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- Introduction
- ============
- Gadget serial driver is divided into two parts.
- 1. f_serial.c : Interacts with USB Gadget Layer
- 2. u_serial.c : Interacts with TTY Layer
- Gadget sdio driver adds capability to interact with SDIO Layer in
- case modem device is inter-connected with sdio interface.
- S/W Description
- ===============
- Gadget SDIO driver is a simple bridge driver between usb serial
- gadget and sdio abstraction layer. It registers with sdio
- abstraction layer with read/write call backs and provides
- USB connect/disconnect call backs usb gadget serial driver.
- S/W Control Flow:
- =================
- Driver maintains two sdio channels, one for data and one for control.
- Data pipe is dedicated sdio channel where as control is a muxed channel.
- Incase of sdio control pipe, driver registers for control information
- chagnes from modem side. Whenever new information is available, it
- would queue a interrupt endpoint w/ new info. Laptop can also send the
- DTR and RTS information as part of SET Encapsulated command.
- Data pipe of sdio channel also has notification mechanism to indicate
- the READ/WRITE availability. When READ is available on SDIO pipe,
- driver would read the data and hands it over to USB In ept and when
- it receives the data from USB driver would queue the same to SDIO
- channel(if write buffers are available).
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