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

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Message-ID: <546E9D75.3000208@roeck-us.net>
Date:	Thu, 20 Nov 2014 18:03:33 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Grant Likely <grant.likely@...retlab.ca>,
	Pantelis Antoniou <pantelis.antoniou@...sulko.com>
CC:	Rob Herring <robherring2@...il.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Matt Porter <matt.porter@...aro.org>,
	Koen Kooi <koen@...inion.thruhere.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Alison Chaiken <Alison_Chaiken@...tor.com>,
	Dinh Nguyen <dinh.linux@...il.com>,
	Jan Lubbe <jluebbe@...net.de>,
	Alexander Sverdlin <alexander.sverdlin@....com>,
	Michael Stickel <ms@...able.de>,
	Dirk Behme <dirk.behme@...il.com>,
	Alan Tull <delicious.quinoa@...il.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Michael Bohan <mbohan@...eaurora.org>,
	Ionut Nicu <ioan.nicu.ext@....com>,
	Michal Simek <monstr@...str.eu>,
	Matt Ranostay <mranostay@...il.com>,
	Joel Becker <jlbec@...lplan.org>, devicetree@...r.kernel.org,
	Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
	Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org, Pete Popov <pete.popov@...sulko.com>,
	Dan Malek <dan.malek@...sulko.com>,
	Georgi Vlaev <georgi.vlaev@...sulko.com>,
	Pantelis Antoniou <panto@...oniou-consulting.com>
Subject: Re: [PATCH v8 6/8] OF: i2c: Add OF notifier handler

On 11/20/2014 05:53 PM, Grant Likely wrote:
> On Tue, 28 Oct 2014 22:36:03 +0200
> , Pantelis Antoniou <pantelis.antoniou@...sulko.com>
>   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@...sulko.com>
>> ---
>>   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@...aro.org>
>
>>   class_err:
>>   #ifdef CONFIG_I2C_COMPAT
>>   	class_compat_unregister(i2c_adapter_compat_class);
>> --
>> 1.7.12
>>
>
>

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