Re: [PATCH v6 02/12] Driver core: Unified device properties interface for platform firmware

[Grant Likely <grant.likely@linaro.org>]

On Tue, 21 Oct 2014 23:15:50 +0200
, "Rafael J. Wysocki" <rjw@rjwysocki.net>
 wrote:
> From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> 
> Add a uniform interface by which device drivers can request device
> properties from the platform firmware by providing a property name
> and the corresponding data type.  The purpose of it is to help to
> write portable code that won't depend on any particular platform
> firmware interface.
> 
> The following general helper functions are added:
> 
> device_property_present()
> device_property_read_u8()
> device_property_read_u16()
> device_property_read_u32()
> device_property_read_u64()
> device_property_read_string()
> device_property_read_u8_array()
> device_property_read_u16_array()
> device_property_read_u32_array()
> device_property_read_u64_array()
> device_property_read_string_array()
> 
> The first one allows the caller to check if the given property is
> present.  The next 5 of them allow single-valued properties of
> various types to be retrieved in a uniform way.  The remaining 5 are
> for reading properties with multiple values (arrays of either numbers
> or strings).
> 
> The interface covers both ACPI and Device Trees.
> 
> This change set includes material from Mika Westerberg and Aaron Lu.
> 
> Signed-off-by: Aaron Lu <aaron.lu@intel.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> 
> Changes from v5:
> - acpi_dev_prop_read() can now handle both list (package) and single-value
>   properties (the latter are tried first for the last argument equal to 1).
> - There is a new macro to generate the bodies of device_property_read_u*_array().
> - device_property_read_u*() are implemented using device_property_read_u*_array().
> - device_property_read_bool() is a new static inline wrapper around
>   device_property_present().
> 
> ---
>  drivers/acpi/property.c  |  178 +++++++++++++++++++++++++++++++++++
>  drivers/base/Makefile    |    2 
>  drivers/base/property.c  |  233 +++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/of/base.c        |  106 ++++++++++++++++++---
>  include/linux/acpi.h     |   32 ++++++
>  include/linux/of.h       |   22 ++++
>  include/linux/property.h |   53 ++++++++++
>  7 files changed, 609 insertions(+), 17 deletions(-)
>  create mode 100644 drivers/base/property.c
>  create mode 100644 include/linux/property.h
> 
> Index: linux-pm/include/linux/property.h
> ===================================================================
> --- /dev/null
> +++ linux-pm/include/linux/property.h
> @@ -0,0 +1,53 @@
> +/*
> + * property.h - Unified device property interface.
> + *
> + * Copyright (C) 2014, Intel Corporation
> + * Authors: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> + *          Mika Westerberg <mika.westerberg@linux.intel.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifndef _LINUX_PROPERTY_H_
> +#define _LINUX_PROPERTY_H_
> +
> +#include <linux/types.h>
> +
> +struct device;
> +
> +enum dev_prop_type {
> +	DEV_PROP_U8,
> +	DEV_PROP_U16,
> +	DEV_PROP_U32,
> +	DEV_PROP_U64,
> +	DEV_PROP_STRING,
> +	DEV_PROP_MAX,
> +};
> +
> +bool device_property_present(struct device *dev, const char *propname);
> +int device_property_read_u8_array(struct device *dev, const char *propname,
> +				  u8 *val, size_t nval);
> +int device_property_read_u16_array(struct device *dev, const char *propname,
> +				   u16 *val, size_t nval);
> +int device_property_read_u32_array(struct device *dev, const char *propname,
> +				   u32 *val, size_t nval);
> +int device_property_read_u64_array(struct device *dev, const char *propname,
> +				   u64 *val, size_t nval);
> +int device_property_read_string_array(struct device *dev, const char *propname,
> +				      char **val, size_t nval);

I'm not sure if I asked this elsewhere. Can 'val' be made a const char **?

g.