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    Subject[PATCH 1/3] usb: misc: Add a driver for TC7USB40MU
    Date
    On the db410c 96boards platform we have a TC7USB40MU[1] on the
    board to mux the D+/D- lines from the SoC between a micro usb
    "device" port and a USB hub for "host" roles. Upon a role switch,
    we need to change this mux to forward the D+/D- lines to either
    the port or the hub. Introduce a driver for this device that
    hooks into the generic mux framework logically asserts a gpio to
    mux the D+/D- lines to the 2D+/2D- output when the state is set
    to "1". Similary, deassert the gpio and mux the D+/D- lines to
    the 1D+/1D- output when the state is set to "0".

    [1] https://toshiba.semicon-storage.com/ap-en/product/logic/bus-switch/detail.TC7USB40MU.html

    Cc: Peter Rosin <peda@axentia.se>
    Cc: Peter Chen <peter.chen@nxp.com>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: <devicetree@vger.kernel.org>
    Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
    ---

    We may be able to ignore this patch and just use mux-gpio.c file. I'll
    investigate that approach but I'd like to keep the compatible string
    in case we need to do something later.

    .../devicetree/bindings/usb/toshiba,tc7usb40mu.txt | 31 +++++++++
    drivers/usb/misc/Kconfig | 11 ++++
    drivers/usb/misc/Makefile | 1 +
    drivers/usb/misc/tc7usb40mu.c | 74 ++++++++++++++++++++++
    4 files changed, 117 insertions(+)
    create mode 100644 Documentation/devicetree/bindings/usb/toshiba,tc7usb40mu.txt
    create mode 100644 drivers/usb/misc/tc7usb40mu.c

    diff --git a/Documentation/devicetree/bindings/usb/toshiba,tc7usb40mu.txt b/Documentation/devicetree/bindings/usb/toshiba,tc7usb40mu.txt
    new file mode 100644
    index 000000000000..5c6b2b39825f
    --- /dev/null
    +++ b/Documentation/devicetree/bindings/usb/toshiba,tc7usb40mu.txt
    @@ -0,0 +1,31 @@
    +Toshiba TC7USB40MU
    +
    +This device muxes USB D+/D- lines between two outputs called 1D+/1D- and
    +2D+/2D-. When the switch pin is asserted, the device muxes out 2D+/2D-, and
    +when it's deasserted it muxes out 1D+/1D-.
    +
    +This can be used to mux USB D+/D- lines between a USB hub and a micro-USB port
    +to provide host mode and device modes with the same USB controller.
    +
    +PROPERTIES
    +
    +- compatible:
    + Usage: required
    + Value type: <string>
    + Definition: Should contain "toshiba,tc7usb40mu"
    +
    +- mux-gpios:
    + Usage: required
    + Value type: <prop-encoded-array>
    + Definition: Should contain the gpio used to toggle the switch. Logically
    + asserting the gpio will cause the device to mux the 2D+/2D-
    + lines and deasserting the gpio will cause the device to mux
    + the 1D+/1D- lines.
    +
    +Example:
    +
    + usb-switch {
    + compatible = "toshiba,tc7usb40mu";
    + mux-gpios = <&gpio 10 GPIO_ACTIVE_HIGH>;
    + #mux-control-cells = <0>;
    + };
    diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
    index 0f9f25db9163..df44c9d16eb1 100644
    --- a/drivers/usb/misc/Kconfig
    +++ b/drivers/usb/misc/Kconfig
    @@ -46,6 +46,17 @@ config USB_SEVSEG
    To compile this driver as a module, choose M here: the
    module will be called usbsevseg.

