Subject: [PATCH v3 09/17] irqchip/irq-mvebu-icu: support ICU subnodes

From: [email-masked] (Miquel Raynal)
Date: Wed, 4 Jul 2018 17:16:22 +0200

Hi Marc,

Marc Zyngier <[email-masked]> wrote on Wed, 4 Jul 2018 13:43:58
+0100:

> On 04/07/18 10:09, Miquel Raynal wrote:
> > Hi Marc,
> > 
> > Marc Zyngier <[email-masked]> wrote on Thu, 28 Jun 2018 13:45:09
> > +0100:
> >   
> >> On 22/06/18 16:14, Miquel Raynal wrote:  
> >>> The ICU can handle several type of interrupt, each of them being handled
> >>> differently on AP side. On CP side, the ICU should be able to make the
> >>> distinction between each interrupt group by pointing to the right parent.
> >>>
> >>> This is done through the introduction of new bindings, presenting the ICU
> >>> node as the parent of multiple ICU sub-nodes, each of them being an
> >>> interrupt type with a different interrupt parent. ICU interrupt 'clients'
> >>> now directly point to the right sub-node, avoiding the need for the extra
> >>> ICU_GRP_* parameter.
> >>>
> >>> ICU subnodes are probed automatically with devm_platform_populate(). If
> >>> the node as no child, the probe function for NSRs will still be called
> >>> 'manually' in order to preserve backward compatibility with DT using the
> >>> old binding.
> >>>
> >>> Signed-off-by: Miquel Raynal <[email-masked]>
> >>> ---
> >>>  drivers/irqchip/irq-mvebu-icu.c | 88 ++++++++++++++++++++++++++++++++++-------
> >>>  1 file changed, 74 insertions(+), 14 deletions(-)
> >>>
> >>> diff --git a/drivers/irqchip/irq-mvebu-icu.c b/drivers/irqchip/irq-mvebu-icu.c
> >>> index 24d45186eb6b..f7c2ede9c222 100644
> >>> --- a/drivers/irqchip/irq-mvebu-icu.c
> >>> +++ b/drivers/irqchip/irq-mvebu-icu.c
> >>> @@ -43,6 +43,7 @@ struct mvebu_icu {
> >>>  	struct regmap *regmap;
> >>>  	struct device *dev;
> >>>  	atomic_t initialized;
> >>> +	bool legacy_bindings;
> >>>  };
> >>>  
> >>>  struct mvebu_icu_irq_data {
> >>> @@ -51,6 +52,30 @@ struct mvebu_icu_irq_data {
> >>>  	unsigned int type;
> >>>  };
> >>>  
> >>> +static struct mvebu_icu *mvebu_icu_dev_get_drvdata(struct platform_device *pdev)
> >>> +{
> >>> +	struct mvebu_icu *icu;
> >>> +
> >>> +	/*
> >>> +	 * Device data being populated means we should be using legacy bindings.
> >>> +	 * Using the _parent_ device data means we should be using new bindings.
> >>> +	 */
> >>> +	icu = dev_get_drvdata(&pdev->dev);
> >>> +	if (icu) {
> >>> +		if (!icu->legacy_bindings)
> >>> +			return ERR_PTR(-EINVAL);
> >>> +	} else {
> >>> +		icu = dev_get_drvdata(pdev->dev.parent);
> >>> +		if (!icu)
> >>> +			return ERR_PTR(-ENODEV);
> >>> +
> >>> +		if (icu->legacy_bindings)
> >>> +			return ERR_PTR(-EINVAL);
> >>> +	}    
> >>
> >> Doesn't this make legacy_bindings completely redundant? Either the
> >> pointer is !NULL in the device, and this is using a legacy binging, or
> >> it is stored in the parent, and this is a new binding. You could even
> >> have a helper for that:
> >>
> >> static bool is_legacy(struct platform_device *pdev)
> >> {
> >> 	return !dev_get_drvdata(&pdev->dev);
> >> }
> >>
> >> The driver really doesn't need to be defending against itself, if
> >> anything, and it would save you quite a bit of error handling in the
> >> callers of this function.  
> > 
> > I simplified the sanity checks but I had to keep an icu->is_legacy
> > boolean because the above function would not have worked, for instance,
> > in the *_translate() hook. As this hook does not receive a struct
> > device * (or platform_device) as parameter, I tried to use icu->dev
> > instead. This cannot work as it always points to the device having the
> > driver data attached.  
> 
> You could still have the pdev as part of the domain host_data, right?
> Isn't that just a matter of having a pointer to the pdev as part of the
> icu data structure?

There is already a 'struct device *dev' pointer in the ICU data
structure. This pointer is set to "&pdev->dev" in the main probe
function.

Legacy: dev is the unique ICU device, the driver data is attached to it.
Now: dev is the 'host' ICU device that is the parent of two other
devices, ICU NSR controller and SEI NSR controller. The driver data is
also attached to this device.

So in both situations checking dev_get_drvdata(icu->dev) would return a
valid pointer.

Does this answer your question?

Kind regards,
Miqu?l