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staging: speakup: add send_xchar, tiocmset and input functionality for tty
This patch adds further TTY-based functionality, specifically implementation of send_xchar and tiocmset methods, and input. send_xchar and tiocmset methods simply delegate to corresponding TTY operations. For input, it implements the receive_buf2 callback in tty_ldisc_ops of speakup's ldisc. If a synth defines read_buff_add method then receive_buf2 simply delegates to that and returns. For spk_ttyio_in, the data is passed from receive_buf2 thread to spk_ttyio_in thread through spk_ldisc_data structure. It has following members: - char buf: represents data received - struct semaphore sem: used to signal to spk_ttyio_in thread that data is available to be read without having to busy wait - bool buf_free: this is used in comination with mb() calls to syncronise the two threads over buf receive_buf2 only writes to buf if buf_free is true. The check for buf_free and writing to buf are separated by mb() to ensure that spk_ttyio_in has read buf before receive_buf2 writes to it. After writing, it ups the semaphore to signal to spk_ttyio_in that there is now data to read. spk_ttyio_in waits for data to read by downing the semaphore. Thus when signalled by receive_buf2 thread above, it reads from buf and sets buf_free to true. These two operations are separated by mb() to ensure that receive_buf2 thread finds buf_free to be true only after buf has been read. After that spk_ttyio_in calls tty_schedule_flip for subsequent data to come in through receive_buf2. Signed-off-by: Okash Khawaja <okash.khawaja@gmail.com> Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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bd697e2996
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6b9ad1c742
3 changed files with 111 additions and 1 deletions
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@ -8,6 +8,8 @@
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#endif
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#include <linux/serial_core.h>
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#include "spk_priv.h"
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/*
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* this is cut&paste from 8250.h. Get rid of the structure, the definitions
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* and this whole broken driver.
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@ -21,7 +23,7 @@ struct old_serial_port {
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};
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/* countdown values for serial timeouts in us */
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#define SPK_SERIAL_TIMEOUT 100000
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#define SPK_SERIAL_TIMEOUT SPK_SYNTH_TIMEOUT
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/* countdown values transmitter/dsr timeouts in us */
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#define SPK_XMITR_TIMEOUT 100000
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/* countdown values cts timeouts in us */
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@ -39,6 +39,7 @@
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#endif
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#define KT_SPKUP 15
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#define SPK_SYNTH_TIMEOUT 100000 /* in micro-seconds */
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const struct old_serial_port *spk_serial_init(int index);
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void spk_stop_serial_interrupt(void);
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@ -1,36 +1,97 @@
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#include <linux/types.h>
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#include <linux/tty.h>
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#include <linux/tty_flip.h>
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#include <linux/slab.h>
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#include "speakup.h"
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#include "spk_types.h"
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#include "spk_priv.h"
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struct spk_ldisc_data {
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char buf;
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struct semaphore sem;
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bool buf_free;
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};
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static struct spk_synth *spk_ttyio_synth;
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static struct tty_struct *speakup_tty;
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static int spk_ttyio_ldisc_open(struct tty_struct *tty)
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{
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struct spk_ldisc_data *ldisc_data;
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if (tty->ops->write == NULL)
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return -EOPNOTSUPP;
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speakup_tty = tty;
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ldisc_data = kmalloc(sizeof(struct spk_ldisc_data), GFP_KERNEL);
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if (!ldisc_data) {
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pr_err("speakup: Failed to allocate ldisc_data.\n");
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return -ENOMEM;
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}
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sema_init(&ldisc_data->sem, 0);
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ldisc_data->buf_free = true;
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speakup_tty->disc_data = ldisc_data;
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return 0;
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}
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static void spk_ttyio_ldisc_close(struct tty_struct *tty)
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{
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kfree(speakup_tty->disc_data);
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speakup_tty = NULL;
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}
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static int spk_ttyio_receive_buf2(struct tty_struct *tty,
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const unsigned char *cp, char *fp, int count)
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{
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struct spk_ldisc_data *ldisc_data = tty->disc_data;
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if (spk_ttyio_synth->read_buff_add) {
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int i;
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for (i = 0; i < count; i++)
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spk_ttyio_synth->read_buff_add(cp[i]);
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return count;
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}
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if (!ldisc_data->buf_free)
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/* ttyio_in will tty_schedule_flip */
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return 0;
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/* Make sure the consumer has read buf before we have seen
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* buf_free == true and overwrite buf */
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mb();
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ldisc_data->buf = cp[0];
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ldisc_data->buf_free = false;
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up(&ldisc_data->sem);
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return 1;
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}
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static struct tty_ldisc_ops spk_ttyio_ldisc_ops = {
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.owner = THIS_MODULE,
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.magic = TTY_LDISC_MAGIC,
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.name = "speakup_ldisc",
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.open = spk_ttyio_ldisc_open,
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.close = spk_ttyio_ldisc_close,
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.receive_buf2 = spk_ttyio_receive_buf2,
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};
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static int spk_ttyio_out(struct spk_synth *in_synth, const char ch);
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static void spk_ttyio_send_xchar(char ch);
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static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear);
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static unsigned char spk_ttyio_in(void);
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static unsigned char spk_ttyio_in_nowait(void);
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struct spk_io_ops spk_ttyio_ops = {
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.synth_out = spk_ttyio_out,
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.send_xchar = spk_ttyio_send_xchar,
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.tiocmset = spk_ttyio_tiocmset,
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.synth_in = spk_ttyio_in,
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.synth_in_nowait = spk_ttyio_in_nowait,
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};
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EXPORT_SYMBOL_GPL(spk_ttyio_ops);
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@ -95,6 +156,51 @@ static int spk_ttyio_out(struct spk_synth *in_synth, const char ch)
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return 0;
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}
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static void spk_ttyio_send_xchar(char ch)
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{
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speakup_tty->ops->send_xchar(speakup_tty, ch);
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}
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static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear)
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{
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speakup_tty->ops->tiocmset(speakup_tty, set, clear);
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}
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static unsigned char ttyio_in(int timeout)
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{
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struct spk_ldisc_data *ldisc_data = speakup_tty->disc_data;
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char rv;
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if (down_timeout(&ldisc_data->sem, usecs_to_jiffies(timeout)) == -ETIME) {
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if (timeout)
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pr_warn("spk_ttyio: timeout (%d) while waiting for input\n",
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timeout);
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return 0xff;
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}
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rv = ldisc_data->buf;
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/* Make sure we have read buf before we set buf_free to let
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* the producer overwrite it */
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mb();
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ldisc_data->buf_free = true;
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/* Let TTY push more characters */
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tty_schedule_flip(speakup_tty->port);
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return rv;
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}
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static unsigned char spk_ttyio_in(void)
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{
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return ttyio_in(SPK_SYNTH_TIMEOUT);
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}
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static unsigned char spk_ttyio_in_nowait(void)
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{
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char rv = ttyio_in(0);
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return (rv == 0xff) ? 0 : rv;
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}
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int spk_ttyio_synth_probe(struct spk_synth *synth)
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{
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int rv = spk_ttyio_initialise_ldisc(synth->ser);
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@ -103,6 +209,7 @@ int spk_ttyio_synth_probe(struct spk_synth *synth)
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return rv;
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synth->alive = 1;
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spk_ttyio_synth = synth;
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return 0;
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}
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