Okash Khawaja, on sam. 29 avril 2017 14:53:18 +0100, wrote:
> 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@xxxxxxxxx>
Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
> Index: linux-staging/drivers/staging/speakup/spk_ttyio.c
> ===================================================================
> --- linux-staging.orig/drivers/staging/speakup/spk_ttyio.c
> +++ linux-staging/drivers/staging/speakup/spk_ttyio.c
> @@ -1,36 +1,97 @@
> #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 semaphore sem;
> + bool buf_free;
> +};
> +
> +static struct spk_synth *spk_ttyio_synth;
> static struct tty_struct *speakup_tty;
>
> static int spk_ttyio_ldisc_open(struct tty_struct *tty)
> {
> + struct spk_ldisc_data *ldisc_data;
> +
> if (tty->ops->write == NULL)
> return -EOPNOTSUPP;
> speakup_tty = tty;
>
> + ldisc_data = kmalloc(sizeof(struct spk_ldisc_data), GFP_KERNEL);
> + if (!ldisc_data) {
> + pr_err("speakup: Failed to allocate ldisc_data.\n");
> + return -ENOMEM;
> + }
> +
> + sema_init(&ldisc_data->sem, 0);
> + ldisc_data->buf_free = true;
> + speakup_tty->disc_data = ldisc_data;
> +
> return 0;
> }
>
> static void spk_ttyio_ldisc_close(struct tty_struct *tty)
> {
> + kfree(speakup_tty->disc_data);
> speakup_tty = NULL;
> }
>
> +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;
> + up(&ldisc_data->sem);
> +
> + 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 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);
> +
> struct spk_io_ops spk_ttyio_ops = {
> .synth_out = spk_ttyio_out,
> + .send_xchar = spk_ttyio_send_xchar,
> + .tiocmset = spk_ttyio_tiocmset,
> + .synth_in = spk_ttyio_in,
> + .synth_in_nowait = spk_ttyio_in_nowait,
> };
> EXPORT_SYMBOL_GPL(spk_ttyio_ops);
>
> @@ -95,6 +156,51 @@
> return 0;
> }
>
> +static void spk_ttyio_send_xchar(char ch)
> +{
> + speakup_tty->ops->send_xchar(speakup_tty, ch);
> +}
> +
> +static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear)
> +{
> + speakup_tty->ops->tiocmset(speakup_tty, set, clear);
> +}
> +
> +static unsigned char ttyio_in(int timeout)
> +{
> + struct spk_ldisc_data *ldisc_data = speakup_tty->disc_data;
> + char rv;
> +
> + if (down_timeout(&ldisc_data->sem, usecs_to_jiffies(timeout)) == -ETIME) {
> + 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)
> +{
> + char rv = ttyio_in(0);
> +
> + return (rv == 0xff) ? 0 : rv;
> +}
> +
> int spk_ttyio_synth_probe(struct spk_synth *synth)
> {
> int rv = spk_ttyio_initialise_ldisc(synth->ser);
> @@ -103,6 +209,7 @@
> return rv;
>
> synth->alive = 1;
> + spk_ttyio_synth = synth;
>
> return 0;
> }
> Index: linux-staging/drivers/staging/speakup/serialio.h
> ===================================================================
> --- linux-staging.orig/drivers/staging/speakup/serialio.h
> +++ linux-staging/drivers/staging/speakup/serialio.h
> @@ -8,6 +8,8 @@
> #endif
> #include <linux/serial_core.h>
>
> +#include "spk_priv.h"
> +
> /*
> * this is cut&paste from 8250.h. Get rid of the structure, the definitions
> * and this whole broken driver.
> @@ -21,7 +23,7 @@
> };
>
> /* countdown values for serial timeouts in us */
> -#define SPK_SERIAL_TIMEOUT 100000
> +#define SPK_SERIAL_TIMEOUT SPK_SYNTH_TIMEOUT
> /* countdown values transmitter/dsr timeouts in us */
> #define SPK_XMITR_TIMEOUT 100000
> /* countdown values cts timeouts in us */
> Index: linux-staging/drivers/staging/speakup/spk_priv.h
> ===================================================================
> --- linux-staging.orig/drivers/staging/speakup/spk_priv.h
> +++ linux-staging/drivers/staging/speakup/spk_priv.h
> @@ -39,6 +39,7 @@
> #endif
>
> #define KT_SPKUP 15
> +#define SPK_SYNTH_TIMEOUT 100000 /* in micro-seconds */
>
> const struct old_serial_port *spk_serial_init(int index);
> void spk_stop_serial_interrupt(void);
>
--
Samuel
<y> t1 faich
<y> les programmes ils segfaultent jamais quand on veut
-+- #ens-mim en plein débogage -+-
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