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 size_t ttyport_receive_buf(struct tty_port *port, const u8 *cp,
  26                                   const u8 *fp, size_t count)
  27 {
  28         struct serdev_controller *ctrl = port->client_data;
  29         struct serport *serport = serdev_controller_get_drvdata(ctrl);
  30         size_t 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 > count,
  38                                 "receive_buf returns %zu (count = %zu)\n",
  39                                 ret, count);
  40         if (ret > count)
  41                 return count;
  42
  43         return ret;
  44 }
  45
  46 static void ttyport_write_wakeup(struct tty_port *port)
  47 {
  48         struct serdev_controller *ctrl = port->client_data;
  49         struct serport *serport = serdev_controller_get_drvdata(ctrl);
  50         struct tty_struct *tty;
  51
  52         tty = tty_port_tty_get(port);
  53         if (!tty)
  54                 return;
  55
  56         if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) &&
  57             test_bit(SERPORT_ACTIVE, &serport->flags))
  58                 serdev_controller_write_wakeup(ctrl);
  59
  60         /* Wake up any tty_wait_until_sent() */
  61         wake_up_interruptible(&tty->write_wait);
  62
  63         tty_kref_put(tty);
  64 }
  65
  66 static const struct tty_port_client_operations client_ops = {
  67         .receive_buf = ttyport_receive_buf,
  68         .write_wakeup = ttyport_write_wakeup,
  69 };
  70
  71 /*
  72  * Callback functions from the serdev core.
  73  */
  74
  75 static ssize_t ttyport_write_buf(struct serdev_controller *ctrl, const u8 *data, size_t len)
  76 {
  77         struct serport *serport = serdev_controller_get_drvdata(ctrl);
  78         struct tty_struct *tty = serport->tty;
  79
  80         if (!test_bit(SERPORT_ACTIVE, &serport->flags))
  81                 return 0;
  82
  83         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
  84         return tty->ops->write(serport->tty, data, len);
  85 }
  86
  87 static void ttyport_write_flush(struct serdev_controller *ctrl)
  88 {
  89         struct serport *serport = serdev_controller_get_drvdata(ctrl);
  90         struct tty_struct *tty = serport->tty;
  91
  92         tty_driver_flush_buffer(tty);
  93 }
  94
  95 static int ttyport_write_room(struct serdev_controller *ctrl)
  96 {
  97         struct serport *serport = serdev_controller_get_drvdata(ctrl);
  98         struct tty_struct *tty = serport->tty;
  99
 100         return tty_write_room(tty);
 101 }
 102
 103 static int ttyport_open(struct serdev_controller *ctrl)
 104 {
 105         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 106         struct tty_struct *tty;
 107         struct ktermios ktermios;
 108         int ret;
 109
 110         tty = tty_init_dev(serport->tty_drv, serport->tty_idx);
 111         if (IS_ERR(tty))
 112                 return PTR_ERR(tty);
 113         serport->tty = tty;
 114
 115         if (!tty->ops->open || !tty->ops->close) {
 116                 ret = -ENODEV;
 117                 goto err_unlock;
 118         }
 119
 120         ret = tty->ops->open(serport->tty, NULL);
 121         if (ret)
 122                 goto err_close;
 123
 124         tty_unlock(serport->tty);
 125
 126         /* Bring the UART into a known 8 bits no parity hw fc state */
 127         ktermios = tty->termios;
 128         ktermios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP |
 129                               INLCR | IGNCR | ICRNL | IXON);
 130         ktermios.c_oflag &= ~OPOST;
 131         ktermios.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
 132         ktermios.c_cflag &= ~(CSIZE | PARENB);
 133         ktermios.c_cflag |= CS8;
 134         ktermios.c_cflag |= CRTSCTS;
 135         /* Hangups are not supported so make sure to ignore carrier detect. */
 136         ktermios.c_cflag |= CLOCAL;
 137         tty_set_termios(tty, &ktermios);
 138
 139         set_bit(SERPORT_ACTIVE, &serport->flags);
 140
 141         return 0;
 142
 143 err_close:
 144         tty->ops->close(tty, NULL);
 145 err_unlock:
 146         tty_unlock(tty);
 147         tty_release_struct(tty, serport->tty_idx);
 148
 149         return ret;
 150 }
 151
 152 static void ttyport_close(struct serdev_controller *ctrl)
 153 {
 154         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 155         struct tty_struct *tty = serport->tty;
 156
 157         clear_bit(SERPORT_ACTIVE, &serport->flags);
 158
 159         tty_lock(tty);
 160         if (tty->ops->close)
 161                 tty->ops->close(tty, NULL);
 162         tty_unlock(tty);
 163
 164         tty_release_struct(tty, serport->tty_idx);
 165 }
 166
 167 static unsigned int ttyport_set_baudrate(struct serdev_controller *ctrl, unsigned int speed)
 168 {
 169         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 170         struct tty_struct *tty = serport->tty;
 171         struct ktermios ktermios = tty->termios;
 172
 173         ktermios.c_cflag &= ~CBAUD;
 174         tty_termios_encode_baud_rate(&ktermios, speed, speed);
 175
 176         /* tty_set_termios() return not checked as it is always 0 */
 177         tty_set_termios(tty, &ktermios);
