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SubjectRe: [PATCH v8 6/8] OF: i2c: Add OF notifier handler
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Hi Grant,

> On Nov 21, 2014, at 17:08 , Grant Likely <grant.likely@secretlab.ca> wrote:
>
> On Thu, 20 Nov 2014 18:03:33 -0800
> , Guenter Roeck <linux@roeck-us.net>
> wrote:
>> On 11/20/2014 05:53 PM, Grant Likely wrote:
>>> On Tue, 28 Oct 2014 22:36:03 +0200
>>> , Pantelis Antoniou <pantelis.antoniou@konsulko.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@konsulko.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 ?
>
> Yes, absolutely. This code should also depend on CONFIG_OF_DYNAMIC too,
> not merely CONFIG_OF.
>
>>

No reason; it just seemed like the most opportune place to put it at the time.

>> 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.
>

I’m fine with doing this if you’d like, it’s pretty simple.

Regards

— Pantelis

> 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@linaro.org>
>>>
>>>> class_err:
>>>> #ifdef CONFIG_I2C_COMPAT
>>>> class_compat_unregister(i2c_adapter_compat_class);
>>>> --
>>>> 1.7.12
>>>>
>>>
>>>
>>
>> --
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