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


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