drivers/tty/serdev/serdev-ttyport.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2016-2017 Linaro Ltd., Rob Herring <robh@kernel.org>
   4  */
   5 #include <linux/kernel.h>
   6 #include <linux/serdev.h>
   7 #include <linux/tty.h>
   8 #include <linux/tty_driver.h>
   9 #include <linux/poll.h>
  10
  11 #define SERPORT_ACTIVE          1
  12
  13 struct serport {
  14         struct tty_port *port;
  15         struct tty_struct *tty;
  16         struct tty_driver *tty_drv;
  17         int tty_idx;
  18         unsigned long flags;
  19 };
  20
  21 /*
  22  * Callback functions from the tty port.
  23  */
  24
  25 static int ttyport_receive_buf(struct tty_port *port, const unsigned char *cp,
  26                                 const unsigned char *fp, size_t count)
  27 {
  28         struct serdev_controller *ctrl = port->client_data;
  29         struct serport *serport = serdev_controller_get_drvdata(ctrl);
  30         int ret;
  31
  32         if (!test_bit(SERPORT_ACTIVE, &serport->flags))
  33                 return 0;
  34
  35         ret = serdev_controller_receive_buf(ctrl, cp, count);
  36
  37         dev_WARN_ONCE(&ctrl->dev, ret < 0 || ret > count,
  38                                 "receive_buf returns %d (count = %zu)\n",
  39                                 ret, count);
  40         if (ret < 0)
  41                 return 0;
  42         else if (ret > count)
  43                 return count;
  44
  45         return ret;
  46 }
  47
  48 static void ttyport_write_wakeup(struct tty_port *port)
  49 {
  50         struct serdev_controller *ctrl = port->client_data;
  51         struct serport *serport = serdev_controller_get_drvdata(ctrl);
  52         struct tty_struct *tty;
  53
  54         tty = tty_port_tty_get(port);
  55         if (!tty)
  56                 return;
  57
  58         if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) &&
  59             test_bit(SERPORT_ACTIVE, &serport->flags))
  60                 serdev_controller_write_wakeup(ctrl);
  61
  62         /* Wake up any tty_wait_until_sent() */
  63         wake_up_interruptible(&tty->write_wait);
  64
  65         tty_kref_put(tty);
  66 }
  67
  68 static const struct tty_port_client_operations client_ops = {
  69         .receive_buf = ttyport_receive_buf,
  70         .write_wakeup = ttyport_write_wakeup,
  71 };
  72
  73 /*
  74  * Callback functions from the serdev core.
  75  */
  76
  77 static int ttyport_write_buf(struct serdev_controller *ctrl, const unsigned char *data, size_t len)
  78 {
  79         struct serport *serport = serdev_controller_get_drvdata(ctrl);
  80         struct tty_struct *tty = serport->tty;
  81
  82         if (!test_bit(SERPORT_ACTIVE, &serport->flags))
  83                 return 0;
  84
  85         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  86         return tty->ops->write(serport->tty, data, len);
  87 }
  88
  89 static void ttyport_write_flush(struct serdev_controller *ctrl)
  90 {
  91         struct serport *serport = serdev_controller_get_drvdata(ctrl);
  92         struct tty_struct *tty = serport->tty;
  93
  94         tty_driver_flush_buffer(tty);
  95 }
  96
  97 static int ttyport_write_room(struct serdev_controller *ctrl)
  98 {
  99         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 100         struct tty_struct *tty = serport->tty;
 101
 102         return tty_write_room(tty);
 103 }
 104
 105 static int ttyport_open(struct serdev_controller *ctrl)
 106 {
 107         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 108         struct tty_struct *tty;
 109         struct ktermios ktermios;
 110         int ret;
 111
 112         tty = tty_init_dev(serport->tty_drv, serport->tty_idx);
 113         if (IS_ERR(tty))
 114                 return PTR_ERR(tty);
 115         serport->tty = tty;
 116
 117         if (!tty->ops->open || !tty->ops->close) {
 118                 ret = -ENODEV;
 119                 goto err_unlock;
 120         }
 121
 122         ret = tty->ops->open(serport->tty, NULL);
 123         if (ret)
 124                 goto err_close;
 125
 126         tty_unlock(serport->tty);
 127
 128         /* Bring the UART into a known 8 bits no parity hw fc state */
 129         ktermios = tty->termios;
 130         ktermios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP |
 131                               INLCR | IGNCR | ICRNL | IXON);
 132         ktermios.c_oflag &= ~OPOST;
 133         ktermios.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
 134         ktermios.c_cflag &= ~(CSIZE | PARENB);
 135         ktermios.c_cflag |= CS8;
 136         ktermios.c_cflag |= CRTSCTS;
 137         /* Hangups are not supported so make sure to ignore carrier detect. */
 138         ktermios.c_cflag |= CLOCAL;
 139         tty_set_termios(tty, &ktermios);
 140
 141         set_bit(SERPORT_ACTIVE, &serport->flags);
 142
 143         return 0;
 144
 145 err_close:
 146         tty->ops->close(tty, NULL);
 147 err_unlock:
 148         tty_unlock(tty);
 149         tty_release_struct(tty, serport->tty_idx);
 150
 151         return ret;
 152 }
 153
 154 static void ttyport_close(struct serdev_controller *ctrl)
 155 {
 156         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 157         struct tty_struct *tty = serport->tty;
 158
 159         clear_bit(SERPORT_ACTIVE, &serport->flags);
 160
 161         tty_lock(tty);
 162         if (tty->ops->close)
