From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Likely Subject: Re: [PATCH] dt: add helper functions to read u32 and string property values Date: Thu, 30 Jun 2011 12:13:53 -0600 Message-ID: <20110630181353.GA6674@ponder.secretlab.ca> References: <1309449370-9554-1-git-send-email-thomas.abraham@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1309449370-9554-1-git-send-email-thomas.abraham-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Thomas Abraham Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, patches-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org List-Id: devicetree@vger.kernel.org On Thu, Jun 30, 2011 at 09:26:10PM +0530, Thomas Abraham wrote: > Add helper functions to retrive unsigned integer and string property values from > properties of a device node. These helper functions can be used to lookup a > property in a device node, perform error checking and read the property value. > > [grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org: Proposal and initial implementation] > Signed-off-by: Thomas Abraham Merged, thanks. Bonus points to anyone who submits patches converting existing code to this new api. g. > --- > drivers/of/base.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/of.h | 4 +++ > 2 files changed, 63 insertions(+), 0 deletions(-) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index 632ebae..4823b53 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -596,6 +596,65 @@ struct device_node *of_find_node_by_phandle(phandle handle) > EXPORT_SYMBOL(of_find_node_by_phandle); > > /** > + * of_property_read_u32 - Find a property in a device node and read the > + * 32-bit property value > + * @np: device node from which the property value is to be read. > + * @propname: name of the property to be searched. > + * @out_value: returned value, valid if return value is 0. > + * > + * Search for a property in a device node and read a 32-bit value from a > + * property. Returns -EINVAL, if the property does not exist, -ENODATA, if > + * property does not have a value, -EOVERFLOW, if the property data isn't > + * large enough, and 0 on success. > + * > + * The out_value is modified only if a valid u32 value can be decoded. > + */ > +int of_property_read_u32(struct device_node *np, char *propname, u32 *out_value) > +{ > + struct property *prop = of_find_property(np, propname, NULL); > + > + if (!prop) > + return -EINVAL; > + if (!prop->value) > + return -ENODATA; > + if (sizeof(*out_value) > prop->length) > + return -EOVERFLOW; > + *out_value = be32_to_cpup(prop->value); > + return 0; > +} > +EXPORT_SYMBOL_GPL(of_property_read_u32); > + > +/** > + * of_property_read_string - Find a property in a device node and return a > + * pointer to the property string value. > + * @np: device node from which the property value is to be read. > + * @propname: name of the property to be searched. > + * @out_string: pointer to a null terminated string, valid only if the return > + * value is 0. > + * > + * Returns a pointer to a null terminated property value string. Returns > + * -EINVAL, if the property does not exist, -ENODATA, if property does not have > + * a value, -EILSEQ, if the string is not null-terminated within the length of > + * the property value, and 0 on success. > + * > + * The out_string value is modified only if a valid string can be decoded. > + */ > +int of_property_read_string(struct device_node *np, char *propname, > + char **out_string) > +{ > + struct property *prop = of_find_property(np, propname, NULL); > + if (!prop) > + return -EINVAL; > + if (!prop->value) > + return -ENODATA; > + if (strnlen(prop->value, prop->length) == prop->length) > + return -EILSEQ; > + *out_string = prop->value; > + return 0; > +} > +EXPORT_SYMBOL_GPL(of_property_read_string); > + > +/** > * of_parse_phandle - Resolve a phandle property to a device_node pointer > * @np: Pointer to device node holding phandle property > * @phandle_name: Name of property holding a phandle value > diff --git a/include/linux/of.h b/include/linux/of.h > index bfc0ed1..4fc4c1b 100644 > --- a/include/linux/of.h > +++ b/include/linux/of.h > @@ -195,6 +195,10 @@ extern struct device_node *of_find_node_with_property( > extern struct property *of_find_property(const struct device_node *np, > const char *name, > int *lenp); > +extern int of_property_read_u32(struct device_node *np, char *propname, > + u32 *out_value); > +extern int of_property_read_string(struct device_node *np, char *propname, > + char **out_string); > extern int of_device_is_compatible(const struct device_node *device, > const char *); > extern int of_device_is_available(const struct device_node *device); > -- > 1.6.6.rc2 >