diff options
Diffstat (limited to 'drivers/accessibility/speakup/spk_ttyio.c')
| -rw-r--r-- | drivers/accessibility/speakup/spk_ttyio.c | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/drivers/accessibility/speakup/spk_ttyio.c b/drivers/accessibility/speakup/spk_ttyio.c new file mode 100644 index 000000000000..9b95f77f9265 --- /dev/null +++ b/drivers/accessibility/speakup/spk_ttyio.c @@ -0,0 +1,384 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/types.h> +#include <linux/tty.h> +#include <linux/tty_flip.h> +#include <linux/slab.h> + +#include "speakup.h" +#include "spk_types.h" +#include "spk_priv.h" + +struct spk_ldisc_data { + char buf; + struct completion completion; + bool buf_free; +}; + +static struct spk_synth *spk_ttyio_synth; +static struct tty_struct *speakup_tty; +/* mutex to protect against speakup_tty disappearing from underneath us while + * we are using it. this can happen when the device physically unplugged, + * while in use. it also serialises access to speakup_tty. + */ +static DEFINE_MUTEX(speakup_tty_mutex); + +static int ser_to_dev(int ser, dev_t *dev_no) +{ + if (ser < 0 || ser > (255 - 64)) { + pr_err("speakup: Invalid ser param. Must be between 0 and 191 inclusive.\n"); + return -EINVAL; + } + + *dev_no = MKDEV(4, (64 + ser)); + return 0; +} + +static int get_dev_to_use(struct spk_synth *synth, dev_t *dev_no) +{ + /* use ser only when dev is not specified */ + if (strcmp(synth->dev_name, SYNTH_DEFAULT_DEV) || + synth->ser == SYNTH_DEFAULT_SER) + return tty_dev_name_to_number(synth->dev_name, dev_no); + + return ser_to_dev(synth->ser, dev_no); +} + +static int spk_ttyio_ldisc_open(struct tty_struct *tty) +{ + struct spk_ldisc_data *ldisc_data; + + if (!tty->ops->write) + return -EOPNOTSUPP; + speakup_tty = tty; + + ldisc_data = kmalloc(sizeof(*ldisc_data), GFP_KERNEL); + if (!ldisc_data) + return -ENOMEM; + + init_completion(&ldisc_data->completion); + ldisc_data->buf_free = true; + speakup_tty->disc_data = ldisc_data; + + return 0; +} + +static void spk_ttyio_ldisc_close(struct tty_struct *tty) +{ + mutex_lock(&speakup_tty_mutex); + kfree(speakup_tty->disc_data); + speakup_tty = NULL; + mutex_unlock(&speakup_tty_mutex); +} + +static int spk_ttyio_receive_buf2(struct tty_struct *tty, + const unsigned char *cp, char *fp, int count) +{ + struct spk_ldisc_data *ldisc_data = tty->disc_data; + + if (spk_ttyio_synth->read_buff_add) { + int i; + + for (i = 0; i < count; i++) + spk_ttyio_synth->read_buff_add(cp[i]); + + return count; + } + + if (!ldisc_data->buf_free) + /* ttyio_in will tty_schedule_flip */ + return 0; + + /* Make sure the consumer has read buf before we have seen + * buf_free == true and overwrite buf + */ + mb(); + + ldisc_data->buf = cp[0]; + ldisc_data->buf_free = false; + complete(&ldisc_data->completion); + + return 1; +} + +static struct tty_ldisc_ops spk_ttyio_ldisc_ops = { + .owner = THIS_MODULE, + .magic = TTY_LDISC_MAGIC, + .name = "speakup_ldisc", + .open = spk_ttyio_ldisc_open, + .close = spk_ttyio_ldisc_close, + .receive_buf2 = spk_ttyio_receive_buf2, +}; + +static int spk_ttyio_out(struct spk_synth *in_synth, const char ch); +static int spk_ttyio_out_unicode(struct