linux-kernel - Re: [PATCH v5 05/23] mailbox: Allow controller specific mapping using fwnode

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Message-ID: <aEmiOFwofEJyXm4R@smile.fi.intel.com>
Date: Wed, 11 Jun 2025 18:35:20 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Anup Patel <apatel@...tanamicro.com>
Cc: Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Jassi Brar <jassisinghbrar@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Uwe Kleine-König <ukleinek@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Len Brown <lenb@...nel.org>, Sunil V L <sunilvl@...tanamicro.com>,
	Rahul Pathak <rpathak@...tanamicro.com>,
	Leyfoon Tan <leyfoon.tan@...rfivetech.com>,
	Atish Patra <atish.patra@...ux.dev>,
	Andrew Jones <ajones@...tanamicro.com>,
	Samuel Holland <samuel.holland@...ive.com>,
	Anup Patel <anup@...infault.org>, linux-clk@...r.kernel.org,
	devicetree@...r.kernel.org, linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 05/23] mailbox: Allow controller specific mapping
 using fwnode

On Wed, Jun 11, 2025 at 11:52:20AM +0530, Anup Patel wrote:
> Introduce optional fw_node() callback which allows a mailbox controller
> driver to provide controller specific mapping using fwnode.
> 
> The Linux OF framework already implements fwnode operations for the
> Linux DD framework so the fw_xlate() callback works fine with device
> tree as well.

...

>  struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
>  {
> +	struct fwnode_reference_args fwspec;

Define

	struct fwnode_handle *fwnode;


>  	struct device *dev = cl->dev;

This better to be just a declaration.

>  	struct mbox_controller *mbox;
>  	struct of_phandle_args spec;
>  	struct mbox_chan *chan;
> +	unsigned int i;
>  	int ret;

With the above the below will look like...

> -	if (!dev || !dev->of_node) {
> -		pr_debug("%s: No owner device node\n", __func__);
> +	if (!dev || !dev_fwnode(dev)) {
> +		pr_debug("No owner %s\n", dev ? "fwnode" : "device");
>  		return ERR_PTR(-ENODEV);
>  	}
>  
> -	ret = of_parse_phandle_with_args(dev->of_node, "mboxes", "#mbox-cells",
> -					 index, &spec);
> +	ret = fwnode_property_get_reference_args(dev_fwnode(dev), "mboxes",
> +						 "#mbox-cells", 0, index, &fwspec);
>  	if (ret) {
>  		dev_err(dev, "%s: can't parse \"mboxes\" property\n", __func__);
>  		return ERR_PTR(ret);
>  	}

...this

	dev = cl->dev;
	if (!dev) {
		pr_debug("No owner device\n");
		return ERR_PTR(-ENODEV);
	}

	fwnode = dev_fwnode(dev);
	if (!fwnode) {
		dev_dbg(dev, "No owner fwnode\n");
		return ERR_PTR(-ENODEV);
	}

	ret = fwnode_property_get_reference_args(fwnode, "mboxes",
						 "#mbox-cells", 0, index, &fwspec);
	if (ret) {
		dev_err(dev, "%s: can't parse \"mboxes\" property\n", __func__);

You may save a few bytes by doing it as

		dev_err(dev, "%s: can't parse \"%s\" property\n", __func__, "mboxes");

		return ERR_PTR(ret);
	}

> +	spec.np = to_of_node(fwspec.fwnode);
> +	spec.args_count = fwspec.nargs;
> +	for (i = 0; i < spec.args_count; i++)
> +		spec.args[i] = fwspec.args[i];
> +
>  	scoped_guard(mutex, &con_mutex) {
>  		chan = ERR_PTR(-EPROBE_DEFER);
> -		list_for_each_entry(mbox, &mbox_cons, node)
> -			if (mbox->dev->of_node == spec.np) {
> +		list_for_each_entry(mbox, &mbox_cons, node) {

> +			if (mbox->fw_xlate && dev_fwnode(mbox->dev) == fwspec.fwnode) {

We have a helper device_match_fwnode()

> +				chan = mbox->fw_xlate(mbox, &fwspec);
> +				if (!IS_ERR(chan))
> +					break;
> +			} else if (mbox->of_xlate && mbox->dev->of_node == spec.np) {

No need to check OF node (again). Instead refactor as

			if (device_match_fwnode(...)) {
				if (fw_xlate) {
					...
				} else if (of_xlate) {
					...
				}
			}

>  				chan = mbox->of_xlate(mbox, &spec);
>  				if (!IS_ERR(chan))
>  					break;
>  			}
> +		}
>  
> -		of_node_put(spec.np);
> +		fwnode_handle_put(fwspec.fwnode);
>  
>  		if (IS_ERR(chan))
>  			return chan;


-- 
With Best Regards,
Andy Shevchenko