You should see something like this:
<...U-Boot banner...>
- Running 20 driver model tests
+ Running 21 driver model tests
Test: dm_test_autobind
Test: dm_test_autoprobe
Test: dm_test_bus_children
Device 'c-test@1': seq 1 is in use by 'd-test'
Test: dm_test_bus_children_funcs
Test: dm_test_bus_parent_data
+ Test: dm_test_bus_parent_ops
Test: dm_test_children
Test: dm_test_fdt
Device 'd-test': seq 3 is in use by 'b-test'
an error.
+Bus Drivers
+-----------
+
+A common use of driver model is to implement a bus, a device which provides
+access to other devices. Example of buses include SPI and I2C. Typically
+the bus provides some sort of transport or translation that makes it
+possible to talk to the devices on the bus.
+
+Driver model provides a few useful features to help with implementing
+buses. Firstly, a bus can request that its children store some 'parent
+data' which can be used to keep track of child state. Secondly, the bus can
+define methods which are called when a child is probed or removed. This is
+similar to the methods the uclass driver provides.
+
+Here an explanation of how a bus fits with a uclass may be useful. Consider
+a USB bus with several devices attached to it, each from a different (made
+up) uclass:
+
+ xhci_usb (UCLASS_USB)
+ eth (UCLASS_ETHERNET)
+ camera (UCLASS_CAMERA)
+ flash (UCLASS_FLASH_STORAGE)
+
+Each of the devices is connected to a different address on the USB bus.
+The bus device wants to store this address and some other information such
+as the bus speed for each device.
+
+To achieve this, the bus device can use dev->parent_priv in each of its
+three children. This can be auto-allocated if the bus driver has a non-zero
+value for per_child_auto_alloc_size. If not, then the bus device can
+allocate the space itself before the child device is probed.
+
+Also the bus driver can define the child_pre_probe() and child_post_remove()
+methods to allow it to do some processing before the child is activated or
+after it is deactivated.
+
+Note that the information that controls this behaviour is in the bus's
+driver, not the child's. In fact it is possible that child has no knowledge
+that it is connected to a bus. The same child device may even be used on two
+different bus types. As an example. the 'flash' device shown above may also
+be connected on a SATA bus or standalone with no bus:
+
+ xhci_usb (UCLASS_USB)
+ flash (UCLASS_FLASH_STORAGE) - parent data/methods defined by USB bus
+
+ sata (UCLASS_SATA)
+ flash (UCLASS_FLASH_STORAGE) - parent data/methods defined by SATA bus
+
+ flash (UCLASS_FLASH_STORAGE) - no parent data/methods (not on a bus)
+
+Above you can see that the driver for xhci_usb/sata controls the child's
+bus methods. In the third example the device is not on a bus, and therefore
+will not have these methods at all. Consider the case where the flash
+device defines child methods. These would be used for *its* children, and
+would be quite separate from the methods defined by the driver for the bus
+that the flash device is connetced to. The act of attaching a device to a
+parent device which is a bus, causes the device to start behaving like a
+bus device, regardless of its own views on the matter.
+
+The uclass for the device can also contain data private to that uclass.
+But note that each device on the bus may be a memeber of a different
+uclass, and this data has nothing to do with the child data for each child
+on the bus.
+
+
Driver Lifecycle
----------------
}
dev->seq = seq;
+ if (dev->parent && dev->parent->driver->child_pre_probe) {
+ ret = dev->parent->driver->child_pre_probe(dev);
+ if (ret)
+ goto fail;
+ }
+
if (drv->ofdata_to_platdata && dev->of_offset >= 0) {
ret = drv->ofdata_to_platdata(dev);
if (ret)
goto err_remove;
}
+ if (dev->parent && dev->parent->driver->child_post_remove) {
+ ret = dev->parent->driver->child_post_remove(dev);
+ if (ret) {
+ dm_warn("%s: Device '%s' failed child_post_remove()",
+ __func__, dev->name);
+ }
+ }
+
device_free(dev);
dev->seq = -1;
dev->flags &= ~DM_FLAG_ACTIVATED;
- return 0;
+ return ret;
err_remove:
/* We can't put the children back */
* @remove: Called to remove a device, i.e. de-activate it
* @unbind: Called to unbind a device from its driver
* @ofdata_to_platdata: Called before probe to decode device tree data
+ * @child_pre_probe: Called before a child device is probed. The device has
+ * memory allocated but it has not yet been probed.
