Re: [PATCH v2 1/2] extcon: Add extcon_set_cable_line_state() to inform the additional state of external connectors

[Roger Quadros <rogerq@ti.com>]

Chanwoo,

On 27/05/15 15:15, Chanwoo Choi wrote:
> This patch adds the extcon_set_cable_line_state() function to inform
> the additional state of each external connector and 'enum extcon_line_state'
> enumeration which include the specific states of each external connector.
>
> The each external connector might need the different line state. So, current
> 'extcon_line_state' enumeration contains the specific state for USB as
> following:
>
> - Following the state mean the state of both ID and VBUS line for USB:
> enum extcon_line_state {
> 	EXTCON_USB_ID_LOW	= BIT(1),	/* ID line is low. */
> 	EXTCON_USB_ID_HIGH	= BIT(2),	/* ID line is high. */

ID_LOW and ID_HIGH cannot happen simultaneously so they can use the same bit position.
if the bit is set means it is high, if it is cleared means it is low.

> 	EXTCON_USB_VBUS_LOW	= BIT(3),	/* VBUS line is low. */
> 	EXTCON_USB_VBUS_HIGH	= BIT(4),	/* VBUS line is high. */

same here.

enum doesn't look like the right type for extcon_line_state as it is more of a bitmask.

> };
>
> Cc: Myungjoo Ham <cw00.choi@samsung.com>
> Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
> ---
>   drivers/extcon/extcon.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++-
>   include/linux/extcon.h  | 24 ++++++++++++++++
>   2 files changed, 97 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
> index 5099c11..142bf0f 100644
> --- a/drivers/extcon/extcon.c
> +++ b/drivers/extcon/extcon.c
> @@ -279,7 +279,9 @@ int extcon_update_state(struct extcon_dev *edev, u32 mask, u32 state)
>
>   		for (index = 0; index < edev->max_supported; index++) {
>   			if (is_extcon_changed(edev->state, state, index, &attached))
> -				raw_notifier_call_chain(&edev->nh[index], attached, edev);
> +				raw_notifier_call_chain(&edev->nh[index],
> +					attached ? EXTCON_ATTACHED :
> +					EXTCON_DETACHED, edev);
>   		}
>
>   		edev->state &= ~mask;
> @@ -418,6 +420,69 @@ int extcon_set_cable_state(struct extcon_dev *edev,
>   EXPORT_SYMBOL_GPL(extcon_set_cable_state);
>
>   /**
> + * extcon_set_cable_line_state() - Set the line state of specific cable.
> + * @edev:		the extcon device that has the cable.
> + * @id:			the unique id of each external connector.
> + * @state:		the line state for specific cable.
> + *
> + * Note that this function support the only USB connector to inform the state
> + * of both ID and VBUS line until now. This function may be extended to support
> + * the additional external connectors.
> + *
> + * If the id is EXTCON_USB, it can support only following line states:
> + * - EXTCON_USB_ID_LOW
> + * - EXTCON_USB_ID_HIGH,
> + * - EXTCON_USB_VBUS_LOW
> + * - EXTCON_USB_VBUS_HIGH
> + */
> +int extcon_set_cable_line_state(struct extcon_dev *edev, enum extcon id,
> +				enum extcon_line_state state)
> +{
> +	unsigned long flags;
> +	unsigned long line_state;
> +	int ret = 0, index;
> +
> +	index = find_cable_index_by_id(edev, id);
> +	if (index < 0)
> +		return index;
> +
> +	spin_lock_irqsave(&edev->lock, flags);
> +	line_state = edev->line_state[index];
> +
> +	switch (id) {
> +	case EXTCON_USB:
> +		if (line_state & state) {
> +			dev_warn(&edev->dev,
> +				"0x%x state is already set for %s\n",
> +				state, extcon_name[id]);
> +			goto err;
> +		}
> +
> +		if ((state & EXTCON_USB_ID_LOW) || (state & EXTCON_USB_ID_HIGH))
> +			line_state &= ~(EXTCON_USB_ID_LOW | EXTCON_USB_ID_HIGH);
> +
> +		if ((state & EXTCON_USB_VBUS_LOW)
> +			|| (state & EXTCON_USB_VBUS_HIGH))
> +			line_state &=
> +				~(EXTCON_USB_VBUS_LOW | EXTCON_USB_VBUS_HIGH);
> +
> +		line_state |= state;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		goto err;
> +	}
> +	edev->line_state[index] = line_state;
> +
> +	ret = raw_notifier_call_chain(&edev->nh[index], line_state, edev);
> +err:
> +	spin_unlock_irqrestore(&edev->lock, flags);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(extcon_set_cable_line_state);
> +
> +/**
>    * extcon_get_extcon_dev() - Get the extcon device instance from the name
>    * @extcon_name:	The extcon name provided with extcon_dev_register()
>    */
> @@ -897,6 +962,13 @@ int extcon_dev_register(struct extcon_dev *edev)
>   		goto err_dev;
>   	}
>
> +	edev->line_state = devm_kzalloc(&edev->dev,
> +		sizeof(*edev->line_state) * edev->max_supported, GFP_KERNEL);
> +	if (!edev->line_state) {
> +		ret = -ENOMEM;
> +		goto err_dev;
> +	}
> +
>   	for (index = 0; index < edev->max_supported; index++)
>   		RAW_INIT_NOTIFIER_HEAD(&edev->nh[index]);
>
> diff --git a/include/linux/extcon.h b/include/linux/extcon.h
> index be9652b..79e5073 100644
> --- a/include/linux/extcon.h
> +++ b/include/linux/extcon.h
> @@ -66,6 +66,19 @@ enum extcon {
>   	EXTCON_END,
>   };
>
> +enum extcon_line_state {
> +	/* Following two definition are used for whether external connectors
> +	 * is attached or detached. */
> +	EXTCON_DETACHED		= 0x0,
> +	EXTCON_ATTACHED		= 0x1,
> +
> +	/* Following states are only used for EXTCON_USB. */
> +	EXTCON_USB_ID_LOW	= BIT(1),	/* ID line is low. */
> +	EXTCON_USB_ID_HIGH	= BIT(2),	/* ID line is high. */
> +	EXTCON_USB_VBUS_LOW	= BIT(3),	/* VBUS line is low. */
> +	EXTCON_USB_VBUS_HIGH	= BIT(4),	/* VBUS line is high. */
> +};

