Subject: [PATCHv5 05/11] of: pci: add registry of MSI chips

From: [email-masked] (Thomas Petazzoni)
Date: Wed, 31 Jul 2013 17:14:22 +0200

Grant,

Would it be possible to get your opinion on the patch below?

You're the one who disagreed about the "of: pci: add registry of MSI
chips", so I implemented something that hopefully is more in line with
what you expected, so it'd be great if you could take some time to
review it.

This MSI stuff has been around for quite some time, the specific patch
you NAKed had originally been posted on June, 6th, and was thought to
be ready for merging thanks to the ACK of Rob Herring. While I
certainly understand that patches can continue to be discussed by other
maintainers, it'd be nice to have quick feedback from you after this NAK
so that we can converge towards an accepted solution to be merged in
3.12.

Thanks a lot,

Thomas

On Mon, 29 Jul 2013 14:26:00 +0200, Thomas Petazzoni wrote:
> Dear Thierry Reding,
> 
> On Mon, 29 Jul 2013 08:54:31 +0200, Thierry Reding wrote:
> 
> > > So what is your suggestion to allow the PCIe controller to retrieve the
> > > correct irq_domain if we have only one DT node for the IRQ controller
> > > that registers two irq_domains ?
> > 
> > If I understand correctly, Grant isn't objecting to the introduction of
> > the lookup function, but rather its implementation. You could add a
> > pointer to a struct msi_chip within struct irq_domain and then iterate
> > over all irq_domain instances (see irq_find_host()) and find one which
> > has the correct device_node pointer and the msi_chip pointer set.
> 
> Ah ok. The only trick is that we have to change irq_find_host() to
> *not* match on MSI domains. Can you check the below patch to see if it
> matches what Grant suggested? It works for me, and it allows to completely
> remove the registry of msi_chip in drivers/of, as well as the of_node
> pointer in struct msi_chip.
> 
> Thanks!
> 
> Thomas
> 
> From c2c0137cb110270f96e1e0fa298a5d585b8d829e Mon Sep 17 00:00:00 2001
> From: Thomas Petazzoni <[email-masked]>
> Date: Mon, 29 Jul 2013 14:12:31 +0200
> Subject: [PATCHv6 05/11] irqdomain: add support to associate an irq_domain
>  with a msi_chip
> 
> Message Signaled Interrupts are a PCI-specific mechanism that allows
> PCI devices to notify interrupts to the CPU using in-band
> messages. The PCI subsystem represents an MSI-capable interrupt
> controller as an msi_chip structure, and this patch improves the
> irqdomain subsystem with a new pointer associating an irq_domain with
> the corresponding msi_chip.
> 
> The __irq_domain_add() function is augmented with an additional
> argument, the 'msi_chip' pointer, and all callers of this function are
> updated.
> 
> A new function irq_domain_add_msi() function is added to allow the
> registration of an MSI-type irq domain.
> 
> The irq_find_host() function is modified to not match on MSI-type irq
> domains: a given DT device node may represent both a normal interrupt
> controller and a MSI interrupt controller. irq_find_host() should
> return the irq_domain that corresponds to the normal interupt
> controller.
> 
> An irq_find_msi() function is added to get the MSI_type irq domain
> given a DT device node.
> 
> Signed-off-by: Thomas Petazzoni <[email-masked]>
> ---
>  include/linux/irqdomain.h | 20 +++++++++++++++++---
>  kernel/irq/irqdomain.c    | 35 +++++++++++++++++++++++++++++++++--
>  2 files changed, 50 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
> index 1ffa336..f1b11c8 100644
> --- a/include/linux/irqdomain.h
> +++ b/include/linux/irqdomain.h
> @@ -38,6 +38,7 @@
>  struct device_node;
>  struct irq_domain;
>  struct of_device_id;
> +struct msi_chip;
>  
>  /* Number of irqs reserved for a legacy isa controller */
>  #define NUM_ISA_INTERRUPTS	16
> @@ -101,6 +102,7 @@ struct irq_domain {
>  	/* Optional data */
>  	struct device_node *of_node;
>  	struct irq_domain_chip_generic *gc;
> +	struct msi_chip *msi_chip;
>  
>  	/* reverse map data. The linear map gets appended to the irq_domain */
>  	irq_hw_number_t hwirq_max;
> @@ -114,6 +116,7 @@ struct irq_domain {
>  struct irq_domain *__irq_domain_add(struct device_node *of_node, int size,
>  				    irq_hw_number_t hwirq_max, int direct_max,
>  				    const struct irq_domain_ops *ops,
> +				    struct msi_chip *msi_chip,
>  				    void *host_data);
>  struct irq_domain *irq_domain_add_simple(struct device_node *of_node,
>  					 unsigned int size,
> @@ -127,6 +130,7 @@ struct irq_domain *irq_domain_add_legacy(struct device_node *of_node,
>  					 const struct irq_domain_ops *ops,
>  					 void *host_data);
>  extern struct irq_domain *irq_find_host(struct device_node *node);
