These functions will be used to simply the serdev rust abstraction. It also contributes to the fixing of 2 race conditions in the serdev rust abstraction.
Signed-off-by: Markus Probst markus.probst@posteo.de --- drivers/tty/serdev/core.c | 50 ++++++++++++++++++++++++++++++++++++- drivers/tty/serdev/serdev-ttyport.c | 32 ++++++++++++++++++++++++ include/linux/serdev.h | 6 +++++ 3 files changed, 87 insertions(+), 1 deletion(-)
diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c index 7500efcdfc21..7d24f16710cb 100644 --- a/drivers/tty/serdev/core.c +++ b/drivers/tty/serdev/core.c @@ -187,6 +187,51 @@ void serdev_device_close(struct serdev_device *serdev) } EXPORT_SYMBOL_GPL(serdev_device_close);
+/** + * serdev_device_pause_rx() - pause data receive + * @serdev: serdev device + * + * Pause calls to receive_buf. + * + * The caller must guarantee that this does not run concurrently with + * `serdev_device_open` or `serdev_device_close`. + * + * Note that if a call to receive_buf is currently executed, the function will + * sleep until it has finished. + */ +void serdev_device_pause_rx(struct serdev_device *serdev) +{ + struct serdev_controller *ctrl = serdev->ctrl; + + if (!ctrl || !ctrl->ops->pause_rx) + return; + + ctrl->ops->pause_rx(ctrl); +} +EXPORT_SYMBOL_GPL(serdev_device_pause_rx); + +/** + * serdev_device_resume_rx() - resume data receive + * @serdev: serdev device + * + * Resume calls to receive_buf. + * + * The caller must guarantee that this does not run concurrently with + * `serdev_device_open` or `serdev_device_close`. + * + * This can be called even if not paused to ensure data receive is active. + */ +void serdev_device_resume_rx(struct serdev_device *serdev) +{ + struct serdev_controller *ctrl = serdev->ctrl; + + if (!ctrl || !ctrl->ops->resume_rx) + return; + + ctrl->ops->resume_rx(ctrl); +} +EXPORT_SYMBOL_GPL(serdev_device_resume_rx); + static void devm_serdev_device_close(void *serdev) { serdev_device_close(serdev); @@ -398,6 +443,7 @@ EXPORT_SYMBOL_GPL(serdev_device_break_ctl); static int serdev_drv_probe(struct device *dev) { const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver); + struct serdev_device *sdev = to_serdev_device(dev); int ret;
ret = dev_pm_domain_attach(dev, PD_FLAG_ATTACH_POWER_ON | @@ -405,7 +451,9 @@ static int serdev_drv_probe(struct device *dev) if (ret) return ret;
- return sdrv->probe(to_serdev_device(dev)); + serdev_device_resume_rx(sdev); + + return sdrv->probe(sdev); }
static void serdev_drv_remove(struct device *dev) diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c index bab1b143b8a6..85ab454c2f13 100644 --- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -6,9 +6,11 @@ #include <linux/serdev.h> #include <linux/tty.h> #include <linux/tty_driver.h> +#include <linux/tty_flip.h> #include <linux/poll.h>
#define SERPORT_ACTIVE 1 +#define SERPORT_PAUSE_RX 2
struct serport { struct tty_port *port; @@ -32,6 +34,9 @@ static size_t ttyport_receive_buf(struct tty_port *port, const u8 *cp, if (!test_bit(SERPORT_ACTIVE, &serport->flags)) return 0;
+ if (test_bit(SERPORT_PAUSE_RX, &serport->flags)) + return 0; + ret = serdev_controller_receive_buf(ctrl, cp, count);
dev_WARN_ONCE(&ctrl->dev, ret > count, @@ -156,6 +161,31 @@ static void ttyport_close(struct serdev_controller *ctrl) tty_release_struct(tty, serport->tty_idx); }
+static void ttyport_pause_rx(struct serdev_controller *ctrl) +{ + struct serport *serport = serdev_controller_get_drvdata(ctrl); + struct tty_struct *tty = serport->tty; + + if (test_bit(SERPORT_ACTIVE, &serport->flags)) + tty_buffer_lock_exclusive(tty->port); + + set_bit(SERPORT_PAUSE_RX, &serport->flags); + + if (test_bit(SERPORT_ACTIVE, &serport->flags)) + tty_buffer_unlock_exclusive(tty->port); +} + +static void ttyport_resume_rx(struct serdev_controller *ctrl) +{ + struct serport *serport = serdev_controller_get_drvdata(ctrl); + struct tty_struct *tty = serport->tty; + + clear_bit(SERPORT_PAUSE_RX, &serport->flags); + + if (test_bit(SERPORT_ACTIVE, &serport->flags)) + tty_flip_buffer_push(tty->port); +} + static unsigned int ttyport_set_baudrate(struct serdev_controller *ctrl, unsigned int speed) { struct serport *serport = serdev_controller_get_drvdata(ctrl); @@ -260,6 +290,8 @@ static const struct serdev_controller_ops ctrl_ops = { .get_tiocm = ttyport_get_tiocm, .set_tiocm = ttyport_set_tiocm, .break_ctl = ttyport_break_ctl, + .pause_rx = ttyport_pause_rx, + .resume_rx = ttyport_resume_rx, };
struct device *serdev_tty_port_register(struct tty_port *port, diff --git a/include/linux/serdev.h b/include/linux/serdev.h index b6c3d957ec15..5cf05df17ddf 100644 --- a/include/linux/serdev.h +++ b/include/linux/serdev.h @@ -89,6 +89,8 @@ struct serdev_controller_ops { int (*get_tiocm)(struct serdev_controller *); int (*set_tiocm)(struct serdev_controller *, unsigned int, unsigned int); int (*break_ctl)(struct serdev_controller *ctrl, unsigned int break_state); + void (*pause_rx)(struct serdev_controller *ctrl); + void (*resume_rx)(struct serdev_controller *ctrl); };
/** @@ -194,6 +196,8 @@ static inline size_t serdev_controller_receive_buf(struct serdev_controller *ctr int serdev_device_open(struct serdev_device *); void serdev_device_close(struct serdev_device *); int devm_serdev_device_open(struct device *, struct serdev_device *); +void serdev_device_pause_rx(struct serdev_device *serdev); +void serdev_device_resume_rx(struct serdev_device *serdev); unsigned int serdev_device_set_baudrate(struct serdev_device *, unsigned int); void serdev_device_set_flow_control(struct serdev_device *, bool); int serdev_device_write_buf(struct serdev_device *, const u8 *, size_t); @@ -233,6 +237,8 @@ static inline int serdev_device_open(struct serdev_device *sdev) return -ENODEV; } static inline void serdev_device_close(struct serdev_device *sdev) {} +static inline void serdev_device_pause_rx(struct serdev_device *serdev) {} +static inline void serdev_device_resume_rx(struct serdev_device *serdev) {} static inline unsigned int serdev_device_set_baudrate(struct serdev_device *sdev, unsigned int baudrate) { return 0;