dm: Provide a function to scan child FDT nodes

At present only root nodes in the device tree are scanned for devices.
But some devices can have children. For example a SPI bus may have
several children for each of its chip selects.

Add a function which scans subnodes and binds devices for each one. This
can be used for the root node scan also, so change it.

A device can call this function in its bind() or probe() methods to bind
its children.

Signed-off-by: Simon Glass <sjg@chromium.org>

doc/driver-model/README.txt

@@ -95,9 +95,13 @@ are provided in test/dm. To run them, try:
 You should see something like this:
 
     <...U-Boot banner...>
-    Running 17 driver model tests
+    Running 18 driver model tests
     Test: dm_test_autobind
     Test: dm_test_autoprobe
+    Test: dm_test_bus_children
+    Device 'd-test': seq 3 is in use by 'b-test'
+    Device 'c-test@0': seq 0 is in use by 'a-test'
+    Device 'c-test@1': seq 1 is in use by 'd-test'
     Test: dm_test_children
     Test: dm_test_fdt
     Device 'd-test': seq 3 is in use by 'b-test'

drivers/core/root.c

@@ -80,29 +80,32 @@ int dm_scan_platdata(bool pre_reloc_only)
 }
 
 #ifdef CONFIG_OF_CONTROL
-int dm_scan_fdt(const void *blob, bool pre_reloc_only)
+int dm_scan_fdt_node(struct udevice *parent, const void *blob, int offset,
+		     bool pre_reloc_only)
 {
-	int offset = 0;
 	int ret = 0, err;
-	int depth = 0;
 
-	do {
-		offset = fdt_next_node(blob, offset, &depth);
-		if (offset > 0 && depth == 1) {
+	for (offset = fdt_first_subnode(blob, offset);
+	     offset > 0;
+	     offset = fdt_next_subnode(blob, offset)) {
 		if (pre_reloc_only &&
 		    !fdt_getprop(blob, offset, "u-boot,dm-pre-reloc", NULL))
 			continue;
-			err = lists_bind_fdt(gd->dm_root, blob, offset);
+		err = lists_bind_fdt(parent, blob, offset);
 		if (err && !ret)
 			ret = err;
 	}
-	} while (offset > 0);
 
 	if (ret)
 		dm_warn("Some drivers failed to bind\n");
 
 	return ret;
 }
+
+int dm_scan_fdt(const void *blob, bool pre_reloc_only)
+{
+	return dm_scan_fdt_node(gd->dm_root, blob, 0, pre_reloc_only);
+}
 #endif
 
 int dm_init_and_scan(bool pre_reloc_only)

include/dm/root.h

@@ -45,6 +45,22 @@ int dm_scan_platdata(bool pre_reloc_only);
  */
 int dm_scan_fdt(const void *blob, bool pre_reloc_only);
 
+/**
+ * dm_scan_fdt_node() - Scan the device tree and bind drivers for a node
+ *
+ * This scans the subnodes of a device tree node and and creates a driver
+ * for each one.
+ *
+ * @parent: Parent device for the devices that will be created
+ * @blob: Pointer to device tree blob
+ * @offset: Offset of node to scan
+ * @pre_reloc_only: If true, bind only drivers with the DM_FLAG_PRE_RELOC
+ * flag. If false bind all drivers.
+ * @return 0 if OK, -ve on error
+ */
+int dm_scan_fdt_node(struct udevice *parent, const void *blob, int offset,
+		     bool pre_reloc_only);
+
 /**
  * dm_init_and_scan() - Initialise Driver Model structures and scan for devices
  *

include/dm/test.h

@@ -155,6 +155,15 @@ int testfdt_ping(struct udevice *dev, int pingval, int *pingret);
 int dm_check_operations(struct dm_test_state *dms, struct udevice *dev,
 			uint32_t base, struct dm_test_priv *priv);
 
