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

[Marc Zyngier <marc.zyngier@arm.com>]

On Tue, 22 Sep 2015 17:00:05 -0700
David Daney <ddaney.cavm@gmail.com> wrote:

> From: David Daney <david.daney@cavium.com>
> 
> 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@cavium.com>
> ---
>  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)
> +{
> +	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;
> +	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;
> +	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;
> +		}
> +		/* We have a good parent_dev and msi_map, let's use them. */
> +		break;
> +	}
> +	if (!msi_map)
> +		goto out;
> +
> +	/* 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);

Rob did suggest to use of_property_read_u32_index() instead of these
be32_to_cpup(). Not sure if that'd be a major improvement though.

> +
> +		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;
> +
> +	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 */

Otherwise looks good to me.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny.