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. So my question is: is it useful to provide this besides fwnode_for_each_named_child_node(), given that both are effectively the same? > struct fwnode_handle *device_get_next_child_node(const struct device *dev, > struct fwnode_handle *child); > > @@ -178,11 +186,19 @@ struct fwnode_handle *device_get_next_child_node(const struct device *dev, > for (child = device_get_next_child_node(dev, NULL); child; \ > child = device_get_next_child_node(dev, child)) > > +#define device_for_each_named_child_node(dev, child, name) \ > + device_for_each_child_node(dev, child) \ > + if (!fwnode_name_eq(child, name)) { } else > + > #define device_for_each_child_node_scoped(dev, child) \ > for (struct fwnode_handle *child __free(fwnode_handle) = \ > device_get_next_child_node(dev, NULL); \ > child; child = device_get_next_child_node(dev, child)) > > +#define device_for_each_named_child_node_scoped(dev, child, name) \ > + device_for_each_child_node_scoped(dev, child) \ > + if (!fwnode_name_eq(child, name)) { } else > + > struct fwnode_handle *fwnode_get_named_child_node(const struct fwnode_handle *fwnode, > const char *childname); > struct fwnode_handle *device_get_named_child_node(const struct device *dev, > @@ -210,6 +226,14 @@ int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name); > > unsigned int device_get_child_node_count(const struct device *dev); > > +unsigned int fwnode_get_named_child_node_count(const struct fwnode_handle *fwnode, > + const char *name); > +static inline unsigned int device_get_named_child_node_count(const struct device *dev, > + const char *name) > +{ > + return fwnode_get_named_child_node_count(dev_fwnode(dev), name); > +} > + > static inline int device_property_read_u8(const struct device *dev, > const char *propname, u8 *val) > { -- Terveisin, Sakari Ailus
