drivers: Add board uclass

Since there is no canonical "board device" that can be used in board
files, it is difficult to use DM function for board initialization in
these cases.

Hence, add a uclass that implements a simple "board device", which can
hold devices not suitable anywhere else in the device tree, and is also
able to read encoded information, e.g. hard-wired GPIOs on a GPIO
expander, read-only memory ICs, etc. that carry information about the
hardware.

The devices of this uclass expose methods to read generic data types
(integers, strings, booleans) to encode the information provided by the
hardware.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>

3 files changed, 73 insertions, 0 deletions

diff --git a/drivers/board/Kconfig b/drivers/board/Kconfig
new file mode 100644
index 0000000000..c9a52dc20e
--- /dev/null
+++ b/drivers/board/Kconfig
@@ -0,0 +1,7 @@
+menuconfig BOARD
+	bool "Device Information"
+	help
+	  Support methods to query hardware configurations from internal
+	  mechanisms (e.g. reading GPIO values, determining the presence of
+	  devices on busses, etc.). This enables the usage of U-Boot with
+	  modular board architectures.
diff --git a/drivers/board/Makefile b/drivers/board/Makefile
new file mode 100644
index 0000000000..12dd2030cf
--- /dev/null
+++ b/drivers/board/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier:	GPL-2.0+
+#
+# (C) Copyright 2017
+# Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+obj-$(CONFIG_BOARD) += board-uclass.o
+obj-$(CONFIG_BOARD_GAZERBEAM) += gazerbeam.o
diff --git a/drivers/board/board-uclass.c b/drivers/board/board-uclass.c
new file mode 100644
index 0000000000..a516ba4962
--- /dev/null
+++ b/drivers/board/board-uclass.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2017
+ * Mario Six,  Guntermann & Drunck GmbH, mario.six@gdsys.cc
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <board.h>
+
+int board_get(struct udevice **devp)
+{
+	return uclass_first_device_err(UCLASS_BOARD, devp);
+}
+
+int board_detect(struct udevice *dev)
+{
+	struct board_ops *ops = board_get_ops(dev);
+
+	if (!ops->detect)
+		return -ENOSYS;
+
+	return ops->detect(dev);
+}
+
+int board_get_bool(struct udevice *dev, int id, bool *val)
+{
+	struct board_ops *ops = board_get_ops(dev);
+
+	if (!ops->get_bool)
+		return -ENOSYS;
+
+	return ops->get_bool(dev, id, val);
+}
+
+int board_get_int(struct udevice *dev, int id, int *val)
+{
+	struct board_ops *ops = board_get_ops(dev);
+
+	if (!ops->get_int)
+		return -ENOSYS;
+
+	return ops->get_int(dev, id, val);
+}
+
+int board_get_str(struct udevice *dev, int id, size_t size, char *val)
+{
+	struct board_ops *ops = board_get_ops(dev);
+
+	if (!ops->get_str)
+		return -ENOSYS;
+
+	return ops->get_str(dev, id, size, val);
+}
+
+UCLASS_DRIVER(board) = {
+	.id		= UCLASS_BOARD,
+	.name		= "board",
+	.post_bind	= dm_scan_fdt_dev,
+};