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    Subject[PATCHv7 01/12] of: introduce of_property_for_each_phandle_with_args()
    Date
    Iterating over a property containing a list of phandles with arguments
    is a common operation for device drivers. This patch adds a new
    of_property_for_each_phandle_with_args() macro to make the iteration
    simpler.

    Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
    Cc: Rob Herring <robherring2@gmail.com>
    Cc: Grant Likely <grant.likely@linaro.org>
    ---
    v7:
    Fixed some minors pointed by Rob and Stephen.

    v6++++:
    Iterate without intrducing a new struct.

    v6+++:
    Introduced a new struct "of_phandle_iter" to keep the state when
    iterating over the list.

    v6++:
    Optimized to avoid O(n^2), suggested by Stephen Warren.
    http://lists.linuxfoundation.org/pipermail/iommu/2013-November/007066.html

    I didn't introduce any struct to hold params and state here.

    v6+:
    Use the description, which Grant Likely proposed, to be full enough
    that a future reader can figure out why a patch was written.

    v5:
    New patch for v5.

    Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
    ---
    drivers/of/base.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
    include/linux/of.h | 32 ++++++++++++++++++++++++++++++++
    2 files changed, 78 insertions(+)

    diff --git a/drivers/of/base.c b/drivers/of/base.c
    index f807d0e..cd4ab05 100644
    --- a/drivers/of/base.c
    +++ b/drivers/of/base.c
    @@ -1201,6 +1201,52 @@ void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
    printk("\n");
    }

    +const __be32 *of_phandle_iter_next(const char *cells_name, int cell_count,
    + const __be32 *cur, const __be32 *end,
    + struct of_phandle_args *out_args)
    +{
    + struct device_node *dn;
    + int i;
    +
    + if (!cells_name && !cell_count)
    + return NULL;
    +
    + if (!cur || (cur >= end))
    + return NULL;
    +
    + dn = of_find_node_by_phandle(be32_to_cpup(cur++));
    + if (!dn)
    + return NULL;
    +
    + if (cells_name)
    + if (of_property_read_u32(dn, cells_name, &cell_count))
    + return NULL;
    +
    + out_args->np = dn;
    + out_args->args_count = cell_count;
    + for (i = 0; i < cell_count; i++)
    + out_args->args[i] = be32_to_cpup(cur++);
    +
    + return cur;
    +}
    +EXPORT_SYMBOL_GPL(of_phandle_iter_next);
    +
    +const __be32 *of_phandle_iter_init(const struct device_node *np,
    + const char *list_name,
    + const __be32 **end)
    +{
    + size_t bytes;
    + const __be32 *cur;
    +
    + cur = of_get_property(np, list_name, &bytes);
    + *end = cur;
    + if (bytes)
    + *end += bytes / sizeof(*cur);
    +
    + return cur;
    +}
    +EXPORT_SYMBOL_GPL(of_phandle_iter_init);
    +
    static int __of_parse_phandle_with_args(const struct device_node *np,
    const char *list_name,
    const char *cells_name,
    diff --git a/include/linux/of.h b/include/linux/of.h
    index 276c546..4345582 100644
    --- a/include/linux/of.h
    +++ b/include/linux/of.h
    @@ -303,6 +303,14 @@ extern int of_parse_phandle_with_fixed_args(const struct device_node *np,
    extern int of_count_phandle_with_args(const struct device_node *np,
    const char *list_name, const char *cells_name);

    +extern const __be32 *of_phandle_iter_init(const struct device_node *np,
    + const char *list_name,
    + const __be32 **end);
    +extern const __be32 *of_phandle_iter_next(const char *cells_name,
    + int cell_count,
    + const __be32 *cur, const __be32 *end,
    + struct of_phandle_args *out_args);
    +
    extern void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align));
    extern int of_alias_get_id(struct device_node *np, const char *stem);

    @@ -527,6 +535,22 @@ static inline int of_count_phandle_with_args(struct device_node *np,
    return -ENOSYS;
    }

    +static inline const __be32 *of_phandle_iter_init(const struct device_node *np,
    + const char *list_name,
    + const __be32 **end)
    +{
    + return NULL;
    +}
    +
    +static inline const __be32 *of_phandle_iter_next(const char *cells_name,
    + int cell_count,
    + const __be32 *cur,
    + const __be32 *end,
    + struct of_phandle_args *out_args);
    +{
    + return NULL;
    +}
    +
    static inline int of_alias_get_id(struct device_node *np, const char *stem)
    {
    return -ENOSYS;
    @@ -613,6 +637,14 @@ static inline int of_property_read_u32(const struct device_node *np,
    s; \
    s = of_prop_next_string(prop, s))

    +#define of_property_for_each_phandle_with_args(node, list_name, cells_name, \
    + cell_count, out_args, cur, end) \
    + for (cur = of_phandle_iter_init(node, list_name, &end), \
    + cur = of_phandle_iter_next(cells_name, cell_count, \
    + cur, end, &out_args); \
    + cur; \
    + cur = of_phandle_iter_next(cells_name, cell_count, cur, end, &out_args))
    +
    #if defined(CONFIG_PROC_FS) && defined(CONFIG_PROC_DEVICETREE)
    extern void proc_device_tree_add_node(struct device_node *, struct proc_dir_entry *);
    extern void proc_device_tree_add_prop(struct proc_dir_entry *pde, struct property *prop);
    --
    1.8.1.5


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