Subject: Re: [PATCH] Add the of_find_i2c_device_by_node function

From: Anton Vorontsov <[email-masked]>
Date: Mon, 20 Oct 2008 01:20:34 +0400

Hi Jon,

On Sun, Oct 19, 2008 at 10:00:40AM -0400, Jon Smirl wrote:
> Add the of_find_i2c_device_by_node function. This allows you to follow
> a reference in the device tree to an i2c device node and then locate
> the linux device instantiated by the device tree. Example use, an i2s
> codec controlled by i2c. Depends on patch exporting i2c root bus symbol.
> 
> Signed-off-by: Jon Smirl <[email-masked]>

Few comments are below.

> ---
>  drivers/of/of_i2c.c |   28 ++++++++++++++++++++++++----
>  1 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/of/of_i2c.c b/drivers/of/of_i2c.c
> index 6a98dc8..ba7b394 100644
> --- a/drivers/of/of_i2c.c
> +++ b/drivers/of/of_i2c.c
> @@ -19,7 +19,7 @@
>  void of_register_i2c_devices(struct i2c_adapter *adap,
>  			     struct device_node *adap_node)
>  {
> -	void *result;
> +	struct i2c_client *i2c_dev;
>  	struct device_node *node;
>  
>  	for_each_child_of_node(adap_node, node) {
> @@ -41,18 +41,38 @@ void of_register_i2c_devices(struct i2c_adapter *adap,
>  
>  		info.addr = *addr;
>  
> -		request_module(info.type);
> +		request_module("%s", info.type);

Patch description doesn't mention this change.

>  
> -		result = i2c_new_device(adap, &info);
> -		if (result == NULL) {
> +		i2c_dev = i2c_new_device(adap, &info);
> +		if (i2c_dev == NULL) {
>  			printk(KERN_ERR
>  			       "of-i2c: Failed to load driver for %s\n",
>  			       info.type);
>  			irq_dispose_mapping(info.irq);
>  			continue;
>  		}
> +		
> +		i2c_dev->dev.archdata.of_node = of_node_get(node);

Would break sparc build. Plus setting this after i2c_new_device() isn't
right... Recently I sent few patches to deal with the archdata, could
you please rebase your patch against these three patches?

http://lkml.org/lkml/2008/10/16/250
http://lkml.org/lkml/2008/10/16/251
http://lkml.org/lkml/2008/10/16/252

>  	}
>  }
>  EXPORT_SYMBOL(of_register_i2c_devices);
>  
> +static int of_dev_node_match(struct device *dev, void *data)
> +{
> +        return dev->archdata.of_node == data;
> +}
> +
> +struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)

This should be documented. Especially the fact that every time you
call this function, you must call device_put() when you're done with
the returned i2c_client.

> +{
> +	struct device *dev;
> +	
> +	dev = bus_find_device(&i2c_bus_type, NULL, node, 
> +					 of_dev_node_match);
> +	if (!dev)
> +		return NULL;
> +		
> +	return to_i2c_client(dev);
> +}
> +EXPORT_SYMBOL(of_find_i2c_device_by_node);
> +
>  MODULE_LICENSE("GPL");
> diff --git a/include/linux/of_i2c.h b/include/linux/of_i2c.h
> index bd2a870..17d5897 100644
> --- a/include/linux/of_i2c.h
> +++ b/include/linux/of_i2c.h
> @@ -16,5 +16,7 @@
>  
>  void of_register_i2c_devices(struct i2c_adapter *adap,
>  			     struct device_node *adap_node);
> +struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
> +			     
>  
>  #endif /* __LINUX_OF_I2C_H */

Thanks,

-- 
Anton Vorontsov
email: [email-masked]
irc://irc.freenode.net/bd2