAL;
+	up->port.fifosize = 16;
+
+	dcr_base = dcr_resource_start(dn, 0);
+	dcr_len = dcr_resource_len(dn, 0);
+	up->port.iobase = dcr_base;
+
+	up->dcr_host = dcr_map(dn, dcr_base, dcr_len);
+	if (!DCR_MAP_OK(up->dcr_host)) {
+		printk("Cannot map DCR resources for SERIAL");
+		return -1;
+	}
+	register_console(&nwpserial_console);
+	return 0;
+}
+console_initcall(nwpserial_console_init);
diff --git a/drivers/serial/of_serial.c b/drivers/serial/of_serial.c
index 8fa0ff5..bb56231 100644
--- a/drivers/serial/of_serial.c
+++ b/drivers/serial/of_serial.c
@@ -14,6 +14,7 @@
 #include <linux/serial_core.h>
 #include <linux/serial_8250.h>
 #include <linux/of_platform.h>
+#include <linux/nwpserial.h>
 
 #include <asm/prom.h>
 
@@ -99,9 +100,16 @@ static int __devinit of_platform_serial_probe(struct of_device *ofdev,
 		goto out;
 
 	switch (port_type) {
+#ifdef CONFIG_SERIAL_8250
 	case PORT_8250 ... PORT_MAX_8250:
 		ret = serial8250_register_port(&port);
 		break;
+#endif
+#ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL
+	case PORT_NWPSERIAL:
+		ret = nwpserial_register_port(&port);
+		break;
+#endif
 	default:
 		/* need to add code for these */
 	case PORT_UNKNOWN:
@@ -129,9 +137,16 @@ static int of_platform_serial_remove(struct of_device *ofdev)
 {
 	struct of_serial_info *info = ofdev->dev.driver_data;
 	switch (info->type) {
+#ifdef CONFIG_SERIAL_8250
 	case PORT_8250 ... PORT_MAX_8250:
 		serial8250_unregister_port(info->line);
 		break;
+#endif
+#ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL
+	case PORT_NWPSERIAL:
+		nwpserial_unregister_port(info->line);
+		break;
+#endif
 	default:
 		/* need to add code for these */
 		break;
@@ -148,6 +163,9 @@ static struct of_device_id __devinitdata of_platform_serial_table[] = {
 	{ .type = "serial", .compatible = "ns16450",  .data = (void *)PORT_16450, },
 	{ .type = "serial", .compatible = "ns16550",  .data = (void *)PORT_16550, },
 	{ .type = "serial", .compatible = "ns16750",  .data = (void *)PORT_16750, },
+#ifdef CONFIG_SERIAL_OF_PLATFORM_NWPSERIAL
+	{ .type = "serial", .compatible = "ibm,qpace-nwpserial",  .data = (void *)PORT_NWPSERIAL, },
+#endif
 	{ .type = "serial",			      .data = (void *)PORT_UNKNOWN, },
 	{ /* end of list */ },
 };
diff --git a/include/linux/nwpserial.h b/include/linux/nwpserial.h
new file mode 100644
index 0000000..9acb215
--- /dev/null
+++ b/include/linux/nwpserial.h
@@ -0,0 +1,18 @@
+/*
+ *  Serial Port driver for a NWP uart device
+ *
+ *    Copyright (C) 2008 IBM Corp., Benjamin Krill <[email-masked]>
+ *
+ *  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.
+ *
+ */
+#ifndef _NWPSERIAL_H
+#define _NWPSERIAL_H
+
+int nwpserial_register_port(struct uart_port *port);
+void nwpserial_unregister_port(int line);
+
+#endif /* _NWPSERIAL_H */
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 4e4f127..4621faf 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -158,6 +158,9 @@
 /* SH-SCI */
 #define PORT_SCIFA	83
 
+/* NWPSERIAL */
+#define PORT_NWPSERIAL	84
+
 #ifdef __KERNEL__
 
 #include <linux/compiler.h>
-- 
1.5.6.5

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