tty: Add msm_smd_tty driver

msm_smd_tty driver provides tty device interface
to 'DS' and 'GPSNMEA' streaming SMD ports.

Cc: Brian Swetland <swetland@google.com>
Signed-off-by: Niranjana Vishwanathapura <nvishwan@codeaurora.org>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/tty/serial/Kconfig

@@ -1600,4 +1600,13 @@ config SERIAL_PCH_UART
 	  Output Hub) which is for IVI(In-Vehicle Infotainment) use.
 	  ML7213 is companion chip for Intel Atom E6xx series.
 	  ML7213 is completely compatible for Intel EG20T PCH.
+
+config SERIAL_MSM_SMD
+	bool "Enable tty device interface for some SMD ports"
+	default n
+	depends on MSM_SMD
+	help
+	  Enables userspace clients to read and write to some streaming SMD
+	  ports via tty device interface for MSM chipset.
+
 endmenu

drivers/tty/serial/Makefile

@@ -92,3 +92,4 @@ obj-$(CONFIG_SERIAL_MRST_MAX3110)	+= mrst_max3110.o
 obj-$(CONFIG_SERIAL_MFD_HSU)	+= mfd.o
 obj-$(CONFIG_SERIAL_IFX6X60)  	+= ifx6x60.o
 obj-$(CONFIG_SERIAL_PCH_UART)	+= pch_uart.o
+obj-$(CONFIG_SERIAL_MSM_SMD)	+= msm_smd_tty.o

