drivers/tty/serial/msm_smd_tty.c

   1 /* drivers/tty/serial/msm_smd_tty.c
   2  *
   3  * Copyright (C) 2007 Google, Inc.
   4  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
   5  * Author: Brian Swetland <swetland@google.com>
   6  *
   7  * This software is licensed under the terms of the GNU General Public
   8  * License version 2, as published by the Free Software Foundation, and
   9  * may be copied, distributed, and modified under those terms.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  */
  17
  18 #include <linux/module.h>
  19 #include <linux/fs.h>
  20 #include <linux/cdev.h>
  21 #include <linux/device.h>
  22 #include <linux/wait.h>
  23
  24 #include <linux/tty.h>
  25 #include <linux/tty_driver.h>
  26 #include <linux/tty_flip.h>
  27
  28 #include <mach/msm_smd.h>
  29
  30 #define MAX_SMD_TTYS 32
  31
  32 struct smd_tty_info {
  33         struct tty_port port;
  34         smd_channel_t *ch;
  35 };
  36
  37 struct smd_tty_channel_desc {
  38         int id;
  39         const char *name;
  40 };
  41
  42 static struct smd_tty_info smd_tty[MAX_SMD_TTYS];
  43
  44 static const struct smd_tty_channel_desc smd_default_tty_channels[] = {
  45         { .id = 0, .name = "SMD_DS" },
  46         { .id = 27, .name = "SMD_GPSNMEA" },
  47 };
  48
  49 static const struct smd_tty_channel_desc *smd_tty_channels =
  50                 smd_default_tty_channels;
  51 static int smd_tty_channels_len = ARRAY_SIZE(smd_default_tty_channels);
  52
  53 static void smd_tty_notify(void *priv, unsigned event)
  54 {
  55         unsigned char *ptr;
  56         int avail;
  57         struct smd_tty_info *info = priv;
  58         struct tty_struct *tty;
  59
  60         if (event != SMD_EVENT_DATA)
  61                 return;
  62
  63         tty = tty_port_tty_get(&info->port);
  64         if (!tty)
  65                 return;
  66
  67         for (;;) {
  68                 if (test_bit(TTY_THROTTLED, &tty->flags))
  69                         break;
  70                 avail = smd_read_avail(info->ch);
  71                 if (avail == 0)
  72                         break;
  73
  74                 avail = tty_prepare_flip_string(tty, &ptr, avail);
  75
  76                 if (smd_read(info->ch, ptr, avail) != avail) {
  77                         /* shouldn't be possible since we're in interrupt
  78                         ** context here and nobody else could 'steal' our
  79                         ** characters.
  80                         */
  81                         pr_err("OOPS - smd_tty_buffer mismatch?!");
  82                 }
  83
  84                 tty_flip_buffer_push(tty);
  85         }
  86
  87         /* XXX only when writable and necessary */
  88         tty_wakeup(tty);
  89         tty_kref_put(tty);
  90 }
  91
  92 static int smd_tty_port_activate(struct tty_port *tport, struct tty_struct *tty)
  93 {
  94         int i, res = 0;
  95         int n = tty->index;
  96         const char *name = NULL;
  97         struct smd_tty_info *info = smd_tty + n;
  98
  99         for (i = 0; i < smd_tty_channels_len; i++) {
 100                 if (smd_tty_channels[i].id == n) {
 101                         name = smd_tty_channels[i].name;
 102                         break;
 103                 }
 104         }
 105         if (!name)
 106                 return -ENODEV;
 107
 108         if (info->ch)
 109                 smd_kick(info->ch);
 110         else
 111                 res = smd_open(name, &info->ch, info, smd_tty_notify);
 112
 113         if (!res)
 114                 tty->driver_data = info;
 115
 116         return res;
 117 }
 118
 119 static void smd_tty_port_shutdown(struct tty_port *tport)
 120 {
 121         struct smd_tty_info *info;
 122         struct tty_struct *tty = tty_port_tty_get(tport);
 123
 124         info = tty->driver_data;
