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Date: Sun, 28 Jun 2015 21:46:25 +0200
From: Marek Belisko <marek@...delico.com>
To: jslaby@...e.cz, gregkh@...uxfoundation.org, arnd@...db.de
Cc: peter@...leysoftware.com, mark.rutland@....com,
gnomes@...rguk.ukuu.org.uk, sre@...nel.org, neil@...wn.name,
grant.likely@...aro.org, linux-kernel@...r.kernel.org,
linux-serial@...r.kernel.org, robh+dt@...nel.org,
pawel.moll@....com, hns@...delico.com,
Marek Belisko <marek@...delico.com>
Subject: [PATCH RFC v2 2/3] tty: serial_core: Add hooks for uart slave drivers
From: "H. Nikolaus Schaller" <hns@...delico.com>
1. allow drivers to get notified in mctrl changes
2. allow drivers to get notified on rx data (indicating to the driver that
the connected chip is active)
Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
Signed-off-by: Marek Belisko <marek@...delico.com>
---
drivers/tty/serial/serial_core.c | 102 +++++++++++++++++++++++++++++++++++++--
include/linux/serial_core.h | 11 ++++-
2 files changed, 107 insertions(+), 6 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index ad61441..c8910c4 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -163,6 +163,84 @@ err0:
}
EXPORT_SYMBOL_GPL(devm_serial_get_uart_by_phandle);
+void uart_register_slave(struct uart_port *uport, void *slave)
+{
+ if (!slave) {
+ uart_register_mctrl_notification(uport, NULL);
+ uart_register_rx_notification(uport, NULL, NULL);
+ }
+ uport->slave = slave;
+}
+
+void uart_register_mctrl_notification(struct uart_port *uport, int (*function)(void *slave, int state))
+{
+ uport->mctrl_notification = function;
+}
+
+static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
+ int init_hw);
+
+static void uart_port_shutdown(struct tty_port *port);
+
+void uart_register_rx_notification(struct uart_port *uport, int (*function)(void *slave, unsigned int *c), struct ktermios *termios)
+{
+ struct uart_state *state = uport->state;
+ struct tty_port *tty_port = &state->port;
+
+ if (!uport->slave)
+ return; /* slave must be registered first */
+
+ uport->rx_notification = function;
+
+ if (tty_port->count == 0) {
+ if (function) {
+ int retval = 0;
+
+ uart_change_pm(state, UART_PM_STATE_ON);
+ retval = uport->ops->startup(uport);
+ if (retval == 0 && termios) {
+ int hw_stopped;
+ /*
+ * Initialise the hardware port settings.
+ */
+ uport->ops->set_termios(uport, termios, NULL);
+
+ /*
+ * Set modem status enables based on termios cflag
+ */
+ spin_lock_irq(&uport->lock);
+ if (termios->c_cflag & CRTSCTS)
+ uport->status |= UPSTAT_CTS_ENABLE;
+ else
+ uport->status &= ~UPSTAT_CTS_ENABLE;
+
+ if (termios->c_cflag & CLOCAL)
+ uport->status &= ~UPSTAT_DCD_ENABLE;
+ else
+ uport->status |= UPSTAT_DCD_ENABLE;
+
+ /* reset sw-assisted CTS flow control based on (possibly) new mode */
+ hw_stopped = uport->hw_stopped;
+ uport->hw_stopped = uart_softcts_mode(uport) &&
+ !(uport->ops->get_mctrl(uport) & TIOCM_CTS);
+ if (uport->hw_stopped) {
+ if (!hw_stopped)
+ uport->ops->stop_tx(uport);
+ } else {
+ if (hw_stopped)
+ uport->ops->start_tx(uport);
+ }
+ spin_unlock_irq(&uport->lock);
+ }
+ } else
+ uart_port_shutdown(tty_port);
+ }
+}
+
+EXPORT_SYMBOL_GPL(uart_register_slave);
+EXPORT_SYMBOL_GPL(uart_register_mctrl_notification);
+EXPORT_SYMBOL_GPL(uart_register_rx_notification);
+
/*
* This routine is used by the interrupt handler to schedule processing in
* the software interrupt portion of the driver.
