Re: [PATCH v6 3/8] i2c: i2c-smbus: add of_i2c_setup_smbus_alert

[Benjamin Tissoires <benjamin.tissoires@redhat.com>]

Hi Phil,

On May 02 2017 or thereabouts, Phil Reid wrote:
> This commit adds of_i2c_setup_smbus_alert which allows the smbalert
> driver to be attached to an i2c adapter via the device tree.
> 
> Signed-off-by: Phil Reid <preid@electromag.com.au>
> ---
>  Documentation/devicetree/bindings/i2c/i2c.txt |  4 +--
>  drivers/i2c/i2c-smbus.c                       | 35 +++++++++++++++++++++++++++
>  include/linux/i2c-smbus.h                     |  9 +++++++
>  3 files changed, 46 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt
> index cee9d50..1126398 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c.txt
> @@ -59,8 +59,8 @@ wants to support one of the below features, it should adapt the bindings below.
>  	interrupts used by the device.
>  
>  - interrupt-names
> -	"irq" and "wakeup" names are recognized by I2C core, other names are
> -	left to individual drivers.
> +	"irq", "wakeup" and "smbus_alert" names are recognized by I2C core,
> +	other names are	left to individual drivers.
>  
>  - host-notify
>  	device uses SMBus host notify protocol instead of interrupt line.
> diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
> index df0e2fa..a8f8439 100644
> --- a/drivers/i2c/i2c-smbus.c
> +++ b/drivers/i2c/i2c-smbus.c
> @@ -21,6 +21,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/of_irq.h>
>  #include <linux/slab.h>
>  #include <linux/workqueue.h>
>  
> @@ -238,6 +239,40 @@ struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
>  }
>  EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
>  
> +int of_i2c_setup_smbus_alert(struct i2c_adapter *adap)
> +{
> +	struct i2c_client *client;
> +	struct i2c_smbus_alert_setup *setup;
> +	struct i2c_board_info info = {
> +		I2C_BOARD_INFO("smbus_alert", 0x0c),
> +	};

Shouldn't you use i2c_setup_smbus_alert() instead of manually recreating
the board_info?
Also i2c_setup_smbus_alert() mentions that the level trigger has to be
explicitely mentioned, and I can't find if this is the case in your
patch.

> +	int irq;
> +
> +	if (!adap->dev.of_node)
> +		return 0;
> +
> +	irq = of_irq_get_byname(adap->dev.of_node, "smbus_alert");
> +	if (irq == -EINVAL || irq == -ENODATA)
> +		return 0;
> +	else if (irq < 0)
> +		return irq;
> +
> +	setup = devm_kzalloc(&adap->dev, sizeof(struct i2c_smbus_alert_setup),
> +		GFP_KERNEL);

Problem is i2c-core doesn't use devres at all for now. So the code is
correct here as it won't segfault but mixing both devres and non-devres
is error prone.

> +	if (!setup)
> +		return -ENOMEM;
> +
> +	setup->irq = irq;
> +	info.platform_data = setup;
> +
> +	client = i2c_new_device(adap, &info);
> +	if (!client)
> +		return -ENODEV;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(of_i2c_setup_smbus_alert);
> +
>  /**
>   * i2c_handle_smbus_alert - Handle an SMBus alert
>   * @ara: the ARA client on the relevant adapter
> diff --git a/include/linux/i2c-smbus.h b/include/linux/i2c-smbus.h
> index a138502..4732d09 100644
> --- a/include/linux/i2c-smbus.h
> +++ b/include/linux/i2c-smbus.h
> @@ -50,4 +50,13 @@ struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
>  					 struct i2c_smbus_alert_setup *setup);
>  int i2c_handle_smbus_alert(struct i2c_client *ara);
>  
> +#if IS_ENABLED(CONFIG_I2C_SMBUS)
> +int of_i2c_setup_smbus_alert(struct i2c_adapter *adap);
> +#else
> +static inline int of_i2c_setup_smbus_alert(struct i2c_adapter *adap)
> +{
> +	return 0;
> +}
> +#endif
> +
>  #endif /* _LINUX_I2C_SMBUS_H */
> -- 
> 1.8.3.1

Cheers,
Benjamin