linux-kernel - Re: [PATCH v3] of: property: Add fw_devlink support for interrupt-map property

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Date: Wed, 8 May 2024 13:54:48 -0700
From: Saravana Kannan <saravanak@...gle.com>
To: Anup Patel <apatel@...tanamicro.com>
Cc: Rob Herring <robh@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Atish Patra <atishp@...shpatra.org>, 
	Andrew Jones <ajones@...tanamicro.com>, Sunil V L <sunilvl@...tanamicro.com>, 
	Anup Patel <anup@...infault.org>, linux-riscv@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v3] of: property: Add fw_devlink support for interrupt-map property

On Mon, Apr 29, 2024 at 9:08 PM Anup Patel <apatel@...tanamicro.com> wrote:
>
> Some of the PCI controllers (such as generic PCI host controller)
> use "interrupt-map" DT property to describe the mapping between
> PCI endpoints and PCI interrupt pins. This the only case where
> the interrupts are not described in DT.
>
> Currently, there is no fw_devlink created based on "interrupt-map"
> DT property so interrupt controller is not guaranteed to be probed
> before PCI host controller. This affects every platform where both
> PCI host controller and interrupt controllers are probed as regular
> platform devices.
>
> This creates fw_devlink between consumers (PCI host controller) and
> supplier (interrupt controller) based on "interrupt-map" DT property.
>
> Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> ---
> Changes since v2:
> - No need for a loop to find #interrupt-cells property value
> - Fix node de-reference leak when index is greater than number
>   of entries in interrupt-map property
> Changes since v1:
> - Updated commit description based on Rob's suggestion
> - Use of_irq_parse_raw() for parsing interrupt-map DT property
> ---
>  drivers/of/property.c | 50 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index a6358ee99b74..7326ca07adfe 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -1311,6 +1311,55 @@ static struct device_node *parse_interrupts(struct device_node *np,
>         return of_irq_parse_one(np, index, &sup_args) ? NULL : sup_args.np;
>  }
>
> +static struct device_node *parse_interrupt_map(struct device_node *np,
> +                                              const char *prop_name, int index)
> +{
> +       const __be32 *imap, *imap_end, *addr;
> +       struct of_phandle_args sup_args;
> +       u32 addrcells, intcells;
> +       int i, imaplen;
> +
> +       if (!IS_ENABLED(CONFIG_OF_IRQ))
> +               return NULL;
> +
> +       if (strcmp(prop_name, "interrupt-map"))
> +               return NULL;
> +
> +       if (of_property_read_u32(np, "#interrupt-cells", &intcells))
> +               return NULL;
> +       addrcells = of_bus_n_addr_cells(np);
> +
> +       imap = of_get_property(np, "interrupt-map", &imaplen);
> +       if (!imap || imaplen <= (addrcells + intcells))
> +               return NULL;
> +       imap_end = imap + imaplen;
> +
> +       sup_args.np = NULL;
> +       while (imap < imap_end) {
> +               addr = imap;
> +               imap += addrcells;
> +
> +               sup_args.np = np;
> +               sup_args.args_count = intcells;
> +               for (i = 0; i < intcells; i++)
> +                       sup_args.args[i] = be32_to_cpu(imap[i]);
> +               imap += intcells;
> +
> +               if (of_irq_parse_raw(addr, &sup_args))
Can you leave a comment above this call saying of_irq_parse_raw()
updates sup_args.np? It's really a problem with the function IMO, but
a comment here would be helpful.

> +                       return NULL;
> +
> +               if (!index)
> +                       return sup_args.np;
> +
> +               of_node_put(sup_args.np);
> +               sup_args.np = NULL;

Why do you need to set it to NULL? Can we just delete this line?

If you take care of these minor comments, then

Reviewed-by: Saravana Kannan <saravanak@...gle.com>

-Saravana

> +               imap += sup_args.args_count + 1;
> +               index--;
> +       }
> +
> +       return NULL;
> +}
> +
>  static struct device_node *parse_remote_endpoint(struct device_node *np,
>                                                  const char *prop_name,
>                                                  int index)
> @@ -1359,6 +1408,7 @@ static const struct supplier_bindings of_supplier_bindings[] = {
>         { .parse_prop = parse_msi_parent, },
>         { .parse_prop = parse_gpio_compat, },
>         { .parse_prop = parse_interrupts, },
> +       { .parse_prop = parse_interrupt_map, },
>         { .parse_prop = parse_regulators, },
>         { .parse_prop = parse_gpio, },
>         { .parse_prop = parse_gpios, },
> --
> 2.34.1
>