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