+/**
+ * dm_check_devices() - check the devices respond to operations correctly
+ *
+ * @dms: Overall test state
+ * @num_devices: Number of test devices to check
+ * @return 0 if OK, -ve on error
+ */
+int dm_check_devices(struct dm_test_state *dms, int num_devices);
+
 /**
  * dm_test_main() - Run all the tests
  *

include/dm/uclass-id.h

@@ -17,6 +17,7 @@ enum uclass_id {
 	UCLASS_DEMO,
 	UCLASS_TEST,
 	UCLASS_TEST_FDT,
+	UCLASS_TEST_BUS,
 
 	/* U-Boot uclasses start here */
 	UCLASS_GPIO,		/* Bank of general-purpose I/O pins */

test/dm/Makefile

@@ -5,6 +5,7 @@
 #
 
 obj-$(CONFIG_CMD_DM) += cmd_dm.o
+obj-$(CONFIG_DM_TEST) += bus.o
 obj-$(CONFIG_DM_TEST) += test-driver.o
 obj-$(CONFIG_DM_TEST) += test-fdt.o
 obj-$(CONFIG_DM_TEST) += test-main.o

test/dm/bus.c

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/root.h>
+#include <dm/test.h>
+#include <dm/ut.h>
+#include <dm/util.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static int testbus_drv_probe(struct udevice *dev)
+{
+	return dm_scan_fdt_node(dev, gd->fdt_blob, dev->of_offset, false);
+}
+
+static const struct udevice_id testbus_ids[] = {
+	{
+		.compatible = "denx,u-boot-test-bus",
+		.data = DM_TEST_TYPE_FIRST },
+	{ }
+};
+
+U_BOOT_DRIVER(testbus_drv) = {
+	.name	= "testbus_drv",
+	.of_match	= testbus_ids,
+	.id	= UCLASS_TEST_BUS,
+	.probe	= testbus_drv_probe,
+	.priv_auto_alloc_size = sizeof(struct dm_test_priv),
+	.platdata_auto_alloc_size = sizeof(struct dm_test_pdata),
+};
+
+UCLASS_DRIVER(testbus) = {
+	.name		= "testbus",
+	.id		= UCLASS_TEST_BUS,
+};
+
+/* Test that we can probe for children */
+static int dm_test_bus_children(struct dm_test_state *dms)
+{
+	int num_devices = 4;
+	struct udevice *bus;
+	struct uclass *uc;
+
+	ut_assertok(uclass_get(UCLASS_TEST_FDT, &uc));
+	ut_asserteq(num_devices, list_count_items(&uc->dev_head));
+
+	/* Probe the bus, which should yield 3 more devices */
+	ut_assertok(uclass_get_device(UCLASS_TEST_BUS, 0, &bus));
+	num_devices += 3;
+
+	ut_assertok(uclass_get(UCLASS_TEST_FDT, &uc));
+	ut_asserteq(num_devices, list_count_items(&uc->dev_head));
+
+	ut_assert(!dm_check_devices(dms, num_devices));
+
+	return 0;
+}
+DM_TEST(dm_test_bus_children, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);

test/dm/test-fdt.c

@@ -91,37 +91,17 @@ UCLASS_DRIVER(testfdt) = {
 	.id		= UCLASS_TEST_FDT,
 };
 
-/* Test that FDT-based binding works correctly */
-static int dm_test_fdt(struct dm_test_state *dms)
+int dm_check_devices(struct dm_test_state *dms, int num_devices)
 {
-	const int num_drivers = 4;
 	struct udevice *dev;
-	struct uclass *uc;
 	int ret;
 	int i;
 
