Re: [PATCH v2 2/3] of/irq: Add new function of_msi_map_rid()

[Rob Herring]

On Tue, Sep 22, 2015 at 7:00 PM, David Daney <ddaney.cavm@xxxxxxxxx> wrote:
> From: David Daney <david.daney@xxxxxxxxxx>
>
> The device tree property "msi-map" specifies how to create the PCI
> requester id used in some MSI controllers.  Add a new function
> of_msi_map_rid() that finds the msi-map property and applies its
> translation to a given requester id.
>
> Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> ---
>  drivers/of/irq.c       | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of_irq.h |  7 ++++
>  2 files changed, 93 insertions(+)
>
> diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> index 55317fa..3f64d2e 100644
> --- a/drivers/of/irq.c
> +++ b/drivers/of/irq.c
> @@ -598,3 +598,89 @@ void of_msi_configure(struct device *dev, struct device_node *np)
>                 d = irq_find_host(msi_np);
>         dev_set_msi_domain(dev, d);
>  }
> +
> +/**
> + * of_msi_map_rid - Map a MSI requester ID for a device.
> + * @dev: device for which the mapping is to be done.
> + * @msi_np: device node of the expected msi controller.
> + * @rid_in: unmapped MSI requester ID for the device.
> + *
> + * Walk up the device hierarchy looking for devices with a "msi-map"
> + * property.  If found, apply the mapping to @rid_in.
> + *
> + * Returns the mapped MSI requester ID.
> + */
> +u32 of_msi_map_rid(struct device *dev, struct device_node *msi_np, u32 rid_in)

Generally, the OF API does not use struct device except for what is in
of/device.c. I'm guessing you need it here because you have devices
without DT nodes?

We may want to handle this more like NUMA node IDs where we populate
data in struct device at creation time and looking at struct device
parents is independent of DT. How would this information be retrieved
with ACPI?

> +{
> +       struct device *parent_dev;
> +       struct device_node *msi_controller_node;
> +       const __be32 *msi_map;

> +       u32 map_mask, masked_rid;
> +       u32 rid_base, msi_base, rid_len, phandle;

One line please.

> +       int msi_map_len;
> +       bool matched;
> +       u32 rid_out = rid_in;
> +
> +       /*
> +        * Walk up the device parent links looking for one with a
> +        * "msi-map" property.
> +        */
> +       msi_map = NULL;

init in the declaration.

> +       for (parent_dev = dev; parent_dev; parent_dev = parent_dev->parent) {
> +               if (!parent_dev->of_node)
> +                       continue;
> +
> +               msi_map = of_get_property(parent_dev->of_node,
> +                                         "msi-map", &msi_map_len);
> +               if (!msi_map)
> +                       continue;
> +
> +               if (msi_map_len % (4 * sizeof(__be32))) {
> +                       dev_err(parent_dev, "Error: Bad msi-map length: %d\n",
> +                               msi_map_len);
> +                       goto out;

Just return here.

> +               }
> +               /* We have a good parent_dev and msi_map, let's use them. */
> +               break;
> +       }
> +       if (!msi_map)
> +               goto out;

Just return here.

> +
> +       /* The default is to select all bits. */
> +       map_mask = 0xffffffff;
> +
> +       /*
> +        * Can be overridden by "msi-map-mask" property.  If
> +        * of_property_read_u32() fails, the default is used.
> +        */
> +       of_property_read_u32(parent_dev->of_node, "msi-map-mask", &map_mask);
> +
> +       masked_rid = map_mask & rid_in;
> +       matched = false;
> +       while (!matched && msi_map_len >= 4 * sizeof(__be32)) {
> +               rid_base = be32_to_cpup(msi_map + 0);
> +               phandle = be32_to_cpup(msi_map + 1);
> +               msi_base = be32_to_cpup(msi_map + 2);
> +               rid_len = be32_to_cpup(msi_map + 3);
> +
> +               msi_controller_node = of_find_node_by_phandle(phandle);
> +
> +               matched = masked_rid >= rid_base &&
> +                       masked_rid < rid_base + rid_len &&
> +                       msi_np == msi_controller_node;
> +
> +               of_node_put(msi_controller_node);
> +               msi_map_len -= 4 * sizeof(__be32);
> +               msi_map += 4;
> +       }
> +       if (!matched)
> +               goto out;

Just return here.

> +
> +       rid_out = masked_rid + msi_base;
> +       dev_dbg(dev,
> +               "msi-map at: %s, using mask %08x, rid-base: %08x, msi-base: %08x, length: %08x, rid: %08x -> %08x\n",
> +               dev_name(parent_dev), map_mask, rid_base, msi_base,
> +               rid_len, rid_in, rid_out);
> +out:
> +       return rid_out;
> +}
> diff --git a/include/linux/of_irq.h b/include/linux/of_irq.h
> index 4bcbd58..8cd9334 100644
> --- a/include/linux/of_irq.h
> +++ b/include/linux/of_irq.h
> @@ -75,6 +75,7 @@ static inline int of_irq_to_resource_table(struct device_node *dev,
>  extern unsigned int irq_of_parse_and_map(struct device_node *node, int index);
>  extern struct device_node *of_irq_find_parent(struct device_node *child);
>  extern void of_msi_configure(struct device *dev, struct device_node *np);
> +u32 of_msi_map_rid(struct device *dev, struct device_node *msi_np, u32 rid_in);
>
>  #else /* !CONFIG_OF */
>  static inline unsigned int irq_of_parse_and_map(struct device_node *dev,
> @@ -87,6 +88,12 @@ static inline void *of_irq_find_parent(struct device_node *child)
>  {
>         return NULL;
>  }
> +
> +static inline u32 of_msi_map_rid(struct device *dev,
> +                                struct device_node *msi_np, u32 rid_in)
> +{
> +       return rid_in;
> +}
>  #endif /* !CONFIG_OF */
>
>  #endif /* __OF_IRQ_H */
> --
> 1.9.1
>
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