[PATCH v5 2/2] drivers: serial: probe all uart devices

[Vabhav Sharma]

From: Vabhav Sharma <vabhav.sharma at nxp.com>

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 at nxp.com>
Reviewed-by: Stefan Roese <sr at denx.de>
Reviewed-by: Simon Glass <sjg at chromium.org>
--
v5:
  Incorporated review comments from Sean Anderson
  - Modified the macro description
  - Added error check

v3:
  Incorporated Simon and Stephan review comment
  - Define generic function uclass_probe_all(enum uclass_id)
    in drivers/core/uclass.c
  - Added the function in caller of serial_find_console_or_panic()
  - Removed repeated sequence with generic function call uclass_probe_all()
  - Dependent on other patch [PATCH] dm: core: add function uclass_probe_all()
    to probe all devices

v2:
  Incorporated Stefan review comment, Update #ifdef with macro
  if (IS_ENABLED)..
---
 drivers/serial/Kconfig         | 16 ++++++++++++++++
 drivers/serial/serial-uclass.c |  9 +++++++++
 2 files changed, 25 insertions(+)

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index b4805a2..1294943 100644
--- 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 f3c25d4..48e0080 100644
--- 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();
 }
 
-- 
2.7.4