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Convert USB documents to ReST, in order to prepare for adding it to the kernel API book, as most of the stuff there are driver or subsystem-related. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
134 lines
3.7 KiB
Plaintext
134 lines
3.7 KiB
Plaintext
==============================================
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ChipIdea Highspeed Dual Role Controller Driver
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==============================================
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1. How to test OTG FSM(HNP and SRP)
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-----------------------------------
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To show how to demo OTG HNP and SRP functions via sys input files
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with 2 Freescale i.MX6Q sabre SD boards.
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1.1 How to enable OTG FSM
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-------------------------
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1.1.1 Select CONFIG_USB_OTG_FSM in menuconfig, rebuild kernel
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Image and modules. If you want to check some internal
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variables for otg fsm, mount debugfs, there are 2 files
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which can show otg fsm variables and some controller registers value::
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cat /sys/kernel/debug/ci_hdrc.0/otg
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cat /sys/kernel/debug/ci_hdrc.0/registers
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1.1.2 Add below entries in your dts file for your controller node
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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::
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otg-rev = <0x0200>;
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adp-disable;
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1.2 Test operations
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-------------------
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1) Power up 2 Freescale i.MX6Q sabre SD boards with gadget class driver loaded
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(e.g. g_mass_storage).
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2) Connect 2 boards with usb cable with one end is micro A plug, the other end
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is micro B plug.
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The A-device(with micro A plug inserted) should enumerate B-device.
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3) Role switch
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On B-device::
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echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
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B-device should take host role and enumerate A-device.
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4) A-device switch back to host.
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On B-device::
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echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
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or, by introducing HNP polling, B-Host can know when A-peripheral wish
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to be host role, so this role switch also can be trigged in A-peripheral
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side by answering the polling from B-Host, this can be done on A-device::
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echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
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A-device should switch back to host and enumerate B-device.
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5) Remove B-device(unplug micro B plug) and insert again in 10 seconds,
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A-device should enumerate B-device again.
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6) Remove B-device(unplug micro B plug) and insert again after 10 seconds,
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A-device should NOT enumerate B-device.
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if A-device wants to use bus:
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On A-device::
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echo 0 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
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echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_req
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if B-device wants to use bus:
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On B-device::
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echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
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7) A-device power down the bus.
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On A-device::
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echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/a_bus_drop
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A-device should disconnect with B-device and power down the bus.
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8) B-device does data pulse for SRP.
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On B-device::
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echo 1 > /sys/bus/platform/devices/ci_hdrc.0/inputs/b_bus_req
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A-device should resume usb bus and enumerate B-device.
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1.3 Reference document
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----------------------
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"On-The-Go and Embedded Host Supplement to the USB Revision 2.0 Specification
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July 27, 2012 Revision 2.0 version 1.1a"
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2. How to enable USB as system wakeup source
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--------------------------------------------
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Below is the example for how to enable USB as system wakeup source
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at imx6 platform.
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2.1 Enable core's wakeup::
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echo enabled > /sys/bus/platform/devices/ci_hdrc.0/power/wakeup
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2.2 Enable glue layer's wakeup::
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echo enabled > /sys/bus/platform/devices/2184000.usb/power/wakeup
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2.3 Enable PHY's wakeup (optional)::
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echo enabled > /sys/bus/platform/devices/20c9000.usbphy/power/wakeup
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2.4 Enable roothub's wakeup::
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echo enabled > /sys/bus/usb/devices/usb1/power/wakeup
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2.5 Enable related device's wakeup::
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echo enabled > /sys/bus/usb/devices/1-1/power/wakeup
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If the system has only one usb port, and you want usb wakeup at this port, you
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can use below script to enable usb wakeup::
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for i in $(find /sys -name wakeup | grep usb);do echo enabled > $i;done;
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