Why do you use enum? How about the following bit definitions for line state.

#define EXTCON_ATTACHED_DETACHED_BIT	BIT(0)
#define EXTCON_USB_ID_BIT		BIT(1)
#define EXTCON_USB_VBUS_BIT		BIT(2)
...

code must check if appropriate bit is set or cleared to get the high/low state.

> +
>   struct extcon_cable;
>
>   /**
> @@ -90,6 +103,8 @@ struct extcon_cable;
>    * @dev:		Device of this extcon.
>    * @state:		Attach/detach state of this extcon. Do not provide at
>    *			register-time.
> + * @line_state:		Line state for each external connecotrs are included in
> + *			this extcon device.
>    * @nh:			Notifier for the state change events from this extcon
>    * @entry:		To support list of extcon devices so that users can
>    *			search for extcon devices based on the extcon name.
> @@ -121,6 +136,7 @@ struct extcon_dev {
>   	int max_supported;
>   	spinlock_t lock;	/* could be called by irq handler */
>   	u32 state;
> +	unsigned long *line_state;
>
>   	/* /sys/class/extcon/.../cable.n/... */
>   	struct device_type extcon_dev_type;
> @@ -217,6 +233,8 @@ extern int extcon_get_cable_state(struct extcon_dev *edev,
>   				  const char *cable_name);
>   extern int extcon_set_cable_state(struct extcon_dev *edev,
>   				  const char *cable_name, bool cable_state);
> +extern int extcon_set_cable_line_state(struct extcon_dev *edev, enum extcon id,
> +					enum extcon_line_state state);
>
>   /*
>    * Following APIs are for notifiees (those who want to be notified)
> @@ -324,6 +342,12 @@ static inline int extcon_set_cable_state(struct extcon_dev *edev,
>   	return 0;
>   }
>
> +static inline int extcon_set_cable_line_state(struct extcon_dev *edev,
> +			enum extcon id, enum extcon_line_state state)
> +{
> +	return 0;
> +}
> +
>   static inline struct extcon_dev *extcon_get_extcon_dev(const char *extcon_name)
>   {
>   	return NULL;
>

cheers,
-roger