spk_synth *in_synth, u16 ch); +static void spk_ttyio_send_xchar(char ch); +static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear); +static unsigned char spk_ttyio_in(void); +static unsigned char spk_ttyio_in_nowait(void); +static void spk_ttyio_flush_buffer(void); + +struct spk_io_ops spk_ttyio_ops = { + .synth_out = spk_ttyio_out, + .synth_out_unicode = spk_ttyio_out_unicode, + .send_xchar = spk_ttyio_send_xchar, + .tiocmset = spk_ttyio_tiocmset, + .synth_in = spk_ttyio_in, + .synth_in_nowait = spk_ttyio_in_nowait, + .flush_buffer = spk_ttyio_flush_buffer, +}; +EXPORT_SYMBOL_GPL(spk_ttyio_ops); + +static inline void get_termios(struct tty_struct *tty, + struct ktermios *out_termios) +{ + down_read(&tty->termios_rwsem); + *out_termios = tty->termios; + up_read(&tty->termios_rwsem); +} + +static int spk_ttyio_initialise_ldisc(struct spk_synth *synth) +{ + int ret = 0; + struct tty_struct *tty; + struct ktermios tmp_termios; + dev_t dev; + + ret = get_dev_to_use(synth, &dev); + if (ret) + return ret; + + tty = tty_kopen(dev); + if (IS_ERR(tty)) + return PTR_ERR(tty); + + if (tty->ops->open) + ret = tty->ops->open(tty, NULL); + else + ret = -ENODEV; + + if (ret) { + tty_unlock(tty); + return ret; + } + + clear_bit(TTY_HUPPED, &tty->flags); + /* ensure hardware flow control is enabled */ + get_termios(tty, &tmp_termios); + if (!(tmp_termios.c_cflag & CRTSCTS)) { + tmp_termios.c_cflag |= CRTSCTS; + tty_set_termios(tty, &tmp_termios); + /* + * check c_cflag to see if it's updated as tty_set_termios + * may not return error even when no tty bits are + * changed by the request. + */ + get_termios(tty, &tmp_termios); + if (!(tmp_termios.c_cflag & CRTSCTS)) + pr_warn("speakup: Failed to set hardware flow control\n"); + } + + tty_unlock(tty); + + ret = tty_set_ldisc(tty, N_SPEAKUP); + if (ret) + pr_err("speakup: Failed to set N_SPEAKUP on tty\n"); + + return ret; +} + +void spk_ttyio_register_ldisc(void) +{ + if (tty_register_ldisc(N_SPEAKUP, &spk_ttyio_ldisc_ops)) + pr_warn("speakup: Error registering line discipline. Most synths won't work.\n"); +} + +void spk_ttyio_unregister_ldisc(void) +{ + if (tty_unregister_ldisc(N_SPEAKUP)) + pr_warn("speakup: Couldn't unregister ldisc\n"); +} + +static int spk_ttyio_out(struct spk_synth *in_synth, const char ch) +{ + mutex_lock(&speakup_tty_mutex); + if (in_synth->alive && speakup_tty && speakup_tty->ops->write) { + int ret = speakup_tty->ops->write(speakup_tty, &ch, 1); + + mutex_unlock(&speakup_tty_mutex); + if (ret == 0) + /* No room */ + return 0; + if (ret < 0) { + pr_warn("%s: I/O error, deactivating speakup\n", + in_synth->long_name); + /* No synth any more, so nobody will restart TTYs, + * and we thus need to do it ourselves. Now that there + * is no synth we can let application flood anyway + */ + in_synth->alive = 0; + speakup_start_ttys(); + return 0; + } + return 1; + } + + mutex_unlock(&speakup_tty_mutex); + return 0; +} + +static int spk_ttyio_out_unicode(struct spk_synth *in_synth, u16 ch) +{ + int ret; + + if (ch < 0x80) { + ret = spk_ttyio_out(in_synth, ch); + } else if (ch < 0x800) { + ret = spk_ttyio_out(in_synth, 0xc0 | (ch >> 6)); + ret &= spk_ttyio_out(in_synth, 0x80 | (ch & 0x3f)); + } else { + ret = spk_ttyio_out(in_synth, 0xe0 | (ch >> 12)); + ret &= spk_ttyio_out(in_synth, 0x80 | ((ch >> 6) & 0x3f)); + ret &= spk_ttyio_out(in_synth, 0x80 | (ch & 0x3f)); + } + return ret; +} + +static int check_tty(struct tty_struct *tty) +{ + if (!tty) { + pr_warn("%s: I/O error, deactivating speakup\n", + spk_ttyio_synth->long_name); + /* No synth any more, so nobody will restart TTYs, and we thus + * need to do it ourselves. Now that there is no synth we can + * let application flood anyway + */ + spk_ttyio_synth->alive = 0; + speakup_start_ttys(); + return 1; + } + + return 0; +} + +static void spk_ttyio_send_xchar(char ch) +{ + mutex_lock(&speakup_tty_mutex); + if (check_tty(speakup_tty)) { + mutex_unlock(&speakup_tty_mutex); + return; + } + + if (speakup_tty->ops->send_xchar) + speakup_tty->ops->send_xchar(speakup_tty, ch); + mutex_unlock(&speakup_tty_mutex); +} + +static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear) +{ + mutex_lock(&speakup_tty_mutex); + if (check_tty(speakup_tty)) { + mutex_unlock(&speakup_tty_mutex); + return; + } + + if (speakup_tty->ops->tiocmset) + speakup_tty->ops->tiocmset(speakup_tty, set, clear); + mutex_unlock(&speakup_tty_mutex); +} + +static unsigned char ttyio_in(int timeout) +{ + struct spk_ldisc_data *ldisc_data = speakup_tty->disc_data; + char rv; + + if (wait_for_completion_timeout(&ldisc_data->completion, + usecs_to_jiffies(timeout)) == 0) { + if (timeout) + pr_warn("spk_ttyio: timeout (%d) while waiting for input\n", + timeout); + return 0xff; + } + + rv = ldisc_data->buf; + /* Make sure we have read buf before we set buf_free to let + * the producer overwrite it + */ + mb(); + ldisc_data->buf_free = true; + /* Let TTY push more characters */ + tty_schedule_flip(speakup_tty->port); + + return rv; +} + +static unsigned char spk_ttyio_in(void) +{ + return ttyio_in(SPK_SYNTH_TIMEOUT); +} + +static unsigned char spk_ttyio_in_nowait(void) +{ + u8 rv = ttyio_in(0); + + return (rv == 0xff) ? 0 : rv; +} + +static void spk_ttyio_flush_buffer(void) +{ + mutex_lock(&speakup_tty_mutex); + if (check_tty(speakup_tty)) { + mutex_unlock(&speakup_tty_mutex); + return; + } + + if (speakup_tty->ops->flush_buffer) + speakup_tty->ops->flush_buffer(speakup_tty); + + mutex_unlock(&speakup_tty_mutex); +} + +int spk_ttyio_synth_probe(struct spk_synth *synth) +{ + int rv = spk_ttyio_initialise_ldisc(synth); + + if (rv) + return rv; + + synth->alive = 1; + spk_ttyio_synth = synth; + + return 0; +} +EXPORT_SYMBOL_GPL(spk_ttyio_synth_probe); + +void spk_ttyio_release(void) +{ + if (!speakup_tty) + return; + + tty_lock(speakup_tty); + + if (speakup_tty->ops->close) + speakup_tty->ops->close(speakup_tty, NULL); + + tty_ldisc_flush(speakup_tty); + tty_unlock(speakup_tty); + tty_kclose(speakup_tty); +} +EXPORT_SYMBOL_GPL(spk_ttyio_release); + +const char *spk_ttyio_synth_immediate(struct spk_synth *synth, const char *buff) +{ + u_char ch; + + while ((ch = *buff)) { + if (ch == '\n') + ch = synth->procspeech; + if (tty_write_room(speakup_tty) < 1 || + !synth->io_ops->synth_out(synth, ch)) + return buff; + buff++; + } + return NULL; +} +EXPORT_SYMBOL_GPL(spk_ttyio_synth_immediate); |