linux-kernel - Re: [PATCH v7 3/6] reset: mchp: sparx5: Map cpu-syscon locally in case of LAN966x

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Message-ID: <71fb65a929e5d5be86f95ab76591beb77e641c14.camel@microchip.com>
Date: Wed, 9 Oct 2024 09:29:52 +0200
From: Steen Hegelund <steen.hegelund@...rochip.com>
To: Herve Codina <herve.codina@...tlin.com>, Geert Uytterhoeven
	<geert@...ux-m68k.org>, Andy Shevchenko <andy.shevchenko@...il.com>, "Simon
 Horman" <horms@...nel.org>, Lee Jones <lee@...nel.org>, Arnd Bergmann
	<arnd@...db.de>, Derek Kiernan <derek.kiernan@....com>, Dragan Cvetic
	<dragan.cvetic@....com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>, Philipp Zabel <p.zabel@...gutronix.de>,
	Lars Povlsen <lars.povlsen@...rochip.com>, Daniel Machon
	<daniel.machon@...rochip.com>, <UNGLinuxDriver@...rochip.com>, Rob Herring
	<robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
	<conor+dt@...nel.org>, Saravana Kannan <saravanak@...gle.com>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Horatiu Vultur <horatiu.vultur@...rochip.com>, "Andrew
 Lunn" <andrew@...n.ch>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
	<linux-pci@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>, "Allan
 Nielsen" <allan.nielsen@...rochip.com>, Luca Ceresoli
	<luca.ceresoli@...tlin.com>, Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v7 3/6] reset: mchp: sparx5: Map cpu-syscon locally in
 case of LAN966x

Hi Herve,

On Thu, 2024-10-03 at 10:16 +0200, Herve Codina wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
> know the content is safe
> 
> In the LAN966x PCI device use case, the syscon API cannot be used as
> it does not support device removal [1]. A syscon device is a core
> "system" device and not a device available in some addon boards and
> so,
> it is not supposed to be removed. The syscon API follows this
> assumption
> but this assumption is no longer valid in the LAN966x use case.
> 
> In order to avoid the use of the syscon API and so, support for
> removal,
> use a local mapping of the syscon device.
> 
> Link:
> https://lore.kernel.org/all/20240923100741.11277439@bootlin.com/ [1]
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> ---
>  drivers/reset/reset-microchip-sparx5.c | 35
> +++++++++++++++++++++++++-
>  1 file changed, 34 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/reset/reset-microchip-sparx5.c
> b/drivers/reset/reset-microchip-sparx5.c
> index 636e85c388b0..48a62d5da78d 100644
> --- a/drivers/reset/reset-microchip-sparx5.c
> +++ b/drivers/reset/reset-microchip-sparx5.c
> @@ -62,6 +62,28 @@ static const struct reset_control_ops
> sparx5_reset_ops = {
>         .reset = sparx5_reset_noop,
>  };
> 
> +static const struct regmap_config mchp_lan966x_syscon_regmap_config
> = {
> +       .reg_bits = 32,
> +       .val_bits = 32,
> +       .reg_stride = 4,
> +};
> +
> +static struct regmap *mchp_lan966x_syscon_to_regmap(struct device
> *dev,
> +                                                   struct
> device_node *syscon_np)
> +{
> +       struct regmap_config regmap_config =
> mchp_lan966x_syscon_regmap_config;
> +       resource_size_t size;
> +       void __iomem *base;
> +
> +       base = devm_of_iomap(dev, syscon_np, 0, &size);
> +       if (IS_ERR(base))
> +               return ERR_CAST(base);
> +
> +       regmap_config.max_register = size - 4;
> +
> +       return devm_regmap_init_mmio(dev, base, &regmap_config);
> +}
> +
>  static int mchp_sparx5_map_syscon(struct platform_device *pdev, char
> *name,
>                                   struct regmap **target)
>  {
> @@ -72,7 +94,18 @@ static int mchp_sparx5_map_syscon(struct
> platform_device *pdev, char *name,
>         syscon_np = of_parse_phandle(pdev->dev.of_node, name, 0);
>         if (!syscon_np)
>                 return -ENODEV;
> -       regmap = syscon_node_to_regmap(syscon_np);
> +
> +       /*
> +        * The syscon API doesn't support syscon device removal.
> +        * When used in LAN966x PCI device, the cpu-syscon device
> needs to be
> +        * removed when the PCI device is removed.
> +        * In case of LAN966x, map the syscon device locally to
> support the
> +        * device removal.
> +        */
> +       if (of_device_is_compatible(pdev->dev.of_node,
> "microchip,lan966x-switch-reset"))
> +               regmap = mchp_lan966x_syscon_to_regmap(&pdev->dev,
> syscon_np);
> +       else
> +               regmap = syscon_node_to_regmap(syscon_np);
>         of_node_put(syscon_np);
>         if (IS_ERR(regmap)) {
>                 err = PTR_ERR(regmap);
> --
> 2.46.1
> 

This looks good to me.

Reviewed-by: Steen Hegelund <Steen.Hegelund@...rochip.com>

BR
Steen