drivers: serial: probe all uart devices

U-Boot DM model probe only single device at a time
which is enabled and configured using device tree
or platform data method.

PL011 UART IP is SBSA compliant and firmware does the
serial port set-up, initialization and let the kernel use
UART port for sending and receiving characters.

Normally software talk to one serial port time but some
LayerScape platform require all the UART devices enabled
in Linux for various use case.

Adding support to probe all enabled serial devices like SBSA
compliant PL011 UART ports probe and initialization by firmware.

Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Sean Anderson <seanga2@gmail.com>

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index b4805a2..1294943 100644 (file)
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -134,6 +134,22 @@ config SERIAL_SEARCH_ALL
 
          If unsure, say N.
 
+config SERIAL_PROBE_ALL
+       bool "Probe all available serial devices"
+       depends on DM_SERIAL
+       default n
+       help
+         The serial subsystem only probes for a single serial device,
+         but does not probe for other remaining serial devices.
+         With this option set, we make probing and searching for
+         all available devices optional.
+         Normally, U-Boot talks to one serial port at a time, but SBSA
+         compliant UART devices like PL011 require initialization
+         by firmware and to let the kernel use serial port for sending
+         and receiving the characters.
+
+         If unsure, say N.
+
 config SPL_DM_SERIAL
        bool "Enable Driver Model for serial drivers in SPL"
        depends on DM_SERIAL && SPL_DM

diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c
index 58a6541..ead0193 100644 (file)
--- a/drivers/serial/serial-uclass.c
+++ b/drivers/serial/serial-uclass.c
@@ -172,6 +172,15 @@ int serial_init(void)
 /* Called after relocation */
 int serial_initialize(void)
 {
+       /* Scanning uclass to probe devices */
+       if (IS_ENABLED(CONFIG_SERIAL_PROBE_ALL)) {
+               int ret;
+
+               ret  = uclass_probe_all(UCLASS_SERIAL);
+               if (ret)
+                       return ret;
+       }
+
        return serial_init();
 }