On Wed, Sep 18, 2019 at 1:47 PM Raghavendra Rao Ananta
<rananta@xxxxxxxxxxxxxx> wrote:
>
> On some embedded systems, the '/memory' dt-property gets updated
> by the bootloader (for example, the DDR configuration) and then
> gets passed onto the kernel. The device drivers may have to read
> the properties at runtime to make decisions. Hence, add
> of_get_memory_prop() for the device drivers to query the requested
Function name doesn't match. Device drivers don't need to access the FDT.
> properties.
>
> Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxxxxxx>
> ---
> drivers/of/fdt.c | 27 +++++++++++++++++++++++++++
> include/linux/of_fdt.h | 1 +
> 2 files changed, 28 insertions(+)
We don't add kernel api's without users.
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 223d617ecfe1..925cf2852433 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -79,6 +79,33 @@ void __init of_fdt_limit_memory(int limit)
> }
> }
>
> +/**
> + * of_fdt_get_memory_prop - Return the requested property from the /memory node
> + *
> + * On match, returns a non-zero positive value which represents the property
> + * value. Otherwise returns -ENOENT.
> + */
> +int of_fdt_get_memory_prop(const char *pname)
> +{
> + int memory;
> + int len;
> + fdt32_t *prop = NULL;
> +
> + if (!pname)
> + return -EINVAL;
> +
> + memory = fdt_path_offset(initial_boot_params, "/memory");
Memory nodes should have a unit-address, so this won't work frequently.
> + if (memory > 0)
> + prop = fdt_getprop_w(initial_boot_params, memory,
> + pname, &len);
> +
> + if (!prop || len != sizeof(u32))
> + return -ENOENT;
> +
> + return fdt32_to_cpu(*prop);
> +}
> +EXPORT_SYMBOL_GPL(of_fdt_get_memory_prop);
> +
> static bool of_fdt_device_is_available(const void *blob, unsigned long node)
> {
> const char *status = fdt_getprop(blob, node, "status", NULL);
> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
> index acf820e88952..537f29373358 100644
> --- a/include/linux/of_fdt.h
> +++ b/include/linux/of_fdt.h
> @@ -38,6 +38,7 @@ extern char __dtb_end[];
> /* Other Prototypes */
> extern u64 of_flat_dt_translate_address(unsigned long node);
> extern void of_fdt_limit_memory(int limit);
> +extern int of_fdt_get_memory_prop(const char *pname);
> #endif /* CONFIG_OF_FLATTREE */
>
> #ifdef CONFIG_OF_EARLY_FLATTREE
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
