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    Subject[PATCH v2 2/5] of: reserved_mem: Accessor for acquiring reserved_mem
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    In some cases drivers referencing a reserved-memory region might want to
    remap the entire region, but when defining the reserved-memory by "size"
    the client driver has no means to know the associated base address of
    the reserved memory region.

    This patch adds an accessor for such drivers to acquire a handle to
    their associated reserved-memory for this purpose.

    A complicating factor for the implementation is that the reserved_mem
    objects are created from the flattened DeviceTree, as such we can't
    use the device_node address for comparison. Fortunately the name of the
    node will be used as "name" of the reserved_mem and will be used when
    building the full_name, so we can compare the "name" with the basename
    of the full_name to find the match.

    Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
    ---

    Changes since v1:
    - Previous patch provided interface to resolve memory-region reference, instead
    of direct lookup by device_node

    drivers/of/of_reserved_mem.c | 26 ++++++++++++++++++++++++++
    include/linux/of_reserved_mem.h | 5 +++++
    2 files changed, 31 insertions(+)

    diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
    index d507c3569a88..b40cfce68fd4 100644
    --- a/drivers/of/of_reserved_mem.c
    +++ b/drivers/of/of_reserved_mem.c
    @@ -397,3 +397,29 @@ void of_reserved_mem_device_release(struct device *dev)
    rmem->ops->device_release(rmem, dev);
    }
    EXPORT_SYMBOL_GPL(of_reserved_mem_device_release);
    +
    +/**
    + * of_reserved_mem_get() - acquire reserved_mem from a device node
    + * @np: node pointer of the desired reserved-memory region
    + *
    + * This function allows drivers to acquire a reference to the reserved_mem
    + * struct based on a device node handle.
    + *
    + * Returns a reserved_mem reference, or NULL on error.
    + */
    +struct reserved_mem *of_reserved_mem_get(struct device_node *np)
    +{
    + const char *name;
    + int i;
    +
    + if (!np->full_name)
    + return NULL;
    +
    + name = kbasename(np->full_name);
    + for (i = 0; i < reserved_mem_count; i++)
    + if (!strcmp(reserved_mem[i].name, name))
    + return &reserved_mem[i];
    +
    + return NULL;
    +}
    +EXPORT_SYMBOL_GPL(of_reserved_mem_get);
    diff --git a/include/linux/of_reserved_mem.h b/include/linux/of_reserved_mem.h
    index f8e1992d6423..91b1eb5076e4 100644
    --- a/include/linux/of_reserved_mem.h
    +++ b/include/linux/of_reserved_mem.h
    @@ -44,6 +44,7 @@ int early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
    void fdt_init_reserved_mem(void);
    void fdt_reserved_mem_save_node(unsigned long node, const char *uname,
    phys_addr_t base, phys_addr_t size);
    +struct reserved_mem *of_reserved_mem_get(struct device_node *np);
    #else
    static inline int of_reserved_mem_device_init_by_idx(struct device *dev,
    struct device_node *np, int idx)
    @@ -55,6 +56,10 @@ static inline void of_reserved_mem_device_release(struct device *pdev) { }
    static inline void fdt_init_reserved_mem(void) { }
    static inline void fdt_reserved_mem_save_node(unsigned long node,
    const char *uname, phys_addr_t base, phys_addr_t size) { }
    +static inline struct reserved_mem *of_reserved_mem_get(struct device_node *np)
    +{
    + return NULL;
    +}
    #endif

    /**
    --
    2.12.0
    \
     
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