linux-kernel - Re: [net-next PATCH v3 09/15] device property: Introduce fwnode_get

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Message-ID: <CAGETcx-7JVz=QLCMWicHqoagWYjeBXdFJmSv1v6MQhtPt2RS=Q@mail.gmail.com>
Date:   Tue, 12 Jan 2021 09:30:31 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     Calvin Johnson <calvin.johnson@....nxp.com>
Cc:     Grant Likely <grant.likely@....com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Jeremy Linton <jeremy.linton@....com>,
        Andrew Lunn <andrew@...n.ch>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Cristi Sovaiala <cristian.sovaiala@....com>,
        Florin Laurentiu Chiculita <florinlaurentiu.chiculita@....com>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Madalin Bucur <madalin.bucur@....nxp.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Pieter Jansen Van Vuuren <pieter.jansenvv@...boosystems.io>,
        Jon <jon@...id-run.com>,
        Diana Madalina Craciun <diana.craciun@....com>,
        LKML <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        linux.cj@...il.com,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [net-next PATCH v3 09/15] device property: Introduce fwnode_get_id()

On Tue, Jan 12, 2021 at 5:42 AM Calvin Johnson
<calvin.johnson@....nxp.com> wrote:
>
> Using fwnode_get_id(), get the reg property value for DT node
> or get the _ADR object value for ACPI node.
>
> Signed-off-by: Calvin Johnson <calvin.johnson@....nxp.com>
> ---
>
> Changes in v3:
> - Modified to retrieve reg property value for ACPI as well
> - Resolved compilation issue with CONFIG_ACPI = n
> - Added more info into documentation
>
> Changes in v2: None
>
>  drivers/base/property.c  | 33 +++++++++++++++++++++++++++++++++
>  include/linux/property.h |  1 +
>  2 files changed, 34 insertions(+)
>
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index 35b95c6ac0c6..2d51108cb936 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -580,6 +580,39 @@ const char *fwnode_get_name_prefix(const struct fwnode_handle *fwnode)
>         return fwnode_call_ptr_op(fwnode, get_name_prefix);
>  }
>
> +/**
> + * fwnode_get_id - Get the id of a fwnode.
> + * @fwnode: firmware node
> + * @id: id of the fwnode
> + *
> + * This function provides the id of a fwnode which can be either
> + * DT or ACPI node. For ACPI, "reg" property value, if present will
> + * be provided or else _ADR value will be provided.
> + * Returns 0 on success or a negative errno.
> + */
> +int fwnode_get_id(struct fwnode_handle *fwnode, u32 *id)
> +{
> +#ifdef CONFIG_ACPI
> +       unsigned long long adr;
> +       acpi_status status;
> +#endif
> +       int ret;
> +
> +       ret = fwnode_property_read_u32(fwnode, "reg", id);
> +       if (!(ret && is_acpi_node(fwnode)))
> +               return ret;
> +
> +#ifdef CONFIG_ACPI
> +       status = acpi_evaluate_integer(ACPI_HANDLE_FWNODE(fwnode),
> +                                      METHOD_NAME__ADR, NULL, &adr);
> +       if (ACPI_FAILURE(status))
> +               return -EINVAL;
> +       *id = (u32)adr;
> +#endif
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(fwnode_get_id);

Please don't do it this way. The whole point of fwnode_operations is
to avoid conditional stuff at the fwnode level. Also ACPI and DT
aren't mutually exclusive if I'm not mistaken.

Also, can you CC me on the entire series please? I want to reply to
some of your other patches too. Most of the fwnode changes don't seem
right. fwnode is lower level that the device-driver framework. Making
it aware of busses like mdio, etc doesn't sound right. Also, there's
already get_dev_from_fwnode() which is a much more efficient way to
look up/get a device from a fwnode instead of looping through a bus.

-Saravana