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

[Grant Likely <grant.likely@xxxxxxxxxxxx>]

On Thu, 20 Nov 2014 18:03:33 -0800
, Guenter Roeck <linux@xxxxxxxxxxxx>
 wrote:
> 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 ?

Yes, absolutely. This code should also depend on CONFIG_OF_DYNAMIC too,
not merely CONFIG_OF.

> 
> Thanks,
> Guenter
> 
> >> +	retval = of_reconfig_notifier_register(&i2c_of_notifier);
> >> +	if (retval)
> >> +		goto notifier_err;
> >> +#endif

We can also get rid of the ugly #ifdef in the body by creating empty
stubs for of_reconfig_notify_{register,unregister}() and doing the
following:

	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
		WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier))

I picked up the patch into my tree and made the above changes because
they're pretty trivial. If Wolfram is okay with it then I can take the
whole series through my tree. Otherwise I'll put the of_reconfig_* empty
stubs into a separate branch that he and broonie can both pull.

g.

> >> +
> >> +	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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