> +extern struct irq_domain *irq_find_msi(struct device_node *node);
>  extern void irq_set_default_host(struct irq_domain *host);
>  
>  /**
> @@ -141,14 +145,15 @@ static inline struct irq_domain *irq_domain_add_linear(struct device_node *of_no
>  					 const struct irq_domain_ops *ops,
>  					 void *host_data)
>  {
> -	return __irq_domain_add(of_node, size, size, 0, ops, host_data);
> +	return __irq_domain_add(of_node, size, size, 0, ops, NULL, host_data);
>  }
>  static inline struct irq_domain *irq_domain_add_nomap(struct device_node *of_node,
>  					 unsigned int max_irq,
>  					 const struct irq_domain_ops *ops,
>  					 void *host_data)
>  {
> -	return __irq_domain_add(of_node, 0, max_irq, max_irq, ops, host_data);
> +	return __irq_domain_add(of_node, 0, max_irq, max_irq, ops, NULL,
> +				host_data);
>  }
>  static inline struct irq_domain *irq_domain_add_legacy_isa(
>  				struct device_node *of_node,
> @@ -162,7 +167,16 @@ static inline struct irq_domain *irq_domain_add_tree(struct device_node *of_node
>  					 const struct irq_domain_ops *ops,
>  					 void *host_data)
>  {
> -	return __irq_domain_add(of_node, 0, ~0, 0, ops, host_data);
> +	return __irq_domain_add(of_node, 0, ~0, 0, ops, NULL, host_data);
> +}
> +static inline struct irq_domain *irq_domain_add_msi(struct device_node *of_node,
> +						    unsigned int size,
> +						    const struct irq_domain_ops *ops,
> +						    struct msi_chip *msi_chip,
> +						    void *host_data)
> +{
> +	return __irq_domain_add(of_node, size, size, 0, ops,
> +				msi_chip, host_data);
>  }
>  
>  extern void irq_domain_remove(struct irq_domain *host);
> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> index b9ddb94..80dc1ca 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -29,6 +29,7 @@ static struct irq_domain *irq_default_domain;
>   * @direct_max: Maximum value of direct maps; Use ~0 for no limit; 0 for no
>   *              direct mapping
>   * @ops: map/unmap domain callbacks
> + * @msi_chip: pointer to MSI chip structure, for MSI domains
>   * @host_data: Controller private data pointer
>   *
>   * Allocates and initialize and irq_domain structure.  Caller is expected to
> @@ -38,6 +39,7 @@ static struct irq_domain *irq_default_domain;
>  struct irq_domain *__irq_domain_add(struct device_node *of_node, int size,
>  				    irq_hw_number_t hwirq_max, int direct_max,
>  				    const struct irq_domain_ops *ops,
> +				    struct msi_chip *msi_chip,
>  				    void *host_data)
>  {
>  	struct irq_domain *domain;
> @@ -52,6 +54,7 @@ struct irq_domain *__irq_domain_add(struct device_node *of_node, int size,
>  	domain->ops = ops;
>  	domain->host_data = host_data;
>  	domain->of_node = of_node_get(of_node);
> +	domain->msi_chip = msi_chip;
>  	domain->hwirq_max = hwirq_max;
>  	domain->revmap_size = size;
>  	domain->revmap_direct_max_irq = direct_max;
> @@ -127,7 +130,7 @@ struct irq_domain *irq_domain_add_simple(struct device_node *of_node,
>  {
>  	struct irq_domain *domain;
>  
> -	domain = __irq_domain_add(of_node, size, size, 0, ops, host_data);
> +	domain = __irq_domain_add(of_node, size, size, 0, ops, NULL, host_data);
>  	if (!domain)
>  		return NULL;
>  
> @@ -172,7 +175,7 @@ struct irq_domain *irq_domain_add_legacy(struct device_node *of_node,
>  	struct irq_domain *domain;
>  
>  	domain = __irq_domain_add(of_node, first_hwirq + size,
> -				  first_hwirq + size, 0, ops, host_data);
> +				  first_hwirq + size, 0, ops, NULL, host_data);
>  	if (!domain)
>  		return NULL;
>  
> @@ -198,6 +201,12 @@ struct irq_domain *irq_find_host(struct device_node *node)
>  	 */
>  	mutex_lock(&irq_domain_mutex);
>  	list_for_each_entry(h, &irq_domain_list, link) {
> +		/*
> +		 * We only want to match normal interrupt domains, not
> +		 * MSI domains
> +		 */
> +		if (h->msi_chip)
> +			continue;
>  		if (h->ops->match)
>  			rc = h->ops->match(h, node);
>  		else
> @@ -214,6 +223,28 @@ struct irq_domain *irq_find_host(struct device_node *node)
>  EXPORT_SYMBOL_GPL(irq_find_host);
>  
>  /**
> + * irq_find_msi() - Locates a MSI domain for a given device node
> + * @node: device-tree node of the interrupt controller
> + */
> +struct irq_domain *irq_find_msi(struct device_node *node)
> +{
> +	struct irq_domain *h, *found = NULL;
> +
> +	mutex_lock(&irq_domain_mutex);
> +	list_for_each_entry(h, &irq_domain_list, link) {
> +		if (!h->msi_chip)
> +			continue;
> +		if (h->of_node && h->of_node == node) {
> +			found = h;
> +			break;
> +		}
> +	}
> +	mutex_unlock(&irq_domain_mutex);
> +	return found;
> +}
> +EXPORT_SYMBOL_GPL(irq_find_msi);
> +
> +/**
>   * irq_set_default_host() - Set a "default" irq domain
>   * @domain: default domain pointer
>   *

-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com