Messages in this thread | | | From | Rob Herring <> | Date | Tue, 29 Sep 2015 12:28:11 -0500 | Subject | Re: [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper function |
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On Tue, Sep 22, 2015 at 12:52 PM, Marc Zyngier <marc.zyngier@arm.com> wrote: > of_parse_phandle_with_args() is slightly inflexible as it doesn't > allow the (unusual) case where the #*-cells property is not defined. > In order to support this, introduce of_parse_phandle_with_opt_args() > which assumes that #*-cells is zero when it is not defined,
zero or cell_count - 1?
I would be okay with always assuming zero rather than being an error if that simplifies things. It is not really the kernel's job to be a dtb validator.
Also, I assume this was done for some compatibility? In general, we should be explicit, so "#msi-cells = <0>" should be recommended and we should update dts files if they are not.
Rob
> as required by the msi-parent binding > > This is done by turning __of_parse_phandle_with_args into an even > bigger monster, which is a bit frightening. > > Acked-by: Mark Rutland <mark.rutland@arm.com> > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> > --- > drivers/of/base.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++-- > include/linux/of.h | 3 +++ > 2 files changed, 65 insertions(+), 2 deletions(-) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index 8b5a187..1612342e 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -1479,6 +1479,10 @@ static int __of_parse_phandle_with_args(const struct device_node *np, > * (i.e. cells_name not set, but cell_count is set), > * except when we're going to return the found node > * below. > + * > + * If #*-cells is not found, but cell_count is set > + * to a non-zero value, use (cell_count-1) as a > + * fallback value. > */ > if (cells_name || cur_index == index) { > node = of_find_node_by_phandle(phandle); > @@ -1490,13 +1494,21 @@ static int __of_parse_phandle_with_args(const struct device_node *np, > } > > if (cells_name) { > - if (of_property_read_u32(node, cells_name, > - &count)) { > + int ret; > + ret = of_property_read_u32(node, cells_name, > + &count); > + if (ret && !cell_count) { > pr_err("%s: could not get %s for %s\n", > np->full_name, cells_name, > node->full_name); > goto err; > } > + if (ret) { > + count = cell_count - 1; > + pr_debug("%s: could not get %s for %s, assuming %d\n", > + np->full_name, cells_name, > + node->full_name, count); > + } > } else { > count = cell_count; > } > @@ -1628,6 +1640,54 @@ int of_parse_phandle_with_args(const struct device_node *np, const char *list_na > EXPORT_SYMBOL(of_parse_phandle_with_args); > > /** > + * of_parse_phandle_with_opt_args() - Find a node pointed by phandle in a list > + * @np: pointer to a device tree node containing a list > + * @list_name: property name that contains a list > + * @cells_name: property name that specifies phandles' arguments count > + * @index: index of a phandle to parse out > + * @out_args: optional pointer to output arguments structure (will be filled) > + * > + * This function is useful to parse lists of phandles and their arguments. > + * If cells_name is not found, then it is assumed to be zero. > + * Returns 0 on success and fills out_args, on error returns appropriate > + * errno value. > + * > + * Caller is responsible to call of_node_put() on the returned out_args->np > + * pointer. > + * > + * Example: > + * > + * phandle1: node1 { > + * #list-cells = <2>; > + * } > + * > + * phandle2: node2 { > + * } > + * > + * phandle3: node3 { > + * #list-cells = <1>; > + * } > + * > + * node3 { > + * list = <&phandle1 1 2 &phandle2 &phandle 3>; > + * } > + * > + * To get a device_node of the `node2' node you may call this: > + * of_parse_phandle_with_args(node3, "list", "#list-cells", 1, &args); > + */ > +int of_parse_phandle_with_opt_args(const struct device_node *np, > + const char *list_name, > + const char *cells_name, int index, > + struct of_phandle_args *out_args) > +{ > + if (index < 0) > + return -EINVAL; > + return __of_parse_phandle_with_args(np, list_name, cells_name, 1, > + index, out_args); > +} > +EXPORT_SYMBOL(of_parse_phandle_with_opt_args); > + > +/** > * of_parse_phandle_with_fixed_args() - Find a node pointed by phandle in a list > * @np: pointer to a device tree node containing a list > * @list_name: property name that contains a list > diff --git a/include/linux/of.h b/include/linux/of.h > index 2194b8c..ae6cd03 100644 > --- a/include/linux/of.h > +++ b/include/linux/of.h > @@ -328,6 +328,9 @@ extern struct device_node *of_parse_phandle(const struct device_node *np, > extern int of_parse_phandle_with_args(const struct device_node *np, > const char *list_name, const char *cells_name, int index, > struct of_phandle_args *out_args); > +extern int of_parse_phandle_with_opt_args(const struct device_node *np, > + const char *list_name, const char *cells_name, int index, > + struct of_phandle_args *out_args); > extern int of_parse_phandle_with_fixed_args(const struct device_node *np, > const char *list_name, int cells_count, int index, > struct of_phandle_args *out_args); > -- > 2.1.4 >
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