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Message-ID: <50991C41.50705@gmail.com>
Date: Tue, 06 Nov 2012 08:18:41 -0600
From: Rob Herring <robherring2@...il.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
CC: rob.herring@...xeda.com, grant.likely@...retlab.ca,
linaro-dev@...ts.linaro.org, andriy.shevchenko@...el.com,
patches@...aro.org, devicetree-discuss@...ts.ozlabs.org,
spear-devel@...t.st.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH Resend V2] dt: add helper function to read u8 & u16 variables
& arrays
On 10/25/2012 11:20 PM, Viresh Kumar wrote:
> This adds following helper routines:
> - of_property_read_u8_array()
> - of_property_read_u16_array()
> - of_property_read_u8()
> - of_property_read_u16()
>
> First two actually share most of the code with of_property_read_u32_array(), so
> the common part is taken out into a macro, which can be used by all three
> *_array() routines.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
> V1->V2:
> -----
> - Use typeof() in of_property_read_array() macro instead of passing type to it
>
> drivers/of/base.c | 73 +++++++++++++++++++++++++++++++++++++++++++-----------
> include/linux/of.h | 30 ++++++++++++++++++++++
> 2 files changed, 89 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index af3b22a..039e178 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -670,6 +670,64 @@ struct device_node *of_find_node_by_phandle(phandle handle)
> }
> EXPORT_SYMBOL(of_find_node_by_phandle);
>
> +#define of_property_read_array(_np, _pname, _out, _sz) \
> + struct property *_prop = of_find_property(_np, _pname, NULL); \
> + const __be32 *_val; \
> + \
> + if (!_prop) \
> + return -EINVAL; \
> + if (!_prop->value) \
> + return -ENODATA; \
> + if ((_sz * sizeof(*_out)) > _prop->length) \
> + return -EOVERFLOW; \
> + \
> + _val = _prop->value; \
> + while (_sz--) \
> + *_out++ = (typeof(*_out))be32_to_cpup(_val++); \
This will not work. You are incrementing _out by 1, 2, or 4 bytes, but
_val is always incremented by 4 bytes.
According to the dtc commit adding this feature, the values are packed:
With this patch the following property assignment:
property = /bits/ 16 <0x1234 0x5678 0x0 0xffff>;
is equivalent to:
property = <0x12345678 0x0000ffff>;
> + return 0;
> +
> +/**
> + * of_property_read_u8_array - Find and read an array of u8 from a property.
> + *
> + * @np: device node from which the property value is to be read.
> + * @propname: name of the property to be searched.
> + * @out_value: pointer to return value, modified only if return value is 0.
> + *
Missing sz
> + * Search for a property in a device node and read 8-bit value(s) from
> + * it. Returns 0 on success, -EINVAL if the property does not exist,
> + * -ENODATA if property does not have a value, and -EOVERFLOW if the
> + * property data isn't large enough.
> + *
> + * The out_value is modified only if a valid u8 value can be decoded.
> + */
> +int of_property_read_u8_array(const struct device_node *np,
> + const char *propname, u8 *out_values, size_t sz)
> +{
> + of_property_read_array(np, propname, out_values, sz);
> +}
> +EXPORT_SYMBOL_GPL(of_property_read_u8_array);
> +
> +/**
> + * of_property_read_u16_array - Find and read an array of u16 from a property.
> + *
> + * @np: device node from which the property value is to be read.
> + * @propname: name of the property to be searched.
> + * @out_value: pointer to return value, modified only if return value is 0.
> + *
Ditto.
> + * Search for a property in a device node and read 16-bit value(s) from
> + * it. Returns 0 on success, -EINVAL if the property does not exist,
> + * -ENODATA if property does not have a value, and -EOVERFLOW if the
> + * property data isn't large enough.
> + *
> + * The out_value is modified only if a valid u16 value can be decoded.
> + */
> +int of_property_read_u16_array(const struct device_node *np,
> + const char *propname, u16 *out_values, size_t sz)
> +{
> + of_property_read_array(np, propname, out_values, sz);
> +}
> +EXPORT_SYMBOL_GPL(of_property_read_u16_array);
> +
> /**
> * of_property_read_u32_array - Find and read an array of 32 bit integers
> * from a property.
> @@ -689,20 +747,7 @@ int of_property_read_u32_array(const struct device_node *np,
> const char *propname, u32 *out_values,
> size_t sz)
> {
> - struct property *prop = of_find_property(np, propname, NULL);
> - const __be32 *val;
> -
> - if (!prop)
> - return -EINVAL;
> - if (!prop->value)
> - return -ENODATA;
> - if ((sz * sizeof(*out_values)) > prop->length)
> - return -EOVERFLOW;
> -
> - val = prop->value;
> - while (sz--)
> - *out_values++ = be32_to_cpup(val++);
> - return 0;
> + of_property_read_array(np, propname, out_values, sz);
> }
> EXPORT_SYMBOL_GPL(of_property_read_u32_array);
>
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 72843b7..e2d9b40 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -223,6 +223,10 @@ 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_u8_array(const struct device_node *np,
> + const char *propname, u8 *out_values, size_t sz);
> +extern int of_property_read_u16_array(const struct device_node *np,
> + const char *propname, u16 *out_values, size_t sz);
> extern int of_property_read_u32_array(const struct device_node *np,
> const char *propname,
> u32 *out_values,
> @@ -357,6 +361,18 @@ static inline struct device_node *of_find_compatible_node(
> return NULL;
> }
>
> +static inline int of_property_read_u8_array(const struct device_node *np,
> + const char *propname, u8 *out_values, size_t sz)
> +{
> + return -ENOSYS;
> +}
> +
> +static inline int of_property_read_u16_array(const struct device_node *np,
> + const char *propname, u16 *out_values, size_t sz)
> +{
> + return -ENOSYS;
> +}
> +
> static inline int of_property_read_u32_array(const struct device_node *np,
> const char *propname,
> u32 *out_values, size_t sz)
> @@ -463,6 +479,20 @@ static inline bool of_property_read_bool(const struct device_node *np,
> return prop ? true : false;
> }
>
> +static inline int of_property_read_u8(const struct device_node *np,
> + const char *propname,
> + u8 *out_value)
> +{
> + return of_property_read_u8_array(np, propname, out_value, 1);
> +}
> +
> +static inline int of_property_read_u16(const struct device_node *np,
> + const char *propname,
> + u16 *out_value)
> +{
> + return of_property_read_u16_array(np, propname, out_value, 1);
> +}
> +
> static inline int of_property_read_u32(const struct device_node *np,
> const char *propname,
> u32 *out_value)
>
--
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