    +config USB_TC7USB40MU
    + tristate "TC7USB40MU USB mux support"
    + depends on (GPIOLIB && MULTIPLEXER) || COMPILE_TEST
    + help
    + Say Y here if you have a TC7USB40MU by Toshiba. A USB controller
    + driver can then use the mux controller provided by this driver to
    + route the D+/D- lines to two different devices downstream. For
    + example, one downstream device could be a micro-USB port, and the
    + other could be a USB hub, allowing a device to provide either
    + device or host mode via a single USB controller.
    +
    config USB_RIO500
    tristate "USB Diamond Rio500 support"
    help
    diff --git a/drivers/usb/misc/Makefile b/drivers/usb/misc/Makefile
    index 7fdb45fc976f..42268fcb8a60 100644
    --- a/drivers/usb/misc/Makefile
    +++ b/drivers/usb/misc/Makefile
    @@ -19,6 +19,7 @@ obj-$(CONFIG_USB_LEGOTOWER) += legousbtower.o
    obj-$(CONFIG_USB_RIO500) += rio500.o
    obj-$(CONFIG_USB_TEST) += usbtest.o
    obj-$(CONFIG_USB_EHSET_TEST_FIXTURE) += ehset.o
    +obj-$(CONFIG_USB_TC7USB40MU) += tc7usb40mu.o
    obj-$(CONFIG_USB_TRANCEVIBRATOR) += trancevibrator.o
    obj-$(CONFIG_USB_USS720) += uss720.o
    obj-$(CONFIG_USB_SEVSEG) += usbsevseg.o
    diff --git a/drivers/usb/misc/tc7usb40mu.c b/drivers/usb/misc/tc7usb40mu.c
    new file mode 100644
    index 000000000000..fbccd2fc0030
    --- /dev/null
    +++ b/drivers/usb/misc/tc7usb40mu.c
    @@ -0,0 +1,74 @@
    +/**
    + * Copyright (C) 2016-2017 Linaro Ltd.
    + *
    + * This program is free software; you can redistribute it and/or modify
    + * it under the terms of the GNU General Public License version 2 as
    + * published by the Free Software Foundation.
    + *
    + * This program is distributed in the hope that it will be useful,
    + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    + * GNU General Public License for more details.
    + */
    +
    +#include <linux/platform_device.h>
    +#include <linux/module.h>
    +#include <linux/gpio/consumer.h>
    +#include <linux/mux/driver.h>
    +
    +struct tc7usb40mu_drv {
    + struct gpio_desc *gpio;
    +};
    +
    +static int tc7usb40mu_mux_set(struct mux_control *mux, int state)
    +{
    + struct tc7usb40mu_drv *drv = mux_chip_priv(mux->chip);
    +
    + gpiod_set_value_cansleep(drv->gpio, state);
    +
    + return 0;
    +}
    +
    +static const struct mux_control_ops tc7usb40mu_mux_ops = {
    + .set = tc7usb40mu_mux_set,
    +};
    +
    +static int tc7usb40mu_probe(struct platform_device *pdev)
    +{
    + struct device *dev = &pdev->dev;
    + struct tc7usb40mu_drv *drv;
    + struct mux_chip *mux_chip;
    +
    + mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*drv));
    + if (!mux_chip)
    + return -ENOMEM;
    +
    + mux_chip->ops = &tc7usb40mu_mux_ops;
    + mux_chip->mux->states = 2; /* 1D+/1D- and 2D+/2D- */
    +
    + drv = mux_chip_priv(mux_chip);
    + drv->gpio = devm_gpiod_get(dev, "mux", GPIOD_ASIS);
    + if (IS_ERR(drv->gpio))
    + return PTR_ERR(drv->gpio);
    +
    + return devm_mux_chip_register(dev, mux_chip);
    +}
    +
    +static const struct of_device_id tc7usb40mu_dt_match[] = {
    + { .compatible = "toshiba,tc7usb40mu", },
    + { }
    +};
    +MODULE_DEVICE_TABLE(of, tc7usb40mu_dt_match);
    +
    +static struct platform_driver tc7usb40mu_driver = {
    + .probe = tc7usb40mu_probe,
    + .driver = {
    + .name = "tc7usb40mu",
    + .of_match_table = tc7usb40mu_dt_match,
    + },
    +};
    +module_platform_driver(tc7usb40mu_driver);
    +
    +MODULE_AUTHOR("Stephen Boyd <stephen.boyd@linaro.org>");
    +MODULE_DESCRIPTION("TC7USB40MU USB multiplexer driver");
    +MODULE_LICENSE("GPL");
    --
    2.10.0.297.gf6727b0
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