 163                 tty->ops->close(tty, NULL);
 164         tty_unlock(tty);
 165
 166         tty_release_struct(tty, serport->tty_idx);
 167 }
 168
 169 static unsigned int ttyport_set_baudrate(struct serdev_controller *ctrl, unsigned int speed)
 170 {
 171         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 172         struct tty_struct *tty = serport->tty;
 173         struct ktermios ktermios = tty->termios;
 174
 175         ktermios.c_cflag &= ~CBAUD;
 176         tty_termios_encode_baud_rate(&ktermios, speed, speed);
 177
 178         /* tty_set_termios() return not checked as it is always 0 */
 179         tty_set_termios(tty, &ktermios);
 180         return ktermios.c_ospeed;
 181 }
 182
 183 static void ttyport_set_flow_control(struct serdev_controller *ctrl, bool enable)
 184 {
 185         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 186         struct tty_struct *tty = serport->tty;
 187         struct ktermios ktermios = tty->termios;
 188
 189         if (enable)
 190                 ktermios.c_cflag |= CRTSCTS;
 191         else
 192                 ktermios.c_cflag &= ~CRTSCTS;
 193
 194         tty_set_termios(tty, &ktermios);
 195 }
 196
 197 static int ttyport_set_parity(struct serdev_controller *ctrl,
 198                               enum serdev_parity parity)
 199 {
 200         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 201         struct tty_struct *tty = serport->tty;
 202         struct ktermios ktermios = tty->termios;
 203
 204         ktermios.c_cflag &= ~(PARENB | PARODD | CMSPAR);
 205         if (parity != SERDEV_PARITY_NONE) {
 206                 ktermios.c_cflag |= PARENB;
 207                 if (parity == SERDEV_PARITY_ODD)
 208                         ktermios.c_cflag |= PARODD;
 209         }
 210
 211         tty_set_termios(tty, &ktermios);
 212
 213         if ((tty->termios.c_cflag & (PARENB | PARODD | CMSPAR)) !=
 214             (ktermios.c_cflag & (PARENB | PARODD | CMSPAR)))
 215                 return -EINVAL;
 216
 217         return 0;
 218 }
 219
 220 static void ttyport_wait_until_sent(struct serdev_controller *ctrl, long timeout)
 221 {
 222         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 223         struct tty_struct *tty = serport->tty;
 224
 225         tty_wait_until_sent(tty, timeout);
 226 }
 227
 228 static int ttyport_get_tiocm(struct serdev_controller *ctrl)
 229 {
 230         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 231         struct tty_struct *tty = serport->tty;
 232
 233         if (!tty->ops->tiocmget)
 234                 return -ENOTSUPP;
 235
 236         return tty->ops->tiocmget(tty);
 237 }
 238
 239 static int ttyport_set_tiocm(struct serdev_controller *ctrl, unsigned int set, unsigned int clear)
 240 {
 241         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 242         struct tty_struct *tty = serport->tty;
 243
 244         if (!tty->ops->tiocmset)
 245                 return -ENOTSUPP;
 246
 247         return tty->ops->tiocmset(tty, set, clear);
 248 }
 249
 250 static const struct serdev_controller_ops ctrl_ops = {
 251         .write_buf = ttyport_write_buf,
 252         .write_flush = ttyport_write_flush,
 253         .write_room = ttyport_write_room,
 254         .open = ttyport_open,
 255         .close = ttyport_close,
 256         .set_flow_control = ttyport_set_flow_control,
 257         .set_parity = ttyport_set_parity,
 258         .set_baudrate = ttyport_set_baudrate,
 259         .wait_until_sent = ttyport_wait_until_sent,
 260         .get_tiocm = ttyport_get_tiocm,
 261         .set_tiocm = ttyport_set_tiocm,
 262 };
 263
 264 struct device *serdev_tty_port_register(struct tty_port *port,
 265                                         struct device *parent,
 266                                         struct tty_driver *drv, int idx)
 267 {
 268         struct serdev_controller *ctrl;
 269         struct serport *serport;
 270         int ret;
 271
 272         if (!port || !drv || !parent)
 273                 return ERR_PTR(-ENODEV);
 274
 275         ctrl = serdev_controller_alloc(parent, sizeof(struct serport));
 276         if (!ctrl)
 277                 return ERR_PTR(-ENOMEM);
 278         serport = serdev_controller_get_drvdata(ctrl);
 279
 280         serport->port = port;
 281         serport->tty_idx = idx;
 282         serport->tty_drv = drv;
 283
 284         ctrl->ops = &ctrl_ops;
 285
 286         port->client_ops = &client_ops;
 287         port->client_data = ctrl;
 288
 289         ret = serdev_controller_add(ctrl);
 290         if (ret)
 291                 goto err_reset_data;
 292
 293         dev_info(&ctrl->dev, "tty port %s%d registered\n", drv->name, idx);
 294         return &ctrl->dev;
 295
 296 err_reset_data:
 297         port->client_data = NULL;
 298         port->client_ops = &tty_port_default_client_ops;
 299         serdev_controller_put(ctrl);
 300
 301         return ERR_PTR(ret);
 302 }
 303
 304 int serdev_tty_port_unregister(struct tty_port *port)
 305 {
 306         struct serdev_controller *ctrl = port->client_data;
 307         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 308
 309         if (!serport)
 310                 return -ENODEV;
 311
 312         serdev_controller_remove(ctrl);
 313         port->client_data = NULL;
 314         port->client_ops = &tty_port_default_client_ops;
 315         serdev_controller_put(ctrl);
 316
 317         return 0;
 318 }