[PATCH fixup v1] of: base: register DT root as device

[Ahmad Fatoum]

Hello,

On 8/12/20 10:55 AM, Oleksij Rempel wrote:
> A usual board file contains at least one of_machine_is_compatible().
> Some of the have a rather long list with complicated version logic.
> 
> To avoid own implementation for driver management, register the root node
> of device tree as platform device. So, the main platform bus can attach
> proper board driver. After this patch a typical board.c file can reuse
> existing driver infrastructure.
> 
> After this patch, you will be able to see all registered board drivers
> with drvinfo as fallow:
> ...
> board-embest-riot
> board-protonic-imx6
>     dt-root.of
> ...
> 
> With devinfo, you'll be able to get some board specific information,
> if this is implemented:
> barebox at Protonic PRTI6Q board:/ devinfo dt-root.of
> Driver: board-protonic-imx6
> Bus: platform
> Parameters:
>   boardid: 0 (type: uint32)
>   boardrev: 1 (type: uint32)
> 
> Signed-off-by: Oleksij Rempel <o.rempel at pengutronix.de>
> ---
>  drivers/of/base.c     | 2 ++
>  drivers/of/platform.c | 5 +++++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 4c633bcd49..6f6cdc9379 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -2149,6 +2149,8 @@ int of_probe(void)
>  	if (firmware)
>  		of_platform_populate(firmware, NULL, NULL);
>  
> +	of_platform_device_create(root_node, NULL);
> +
>  	of_clk_init(root_node, NULL);
>  	of_platform_populate(root_node, of_default_bus_match_table, NULL);
>  
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index ca84cede23..767beebe06 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -50,6 +50,11 @@ static void of_device_make_bus_id(struct device_d *dev)
>  	const __be32 *reg;
>  	u64 addr;
>  
> +	if (!node->parent) {
> +		dev_set_name(dev, "dt-root.of");

Couldn't we drop the dt-? just let it be root.of.
dashes make use of device parameters less convenient should we
want to use those in future IIRC.

> +		return;
> +	}

of_platform_device_create does:

[-] check if device is available: not applicable to root node
[-] populate io resources: not applicable to root node
[-] use of_device_make_bus_id to get a name: not applicable to root node (prior to this patch)
[-] configure dma: not applicable to root node
[x] call platform_device_register

So why not just call platform_device_register yourself?
I'd assume you just need:

 dev = xzalloc(sizeof(*dev));
 dev->id = DEVICE_ID_SINGLE;
 dev->device_node = root_node;
 dev_set_name(dev, "dt-root.of")

 ret = platform_device_register(dev);
 if (!ret)
         return dev;


I'll test your patch layer anyway and report back if it fixes the issue I observed.
(Looks like it should though).

> +
>  	/* Construct the name, using parent nodes if necessary to ensure uniqueness */
>  	while (node->parent) {
>  		/*
> 

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