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usb: common: add function to get interval expressed in us unit

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Add a new function to convert bInterval into the time expressed
in 1us unit.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/25c8a09b055f716c1e5bf11fea72c3418f844482.1615170625.git.chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Chunfeng Yun
2021-03-08 10:52:05 +08:00
committed by Greg Kroah-Hartman
parent 14295a1500
commit fb95c7cf56
4 changed files with 52 additions and 48 deletions
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41
drivers/usb/common/common.c
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@ -165,6 +165,47 @@ enum usb_dr_mode usb_get_dr_mode(struct device *dev)
}
EXPORT_SYMBOL_GPL(usb_get_dr_mode);
/**
* usb_decode_interval - Decode bInterval into the time expressed in 1us unit
* @epd: The descriptor of the endpoint
* @speed: The speed that the endpoint works as
*
* Function returns the interval expressed in 1us unit for servicing
* endpoint for data transfers.
*/
unsigned int usb_decode_interval(const struct usb_endpoint_descriptor *epd,
enum usb_device_speed speed)
{
unsigned int interval = 0;
switch (usb_endpoint_type(epd)) {
case USB_ENDPOINT_XFER_CONTROL:
/* uframes per NAK */
if (speed == USB_SPEED_HIGH)
interval = epd->bInterval;
break;
case USB_ENDPOINT_XFER_ISOC:
interval = 1 << (epd->bInterval - 1);
break;
case USB_ENDPOINT_XFER_BULK:
/* uframes per NAK */
if (speed == USB_SPEED_HIGH && usb_endpoint_dir_out(epd))
interval = epd->bInterval;
break;
case USB_ENDPOINT_XFER_INT:
if (speed >= USB_SPEED_HIGH)
interval = 1 << (epd->bInterval - 1);
else
interval = epd->bInterval;
break;
}
interval *= (speed >= USB_SPEED_HIGH) ? 125 : 1000;
return interval;
}
EXPORT_SYMBOL_GPL(usb_decode_interval);
#ifdef CONFIG_OF
/**
* of_usb_get_dr_mode_by_phy - Get dual role mode for the controller device