kernel/drivers/tty/serial/msm_smd_tty.c

   1 /*
   2  * Copyright (C) 2007 Google, Inc.
   3  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
   4  * Author: Brian Swetland <swetland@google.com>
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/fs.h>
  19 #include <linux/cdev.h>
  20 #include <linux/device.h>
  21 #include <linux/wait.h>
  22
  23 #include <linux/tty.h>
  24 #include <linux/tty_driver.h>
  25 #include <linux/tty_flip.h>
  26
  27 #include <mach/msm_smd.h>
  28
  29 #define MAX_SMD_TTYS 32
  30
  31 struct smd_tty_info {
  32         struct tty_port port;
  33         smd_channel_t *ch;
  34 };
  35
  36 struct smd_tty_channel_desc {
  37         int id;
  38         const char *name;
  39 };
  40
  41 static struct smd_tty_info smd_tty[MAX_SMD_TTYS];
  42
  43 static const struct smd_tty_channel_desc smd_default_tty_channels[] = {
  44         { .id = 0, .name = "SMD_DS" },
  45         { .id = 27, .name = "SMD_GPSNMEA" },
  46 };
  47
  48 static const struct smd_tty_channel_desc *smd_tty_channels =
  49                 smd_default_tty_channels;
  50 static int smd_tty_channels_len = ARRAY_SIZE(smd_default_tty_channels);
  51
  52 static void smd_tty_notify(void *priv, unsigned event)
  53 {
  54         unsigned char *ptr;
  55         int avail;
  56         struct smd_tty_info *info = priv;
  57         struct tty_struct *tty;
  58
  59         if (event != SMD_EVENT_DATA)
  60                 return;
  61
  62         tty = tty_port_tty_get(&info->port);
  63         if (!tty)
  64                 return;
  65
  66         for (;;) {
  67                 if (test_bit(TTY_THROTTLED, &tty->flags))
  68                         break;
  69                 avail = smd_read_avail(info->ch);
  70                 if (avail == 0)
  71                         break;
  72
  73                 avail = tty_prepare_flip_string(&info->port, &ptr, avail);
  74
  75                 if (smd_read(info->ch, ptr, avail) != avail) {
  76                         /* shouldn't be possible since we're in interrupt
  77                         ** context here and nobody else could 'steal' our
  78                         ** characters.
  79                         */
  80                         pr_err("OOPS - smd_tty_buffer mismatch?!");
  81                 }
  82
  83                 tty_flip_buffer_push(&info->port);
  84         }
  85
  86         /* XXX only when writable and necessary */
  87         tty_wakeup(tty);
  88         tty_kref_put(tty);
  89 }
  90
  91 static int smd_tty_port_activate(struct tty_port *tport, struct tty_struct *tty)
  92 {
  93         struct smd_tty_info *info = container_of(tport, struct smd_tty_info,
  94                         port);
  95         int i, res = 0;
  96         const char *name = NULL;
  97
  98         for (i = 0; i < smd_tty_channels_len; i++) {
  99                 if (smd_tty_channels[i].id == tty->index) {
 100                         name = smd_tty_channels[i].name;
 101                         break;
 102                 }
 103         }
 104         if (!name)
 105                 return -ENODEV;
 106
 107         if (info->ch)
 108                 smd_kick(info->ch);
 109         else
 110                 res = smd_open(name, &info->ch, info, smd_tty_notify);
 111
 112         if (!res)
 113                 tty->driver_data = info;
 114
 115         return res;
 116 }
 117
 118 static void smd_tty_port_shutdown(struct tty_port *tport)
 119 {
 120         struct smd_tty_info *info = container_of(tport, struct smd_tty_info,
 121                         port);
 122
 123         if (info->ch) {
 124                 smd_close(info->ch);
 125                 info->ch = 0;
 126         }
 127 }
 128
 129 static int smd_tty_open(struct tty_struct *tty, struct file *f)
 130 {
 131         struct smd_tty_info *info = smd_tty + tty->index;
 132
 133         return tty_port_open(&info->port, tty, f);
 134 }
 135
 136 static void smd_tty_close(struct tty_struct *tty, struct file *f)
 137 {
 138         struct smd_tty_info *info = tty->driver_data;
 139
 140         tty_port_close(&info->port, tty, f);
 141 }
 142
 143 static int smd_tty_write(struct tty_struct *tty,
 144                          const unsigned char *buf, int len)
 145 {
 146         struct smd_tty_info *info = tty->driver_data;
 147         int avail;
 148
 149         /* if we're writing to a packet channel we will
 150         ** never be able to write more data than there
 151         ** is currently space for
 152         */
 153         avail = smd_write_avail(info->ch);
 154         if (len > avail)
 155                 len = avail;
 156
 157         return smd_write(info->ch, buf, len);
 158 }
 159
 160 static int smd_tty_write_room(struct tty_struct *tty)
 161 {
 162         struct smd_tty_info *info = tty->driver_data;
 163         return smd_write_avail(info->ch);
 164 }
 165
 166 static int smd_tty_chars_in_buffer(struct tty_struct *tty)
 167 {
 168         struct smd_tty_info *info = tty->driver_data;
 169         return smd_read_avail(info->ch);
 170 }
 171
 172 static void smd_tty_unthrottle(struct tty_struct *tty)
 173 {
 174         struct smd_tty_info *info = tty->driver_data;
 175         smd_kick(info->ch);
 176 }
 177
 178 static const struct tty_port_operations smd_tty_port_ops = {
 179         .shutdown = smd_tty_port_shutdown,
 180         .activate = smd_tty_port_activate,
 181 };
 182
 183 static const struct tty_operations smd_tty_ops = {
 184         .open = smd_tty_open,
 185         .close = smd_tty_close,
 186         .write = smd_tty_write,
 187         .write_room = smd_tty_write_room,
 188         .chars_in_buffer = smd_tty_chars_in_buffer,
 189         .unthrottle = smd_tty_unthrottle,
 190 };
 191
 192 static struct tty_driver *smd_tty_driver;
 193
 194 static int __init smd_tty_init(void)
 195 {
 196         int ret, i;
 197
 198         smd_tty_driver = alloc_tty_driver(MAX_SMD_TTYS);
 199         if (smd_tty_driver == 0)
 200                 return -ENOMEM;
 201
 202         smd_tty_driver->driver_name = "smd_tty_driver";
 203         smd_tty_driver->name = "smd";
 204         smd_tty_driver->major = 0;
 205         smd_tty_driver->minor_start = 0;
 206         smd_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
 207         smd_tty_driver->subtype = SERIAL_TYPE_NORMAL;
 208         smd_tty_driver->init_termios = tty_std_termios;
 209         smd_tty_driver->init_termios.c_iflag = 0;
 210         smd_tty_driver->init_termios.c_oflag = 0;
 211         smd_tty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 212         smd_tty_driver->init_termios.c_lflag = 0;
 213         smd_tty_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 214                 TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 215         tty_set_operations(smd_tty_driver, &smd_tty_ops);
 216
 217         ret = tty_register_driver(smd_tty_driver);
 218         if (ret)
 219                 return ret;
 220
 221         for (i = 0; i < smd_tty_channels_len; i++) {
 222                 struct tty_port *port = &smd_tty[smd_tty_channels[i].id].port;
 223                 tty_port_init(port);
 224                 port->ops = &smd_tty_port_ops;
 225                 tty_port_register_device(port, smd_tty_driver,
 226                                 smd_tty_channels[i].id, NULL);
 227         }
 228
 229         return 0;
 230 }
 231
 232 module_init(smd_tty_init);