Re: [PATCH v8 6/8] OF: i2c: Add OF notifier handler

[Guenter Roeck]

On 11/20/2014 05:53 PM, Grant Likely wrote:
> On Tue, 28 Oct 2014 22:36:03 +0200
> , Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
>   wrote:
> > Add OF notifier handler needed for creating/destroying i2c devices
> > according to dynamic runtime changes in the DT live tree.
> >
> > Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
> > ---
> >   drivers/i2c/i2c-core.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++-
> >   1 file changed, 78 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> > index e6da9d3..e751b78 100644
> > --- a/drivers/i2c/i2c-core.c
> > +++ b/drivers/i2c/i2c-core.c
> > @@ -1470,6 +1470,7 @@ struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
> >   	return i2c_verify_adapter(dev);
> >   }
> >   EXPORT_SYMBOL(of_find_i2c_adapter_by_node);
> > +
> >   #else
> >   static void of_i2c_register_devices(struct i2c_adapter *adap) { }
> >   #endif /* CONFIG_OF */
> > @@ -1955,6 +1956,71 @@ void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
> >   }
> >   EXPORT_SYMBOL(i2c_clients_command);
> >
> > +#if IS_ENABLED(CONFIG_OF)
> > +
> > +static int of_i2c_notify(struct notifier_block *nb,
> > +				unsigned long action, void *arg)
> > +{
> > +	struct device_node *dn;
> > +	struct i2c_adapter *adap;
> > +	struct i2c_client *client;
> > +	int state;
> > +
> > +	state = of_reconfig_get_state_change(action, arg);
> > +	if (state == -1)
> > +		return NOTIFY_OK;
> > +
> > +	switch (action) {
> > +	case OF_RECONFIG_ATTACH_NODE:
> > +	case OF_RECONFIG_DETACH_NODE:
> > +		dn = arg;
> > +		break;
> > +	case OF_RECONFIG_ADD_PROPERTY:
> > +	case OF_RECONFIG_REMOVE_PROPERTY:
> > +	case OF_RECONFIG_UPDATE_PROPERTY:
> > +		dn = ((struct of_prop_reconfig *)arg)->dn;
> > +		break;
> > +	default:
> > +		return NOTIFY_OK;
> > +	}
> > +
> > +	if (state) {
> > +
> > +		adap = of_find_i2c_adapter_by_node(dn->parent);
> > +		if (adap == NULL)
> > +			return NOTIFY_OK;	/* not for us */
> > +
> > +		client = of_i2c_register_device(adap, dn);
> > +		put_device(&adap->dev);
> > +
> > +		if (IS_ERR(client)) {
> > +			pr_err("%s: failed to create for '%s'\n",
> > +					__func__, dn->full_name);
> > +			return notifier_from_errno(PTR_ERR(client));
> > +		}
> > +
> > +	} else {
> > +
> > +		/* find our device by node */
> > +		client = of_find_i2c_device_by_node(dn);
> > +		if (client == NULL)
> > +			return NOTIFY_OK;	/* no? not meant for us */
> > +
> > +		/* unregister takes one ref away */
> > +		i2c_unregister_device(client);
> > +
> > +		/* and put the reference of the find */
> > +		put_device(&client->dev);
> > +
> > +	}
>
> Nit: odd whitespace
>
> > +
> > +	return NOTIFY_OK;
> > +}
> > +
> > +static struct notifier_block i2c_of_notifier;
> > +
> > +#endif
> > +
> >   static int __init i2c_init(void)
> >   {
> >   	int retval;
> > @@ -1972,8 +2038,19 @@ static int __init i2c_init(void)
> >   	retval = i2c_add_driver(&dummy_driver);
> >   	if (retval)
> >   		goto class_err;
> > -	return 0;
> >
> > +#if IS_ENABLED(CONFIG_OF)
> > +	i2c_of_notifier.notifier_call = of_i2c_notify;

Wouldn't it be easier to just initialize i2c_of_notifier above instead of
here in the code ? Or is there a reason for doing it here ?

Thanks,
Guenter

> > +	retval = of_reconfig_notifier_register(&i2c_of_notifier);
> > +	if (retval)
> > +		goto notifier_err;
> > +#endif
> > +
> > +	return 0;
> > +#if IS_ENABLED(CONFIG_OF)
> > +notifier_err:
> > +	i2c_del_driver(&dummy_driver);
> > +#endif
>
> Similar to my comment on the platform bus, don't break the entire bus if
> registration of the notifier fails. I would drop the error case and just
> do a WARN_ON() if it fails.
>
> Otherwise:
>
> Acked-by: Grant Likely <grant.likely@xxxxxxxxxx>
>
> >   class_err:
> >   #ifdef CONFIG_I2C_COMPAT
> >   	class_compat_unregister(i2c_adapter_compat_class);
> > --
> > 1.7.12

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