+ * @child_post_remove: Called after a child device is removed. The device
+ * has memory allocated but its device_remove() method has been called.
* @priv_auto_alloc_size: If non-zero this is the size of the private data
* to be allocated in the device's ->priv pointer. If zero, then the driver
* is responsible for allocating any data required.
int (*remove)(struct udevice *dev);
int (*unbind)(struct udevice *dev);
int (*ofdata_to_platdata)(struct udevice *dev);
+ int (*child_pre_probe)(struct udevice *dev);
+ int (*child_post_remove)(struct udevice *dev);
int priv_auto_alloc_size;
int platdata_auto_alloc_size;
int per_child_auto_alloc_size;
* struct dm_test_parent_data - parent's information on each child
*
* @sum: Test value used to check parent data works correctly
+ * @flag: Used to track calling of parent operations
*/
struct dm_test_parent_data {
int sum;
+ int flag;
};
/*
* @fail_count: Number of tests that failed
* @force_fail_alloc: Force all memory allocs to fail
* @skip_post_probe: Skip uclass post-probe processing
+ * @removed: Used to keep track of a device that was removed
*/
struct dm_test_state {
struct udevice *root;
int fail_count;
int force_fail_alloc;
int skip_post_probe;
+ struct udevice *removed;
};
/* Test flags for each test */
DECLARE_GLOBAL_DATA_PTR;
+enum {
+ FLAG_CHILD_PROBED = 10,
+ FLAG_CHILD_REMOVED = -7,
+};
+
+static struct dm_test_state *test_state;
+
static int testbus_drv_probe(struct udevice *dev)
{
return dm_scan_fdt_node(dev, gd->fdt_blob, dev->of_offset, false);
}
+static int testbus_child_pre_probe(struct udevice *dev)
+{
+ struct dm_test_parent_data *parent_data = dev_get_parentdata(dev);
+
+ parent_data->flag += FLAG_CHILD_PROBED;
+
+ return 0;
+}
+
+static int testbus_child_post_remove(struct udevice *dev)
+{
+ struct dm_test_parent_data *parent_data = dev_get_parentdata(dev);
+ struct dm_test_state *dms = test_state;
+
+ parent_data->flag += FLAG_CHILD_REMOVED;
+ if (dms)
+ dms->removed = dev;
+
+ return 0;
+}
+
static const struct udevice_id testbus_ids[] = {
{
.compatible = "denx,u-boot-test-bus",
.priv_auto_alloc_size = sizeof(struct dm_test_priv),
.platdata_auto_alloc_size = sizeof(struct dm_test_pdata),
.per_child_auto_alloc_size = sizeof(struct dm_test_parent_data),
+ .child_pre_probe = testbus_child_pre_probe,
+ .child_post_remove = testbus_child_post_remove,
};
UCLASS_DRIVER(testbus) = {
}
DM_TEST(dm_test_bus_parent_data, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test that the bus ops are called when a child is probed/removed */
+static int dm_test_bus_parent_ops(struct dm_test_state *dms)
+{
+ struct dm_test_parent_data *parent_data;
+ struct udevice *bus, *dev;
+ struct uclass *uc;
+
+ test_state = dms;
+ ut_assertok(uclass_get_device(UCLASS_TEST_BUS, 0, &bus));
+ ut_assertok(uclass_get(UCLASS_TEST_FDT, &uc));
+
+ uclass_foreach_dev(dev, uc) {
+ /* Ignore these if they are not on this bus */
+ if (dev->parent != bus)
+ continue;
+ ut_asserteq_ptr(NULL, dev_get_parentdata(dev));
+
+ ut_assertok(device_probe(dev));
+ parent_data = dev_get_parentdata(dev);
+ ut_asserteq(FLAG_CHILD_PROBED, parent_data->flag);
+ }
+
+ uclass_foreach_dev(dev, uc) {
+ /* Ignore these if they are not on this bus */
+ if (dev->parent != bus)
+ continue;
+ parent_data = dev_get_parentdata(dev);
+ ut_asserteq(FLAG_CHILD_PROBED, parent_data->flag);
+ ut_assertok(device_remove(dev));
+ ut_asserteq_ptr(NULL, dev_get_parentdata(dev));
+ ut_asserteq_ptr(dms->removed, dev);
+ }
+ test_state = NULL;
+
+ return 0;
+}
+DM_TEST(dm_test_bus_parent_ops, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
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