Re: [Qemu-devel] [PATCH v2 3/7] device_tree: introduce qemu_fdt_node_path

[Eric Auger]

Hi David,
On 01/11/2016 03:38 AM, David Gibson wrote:
> On Wed, Jan 06, 2016 at 03:13:21PM +0000, Eric Auger wrote:
>> This new helper routine returns the node path of a device
>> referred to by its node name and compat string.
> 
> What if there are multiple nodes matching the name and compat?
The function would return the first one. I can improve the doc comment.
Do you think it is a problem stopping at the first one? Is it a real
life test case I have to handle here?

Thanks

Eric
> 
>>
>> Signed-off-by: Eric Auger <address@hidden>
>>
>> ---
>>
>> v1 -> v2:
>> - move doc comment in header file
>> - do not use a fixed size buffer
>> - break on errors in while loop
>> - use strcmp instead of strncmp
>>
>> RFC -> v1:
>> - improve error handling according to Alex' comments
>> ---
>>  device_tree.c                | 37 +++++++++++++++++++++++++++++++++++++
>>  include/sysemu/device_tree.h | 14 ++++++++++++++
>>  2 files changed, 51 insertions(+)
>>
>> diff --git a/device_tree.c b/device_tree.c
>> index b262c2d..8441e01 100644
>> --- a/device_tree.c
>> +++ b/device_tree.c
>> @@ -231,6 +231,43 @@ static int findnode_nofail(void *fdt, const char 
>> *node_path)
>>      return offset;
>>  }
>>  
>> +int qemu_fdt_node_path(void *fdt, const char *name, char *compat,
>> +                       char **node_path)
>> +{
>> +    int offset, len, ret;
>> +    const char *iter_name;
>> +    unsigned int path_len = 16;
>> +    char *path;
>> +
>> +    *node_path = NULL;
>> +    offset = fdt_node_offset_by_compatible(fdt, -1, compat);
>> +
>> +    while (offset >= 0) {
>> +        iter_name = fdt_get_name(fdt, offset, &len);
>> +        if (!iter_name) {
>> +            offset = len;
>> +            break;
>> +        }
>> +        if (!strcmp(iter_name, name)) {
>> +            goto found;
>> +        }
>> +        offset = fdt_node_offset_by_compatible(fdt, offset, compat);
>> +    }
>> +    return offset;
>> +
>> +found:
>> +    path = g_malloc(path_len);
>> +    while ((ret = fdt_get_path(fdt, offset, path, path_len))
>> +            == -FDT_ERR_NOSPACE) {
>> +        path_len += 16;
>> +        path = g_realloc(path, path_len);
>> +    }
>> +    if (!ret) {
>> +        *node_path = path;
>> +    }
>> +    return ret;
>> +}
>> +
>>  int qemu_fdt_setprop(void *fdt, const char *node_path,
>>                       const char *property, const void *val, int size)
>>  {
>> diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
>> index fdf25a4..269cb1c 100644
>> --- a/include/sysemu/device_tree.h
>> +++ b/include/sysemu/device_tree.h
>> @@ -20,6 +20,20 @@ void *load_device_tree(const char *filename_path, int 
>> *sizep);
>>  void *load_device_tree_from_sysfs(void);
>>  #endif
>>  
>> +/**
>> + * qemu_fdt_node_path: return the node path of a device, given its
>> + * node name and its compat string
>> + * @fdt: pointer to the dt blob
>> + * @name: device node name
>> + * @compat: compatibility string of the device
>> + * @node_path: returned node path
>> + *
>> + * upon success, the path is output at node_path address
>> + * returns 0 on success, < 0 on failure
>> + */
>> +int qemu_fdt_node_path(void *fdt, const char *name, char *compat,
>> +                       char **node_path);
>> +
>>  int qemu_fdt_setprop(void *fdt, const char *node_path,
>>                       const char *property, const void *val, int size);
>>  int qemu_fdt_setprop_cell(void *fdt, const char *node_path,
>