Re: [PATCH v6 04/16] drivers: iommu: make of_iommu_set/get_ops() DT agnostic

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Tue, Nov 01, 2016 at 04:36:10PM +0000, Robin Murphy wrote:
> Bikeshed alert...
> 
> On 18/10/16 17:04, Lorenzo Pieralisi wrote:
> > The of_iommu_{set/get}_ops() API is used to associate a device
> > tree node with a specific set of IOMMU operations. The same
> > kernel interface is required on systems booting with ACPI, where
> > devices are not associated with a device tree node, therefore
> > the interface requires generalization.
> > 
> > The struct device fwnode member represents the fwnode token
> > associated with the device and the struct it points at is firmware
> > specific; regardless, it is initialized on both ACPI and DT systems
> > and makes an ideal candidate to use it to associate a set of IOMMU
> > operations to a given device, through its struct device.fwnode member
> > pointer.
> > 
> > Convert the DT specific of_iommu_{set/get}_ops() interface to
> > use struct device.fwnode as a look-up token, making the interface
> > usable on ACPI systems.
> > 
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > Cc: Will Deacon <will.deacon@arm.com>
> > Cc: Hanjun Guo <hanjun.guo@linaro.org>
> > Cc: Robin Murphy <robin.murphy@arm.com>
> > Cc: Joerg Roedel <joro@8bytes.org>
> > ---
> >  drivers/iommu/iommu.c    | 43 +++++++++++++++++++++++++++++++++++++++++++
> >  drivers/iommu/of_iommu.c | 39 ---------------------------------------
> >  include/linux/iommu.h    | 14 ++++++++++++++
> >  include/linux/of_iommu.h | 12 ++++++++++--
> >  4 files changed, 67 insertions(+), 41 deletions(-)
> > 
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 9a2f196..320eb8c 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -1615,6 +1615,49 @@ int iommu_request_dm_for_dev(struct device *dev)
> >  	return ret;
> >  }
> >  
> > +struct fwnode_iommu_node {
> 
> Having just pulled in this patch in isolation for some hacking, I
> realise that by about the fifth time one reads "fwnode_iommu_node" it
> just looks like meaningless gibberish. Can we just call it
> "iommu_instance" instead, as that's what it's representing here?

Agreed, how about iommu_(fw)entry ? Anyway, I will do, point taken.

> > +	struct list_head list;
> > +	struct fwnode_handle *fwnode;
> > +	const struct iommu_ops *ops;
> > +};
> > +static LIST_HEAD(fwnode_iommu_list);
> > +static DEFINE_SPINLOCK(fwnode_iommu_lock);
> > +
> > +void fwnode_iommu_set_ops(struct fwnode_handle *fwnode,
> > +			  const struct iommu_ops *ops)
> > +{
> > +	struct fwnode_iommu_node *iommu =
> > +				kzalloc(sizeof(*iommu), GFP_KERNEL);
> 
> (plus it shortens this line so it really doesn't the awkward break)
> 
> Apologies, (the original rubbish name was my fault anyway)

No worries, you have a point, will update for next (hopefully last)
posting.

