Hei Matti, On Wed, Mar 19, 2025 at 08:02:24AM +0200, Matti Vaittinen wrote: > Moro Sakari, > > Thanks for the review. > > On 18/03/2025 17:24, Sakari Ailus wrote: > > Moi, > > > > On Mon, Mar 17, 2025 at 05:50:38PM +0200, Matti Vaittinen wrote: > > > There are a few use-cases where child nodes with a specific name need to > > > be parsed. Code like: > > > > > > fwnode_for_each_child_node() > > > if (fwnode_name_eq()) > > > ... > > > > > > can be found from a various drivers/subsystems. Adding a macro for this > > > can simplify things a bit. > > > > > > In a few cases the data from the found nodes is later added to an array, > > > which is allocated based on the number of found nodes. One example of > > > such use is the IIO subsystem's ADC channel nodes, where the relevant > > > nodes are named as channel[@N]. > > > > > > Add helpers for iterating and counting device's sub-nodes with certain > > > name instead of open-coding this in every user. > > > > > > Suggested-by: Jonathan Cameron <jic23@xxxxxxxxxx> > > > Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx> > > > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> > > > Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@xxxxxxxxx> > > > --- > > > Revision history: > > > v7 => v8: > > > - Fix the example in fwnode_get_named_child_node_count() documentation > > > to use the fwnode_get_named_child_node_count() and not the > > > device_get_named_child_node_count() > > > - Fix the rest of the new macro's indentiations > > > v6 => v7: > > > - Improve kerneldoc > > > - Inline device_get_named_child_node_count() and change it to call > > > fwnode_get_named_child_node_count() inside > > > - Fix indentiation of the new macros > > > v5 => v6: > > > - Add helpers to also iterate through the nodes. > > > v4 => v5: > > > - Use given name instead of string 'channel' when counting the nodes > > > - Add also fwnode_get_child_node_count_named() as suggested by Rob. > > > v3 => v4: > > > - New patch as suggested by Jonathan, see discussion in: > > > https://lore.kernel.org/lkml/20250223161338.5c896280@jic23-huawei/ > > > --- > > > drivers/base/property.c | 27 +++++++++++++++++++++++++++ > > > include/linux/property.h | 24 ++++++++++++++++++++++++ > > > 2 files changed, 51 insertions(+) > > > > > > diff --git a/drivers/base/property.c b/drivers/base/property.c > > > index c1392743df9c..f42f32ff45fc 100644 > > > --- a/drivers/base/property.c > > > +++ b/drivers/base/property.c > > > @@ -945,6 +945,33 @@ unsigned int device_get_child_node_count(const struct device *dev) > > > } > > > EXPORT_SYMBOL_GPL(device_get_child_node_count); > > > +/** > > > + * fwnode_get_named_child_node_count - number of child nodes with given name > > > + * @fwnode: Node which child nodes are counted. > > > + * @name: String to match child node name against. > > > + * > > > + * Scan child nodes and count all the nodes with a specific name. Potential > > > + * 'number' -ending after the 'at sign' for scanned names is ignored. > > > + * E.g.:: > > > + * fwnode_get_named_child_node_count(fwnode, "channel"); > > > + * would match all the nodes:: > > > + * channel { }, channel@0 {}, channel@0xabba {}... > > > + * > > > + * Return: the number of child nodes with a matching name for a given device. > > > + */ > > > +unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode, > > > + const char *name) > > > +{ > > > + struct fwnode_handle *child; > > > + unsigned int count = 0; > > > + > > > + fwnode_for_each_named_child_node(fwnode, child, name) > > > + count++; > > > + > > > + return count; > > > +} > > > +EXPORT_SYMBOL_GPL(fwnode_get_named_child_node_count); > > > + > > > bool device_dma_supported(const struct device *dev) > > > { > > > return fwnode_call_bool_op(dev_fwnode(dev), device_dma_supported); > > > diff --git a/include/linux/property.h b/include/linux/property.h > > > index e214ecd241eb..a1856e6b714c 100644 > > > --- a/include/linux/property.h > > > +++ b/include/linux/property.h > > > @@ -167,10 +167,18 @@ struct fwnode_handle *fwnode_get_next_available_child_node( > > > for (child = fwnode_get_next_child_node(fwnode, NULL); child; \ > > > child = fwnode_get_next_child_node(fwnode, child)) > > > +#define fwnode_for_each_named_child_node(fwnode, child, name) \ > > > + fwnode_for_each_child_node(fwnode, child) \ > > > + if (!fwnode_name_eq(child, name)) { } else > > > + > > > #define fwnode_for_each_available_child_node(fwnode, child) \ > > > for (child = fwnode_get_next_available_child_node(fwnode, NULL); child;\ > > > child = fwnode_get_next_available_child_node(fwnode, child)) > > > +#define fwnode_for_each_available_named_child_node(fwnode, child, name) \ > > > + fwnode_for_each_available_child_node(fwnode, child) \ > > > + if (!fwnode_name_eq(child, name)) { } else > > > + > > > > OF only enumerates available nodes via the fwnode API, software nodes don't > > have the concept but on ACPI I guess you could have a difference in nodes > > where you have device sub-nodes that aren't available. Still, these ACPI > > device nodes don't have meaningful names in this context (they're > > 4-character object names) so you wouldn't use them like this anyway. > > I believe you have far better understanding on these concepts than I do. The > reason behind adding fwnode_for_each_available_child_node() was the patch > 10/10: > > - fwnode_for_each_available_child_node(sensors, node) { > - if (fwnode_name_eq(node, "sensor")) { > - if (!thp7312_sensor_parse_dt(thp7312, node)) > - num_sensors++; > - } > + fwnode_for_each_available_named_child_node(sensors, node, "sensor") { > + if (!thp7312_sensor_parse_dt(thp7312, node)) > + num_sensors++; > } > > > > So my question is: is it useful to provide this besides > > fwnode_for_each_named_child_node(), given that both are effectively the > > same? > > So, I suppose you're saying the existing thp7312 -driver has no real reason > to use the 'fwnode_for_each_available_child_node()', but it could be using > fwnode_for_each_child_node() instead? > > If so, I am Ok with dropping the > 'fwnode_for_each_available_named_child_node()' and changing the 10/10 to: > > - fwnode_for_each_available_child_node(sensors, node) { > - if (fwnode_name_eq(node, "sensor")) { > - if (!thp7312_sensor_parse_dt(thp7312, node)) > - num_sensors++; > - } > + fwnode_for_each_named_child_node(sensors, node, "sensor") { > + if (!thp7312_sensor_parse_dt(thp7312, node)) > + num_sensors++; > } > > Do you think that'd be correct? I'd say so. Feel free to cc me to the last patch as well. I guess one way to make this clearer is to switch to fwnode_for_each_child_node() in a separate patch before fwnode_for_each_named_child_node() conversion. There are also just a handful of users of fwnode_for_each_available_child_node() and I guess these could be converted, too, but I think it's outside the scope of the set. -- Terveisin, Sakari Ailus
