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phy: rcar-gen3-usb2: add sysfs for usb role swap

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This patch adds sysfs "role" for usb role swap. This parameter can be
read and write. If you use this file as the following, you can swap
the usb role.

For example:
 1) Connect a usb cable using 2 Salvator-x boards
 2) On A-Device (ID pin is low), you input the following command:
   # echo peripheral > /sys/devices/platform/soc/ee080200.usb-phy/role
 3) On B-Device (ID pin is high), you input the following command:
   # echo host > /sys/devices/platform/soc/ee080200.usb-phy/role

Then, the A-device acts as a peripheral and the B-device acts as a host.
Please note that A-Device must input the following command if you
want the board to act as a host again. (even if you disconnect the usb
cable, since id state may be the same, the A-Device keeps to act as
peripheral.)
 # echo host > /sys/devices/platform/soc/ee080200.usb-phy/role

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
This commit is contained in:
Yoshihiro Shimoda
2016-11-09 11:30:25 +09:00
committed by Kishon Vijay Abraham I
parent 23e9b38d8e
commit 9bb86777fb
2 changed files with 132 additions and 1 deletions
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Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb2 Normal file
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What: /sys/devices/platform/<phy-name>/role
Date: October 2016
KernelVersion: 4.10
Contact: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Description:
This file can be read and write.
The file can show/change the phy mode for role swap of usb.
Write the following strings to change the mode:
"host" - switching mode from peripheral to host.
"peripheral" - switching mode from host to peripheral.
Read the file, then it shows the following strings:
"host" - The mode is host now.
"peripheral" - The mode is peripheral now.