On some boards, serial devices may or may not be muxed properly to actual pins, depending on firmware configuration. To determine whether we should use a serial device for U-Boot in-/output, we need to check whether it is muxed properly.
This is something only the board file can do, so let's expose a weak function that a board can override to explicitly allow or disallow usage of certain serial devices.
Signed-off-by: Alexander Graf agraf@suse.de --- drivers/serial/serial-uclass.c | 11 +++++++++++ include/serial.h | 11 +++++++++++ 2 files changed, 22 insertions(+)
diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c index 68ca2d09d1..ecd64f8e86 100644 --- a/drivers/serial/serial-uclass.c +++ b/drivers/serial/serial-uclass.c @@ -366,6 +366,16 @@ static int on_baudrate(const char *name, const char *value, enum env_op op, U_BOOT_ENV_CALLBACK(baudrate, on_baudrate);
#if CONFIG_IS_ENABLED(SERIAL_PRESENT) +__weak int board_check_serial(struct udevice *dev) +{ + return 0; +} + +static int serial_pre_probe(struct udevice *dev) +{ + return board_check_serial(dev); +} + static int serial_post_probe(struct udevice *dev) { struct dm_serial_ops *ops = serial_get_ops(dev); @@ -438,6 +448,7 @@ UCLASS_DRIVER(serial) = { .name = "serial", .flags = DM_UC_FLAG_SEQ_ALIAS, .post_probe = serial_post_probe, + .pre_probe = serial_pre_probe, .pre_remove = serial_pre_remove, .per_device_auto_alloc_size = sizeof(struct serial_dev_priv), }; diff --git a/include/serial.h b/include/serial.h index d87f01082a..221b3e1402 100644 --- a/include/serial.h +++ b/include/serial.h @@ -207,4 +207,15 @@ void sh_serial_initialize(void); void uartlite_serial_initialize(void); void zynq_serial_initialize(void);
+/** + * board_check_serial() - Determine whether a serial device works + * + * This is a board callback that allows boards to override whether a serial + * device is usable. By default, all devices are declared usable. + * + * @dev: Device pointer + * @return 0 if the device is usable, !0 otherwise + */ +int board_check_serial(struct udevice *dev); + #endif