linux-kernel - Re: [PATCH 1/2] of: property: add of_property_for_each

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Message-ID: <20240627214355.GA601888-robh@kernel.org>
Date: Thu, 27 Jun 2024 15:43:55 -0600
From: Rob Herring <robh@...nel.org>
To: "Peng Fan (OSS)" <peng.fan@....nxp.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>
Cc: Saravana Kannan <saravanak@...gle.com>,
	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
	Peng Fan <peng.fan@....com>
Subject: Re: [PATCH 1/2] of: property: add of_property_for_each_u64

+Luca

On Fri, Jun 21, 2024 at 08:36:39PM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@....com>
> 
> Preparing for assigned-clock-rates-u64 support, add function
> of_property_for_each_u64 to iterate each u64 value
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  drivers/of/property.c | 23 +++++++++++++++++++++++
>  include/linux/of.h    | 24 ++++++++++++++++++++++++
>  2 files changed, 47 insertions(+)
> 
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index 164d77cb9445..b89c3ab01d44 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -548,6 +548,29 @@ const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
>  }
>  EXPORT_SYMBOL_GPL(of_prop_next_u32);
>  
> +const __be32 *of_prop_next_u64(struct property *prop, const __be32 *cur,
> +			       u64 *pu)

struct property can be const

> +{
> +	const void *curv = cur;
> +
> +	if (!prop)
> +		return NULL;
> +
> +	if (!cur) {
> +		curv = prop->value;
> +		goto out_val;
> +	}
> +
> +	curv += sizeof(*cur) * 2;
> +	if (curv >= prop->value + prop->length)
> +		return NULL;
> +
> +out_val:
> +	*pu = of_read_number(curv, 2);
> +	return curv;
> +}
> +EXPORT_SYMBOL_GPL(of_prop_next_u64);
> +
>  const char *of_prop_next_string(struct property *prop, const char *cur)
>  {
>  	const void *curv = cur;
> diff --git a/include/linux/of.h b/include/linux/of.h
> index 13cf7a43b473..464eca6a4636 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -439,6 +439,18 @@ extern int of_detach_node(struct device_node *);
>   */
>  const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
>  			       u32 *pu);
> +
> +/*
> + * struct property *prop;
> + * const __be32 *p;
> + * u64 u;
> + *
> + * of_property_for_each_u64(np, "propname", prop, p, u)
> + *         printk("U64 value: %llx\n", u);
> + */
> +const __be32 *of_prop_next_u64(struct property *prop, const __be32 *cur,
> +			       u64 *pu);
> +
>  /*
>   * struct property *prop;
>   * const char *s;
> @@ -834,6 +846,12 @@ static inline const __be32 *of_prop_next_u32(struct property *prop,
>  	return NULL;
>  }
>  
> +static inline const __be32 *of_prop_next_u64(struct property *prop,
> +		const __be32 *cur, u64 *pu)
> +{
> +	return NULL;
> +}
> +
>  static inline const char *of_prop_next_string(struct property *prop,
>  		const char *cur)
>  {
> @@ -1437,6 +1455,12 @@ static inline int of_property_read_s32(const struct device_node *np,
>  		p;						\
>  		p = of_prop_next_u32(prop, p, &u))
>  
> +#define of_property_for_each_u64(np, propname, prop, p, u)	\
> +	for (prop = of_find_property(np, propname, NULL),	\
> +		p = of_prop_next_u64(prop, NULL, &u);		\
> +		p;						\
> +		p = of_prop_next_u64(prop, p, &u))

I think we want to define this differently to avoid exposing struct 
property and the property data directly. Like this:

#define of_property_for_each_u64(np, propname, u) \
  for (struct property *_prop = of_find_property(np, propname, NULL),
         const __be32 *_p = of_prop_next_u64(_prop, NULL, &u);
         _p;
         _p = of_prop_next_u64(_prop, _p, &u))

See this discussion for context[1].

Rob

[1] https://lore.kernel.org/all/20240624232122.3cfe03f8@booty/