drivers/tty/serial/msm_smd_tty.c

@@ -0,0 +1,236 @@
+/* drivers/tty/serial/msm_smd_tty.c
+ *
+ * Copyright (C) 2007 Google, Inc.
+ * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
+ * Author: Brian Swetland <swetland@google.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/wait.h>
+
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+
+#include <mach/msm_smd.h>
+
+#define MAX_SMD_TTYS 32
+
+struct smd_tty_info {
+	struct tty_port port;
+	smd_channel_t *ch;
+};
+
+struct smd_tty_channel_desc {
+	int id;
+	const char *name;
+};
+
+static struct smd_tty_info smd_tty[MAX_SMD_TTYS];
+
+static const struct smd_tty_channel_desc smd_default_tty_channels[] = {
+	{ .id = 0, .name = "SMD_DS" },
+	{ .id = 27, .name = "SMD_GPSNMEA" },
+};
+
+static const struct smd_tty_channel_desc *smd_tty_channels =
+		smd_default_tty_channels;
+static int smd_tty_channels_len = ARRAY_SIZE(smd_default_tty_channels);
+
+static void smd_tty_notify(void *priv, unsigned event)
+{
+	unsigned char *ptr;
+	int avail;
+	struct smd_tty_info *info = priv;
+	struct tty_struct *tty;
+
+	if (event != SMD_EVENT_DATA)
+		return;
+
+	tty = tty_port_tty_get(&info->port);
+	if (!tty)
+		return;
+
+	for (;;) {
+		if (test_bit(TTY_THROTTLED, &tty->flags))
+			break;
+		avail = smd_read_avail(info->ch);
+		if (avail == 0)
+			break;
+
+		avail = tty_prepare_flip_string(tty, &ptr, avail);
+
+		if (smd_read(info->ch, ptr, avail) != avail) {
+			/* shouldn't be possible since we're in interrupt
+			** context here and nobody else could 'steal' our
+			** characters.
+			*/
+			pr_err("OOPS - smd_tty_buffer mismatch?!");
+		}
+
+		tty_flip_buffer_push(tty);
+	}
+
+	/* XXX only when writable and necessary */
+	tty_wakeup(tty);
+	tty_kref_put(tty);
+}
+
+static int smd_tty_port_activate(struct tty_port *tport, struct tty_struct *tty)
+{
+	int i, res = 0;
+	int n = tty->index;
+	const char *name = NULL;
+	struct smd_tty_info *info = smd_tty + n;
+
+	for (i = 0; i < smd_tty_channels_len; i++) {
+		if (smd_tty_channels[i].id == n) {
+			name = smd_tty_channels[i].name;
+			break;
+		}
+	}
+	if (!name)
+		return -ENODEV;
+
+	if (info->ch)
+		smd_kick(info->ch);
+	else
+		res = smd_open(name, &info->ch, info, smd_tty_notify);
+
+	if (!res)
+		tty->driver_data = info;
+
+	return res;
+}
+
+static void smd_tty_port_shutdown(struct tty_port *tport)
+{
+	struct smd_tty_info *info;
+	struct tty_struct *tty = tty_port_tty_get(tport);
+
+	info = tty->driver_data;
+	if (info->ch) {
+		smd_close(info->ch);
+		info->ch = 0;
+	}
+
+	tty->driver_data = 0;
+	tty_kref_put(tty);
+}
+
+static int smd_tty_open(struct tty_struct *tty, struct file *f)
+{
+	struct smd_tty_info *info = smd_tty + tty->index;
+
+	return tty_port_open(&info->port, tty, f);
+}
+
+static void smd_tty_close(struct tty_struct *tty, struct file *f)
+{
+	struct smd_tty_info *info = tty->driver_data;
+
+	tty_port_close(&info->port, tty, f);
+}
+
+static int smd_tty_write(struct tty_struct *tty,
+			 const unsigned char *buf, int len)
+{
+	struct smd_tty_info *info = tty->driver_data;
+	int avail;
+
+	/* if we're writing to a packet channel we will
+	** never be able to write more data than there
+	** is currently space for
+	*/
+	avail = smd_write_avail(info->ch);
+	if (len > avail)
+		len = avail;
+
+	return smd_write(info->ch, buf, len);
+}
+
+static int smd_tty_write_room(struct tty_struct *tty)
+{
+	struct smd_tty_info *info = tty->driver_data;
+	return smd_write_avail(info->ch);
+}
+
+static int smd_tty_chars_in_buffer(struct tty_struct *tty)
+{
+	struct smd_tty_info *info = tty->driver_data;
+	return smd_read_avail(info->ch);
+}
+
+static void smd_tty_unthrottle(struct tty_struct *tty)
+{
+	struct smd_tty_info *info = tty->driver_data;
+	smd_kick(info->ch);
+}
+
+static const struct tty_port_operations smd_tty_port_ops = {
+	.shutdown = smd_tty_port_shutdown,
+	.activate = smd_tty_port_activate,
+};
+
+static const struct tty_operations smd_tty_ops = {
+	.open = smd_tty_open,
+	.close = smd_tty_close,
+	.write = smd_tty_write,
+	.write_room = smd_tty_write_room,
+	.chars_in_buffer = smd_tty_chars_in_buffer,
+	.unthrottle = smd_tty_unthrottle,
+};
+
+static struct tty_driver *smd_tty_driver;
+
+static int __init smd_tty_init(void)
+{
+	int ret, i;
+
+	smd_tty_driver = alloc_tty_driver(MAX_SMD_TTYS);
+	if (smd_tty_driver == 0)
+		return -ENOMEM;
+
+	smd_tty_driver->owner = THIS_MODULE;
+	smd_tty_driver->driver_name = "smd_tty_driver";
+	smd_tty_driver->name = "smd";
+	smd_tty_driver->major = 0;
+	smd_tty_driver->minor_start = 0;
+	smd_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
+	smd_tty_driver->subtype = SERIAL_TYPE_NORMAL;
+	smd_tty_driver->init_termios = tty_std_termios;
+	smd_tty_driver->init_termios.c_iflag = 0;
+	smd_tty_driver->init_termios.c_oflag = 0;
+	smd_tty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
+	smd_tty_driver->init_termios.c_lflag = 0;
+	smd_tty_driver->flags = TTY_DRIVER_RESET_TERMIOS |
+		TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
+	tty_set_operations(smd_tty_driver, &smd_tty_ops);
+
+	ret = tty_register_driver(smd_tty_driver);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < smd_tty_channels_len; i++) {
+		tty_port_init(&smd_tty[smd_tty_channels[i].id].port);
+		smd_tty[smd_tty_channels[i].id].port.ops = &smd_tty_port_ops;
+		tty_register_device(smd_tty_driver, smd_tty_channels[i].id, 0);
+	}
+
+	return 0;
+}
+
+module_init(smd_tty_init);