[PATCH] of: Add a reg-names property to name reg entries

[Grant Likely]

On Mon, Oct 24, 2011 at 05:54:57PM +0200, Benoit Cousson wrote:
> In a HW system, resources in general have name to identify them.
> The is the case as well for DT "reg" entries.
> The current DT mechanism is relying on the "reg" order to identify
> the proper resource.
> Add a reg-names property to allow the possiblity to provide a name
> to any reg entries.
> If the name is available, use it to name the resource, otherwise
> keep the legacy device name.
> 
> Signed-off-by: Benoit Cousson <b-cousson at ti.com>
> Cc: Grant Likely <grant.likely at secretlab.ca>
> Cc: Rob Herring <rob.herring at calxeda.com>
> ---
> 
>  Documentation/devicetree/bindings/reg-names.txt |   48 +++++++++++++++++++++++
>  drivers/of/address.c                            |   22 ++++++++--
>  2 files changed, 65 insertions(+), 5 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/reg-names.txt
> 
> diff --git a/Documentation/devicetree/bindings/reg-names.txt b/Documentation/devicetree/bindings/reg-names.txt
> new file mode 100644
> index 0000000..5554065
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reg-names.txt
> @@ -0,0 +1,48 @@
> +reg-names property
> +
> +In a HW system, resources in general have name to identify them.
> +The is the case as well for register entries.
> +The current DT mechanism is relying on the "reg" order to identify
> +the proper resource. The reg-names is adding the possiblity to
> +provide a name to reg entries.
> +
> +Usage:
> +
> +This attribute must be used along with a regular reg entry. If not
> +it will be simply ignored.
> +The number of entry must match otherwise the default device name will
> +be used to as the resource name.
> +
> +
> +Example:
> +
> +
> +l4-abe {
> +	compatible = "simple-bus";
> +	#address-cells = <2>;
> +	#size-cells = <1>;
> +	ranges = <0 0 0x48000000 0x00001000>, /* MPU path */
> +		 <1 0 0x49000000 0x00001000>; /* L3 path */
> +	mcasp {
> +		compatible = "ti,mcasp";
> +		reg = <0 0x10 0x10>, <0 0x20 0x10>,
> +		      <1 0x10 0x10>, <1 0x20 0x10>;
> +		reg-names = "mpu", "dat",
> +			    "dma", "dma_dat";
> +	};
> +
> +	timer {
> +		compatible = "ti,timer";
> +		reg = <0 0x40 0x10>, <1 0x40 0x10>;
> +		reg-names = "mpu", "dma";
> +	};
> +};
> +
> +
> +usb {
> +	compatible = "ti,usb-host";
> +	reg = <0x4a064000 0x800>, <0x4a064800 0x200>,
> +	      <0x4a064c00 0x200>;
> +	reg-names = "config", "ohci", "ehci";
> +};
> +
> diff --git a/drivers/of/address.c b/drivers/of/address.c
> index 72c33fb..1f9f8cb 100644
> --- a/drivers/of/address.c
> +++ b/drivers/of/address.c
> @@ -14,7 +14,7 @@
>  static struct of_bus *of_match_bus(struct device_node *np);
>  static int __of_address_to_resource(struct device_node *dev,
>  		const __be32 *addrp, u64 size, unsigned int flags,
> -				    struct resource *r);
> +		const char *name, struct resource *r);
>  
>  /* Debug utility */
>  #ifdef DEBUG
> @@ -215,7 +215,7 @@ int of_pci_address_to_resource(struct device_node *dev, int bar,
>  	addrp = of_get_pci_address(dev, bar, &size, &flags);
>  	if (addrp == NULL)
>  		return -EINVAL;
> -	return __of_address_to_resource(dev, addrp, size, flags, r);
> +	return __of_address_to_resource(dev, addrp, size, flags, NULL, r);
>  }
>  EXPORT_SYMBOL_GPL(of_pci_address_to_resource);
>  #endif /* CONFIG_PCI */
> @@ -529,7 +529,7 @@ EXPORT_SYMBOL(of_get_address);
>  
>  static int __of_address_to_resource(struct device_node *dev,
>  		const __be32 *addrp, u64 size, unsigned int flags,
> -				    struct resource *r)
> +		const char *name, struct resource *r)
>  {
>  	u64 taddr;
>  
> @@ -551,7 +551,11 @@ static int __of_address_to_resource(struct device_node *dev,
>  		r->end = taddr + size - 1;
>  	}
>  	r->flags = flags;
> -	r->name = dev->full_name;
> +	if (name)
> +		r->name = name;
> +	else
> +		r->name = dev->full_name;

This form please:
	r->name = name ? name : dev->full_name;

In general, I'm inclined to accept this patch as we talked about at
plumbers.  However, this particular hunk gives me pause as there is
still the objection that Russell raised about the (ab)use of r->name
for insert the resource name.

So, no I won't reject this patch, but I first what to have some idea
of what the plan is to migrate away from using r->name.  Perhaps we
can talk about this tomorrow.

>  	return 0;
>  }
>  
> @@ -569,11 +573,19 @@ int of_address_to_resource(struct device_node *dev, int index,
>  	const __be32	*addrp;
>  	u64		size;
>  	unsigned int	flags;
> +	const char	*name = NULL;
> +	int		name_cnt;
>  
>  	addrp = of_get_address(dev, index, &size, &flags);
>  	if (addrp == NULL)
>  		return -EINVAL;
> -	return __of_address_to_resource(dev, addrp, size, flags, r);
> +
> +	/* Get "reg-names" property to add a name to a resource */
> +	name_cnt = of_property_count_strings(dev, "reg-names");
> +	if (name_cnt > 0)
> +		of_property_read_string_index(dev, "reg-names",	index, &name);

Why not simply:
	of_property_read_string_index(dev, "reg-names", index, &name);

If it fails, then name remains NULL and everything works.


> +
> +	return __of_address_to_resource(dev, addrp, size, flags, name, r);
>  }
>  EXPORT_SYMBOL_GPL(of_address_to_resource);
>  
> -- 
> 1.7.5.4
> 
> 
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