Thanks !
Lorenzo

> Robin.
> 
> > +
> > +	if (WARN_ON(!iommu))
> > +		return;
> > +
> > +	if (is_of_node(fwnode))
> > +		of_node_get(to_of_node(fwnode));
> > +
> > +	INIT_LIST_HEAD(&iommu->list);
> > +	iommu->fwnode = fwnode;
> > +	iommu->ops = ops;
> > +	spin_lock(&fwnode_iommu_lock);
> > +	list_add_tail(&iommu->list, &fwnode_iommu_list);
> > +	spin_unlock(&fwnode_iommu_lock);
> > +}
> > +
> > +const struct iommu_ops *fwnode_iommu_get_ops(struct fwnode_handle *fwnode)
> > +{
> > +	struct fwnode_iommu_node *node;
> > +	const struct iommu_ops *ops = NULL;
> > +
> > +	spin_lock(&fwnode_iommu_lock);
> > +	list_for_each_entry(node, &fwnode_iommu_list, list)
> > +		if (node->fwnode == fwnode) {
> > +			ops = node->ops;
> > +			break;
> > +		}
> > +	spin_unlock(&fwnode_iommu_lock);
> > +	return ops;
> > +}
> > +
> >  int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
> >  		      const struct iommu_ops *ops)
> >  {
> > diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> > index 5b82862..0f57ddc 100644
> > --- a/drivers/iommu/of_iommu.c
> > +++ b/drivers/iommu/of_iommu.c
> > @@ -96,45 +96,6 @@ int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
> >  }
> >  EXPORT_SYMBOL_GPL(of_get_dma_window);
> >  
> > -struct of_iommu_node {
> > -	struct list_head list;
> > -	struct device_node *np;
> > -	const struct iommu_ops *ops;
> > -};
> > -static LIST_HEAD(of_iommu_list);
> > -static DEFINE_SPINLOCK(of_iommu_lock);
> > -
> > -void of_iommu_set_ops(struct device_node *np, const struct iommu_ops *ops)
> > -{
> > -	struct of_iommu_node *iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
> > -
> > -	if (WARN_ON(!iommu))
> > -		return;
> > -
> > -	of_node_get(np);
> > -	INIT_LIST_HEAD(&iommu->list);
> > -	iommu->np = np;
> > -	iommu->ops = ops;
> > -	spin_lock(&of_iommu_lock);
> > -	list_add_tail(&iommu->list, &of_iommu_list);
> > -	spin_unlock(&of_iommu_lock);
> > -}
> > -
> > -const struct iommu_ops *of_iommu_get_ops(struct device_node *np)
> > -{
> > -	struct of_iommu_node *node;
> > -	const struct iommu_ops *ops = NULL;
> > -
> > -	spin_lock(&of_iommu_lock);
> > -	list_for_each_entry(node, &of_iommu_list, list)
> > -		if (node->np == np) {
> > -			ops = node->ops;
> > -			break;
> > -		}
> > -	spin_unlock(&of_iommu_lock);
> > -	return ops;
> > -}
> > -
> >  static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
> >  {
> >  	struct of_phandle_args *iommu_spec = data;
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > index 436dc21..15d5478 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -351,6 +351,9 @@ int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
> >  		      const struct iommu_ops *ops);
> >  void iommu_fwspec_free(struct device *dev);
> >  int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids);
> > +void fwnode_iommu_set_ops(struct fwnode_handle *fwnode,
> > +			  const struct iommu_ops *ops);
> > +const struct iommu_ops *fwnode_iommu_get_ops(struct fwnode_handle *fwnode);
> >  
> >  #else /* CONFIG_IOMMU_API */
> >  
> > @@ -580,6 +583,17 @@ static inline int iommu_fwspec_add_ids(struct device *dev, u32 *ids,
> >  	return -ENODEV;
> >  }
> >  
> > +static inline void fwnode_iommu_set_ops(struct fwnode_handle *fwnode,
> > +					const struct iommu_ops *ops)
> > +{
> > +}
> > +
> > +static inline
> > +const struct iommu_ops *fwnode_iommu_get_ops(struct fwnode_handle *fwnode)
> > +{
> > +	return NULL;
> > +}
> > +
> >  #endif /* CONFIG_IOMMU_API */
> >  
> >  #endif /* __LINUX_IOMMU_H */
> > diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
> > index e80b9c7..7681007 100644
> > --- a/include/linux/of_iommu.h
> > +++ b/include/linux/of_iommu.h
> > @@ -31,8 +31,16 @@ static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
> >  
> >  #endif	/* CONFIG_OF_IOMMU */
> >  
> > -void of_iommu_set_ops(struct device_node *np, const struct iommu_ops *ops);
> > -const struct iommu_ops *of_iommu_get_ops(struct device_node *np);
> > +static inline void of_iommu_set_ops(struct device_node *np,
> > +				    const struct iommu_ops *ops)
> > +{
> > +	fwnode_iommu_set_ops(&np->fwnode, ops);
> > +}
> > +
> > +static inline const struct iommu_ops *of_iommu_get_ops(struct device_node *np)
> > +{
> > +	return fwnode_iommu_get_ops(&np->fwnode);
> > +}
> >  
> >  extern struct of_device_id __iommu_of_table;
> >  
> > 
>