Re: [PATCH] device property: make device_property functions take const device *

[Chris Packham]

Hi Guenter,

On 20/04/23 04:41, Guenter Roeck wrote:
> device_property functions do not modify the device pointer passed to them.
> The underlying of_device and fwnode_ functions actually already take
> const * arguments. Mark the parameter constant to simplify conversion
> from of_property to device_property functions, and to let the calling code
> use const device pointers where possible.
>
> Cc: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>

Looks good to me. It eliminates the compiler warnings with my conversion 
patch.

For what it's worth

Reviewed-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>

> ---
> Found by Chris when trying to convert a driver from of_property_ to
> device_property_ functions. I don't really see a reason why the device
> parameter to device_property functions should not be const.
> Please let me know if I am missing sonething.
>
>   drivers/base/property.c  | 16 ++++++++--------
>   include/linux/property.h | 36 ++++++++++++++++++------------------
>   2 files changed, 26 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index 083a95791d3b..21d7a5d13e05 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -38,7 +38,7 @@ EXPORT_SYMBOL_GPL(__dev_fwnode_const);
>    *
>    * Check if property @propname is present in the device firmware description.
>    */
> -bool device_property_present(struct device *dev, const char *propname)
> +bool device_property_present(const struct device *dev, const char *propname)
>   {
>   	return fwnode_property_present(dev_fwnode(dev), propname);
>   }
> @@ -86,7 +86,7 @@ EXPORT_SYMBOL_GPL(fwnode_property_present);
>    *	   %-EOVERFLOW if the size of the property is not as expected.
>    *	   %-ENXIO if no suitable firmware interface is present.
>    */
> -int device_property_read_u8_array(struct device *dev, const char *propname,
> +int device_property_read_u8_array(const struct device *dev, const char *propname,
>   				  u8 *val, size_t nval)
>   {
>   	return fwnode_property_read_u8_array(dev_fwnode(dev), propname, val, nval);
> @@ -114,7 +114,7 @@ EXPORT_SYMBOL_GPL(device_property_read_u8_array);
>    *	   %-EOVERFLOW if the size of the property is not as expected.
>    *	   %-ENXIO if no suitable firmware interface is present.
>    */
> -int device_property_read_u16_array(struct device *dev, const char *propname,
> +int device_property_read_u16_array(const struct device *dev, const char *propname,
>   				   u16 *val, size_t nval)
>   {
>   	return fwnode_property_read_u16_array(dev_fwnode(dev), propname, val, nval);
> @@ -142,7 +142,7 @@ EXPORT_SYMBOL_GPL(device_property_read_u16_array);
>    *	   %-EOVERFLOW if the size of the property is not as expected.
>    *	   %-ENXIO if no suitable firmware interface is present.
>    */
> -int device_property_read_u32_array(struct device *dev, const char *propname,
> +int device_property_read_u32_array(const struct device *dev, const char *propname,
>   				   u32 *val, size_t nval)
>   {
>   	return fwnode_property_read_u32_array(dev_fwnode(dev), propname, val, nval);
> @@ -170,7 +170,7 @@ EXPORT_SYMBOL_GPL(device_property_read_u32_array);
>    *	   %-EOVERFLOW if the size of the property is not as expected.
>    *	   %-ENXIO if no suitable firmware interface is present.
>    */
> -int device_property_read_u64_array(struct device *dev, const char *propname,
> +int device_property_read_u64_array(const struct device *dev, const char *propname,
>   				   u64 *val, size_t nval)
>   {
>   	return fwnode_property_read_u64_array(dev_fwnode(dev), propname, val, nval);
> @@ -198,7 +198,7 @@ EXPORT_SYMBOL_GPL(device_property_read_u64_array);
>    *	   %-EOVERFLOW if the size of the property is not as expected.
>    *	   %-ENXIO if no suitable firmware interface is present.
>    */
> -int device_property_read_string_array(struct device *dev, const char *propname,
> +int device_property_read_string_array(const struct device *dev, const char *propname,
>   				      const char **val, size_t nval)
>   {
>   	return fwnode_property_read_string_array(dev_fwnode(dev), propname, val, nval);
> @@ -220,7 +220,7 @@ EXPORT_SYMBOL_GPL(device_property_read_string_array);
>    *	   %-EPROTO or %-EILSEQ if the property type is not a string.
>    *	   %-ENXIO if no suitable firmware interface is present.
>    */
> -int device_property_read_string(struct device *dev, const char *propname,
> +int device_property_read_string(const struct device *dev, const char *propname,
>   				const char **val)
>   {
>   	return fwnode_property_read_string(dev_fwnode(dev), propname, val);
> @@ -242,7 +242,7 @@ EXPORT_SYMBOL_GPL(device_property_read_string);
>    *	   %-EPROTO if the property is not an array of strings,
>    *	   %-ENXIO if no suitable firmware interface is present.
>    */
> -int device_property_match_string(struct device *dev, const char *propname,
