Re: [PATCH 1/1] Bluetooth: hidp: Add support for hidraw HIDIOCGFEATURE and HIDIOCSFEATURE

[Marcel Holtmann <marcel@holtmann.org>]

Hi Alan,

> This patch adds support or getting and setting feature reports for bluetooth
> HID devices from HIDRAW.
> 
> Signed-off-by: Alan Ott <alan@signal11.us>
> ---
>  net/bluetooth/hidp/core.c |  121 +++++++++++++++++++++++++++++++++++++++++++--
>  net/bluetooth/hidp/hidp.h |    8 +++
>  2 files changed, 125 insertions(+), 4 deletions(-)
> 
> diff --git a/net/bluetooth/hidp/core.c b/net/bluetooth/hidp/core.c
> index bfe641b..0f068a0 100644
> --- a/net/bluetooth/hidp/core.c
> +++ b/net/bluetooth/hidp/core.c
> @@ -36,6 +36,7 @@
>  #include <linux/file.h>
>  #include <linux/init.h>
>  #include <linux/wait.h>
> +#include <linux/mutex.h>
>  #include <net/sock.h>
>  
>  #include <linux/input.h>
> @@ -313,6 +314,93 @@ static int hidp_send_report(struct hidp_session *session, struct hid_report *rep
>  	return hidp_queue_report(session, buf, rsize);
>  }
>  
> +static int hidp_get_raw_report(struct hid_device *hid,
> +		unsigned char report_number,
> +		unsigned char *data, size_t count,
> +		unsigned char report_type)
> +{
> +	struct hidp_session *session = hid->driver_data;
> +	struct sk_buff *skb;
> +	size_t len;
> +	int numbered_reports = hid->report_enum[report_type].numbered;
> +
> +	switch (report_type) {
> +	case HID_FEATURE_REPORT:
> +		report_type = HIDP_TRANS_GET_REPORT | HIDP_DATA_RTYPE_FEATURE;
> +		break;
> +	case HID_INPUT_REPORT:
> +		report_type = HIDP_TRANS_GET_REPORT | HIDP_DATA_RTYPE_INPUT;
> +		break;
> +	case HID_OUTPUT_REPORT:
> +		report_type = HIDP_TRANS_GET_REPORT | HIDP_DATA_RTYPE_OUPUT;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	if (mutex_lock_interruptible(&session->report_mutex))
> +		return -ERESTARTSYS;
> +
> +	/* Set up our wait, and send the report request to the device. */
> +	session->waiting_report_type = report_type & HIDP_DATA_RTYPE_MASK;
> +	session->waiting_report_number = numbered_reports ? report_number : -1;
> +	set_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
> +	data[0] = report_number;
> +	if (hidp_send_ctrl_message(hid->driver_data, report_type, data, 1))
> +		goto err_eio;
> +
> +	/* Wait for the return of the report. The returned report
> +	   gets put in session->report_return.  */
> +	while (test_bit(HIDP_WAITING_FOR_RETURN, &session->flags)) {
> +		int res;
> +
> +		res = wait_event_interruptible_timeout(session->report_queue,
> +			!test_bit(HIDP_WAITING_FOR_RETURN, &session->flags),
> +			5*HZ);
> +		if (res == 0) {
> +			/* timeout */
> +			goto err_eio;
> +		}
> +		if (res < 0) {
> +			/* signal */
> +			goto err_restartsys;
> +		}
> +	}
> +
> +	skb = session->report_return;
> +	if (skb) {
> +		if (numbered_reports) {
> +			/* Strip off the report number. */
> +			size_t rpt_len = skb->len-1;
> +			len = rpt_len < count ? rpt_len : count;
> +			memcpy(data, skb->data+1, len);
> +		} else {
> +			len = skb->len < count ? skb->len : count;
> +			memcpy(data, skb->data, len);
> +		}
> +
> +		kfree_skb(skb);
> +		session->report_return = NULL;
> +	} else {
> +		/* Device returned a HANDSHAKE, indicating  protocol error. */
> +		len = -EIO;
> +	}
> +
> +	clear_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
> +	mutex_unlock(&session->report_mutex);
> +
> +	return len;
> +
> +err_restartsys:
> +	clear_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
> +	mutex_unlock(&session->report_mutex);
> +	return -ERESTARTSYS;
> +err_eio:
> +	clear_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
> +	mutex_unlock(&session->report_mutex);
> +	return -EIO;
> +}
> +
>  static int hidp_output_raw_report(struct hid_device *hid, unsigned char *data, size_t count,
>  		unsigned char report_type)
>  {
> @@ -367,6 +455,10 @@ static void hidp_process_handshake(struct hidp_session *session,
>  	case HIDP_HSHK_ERR_INVALID_REPORT_ID:
>  	case HIDP_HSHK_ERR_UNSUPPORTED_REQUEST:
>  	case HIDP_HSHK_ERR_INVALID_PARAMETER:
> +		if (test_bit(HIDP_WAITING_FOR_RETURN, &session->flags)) {
> +			clear_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
> +			wake_up_interruptible(&session->report_queue);
> +		}
