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tty_port: Add port client functions
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Introduce a client (upward direction) operations struct for tty_port
clients. Initially supported operations are for receiving data and write
wake-up. This will allow for having clients other than an ldisc.

Convert the calls to the ldisc to use the client ops as the default
operations.

Signed-off-by: Rob Herring <[email protected]>
Reviewed-By: Sebastian Reichel <[email protected]>
Tested-By: Sebastian Reichel <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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robherring authored and gregkh committed Feb 3, 2017
1 parent a380ed4 commit c3485ee
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Showing 3 changed files with 51 additions and 21 deletions.
17 changes: 3 additions & 14 deletions drivers/tty/tty_buffer.c
Original file line number Diff line number Diff line change
Expand Up @@ -437,15 +437,15 @@ int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p,
EXPORT_SYMBOL_GPL(tty_ldisc_receive_buf);

static int
receive_buf(struct tty_ldisc *ld, struct tty_buffer *head, int count)
receive_buf(struct tty_port *port, struct tty_buffer *head, int count)
{
unsigned char *p = char_buf_ptr(head, head->read);
char *f = NULL;

if (~head->flags & TTYB_NORMAL)
f = flag_buf_ptr(head, head->read);

return tty_ldisc_receive_buf(ld, p, f, count);
return port->client_ops->receive_buf(port, p, f, count);
}

/**
Expand All @@ -465,16 +465,6 @@ static void flush_to_ldisc(struct work_struct *work)
{
struct tty_port *port = container_of(work, struct tty_port, buf.work);
struct tty_bufhead *buf = &port->buf;
struct tty_struct *tty;
struct tty_ldisc *disc;

tty = READ_ONCE(port->itty);
if (tty == NULL)
return;

disc = tty_ldisc_ref(tty);
if (disc == NULL)
return;

mutex_lock(&buf->lock);

Expand Down Expand Up @@ -504,15 +494,14 @@ static void flush_to_ldisc(struct work_struct *work)
continue;
}

count = receive_buf(disc, head, count);
count = receive_buf(port, head, count);
if (!count)
break;
head->read += count;
}

mutex_unlock(&buf->lock);

tty_ldisc_deref(disc);
}

/**
Expand Down
46 changes: 40 additions & 6 deletions drivers/tty/tty_port.c
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,44 @@
#include <linux/delay.h>
#include <linux/module.h>

static int tty_port_default_receive_buf(struct tty_port *port,
const unsigned char *p,
const unsigned char *f, size_t count)
{
int ret;
struct tty_struct *tty;
struct tty_ldisc *disc;

tty = READ_ONCE(port->itty);
if (!tty)
return 0;

disc = tty_ldisc_ref(tty);
if (!disc)
return 0;

ret = tty_ldisc_receive_buf(disc, p, (char *)f, count);

tty_ldisc_deref(disc);

return ret;
}

static void tty_port_default_wakeup(struct tty_port *port)
{
struct tty_struct *tty = tty_port_tty_get(port);

if (tty) {
tty_wakeup(tty);
tty_kref_put(tty);
}
}

static const struct tty_port_client_operations default_client_ops = {
.receive_buf = tty_port_default_receive_buf,
.write_wakeup = tty_port_default_wakeup,
};

void tty_port_init(struct tty_port *port)
{
memset(port, 0, sizeof(*port));
Expand All @@ -28,6 +66,7 @@ void tty_port_init(struct tty_port *port)
spin_lock_init(&port->lock);
port->close_delay = (50 * HZ) / 100;
port->closing_wait = (3000 * HZ) / 100;
port->client_ops = &default_client_ops;
kref_init(&port->kref);
}
EXPORT_SYMBOL(tty_port_init);
Expand Down Expand Up @@ -272,12 +311,7 @@ EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
*/
void tty_port_tty_wakeup(struct tty_port *port)
{
struct tty_struct *tty = tty_port_tty_get(port);

if (tty) {
tty_wakeup(tty);
tty_kref_put(tty);
}
port->client_ops->write_wakeup(port);
}
EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);

Expand Down
9 changes: 8 additions & 1 deletion include/linux/tty.h
Original file line number Diff line number Diff line change
Expand Up @@ -217,12 +217,18 @@ struct tty_port_operations {
/* Called on the final put of a port */
void (*destruct)(struct tty_port *port);
};


struct tty_port_client_operations {
int (*receive_buf)(struct tty_port *port, const unsigned char *, const unsigned char *, size_t);
void (*write_wakeup)(struct tty_port *port);
};

struct tty_port {
struct tty_bufhead buf; /* Locked internally */
struct tty_struct *tty; /* Back pointer */
struct tty_struct *itty; /* internal back ptr */
const struct tty_port_operations *ops; /* Port operations */
const struct tty_port_client_operations *client_ops; /* Port client operations */
spinlock_t lock; /* Lock protecting tty field */
int blocked_open; /* Waiting to open */
int count; /* Usage count */
Expand All @@ -241,6 +247,7 @@ struct tty_port {
based drain is needed else
set to size of fifo */
struct kref kref; /* Ref counter */
void *client_data;
};

/* tty_port::iflags bits -- use atomic bit ops */
Expand Down

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