Re: [PATCH v2 06/17] xen/device-tree: Add dt_property_read_variable_u32_array helper

[Rahul Singh <Rahul.Singh@xxxxxxx>]

Hi Stefano,

> On 23 Sep 2021, at 12:06 am, Stefano Stabellini <sstabellini@xxxxxxxxxx> 
> wrote:
> 
> On Wed, 22 Sep 2021, Rahul Singh wrote:
>> Based on tag Linux v5.14.2 commit bbdd3de144fc142f2f4b9834c9241cc4e7f3d3fc
> 
> I'd prefer the upstream commit id if possible, not one based on the
> stable trees (the commit id doesn't resolve at all on Linus's tree).
> Aside from that, the patch is fine.
> 

Ok. I will change the stable commit id to  upstream commit id.

Regards,
Rahul
> 
>> Import the Linux helper of_property_read_variable_u32_array. This
>> function find and read an array of 32 bit integers from a property,
>> with bounds on the minimum and maximum array size.
>> 
>> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
>> ---
>> Change in v2: Patch introduced in v2
>> ---
>> xen/common/device_tree.c      | 61 +++++++++++++++++++++++++++++++++++
>> xen/include/xen/device_tree.h | 26 +++++++++++++++
>> 2 files changed, 87 insertions(+)
>> 
>> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
>> index 03d25a81ce..53160d61f8 100644
>> --- a/xen/common/device_tree.c
>> +++ b/xen/common/device_tree.c
>> @@ -208,6 +208,67 @@ int dt_property_read_string(const struct dt_device_node 
>> *np,
>>     return 0;
>> }
>> 
>> +/**
>> + * dt_find_property_value_of_size
>> + *
>> + * @np:     device node from which the property value is to be read.
>> + * @propname:   name of the property to be searched.
>> + * @min:    minimum allowed length of property value
>> + * @max:    maximum allowed length of property value (0 means unlimited)
>> + * @len:    if !=NULL, actual length is written to here
>> + *
>> + * Search for a property in a device node and valid the requested size.
>> + *
>> + * Return: The property value on success, -EINVAL if the property does not
>> + * exist, -ENODATA if property does not have a value, and -EOVERFLOW if the
>> + * property data is too small or too large.
>> + */
>> +static void *dt_find_property_value_of_size(const struct dt_device_node *np,
>> +                                            const char *propname, u32 min,
>> +                                            u32 max, size_t *len)
>> +{
>> +    const struct dt_property *prop = dt_find_property(np, propname, NULL);
>> +
>> +    if ( !prop )
>> +        return ERR_PTR(-EINVAL);
>> +    if ( !prop->value )
>> +        return ERR_PTR(-ENODATA);
>> +    if ( prop->length < min )
>> +        return ERR_PTR(-EOVERFLOW);
>> +    if ( max && prop->length > max )
>> +        return ERR_PTR(-EOVERFLOW);
>> +
>> +    if ( len )
>> +        *len = prop->length;
>> +
>> +    return prop->value;
>> +}
>> +
>> +int dt_property_read_variable_u32_array(const struct dt_device_node *np,
>> +                                        const char *propname, u32 
>> *out_values,
>> +                                        size_t sz_min, size_t sz_max)
>> +{
>> +    size_t sz, count;
>> +    const __be32 *val = dt_find_property_value_of_size(np, propname,
>> +                        (sz_min * sizeof(*out_values)),
>> +                        (sz_max * sizeof(*out_values)),
>> +                        &sz);
>> +
>> +    if ( IS_ERR(val) )
>> +        return PTR_ERR(val);
>> +
>> +    if ( !sz_max )
>> +        sz = sz_min;
>> +    else
>> +        sz /= sizeof(*out_values);
>> +
>> +    count = sz;
>> +    while ( count-- )
>> +        *out_values++ = be32_to_cpup(val++);
>> +
>> +    return sz;
>> +}
>> +
>> int dt_property_match_string(const struct dt_device_node *np,
>>                              const char *propname, const char *string)
>> {
>> diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
>> index b02696be94..1693fb8e8c 100644
>> --- a/xen/include/xen/device_tree.h
>> +++ b/xen/include/xen/device_tree.h
>> @@ -366,6 +366,32 @@ bool_t dt_property_read_u32(const struct dt_device_node 
>> *np,
>> bool_t dt_property_read_u64(const struct dt_device_node *np,
>>                             const char *name, u64 *out_value);
>> 
>> +
>> +/**
>> + * dt_property_read_variable_u32_array - Find and read an array of 32 bit
>> + * integers from a property, with bounds on the minimum and maximum array 
>> size.
>> + *
>> + * @np:     device node from which the property value is to be read.
>> + * @propname:   name of the property to be searched.
>> + * @out_values: pointer to return found values.
>> + * @sz_min: minimum number of array elements to read
>> + * @sz_max: maximum number of array elements to read, if zero there is no
>> + *      upper limit on the number of elements in the dts entry but only
>> + *      sz_min will be read.
>> + *
>> + * Search for a property in a device node and read 32-bit value(s) from
>> + * it.
>> + *
>> + * Return: The number of elements read on success, -EINVAL if the property
>> + * does not exist, -ENODATA if property does not have a value, and 
>> -EOVERFLOW
>> + * if the property data is smaller than sz_min or longer than sz_max.
>> + *
>> + * The out_values is modified only if a valid u32 value can be decoded.
>> + */
>> +int dt_property_read_variable_u32_array(const struct dt_device_node *np,
>> +                                        const char *propname, u32 
>> *out_values,
>> +                                        size_t sz_min, size_t sz_max);
>> +
>> /**
>>  * dt_property_read_bool - Check if a property exists
>>  * @np: node to get the value
>> -- 
>> 2.17.1
>>