 178         return ktermios.c_ospeed;
 179 }
 180
 181 static void ttyport_set_flow_control(struct serdev_controller *ctrl, bool enable)
 182 {
 183         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 184         struct tty_struct *tty = serport->tty;
 185         struct ktermios ktermios = tty->termios;
 186
 187         if (enable)
 188                 ktermios.c_cflag |= CRTSCTS;
 189         else
 190                 ktermios.c_cflag &= ~CRTSCTS;
 191
 192         tty_set_termios(tty, &ktermios);
 193 }
 194
 195 static int ttyport_set_parity(struct serdev_controller *ctrl,
 196                               enum serdev_parity parity)
 197 {
 198         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 199         struct tty_struct *tty = serport->tty;
 200         struct ktermios ktermios = tty->termios;
 201
 202         ktermios.c_cflag &= ~(PARENB | PARODD | CMSPAR);
 203         if (parity != SERDEV_PARITY_NONE) {
 204                 ktermios.c_cflag |= PARENB;
 205                 if (parity == SERDEV_PARITY_ODD)
 206                         ktermios.c_cflag |= PARODD;
 207         }
 208
 209         tty_set_termios(tty, &ktermios);
 210
 211         if ((tty->termios.c_cflag & (PARENB | PARODD | CMSPAR)) !=
 212             (ktermios.c_cflag & (PARENB | PARODD | CMSPAR)))
 213                 return -EINVAL;
 214
 215         return 0;
 216 }
 217
 218 static void ttyport_wait_until_sent(struct serdev_controller *ctrl, long timeout)
 219 {
 220         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 221         struct tty_struct *tty = serport->tty;
 222
 223         tty_wait_until_sent(tty, timeout);
 224 }
 225
 226 static int ttyport_get_tiocm(struct serdev_controller *ctrl)
 227 {
 228         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 229         struct tty_struct *tty = serport->tty;
 230
 231         if (!tty->ops->tiocmget)
 232                 return -EOPNOTSUPP;
 233
 234         return tty->ops->tiocmget(tty);
 235 }
 236
 237 static int ttyport_set_tiocm(struct serdev_controller *ctrl, unsigned int set, unsigned int clear)
 238 {
 239         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 240         struct tty_struct *tty = serport->tty;
 241
 242         if (!tty->ops->tiocmset)
 243                 return -EOPNOTSUPP;
 244
 245         return tty->ops->tiocmset(tty, set, clear);
 246 }
 247
 248 static int ttyport_break_ctl(struct serdev_controller *ctrl, unsigned int break_state)
 249 {
 250         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 251         struct tty_struct *tty = serport->tty;
 252
 253         if (!tty->ops->break_ctl)
 254                 return -EOPNOTSUPP;
 255
 256         return tty->ops->break_ctl(tty, break_state);
 257 }
 258
 259 static const struct serdev_controller_ops ctrl_ops = {
 260         .write_buf = ttyport_write_buf,
 261         .write_flush = ttyport_write_flush,
 262         .write_room = ttyport_write_room,
 263         .open = ttyport_open,
 264         .close = ttyport_close,
 265         .set_flow_control = ttyport_set_flow_control,
 266         .set_parity = ttyport_set_parity,
 267         .set_baudrate = ttyport_set_baudrate,
 268         .wait_until_sent = ttyport_wait_until_sent,
 269         .get_tiocm = ttyport_get_tiocm,
 270         .set_tiocm = ttyport_set_tiocm,
 271         .break_ctl = ttyport_break_ctl,
 272 };
 273
 274 struct device *serdev_tty_port_register(struct tty_port *port,
 275                                         struct device *host,
 276                                         struct device *parent,
 277                                         struct tty_driver *drv, int idx)
 278 {
 279         struct serdev_controller *ctrl;
 280         struct serport *serport;
 281         int ret;
 282
 283         if (!port || !drv || !parent)
 284                 return ERR_PTR(-ENODEV);
 285
 286         ctrl = serdev_controller_alloc(host, parent, sizeof(struct serport));
 287         if (!ctrl)
 288                 return ERR_PTR(-ENOMEM);
 289         serport = serdev_controller_get_drvdata(ctrl);
 290
 291         serport->port = port;
 292         serport->tty_idx = idx;
 293         serport->tty_drv = drv;
 294
 295         ctrl->ops = &ctrl_ops;
 296
 297         port->client_ops = &client_ops;
 298         port->client_data = ctrl;
 299
 300         ret = serdev_controller_add(ctrl);
 301         if (ret)
 302                 goto err_reset_data;
 303
 304         dev_info(&ctrl->dev, "tty port %s%d registered\n", drv->name, idx);
 305         return &ctrl->dev;
 306
 307 err_reset_data:
 308         port->client_data = NULL;
 309         port->client_ops = &tty_port_default_client_ops;
 310         serdev_controller_put(ctrl);
 311
 312         return ERR_PTR(ret);
 313 }
 314
 315 int serdev_tty_port_unregister(struct tty_port *port)
 316 {
 317         struct serdev_controller *ctrl = port->client_data;
 318         struct serport *serport = serdev_controller_get_drvdata(ctrl);
 319
 320         if (!serport)
 321                 return -ENODEV;
 322
 323         serdev_controller_remove(ctrl);
 324         port->client_data = NULL;
 325         port->client_ops = &tty_port_default_client_ops;
 326         serdev_controller_put(ctrl);
 327
 328         return 0;
 329 }