> +int device_property_match_string(const struct device *dev, const char *propname,
>   				 const char *string)
>   {
>   	return fwnode_property_match_string(dev_fwnode(dev), propname, string);
> diff --git a/include/linux/property.h b/include/linux/property.h
> index 0a29db15ff34..66fe73ee430d 100644
> --- a/include/linux/property.h
> +++ b/include/linux/property.h
> @@ -40,20 +40,20 @@ struct fwnode_handle *__dev_fwnode(struct device *dev);
>   		 const struct device *: __dev_fwnode_const,	\
>   		 struct device *: __dev_fwnode)(dev)
>   
> -bool device_property_present(struct device *dev, const char *propname);
> -int device_property_read_u8_array(struct device *dev, const char *propname,
> +bool device_property_present(const struct device *dev, const char *propname);
> +int device_property_read_u8_array(const struct device *dev, const char *propname,
>   				  u8 *val, size_t nval);
> -int device_property_read_u16_array(struct device *dev, const char *propname,
> +int device_property_read_u16_array(const struct device *dev, const char *propname,
>   				   u16 *val, size_t nval);
> -int device_property_read_u32_array(struct device *dev, const char *propname,
> +int device_property_read_u32_array(const struct device *dev, const char *propname,
>   				   u32 *val, size_t nval);
> -int device_property_read_u64_array(struct device *dev, const char *propname,
> +int device_property_read_u64_array(const struct device *dev, const char *propname,
>   				   u64 *val, size_t nval);
> -int device_property_read_string_array(struct device *dev, const char *propname,
> +int device_property_read_string_array(const struct device *dev, const char *propname,
>   				      const char **val, size_t nval);
> -int device_property_read_string(struct device *dev, const char *propname,
> +int device_property_read_string(const struct device *dev, const char *propname,
>   				const char **val);
> -int device_property_match_string(struct device *dev,
> +int device_property_match_string(const struct device *dev,
>   				 const char *propname, const char *string);
>   
>   bool fwnode_property_present(const struct fwnode_handle *fwnode,
> @@ -143,57 +143,57 @@ int fwnode_irq_get_byname(const struct fwnode_handle *fwnode, const char *name);
>   
>   unsigned int device_get_child_node_count(const struct device *dev);
>   
> -static inline bool device_property_read_bool(struct device *dev,
> +static inline bool device_property_read_bool(const struct device *dev,
>   					     const char *propname)
>   {
>   	return device_property_present(dev, propname);
>   }
>   
> -static inline int device_property_read_u8(struct device *dev,
> +static inline int device_property_read_u8(const struct device *dev,
>   					  const char *propname, u8 *val)
>   {
>   	return device_property_read_u8_array(dev, propname, val, 1);
>   }
>   
> -static inline int device_property_read_u16(struct device *dev,
> +static inline int device_property_read_u16(const struct device *dev,
>   					   const char *propname, u16 *val)
>   {
>   	return device_property_read_u16_array(dev, propname, val, 1);
>   }
>   
> -static inline int device_property_read_u32(struct device *dev,
> +static inline int device_property_read_u32(const struct device *dev,
>   					   const char *propname, u32 *val)
>   {
>   	return device_property_read_u32_array(dev, propname, val, 1);
>   }
>   
> -static inline int device_property_read_u64(struct device *dev,
> +static inline int device_property_read_u64(const struct device *dev,
>   					   const char *propname, u64 *val)
>   {
>   	return device_property_read_u64_array(dev, propname, val, 1);
>   }
>   
> -static inline int device_property_count_u8(struct device *dev, const char *propname)
> +static inline int device_property_count_u8(const struct device *dev, const char *propname)
>   {
>   	return device_property_read_u8_array(dev, propname, NULL, 0);
>   }
>   
> -static inline int device_property_count_u16(struct device *dev, const char *propname)
> +static inline int device_property_count_u16(const struct device *dev, const char *propname)
>   {
>   	return device_property_read_u16_array(dev, propname, NULL, 0);
>   }
>   
> -static inline int device_property_count_u32(struct device *dev, const char *propname)
> +static inline int device_property_count_u32(const struct device *dev, const char *propname)
>   {
>   	return device_property_read_u32_array(dev, propname, NULL, 0);
>   }
>   
> -static inline int device_property_count_u64(struct device *dev, const char *propname)
> +static inline int device_property_count_u64(const struct device *dev, const char *propname)
>   {
>   	return device_property_read_u64_array(dev, propname, NULL, 0);
>   }
>   
> -static inline int device_property_string_array_count(struct device *dev,
> +static inline int device_property_string_array_count(const struct device *dev,
>   						     const char *propname)
>   {
>   	return device_property_read_string_array(dev, propname, NULL, 0);