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- Introduction
- --------------
- ksbridge is a simple misc device which bridges Kickstart application
- to HSIC h/w. Driver supports two instances, one instance for
- flash-less-boot/ram-dumps and other instance for EFS Sync.
- Initialization
- --------------
- Create two bridge instances and register for usb devices 0x9008 and
- 0x9048/0x904C. Misc device name depends on the USB PID.
- For PID: 9008, misc device name is ks_bridge and for PID:9048/904C,
- misc device name is efs_bridge. After KS opens the misc device, IN
- URBs will be submitted to H/W; By default IN URBS are configured
- to 20.
- TX PATH
- -------
- Transmit path is very simple. Bridge driver will exposes write system
- call to kickstart. Data from write call will be put into a list and a
- work is scheduled to take the data from the list and write to HSIC.
- Functions:
- ksb_fs_write: System call invoked when kickstart writes the data
- ksb_tomdm_work: Work function which submits data to HSIC h/w.
- Data Structures:
- to_mdm_list: Data is stored in this list
- to_mdm_work: mapped to ksb_tomdm_work function
- RX PATH
- -------
- During initialization 20 IN URBs are submitted to hsic controller. In
- completion handler of each URB, buffer is de-queued and add to a list.
- Read function is woken-up. A new buffer is created and submitted to
- controller.
- Functions:
- ksb_fs_read: system call invoked by ks when it tries to read the data
- ksb_rx_cb: rx urb completion handler
- ksb_start_rx_work: function called during initialization.
- Data Structures:
- ks_wait_q: read system call will block on this queue until data is
- available or device is disconnected
- to_ks_list: data queued to this list by rx urb completion handler,
- later de-queued by read system call.
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