-	ret = dm_scan_fdt(gd->fdt_blob, false);
-	ut_assert(!ret);
-
-	ret = uclass_get(UCLASS_TEST_FDT, &uc);
-	ut_assert(!ret);
-
-	/* These are num_drivers compatible root-level device tree nodes */
-	ut_asserteq(num_drivers, list_count_items(&uc->dev_head));
-
-	/* Each should have no platdata / priv */
-	for (i = 0; i < num_drivers; i++) {
-		ret = uclass_find_device(UCLASS_TEST_FDT, i, &dev);
-		ut_assert(!ret);
-		ut_assert(!dev_get_priv(dev));
-		ut_assert(!dev->platdata);
-	}
-
 	/*
 	 * Now check that the ping adds are what we expect. This is using the
 	 * ping-add property in each node.
 	 */
-	for (i = 0; i < num_drivers; i++) {
+	for (i = 0; i < num_devices; i++) {
 		uint32_t base;
 
 		ret = uclass_get_device(UCLASS_TEST_FDT, i, &dev);
@@ -144,6 +124,37 @@ static int dm_test_fdt(struct dm_test_state *dms)
 
 	return 0;
 }
+
+/* Test that FDT-based binding works correctly */
+static int dm_test_fdt(struct dm_test_state *dms)
+{
+	const int num_devices = 4;
+	struct udevice *dev;
+	struct uclass *uc;
+	int ret;
+	int i;
+
+	ret = dm_scan_fdt(gd->fdt_blob, false);
+	ut_assert(!ret);
+
+	ret = uclass_get(UCLASS_TEST_FDT, &uc);
+	ut_assert(!ret);
+
+	/* These are num_devices compatible root-level device tree nodes */
+	ut_asserteq(num_devices, list_count_items(&uc->dev_head));
+
+	/* Each should have no platdata / priv */
+	for (i = 0; i < num_devices; i++) {
+		ret = uclass_find_device(UCLASS_TEST_FDT, i, &dev);
+		ut_assert(!ret);
+		ut_assert(!dev_get_priv(dev));
+		ut_assert(!dev->platdata);
+	}
+
+	ut_assertok(dm_check_devices(dms, num_devices));
+
+	return 0;
+}
 DM_TEST(dm_test_fdt, 0);
 
 static int dm_test_fdt_pre_reloc(struct dm_test_state *dms)
@@ -187,7 +198,10 @@ static int dm_test_fdt_uclass_seq(struct dm_test_state *dms)
 	ut_asserteq(-ENODEV, uclass_find_device_by_seq(UCLASS_TEST_FDT, 7,
 						       true, &dev));
 
-	/* Note that c-test is not probed since it is not a top-level node */
+	/*
+	 * Note that c-test nodes are not probed since it is not a top-level
+	 * node
+	 */
 	ut_assertok(uclass_get_device_by_seq(UCLASS_TEST_FDT, 3, &dev));
 	ut_asserteq_str("b-test", dev->name);
 
@@ -236,12 +250,11 @@ static int dm_test_fdt_offset(struct dm_test_state *dms)
 							    node, &dev));
 
 	/* This is not a top level node so should not be probed */
-	node = fdt_path_offset(blob, "/some-bus/c-test");
+	node = fdt_path_offset(blob, "/some-bus/c-test@5");
 	ut_assert(node > 0);
 	ut_asserteq(-ENODEV, uclass_get_device_by_of_offset(UCLASS_TEST_FDT,
 							    node, &dev));
 
 	return 0;
 }
-
 DM_TEST(dm_test_fdt_offset, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);

test/dm/test.dts

@@ -43,14 +43,28 @@
 	some-bus {
 		#address-cells = <1>;
 		#size-cells = <0>;
+		compatible = "denx,u-boot-test-bus";
 		reg = <3>;
 		ping-expect = <4>;
 		ping-add = <4>;
-		c-test {
+		c-test@5 {
 			compatible = "denx,u-boot-fdt-test";
 			reg = <5>;
+			ping-expect = <5>;
 			ping-add = <5>;
 		};
+		c-test@0 {
+			compatible = "denx,u-boot-fdt-test";
+			reg = <0>;
+			ping-expect = <6>;
+			ping-add = <6>;
+		};
+		c-test@1 {
+			compatible = "denx,u-boot-fdt-test";
+			reg = <1>;
+			ping-expect = <7>;
+			ping-add = <7>;
+		};
 	};
 
 	d-test {