 125         if (info->ch) {
 126                 smd_close(info->ch);
 127                 info->ch = 0;
 128         }
 129
 130         tty->driver_data = 0;
 131         tty_kref_put(tty);
 132 }
 133
 134 static int smd_tty_open(struct tty_struct *tty, struct file *f)
 135 {
 136         struct smd_tty_info *info = smd_tty + tty->index;
 137
 138         return tty_port_open(&info->port, tty, f);
 139 }
 140
 141 static void smd_tty_close(struct tty_struct *tty, struct file *f)
 142 {
 143         struct smd_tty_info *info = tty->driver_data;
 144
 145         tty_port_close(&info->port, tty, f);
 146 }
 147
 148 static int smd_tty_write(struct tty_struct *tty,
 149                          const unsigned char *buf, int len)
 150 {
 151         struct smd_tty_info *info = tty->driver_data;
 152         int avail;
 153
 154         /* if we're writing to a packet channel we will
 155         ** never be able to write more data than there
 156         ** is currently space for
 157         */
 158         avail = smd_write_avail(info->ch);
 159         if (len > avail)
 160                 len = avail;
 161
 162         return smd_write(info->ch, buf, len);
 163 }
 164
 165 static int smd_tty_write_room(struct tty_struct *tty)
 166 {
 167         struct smd_tty_info *info = tty->driver_data;
 168         return smd_write_avail(info->ch);
 169 }
 170
 171 static int smd_tty_chars_in_buffer(struct tty_struct *tty)
 172 {
 173         struct smd_tty_info *info = tty->driver_data;
 174         return smd_read_avail(info->ch);
 175 }
 176
 177 static void smd_tty_unthrottle(struct tty_struct *tty)
 178 {
 179         struct smd_tty_info *info = tty->driver_data;
 180         smd_kick(info->ch);
 181 }
 182
 183 static const struct tty_port_operations smd_tty_port_ops = {
 184         .shutdown = smd_tty_port_shutdown,
 185         .activate = smd_tty_port_activate,
 186 };
 187
 188 static const struct tty_operations smd_tty_ops = {
 189         .open = smd_tty_open,
 190         .close = smd_tty_close,
 191         .write = smd_tty_write,
 192         .write_room = smd_tty_write_room,
 193         .chars_in_buffer = smd_tty_chars_in_buffer,
 194         .unthrottle = smd_tty_unthrottle,
 195 };
 196
 197 static struct tty_driver *smd_tty_driver;
 198
 199 static int __init smd_tty_init(void)
 200 {
 201         int ret, i;
 202
 203         smd_tty_driver = alloc_tty_driver(MAX_SMD_TTYS);
 204         if (smd_tty_driver == 0)
 205                 return -ENOMEM;
 206
 207         smd_tty_driver->owner = THIS_MODULE;
 208         smd_tty_driver->driver_name = "smd_tty_driver";
 209         smd_tty_driver->name = "smd";
 210         smd_tty_driver->major = 0;
 211         smd_tty_driver->minor_start = 0;
 212         smd_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
 213         smd_tty_driver->subtype = SERIAL_TYPE_NORMAL;
 214         smd_tty_driver->init_termios = tty_std_termios;
 215         smd_tty_driver->init_termios.c_iflag = 0;
 216         smd_tty_driver->init_termios.c_oflag = 0;
 217         smd_tty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 218         smd_tty_driver->init_termios.c_lflag = 0;
 219         smd_tty_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 220                 TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 221         tty_set_operations(smd_tty_driver, &smd_tty_ops);
 222
 223         ret = tty_register_driver(smd_tty_driver);
 224         if (ret)
 225                 return ret;
 226
 227         for (i = 0; i < smd_tty_channels_len; i++) {
 228                 tty_port_init(&smd_tty[smd_tty_channels[i].id].port);
 229                 smd_tty[smd_tty_channels[i].id].port.ops = &smd_tty_port_ops;
 230                 tty_register_device(smd_tty_driver, smd_tty_channels[i].id, 0);
 231         }
 232
 233         return 0;
 234 }
 235
 236 module_init(smd_tty_init);