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    SubjectRe: [PATCH v3 2/5] of: reserved_mem: Accessor for acquiring reserved_mem
    On Wed, Oct 4, 2017 at 10:32 PM, Bjorn Andersson
    <bjorn.andersson@linaro.org> wrote:
    > 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 v2:
    > - None
    >
    > 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

    *_get() generally implies reference counting. Maybe "lookup" instead. Otherwise,

    Reviewed-by: Rob Herring <robh@kernel.org>

    > + * @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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