>  		/* FIXME: Call into SET_ GET_ handlers here */
>  		break;
>  
> @@ -403,9 +495,11 @@ static void hidp_process_hid_control(struct hidp_session *session,
>  	}
>  }
>  
> -static void hidp_process_data(struct hidp_session *session, struct sk_buff *skb,
> +/* Returns true if the passed-in skb should be freed by the caller. */
> +static int hidp_process_data(struct hidp_session *session, struct sk_buff *skb,
>  				unsigned char param)
>  {
> +	int done_with_skb = 1;
>  	BT_DBG("session %p skb %p len %d param 0x%02x", session, skb, skb->len, param);
>  
>  	switch (param) {
> @@ -417,7 +511,6 @@ static void hidp_process_data(struct hidp_session *session, struct sk_buff *skb,
>  
>  		if (session->hid)
>  			hid_input_report(session->hid, HID_INPUT_REPORT, skb->data, skb->len, 0);
> -
>  		break;
>  
>  	case HIDP_DATA_RTYPE_OTHER:
> @@ -429,12 +522,27 @@ static void hidp_process_data(struct hidp_session *session, struct sk_buff *skb,
>  		__hidp_send_ctrl_message(session,
>  			HIDP_TRANS_HANDSHAKE | HIDP_HSHK_ERR_INVALID_PARAMETER, NULL, 0);
>  	}
> +
> +	if (test_bit(HIDP_WAITING_FOR_RETURN, &session->flags) &&
> +				param == session->waiting_report_type) {
> +		if (session->waiting_report_number < 0 ||
> +		    session->waiting_report_number == skb->data[0]) {
> +			/* hidp_get_raw_report() is waiting on this report. */
> +			session->report_return = skb;
> +			done_with_skb = 0;
> +			clear_bit(HIDP_WAITING_FOR_RETURN, &session->flags);
> +			wake_up_interruptible(&session->report_queue);
> +		}
> +	}
> +
> +	return done_with_skb;
>  }
>  
>  static void hidp_recv_ctrl_frame(struct hidp_session *session,
>  					struct sk_buff *skb)
>  {
>  	unsigned char hdr, type, param;
> +	int free_skb = 1;
>  
>  	BT_DBG("session %p skb %p len %d", session, skb, skb->len);
>  
> @@ -454,7 +562,7 @@ static void hidp_recv_ctrl_frame(struct hidp_session *session,
>  		break;
>  
>  	case HIDP_TRANS_DATA:
> -		hidp_process_data(session, skb, param);
> +		free_skb = hidp_process_data(session, skb, param);
>  		break;
>  
>  	default:
> @@ -463,7 +571,8 @@ static void hidp_recv_ctrl_frame(struct hidp_session *session,
>  		break;
>  	}
>  
> -	kfree_skb(skb);
> +	if (free_skb)
> +		kfree_skb(skb);
>  }
>  
>  static void hidp_recv_intr_frame(struct hidp_session *session,
> @@ -797,6 +906,7 @@ static int hidp_setup_hid(struct hidp_session *session,
>  	hid->dev.parent = hidp_get_device(session);
>  	hid->ll_driver = &hidp_hid_driver;
>  
> +	hid->hid_get_raw_report = hidp_get_raw_report;
>  	hid->hid_output_raw_report = hidp_output_raw_report;
>  
>  	err = hid_add_device(hid);
> @@ -857,6 +967,9 @@ int hidp_add_connection(struct hidp_connadd_req *req, struct socket *ctrl_sock,
>  	skb_queue_head_init(&session->ctrl_transmit);
>  	skb_queue_head_init(&session->intr_transmit);
>  
> +	mutex_init(&session->report_mutex);
> +	init_waitqueue_head(&session->report_queue);
> +
>  	session->flags   = req->flags & (1 << HIDP_BLUETOOTH_VENDOR_ID);
>  	session->idle_to = req->idle_to;
>  
> diff --git a/net/bluetooth/hidp/hidp.h b/net/bluetooth/hidp/hidp.h
> index 8d934a1..00e71dd 100644
> --- a/net/bluetooth/hidp/hidp.h
> +++ b/net/bluetooth/hidp/hidp.h
> @@ -80,6 +80,7 @@
>  #define HIDP_VIRTUAL_CABLE_UNPLUG	0
>  #define HIDP_BOOT_PROTOCOL_MODE		1
>  #define HIDP_BLUETOOTH_VENDOR_ID	9
> +#define	HIDP_WAITING_FOR_RETURN		10
>  
>  struct hidp_connadd_req {
>  	int   ctrl_sock;	// Connected control socket
> @@ -154,6 +155,13 @@ struct hidp_session {
>  	struct sk_buff_head ctrl_transmit;
>  	struct sk_buff_head intr_transmit;
>  
> +	/* Used in hidp_get_raw_report() */
> +	int waiting_report_type; /* HIDP_DATA_RTYPE_* */
> +	int waiting_report_number; /* -1 for not numbered */
> +	struct mutex report_mutex;
> +	struct sk_buff *report_return;
> +	wait_queue_head_t report_queue;
> +
>  	/* Report descriptor */
>  	__u8 *rd_data;
>  	uint rd_size;

I looked at this and I am bit worried that this should not be done in
this detail in the HIDP driver. Essentially HIDP is a pure transport
driver. It should not handle all these details. Can we make this a bit
easier for the transport drivers to support such features?

Regards

Marcel