@@ -220,6 +298,10 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
port->mctrl = (old & ~clear) | set;
if (old != port->mctrl)
port->ops->set_mctrl(port, port->mctrl);
+
+ if (port->mctrl_notification)
+ (*port->mctrl_notification)(port->slave, port->mctrl);
+
spin_unlock_irqrestore(&port->lock, flags);
}
@@ -259,7 +341,8 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
uart_circ_clear(&state->xmit);
}
- retval = uport->ops->startup(uport);
+ if (!state->uart_port->rx_notification)
+ retval = uport->ops->startup(uport);
if (retval == 0) {
if (uart_console(uport) && uport->cons->cflag) {
tty->termios.c_cflag = uport->cons->cflag;
@@ -295,7 +378,7 @@ static int uart_startup(struct tty_struct *tty, struct uart_state *state,
int init_hw)
{
struct tty_port *port = &state->port;
- int retval;
+ int retval = 0;
if (port->flags & ASYNC_INITIALIZED)
return 0;
@@ -341,8 +424,12 @@ static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
if (!tty || (tty->termios.c_cflag & HUPCL))
uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
-
- uart_port_shutdown(port);
+ /*
+ * if we have a slave that has registered for rx_notifications
+ * we do not shut down the uart port to be able to monitor the device
+ */
+ if (!uport->rx_notification)
+ uart_port_shutdown(port);
}
/*
@@ -1489,8 +1576,9 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
/*
* At this point, we stop accepting input. To do this, we
* disable the receive line status interrupts.
+ * Unless a slave driver wants to keep input running
*/
- if (port->flags & ASYNC_INITIALIZED) {
+ if (!uport->rx_notification && (port->flags & ASYNC_INITIALIZED)) {
unsigned long flags;
spin_lock_irqsave(&uport->lock, flags);
uport->ops->stop_rx(uport);
@@ -3018,6 +3106,10 @@ void uart_insert_char(struct uart_port *port, unsigned int status,
{
struct tty_port *tport = &port->state->port;
+ if (port->rx_notification)
+ if ((*port->rx_notification)(port->slave, &ch))
+ return; /* slave told us to ignore character */
+
if ((status & port->ignore_status_mask & ~overrun) == 0)
if (tty_insert_flip_char(tport, ch, flag) == 0)
++port->icount.buf_overrun;
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index ba23718..77029781 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -35,7 +35,7 @@
#define uart_console(port) \
((port)->cons && (port)->cons->index == (port)->line)
#else
-#define uart_console(port) ({ (void)port; 0; })
+#define uart_console(port) (0)
#endif
struct uart_port;
@@ -247,7 +247,11 @@ struct uart_port {
const struct attribute_group **tty_groups; /* all attributes (serial core use only) */
struct serial_rs485 rs485;
void *private_data; /* generic platform data pointer */
+ /* UART slave support */
struct list_head head; /* list of uarts e.g. to look up by phandle */
+ void *slave; /* optional slave (there can be only one) */
+ int (*mctrl_notification)(void *slave, int state);
+ int (*rx_notification)(void *slave, unsigned int *c);
};
static inline int serial_port_in(struct uart_port *up, int offset)
@@ -485,4 +489,9 @@ static inline int uart_handle_break(struct uart_port *port)
*/
extern struct uart_port *devm_serial_get_uart_by_phandle(struct device *dev,
const char *phandle, u8 index);
+/* register to receive notifications */
+extern void uart_register_slave(struct uart_port *uart, void *slave);
+extern void uart_register_mctrl_notification(struct uart_port *uart, int (*function)(void *slave, int state));
+extern void uart_register_rx_notification(struct uart_port *uart, int (*function)(void *slave, unsigned int *c), struct ktermios *termios);
+
#endif /* LINUX_SERIAL_CORE_H */
--
1.9.1
--
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